1

CSCD 433Network ProgrammingFall 2011

Lecture 6Ethernet Evolution and Performance

Topics

bull Ethernet Revisitedbull Faster and Faster Ethernetbull Up to 10 Gigabit and beyond

2

Ethernet Performance

bull Ethernet was designed by Bob _________ in 1973 at the Xerox Company in Palo Alto CA

bull Since the 1970s Ethernet has become fasterbull Why

Ethernet

1 Changes in physical medium Coaxial UTP cables Fiber optic

2 Improved media access control methods CSMA to CSMACD to none needed

3 Improved signal encoding methods Manchester encoding to 4B5B 8B10B and more

4 Cables to hubs to switches

5 Mandating Full Duplex

Ethernet Speedup

History of Ethernet

7

An Introduction of Ethernet

bull The History of Ethernet Technology

ndash 1973 Metcalfe developed Ethernet at Palo Alto

ndash 1980 Digital Intel and Xerox developed the standard of 10Mpbs Ethernet

ndash 1992 the Grand Junction Network Company brought up the structure of 100Mbps Ethernet

ndash 1998 addressed the standard of Gigabit Ethernet

ndash 2002 10 Gigabit standard httpwwwtrendcommscommultimediatrainingbroadband

20networkswebmainethernetthemechapter1EnetIntroductionhtml

Classical or Standard Ethernet

9

Categories of Standard Ethernet

Ethernet Recap

bull Classic Ethernet bull One long cable 500 meter max segmentbull Snaked around building as single long cablebull All computers attached

bull Thick Ethernetbull Began as thick yellow cable marked every

25 meters to show computer attachments

bull Thin Ethernetbull Thinner bent more easily connections with

BNC connectorsbull Cheaper to install 185 meter max segment

11

10Base5 implementation

Ethernet segment length

12

10Base2 Implementation

Ethernet segment length

13

bull Coaxial cable has single copper conductor at its center

bull A plastic layer provides insulation between center conductor and a braided metal shield

bull Metal shield helps to block any outside interference from fluorescent lights motors and other computers

bull Resistant to signal interference and can support greater cable lengths between network devices than twisted pair cable

bull Only half-duplex is possible with coaxial cable

EfficiencyCoaxial Cable

A outer plastic sheathB woven copper shieldC inner dielectric insulatorD copper core

14

10Base-T implementation

UTP = Unshielded Twisted Pair

15

Efficiency Twisted Pairbull Twisted pair cabling comes in two varieties

Shielded and Unshielded Unshielded twisted pair (UTP) is the most popular bull Cable has four pairs of wires inside jacketbull Each pair twisted with different number of

twists per inchbull Eliminate interference from adjacent pairs

and other electrical devicesbull Tighter twisting higher supported

transmission rate and greater cost per footbull Most important

bull Two connections for each host Full duplex is now possible

2 Pairs of Wires in a UTP Cable Are Always Used

No matter whether the device is a hub or a switch 2 pairs of wires in a UTP cable are always used to connect a host to the device

2 pairs

12- 16

17

Efficiency Twisted Pair

Category Speed Use

1 1 Mbps Voice Only (Telephone Wire)

2 4 Mbps LocalTalk amp Telephone (Rarely used)

3 16 Mbps 10BaseT Ethernet

4 20 Mbps Token Ring (Rarely used)

5 100 Mbps (2 pair) 100BaseT Ethernet

1000 Mbps (4 pair) Gigabit Ethernet

5e 1000 Mbps Gigabit Ethernet

6 10000 Mbps Gigabit Ethernet

18

Ethernet CablingThe most common kinds of Ethernet cabling

Three kinds of Ethernet cabling

(a) 10Base5 (b) 10Base2 (c) 10Base-T

Difference in Segment length

Costs Less

Ethernet Recap

bull Used Manchester encoding bull More later

bull Ethernet could contain multiple segments and multiple repeaters

bull Used CSMACD for shared media bull What does CSMACD stand for

Carrier Sense Multiple AccessCollision Detection

bull Review this

20

CSMACD Protocol

All hosts transmit amp receive on one channelPackets are of variable size

When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before

transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random

time then return to step 1 binary exponential backoff

21

Ethernet CSMACD algorithm

Algorithm1 NIC receives datagram from network

layer creates frame

2 If NIC senses channel idle starts frame transmission

If NIC senses channel busy waits until channel idle then transmits

3 If NIC transmits entire frame without detecting another transmission NIC is done with frame

Ethernet CSMACD algorithm

4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time

bull Returns to Step 2

22

Minimum Frame Size

bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)

bull Consequently small frames must be padded out to reach MFS

bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)

bull Ethernet and Fast Ethernet the MFS is 64 bytes

bull Gigabit Ethernet it is 416 or 520 bytes

bull Full duplex versions of Ethernet

bull Collisions are avoided and so MFS does not apply

Ethernet Performancebull One result of sharingldquoEtherrdquo

bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance

bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60

percent of the expected value of 10 Mbpsbull How would you increase performance

bull Fewer Collisions reduce the collision domain

Fast Ethernet

Fast Ethernet 8023u

bull When switches became popular bull 10 Mbps Ethernet was standard back in

1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE

Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u

bull Not really New - Kept everything the same

bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science

Fast Ethernetbull Primary concern of Fast Ethernet developers

bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate

bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional

Ethernet installationsbull One version of the Fast Ethernet standard

runs on older Category 3 cable installations

Fast Ethernet

bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps

could coexist

bull How bull A Fast Ethernet-compatible hub does speed

matching when exchanging framesbull Has auto-negotiate feature

bull Devices detect speed of incoming transmissions and adjust appropriately

29

IEEE 8023u - Fast Ethernet

bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard

bull Transmission rate is 100 Mbps

bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)

bull Uses category 3 and category 5 UTP STP and fibre cables

Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5

data-grade twisted-pair wire max distance 100 meters between hub and workstation

bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation

bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration

bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics

Fiber Optic Cablingbull Fiber optic cabling consists of center glass

core surrounded by layers of

protective materials bull Fiber optic cable transmits signals over longer

distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater

speedsbull Center core of fiber cables is made from glass or

plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage

bull Outer insulating jacket made of teflon or PVC

Fiber Optic Cabling

bull Two types of fiber cables

bull Single mode

bull Multimode

bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation

bull Both cables provide high bandwidth at high speeds

bull Single mode can provide more distance but it is more expensive

Fast Ethernetbull Higher frequency used in Fast Ethernet

standard is prone to attenuation

bull Cable distance is more limited than in old Ethernet 10Base-T

bull If encoding scheme of traditional Ethernet were used with Fast Ethernet

bull High-end frequency would be above 200 Mhz

bull Double maximum frequency rating of Category 5 cable

bull New encoding schemes were implemented to allow higher-frequency transmissions

Encoding Schemes for Ethernet

bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by

physical layer

bull Recall Manchester encoding

bull 0 is indicated by a 0 to 1 transition at center of bit

bull 1 is indicated by a 1 to 0 transition at center of bit

bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit

bull Manchester Encodingbull Up transition = 1

bull Down transition = 0

Manchester EncodingStandard Ethernet

Manchester EncodingStandard Ethernet

bull Drawbackbull Manchester encoding can consume up to

approximately twice bandwidth of original signal (20 MHz)

bull Penalty for introducing frequent transitions

bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz

bull Additional bandwidth is not significant issue for coaxial cable transmission but

bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method

Fast Ethernet Encoding

bull 4B5B encoding is a type of Block coding

bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)

bull Group of 4 bits encoded so that an extra 5th bit is added

bull 4B5B encoding (Frame Encoding ndash shorthand)

bull All data is encoded prior to transmission

bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)

bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur

bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used

bull Multi-Level Transmit-3 levels

bull No transition = 0

bull Any transition (up or down) = 1

bull Reduces frequency of signal

Fast Ethernet Encoding

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

Topics

bull Ethernet Revisitedbull Faster and Faster Ethernetbull Up to 10 Gigabit and beyond

2

Ethernet Performance

bull Ethernet was designed by Bob _________ in 1973 at the Xerox Company in Palo Alto CA

bull Since the 1970s Ethernet has become fasterbull Why

Ethernet

1 Changes in physical medium Coaxial UTP cables Fiber optic

2 Improved media access control methods CSMA to CSMACD to none needed

3 Improved signal encoding methods Manchester encoding to 4B5B 8B10B and more

4 Cables to hubs to switches

5 Mandating Full Duplex

Ethernet Speedup

History of Ethernet

7

An Introduction of Ethernet

bull The History of Ethernet Technology

ndash 1973 Metcalfe developed Ethernet at Palo Alto

ndash 1980 Digital Intel and Xerox developed the standard of 10Mpbs Ethernet

ndash 1992 the Grand Junction Network Company brought up the structure of 100Mbps Ethernet

ndash 1998 addressed the standard of Gigabit Ethernet

ndash 2002 10 Gigabit standard httpwwwtrendcommscommultimediatrainingbroadband

20networkswebmainethernetthemechapter1EnetIntroductionhtml

Classical or Standard Ethernet

9

Categories of Standard Ethernet

Ethernet Recap

bull Classic Ethernet bull One long cable 500 meter max segmentbull Snaked around building as single long cablebull All computers attached

bull Thick Ethernetbull Began as thick yellow cable marked every

25 meters to show computer attachments

bull Thin Ethernetbull Thinner bent more easily connections with

BNC connectorsbull Cheaper to install 185 meter max segment

11

10Base5 implementation

Ethernet segment length

12

10Base2 Implementation

Ethernet segment length

13

bull Coaxial cable has single copper conductor at its center

bull A plastic layer provides insulation between center conductor and a braided metal shield

bull Metal shield helps to block any outside interference from fluorescent lights motors and other computers

bull Resistant to signal interference and can support greater cable lengths between network devices than twisted pair cable

bull Only half-duplex is possible with coaxial cable

EfficiencyCoaxial Cable

A outer plastic sheathB woven copper shieldC inner dielectric insulatorD copper core

14

10Base-T implementation

UTP = Unshielded Twisted Pair

15

Efficiency Twisted Pairbull Twisted pair cabling comes in two varieties

Shielded and Unshielded Unshielded twisted pair (UTP) is the most popular bull Cable has four pairs of wires inside jacketbull Each pair twisted with different number of

twists per inchbull Eliminate interference from adjacent pairs

and other electrical devicesbull Tighter twisting higher supported

transmission rate and greater cost per footbull Most important

bull Two connections for each host Full duplex is now possible

2 Pairs of Wires in a UTP Cable Are Always Used

No matter whether the device is a hub or a switch 2 pairs of wires in a UTP cable are always used to connect a host to the device

2 pairs

12- 16

17

Efficiency Twisted Pair

Category Speed Use

1 1 Mbps Voice Only (Telephone Wire)

2 4 Mbps LocalTalk amp Telephone (Rarely used)

3 16 Mbps 10BaseT Ethernet

4 20 Mbps Token Ring (Rarely used)

5 100 Mbps (2 pair) 100BaseT Ethernet

1000 Mbps (4 pair) Gigabit Ethernet

5e 1000 Mbps Gigabit Ethernet

6 10000 Mbps Gigabit Ethernet

18

Ethernet CablingThe most common kinds of Ethernet cabling

Three kinds of Ethernet cabling

(a) 10Base5 (b) 10Base2 (c) 10Base-T

Difference in Segment length

Costs Less

Ethernet Recap

bull Used Manchester encoding bull More later

bull Ethernet could contain multiple segments and multiple repeaters

bull Used CSMACD for shared media bull What does CSMACD stand for

Carrier Sense Multiple AccessCollision Detection

bull Review this

20

CSMACD Protocol

All hosts transmit amp receive on one channelPackets are of variable size

When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before

transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random

time then return to step 1 binary exponential backoff

21

Ethernet CSMACD algorithm

Algorithm1 NIC receives datagram from network

layer creates frame

2 If NIC senses channel idle starts frame transmission

If NIC senses channel busy waits until channel idle then transmits

3 If NIC transmits entire frame without detecting another transmission NIC is done with frame

Ethernet CSMACD algorithm

4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time

bull Returns to Step 2

22

Minimum Frame Size

bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)

bull Consequently small frames must be padded out to reach MFS

bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)

bull Ethernet and Fast Ethernet the MFS is 64 bytes

bull Gigabit Ethernet it is 416 or 520 bytes

bull Full duplex versions of Ethernet

bull Collisions are avoided and so MFS does not apply

Ethernet Performancebull One result of sharingldquoEtherrdquo

bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance

bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60

percent of the expected value of 10 Mbpsbull How would you increase performance

bull Fewer Collisions reduce the collision domain

Fast Ethernet

Fast Ethernet 8023u

bull When switches became popular bull 10 Mbps Ethernet was standard back in

1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE

Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u

bull Not really New - Kept everything the same

bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science

Fast Ethernetbull Primary concern of Fast Ethernet developers

bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate

bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional

Ethernet installationsbull One version of the Fast Ethernet standard

runs on older Category 3 cable installations

Fast Ethernet

bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps

could coexist

bull How bull A Fast Ethernet-compatible hub does speed

matching when exchanging framesbull Has auto-negotiate feature

bull Devices detect speed of incoming transmissions and adjust appropriately

29

IEEE 8023u - Fast Ethernet

bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard

bull Transmission rate is 100 Mbps

bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)

bull Uses category 3 and category 5 UTP STP and fibre cables

Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5

data-grade twisted-pair wire max distance 100 meters between hub and workstation

bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation

bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration

bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics

Fiber Optic Cablingbull Fiber optic cabling consists of center glass

core surrounded by layers of

protective materials bull Fiber optic cable transmits signals over longer

distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater

speedsbull Center core of fiber cables is made from glass or

plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage

bull Outer insulating jacket made of teflon or PVC

Fiber Optic Cabling

bull Two types of fiber cables

bull Single mode

bull Multimode

bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation

bull Both cables provide high bandwidth at high speeds

bull Single mode can provide more distance but it is more expensive

Fast Ethernetbull Higher frequency used in Fast Ethernet

standard is prone to attenuation

bull Cable distance is more limited than in old Ethernet 10Base-T

bull If encoding scheme of traditional Ethernet were used with Fast Ethernet

bull High-end frequency would be above 200 Mhz

bull Double maximum frequency rating of Category 5 cable

bull New encoding schemes were implemented to allow higher-frequency transmissions

Encoding Schemes for Ethernet

bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by

physical layer

bull Recall Manchester encoding

bull 0 is indicated by a 0 to 1 transition at center of bit

bull 1 is indicated by a 1 to 0 transition at center of bit

bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit

bull Manchester Encodingbull Up transition = 1

bull Down transition = 0

Manchester EncodingStandard Ethernet

Manchester EncodingStandard Ethernet

bull Drawbackbull Manchester encoding can consume up to

approximately twice bandwidth of original signal (20 MHz)

bull Penalty for introducing frequent transitions

bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz

bull Additional bandwidth is not significant issue for coaxial cable transmission but

bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method

Fast Ethernet Encoding

bull 4B5B encoding is a type of Block coding

bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)

bull Group of 4 bits encoded so that an extra 5th bit is added

bull 4B5B encoding (Frame Encoding ndash shorthand)

bull All data is encoded prior to transmission

bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)

bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur

bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used

bull Multi-Level Transmit-3 levels

bull No transition = 0

bull Any transition (up or down) = 1

bull Reduces frequency of signal

Fast Ethernet Encoding

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

Ethernet Performance

bull Ethernet was designed by Bob _________ in 1973 at the Xerox Company in Palo Alto CA

bull Since the 1970s Ethernet has become fasterbull Why

Ethernet

1 Changes in physical medium Coaxial UTP cables Fiber optic

2 Improved media access control methods CSMA to CSMACD to none needed

3 Improved signal encoding methods Manchester encoding to 4B5B 8B10B and more

4 Cables to hubs to switches

5 Mandating Full Duplex

Ethernet Speedup

History of Ethernet

7

An Introduction of Ethernet

bull The History of Ethernet Technology

ndash 1973 Metcalfe developed Ethernet at Palo Alto

ndash 1980 Digital Intel and Xerox developed the standard of 10Mpbs Ethernet

ndash 1992 the Grand Junction Network Company brought up the structure of 100Mbps Ethernet

ndash 1998 addressed the standard of Gigabit Ethernet

ndash 2002 10 Gigabit standard httpwwwtrendcommscommultimediatrainingbroadband

20networkswebmainethernetthemechapter1EnetIntroductionhtml

Classical or Standard Ethernet

9

Categories of Standard Ethernet

Ethernet Recap

bull Classic Ethernet bull One long cable 500 meter max segmentbull Snaked around building as single long cablebull All computers attached

bull Thick Ethernetbull Began as thick yellow cable marked every

25 meters to show computer attachments

bull Thin Ethernetbull Thinner bent more easily connections with

BNC connectorsbull Cheaper to install 185 meter max segment

11

10Base5 implementation

Ethernet segment length

12

10Base2 Implementation

Ethernet segment length

13

bull Coaxial cable has single copper conductor at its center

bull A plastic layer provides insulation between center conductor and a braided metal shield

bull Metal shield helps to block any outside interference from fluorescent lights motors and other computers

bull Resistant to signal interference and can support greater cable lengths between network devices than twisted pair cable

bull Only half-duplex is possible with coaxial cable

EfficiencyCoaxial Cable

A outer plastic sheathB woven copper shieldC inner dielectric insulatorD copper core

14

10Base-T implementation

UTP = Unshielded Twisted Pair

15

Efficiency Twisted Pairbull Twisted pair cabling comes in two varieties

Shielded and Unshielded Unshielded twisted pair (UTP) is the most popular bull Cable has four pairs of wires inside jacketbull Each pair twisted with different number of

twists per inchbull Eliminate interference from adjacent pairs

and other electrical devicesbull Tighter twisting higher supported

transmission rate and greater cost per footbull Most important

bull Two connections for each host Full duplex is now possible

2 Pairs of Wires in a UTP Cable Are Always Used

No matter whether the device is a hub or a switch 2 pairs of wires in a UTP cable are always used to connect a host to the device

2 pairs

12- 16

17

Efficiency Twisted Pair

Category Speed Use

1 1 Mbps Voice Only (Telephone Wire)

2 4 Mbps LocalTalk amp Telephone (Rarely used)

3 16 Mbps 10BaseT Ethernet

4 20 Mbps Token Ring (Rarely used)

5 100 Mbps (2 pair) 100BaseT Ethernet

1000 Mbps (4 pair) Gigabit Ethernet

5e 1000 Mbps Gigabit Ethernet

6 10000 Mbps Gigabit Ethernet

18

Ethernet CablingThe most common kinds of Ethernet cabling

Three kinds of Ethernet cabling

(a) 10Base5 (b) 10Base2 (c) 10Base-T

Difference in Segment length

Costs Less

Ethernet Recap

bull Used Manchester encoding bull More later

bull Ethernet could contain multiple segments and multiple repeaters

bull Used CSMACD for shared media bull What does CSMACD stand for

Carrier Sense Multiple AccessCollision Detection

bull Review this

20

CSMACD Protocol

All hosts transmit amp receive on one channelPackets are of variable size

When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before

transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random

time then return to step 1 binary exponential backoff

21

Ethernet CSMACD algorithm

Algorithm1 NIC receives datagram from network

layer creates frame

2 If NIC senses channel idle starts frame transmission

If NIC senses channel busy waits until channel idle then transmits

3 If NIC transmits entire frame without detecting another transmission NIC is done with frame

Ethernet CSMACD algorithm

4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time

bull Returns to Step 2

22

Minimum Frame Size

bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)

bull Consequently small frames must be padded out to reach MFS

bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)

bull Ethernet and Fast Ethernet the MFS is 64 bytes

bull Gigabit Ethernet it is 416 or 520 bytes

bull Full duplex versions of Ethernet

bull Collisions are avoided and so MFS does not apply

Ethernet Performancebull One result of sharingldquoEtherrdquo

bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance

bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60

percent of the expected value of 10 Mbpsbull How would you increase performance

bull Fewer Collisions reduce the collision domain

Fast Ethernet

Fast Ethernet 8023u

bull When switches became popular bull 10 Mbps Ethernet was standard back in

1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE

Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u

bull Not really New - Kept everything the same

bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science

Fast Ethernetbull Primary concern of Fast Ethernet developers

bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate

bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional

Ethernet installationsbull One version of the Fast Ethernet standard

runs on older Category 3 cable installations

Fast Ethernet

bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps

could coexist

bull How bull A Fast Ethernet-compatible hub does speed

matching when exchanging framesbull Has auto-negotiate feature

bull Devices detect speed of incoming transmissions and adjust appropriately

29

IEEE 8023u - Fast Ethernet

bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard

bull Transmission rate is 100 Mbps

bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)

bull Uses category 3 and category 5 UTP STP and fibre cables

Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5

data-grade twisted-pair wire max distance 100 meters between hub and workstation

bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation

bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration

bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics

Fiber Optic Cablingbull Fiber optic cabling consists of center glass

core surrounded by layers of

protective materials bull Fiber optic cable transmits signals over longer

distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater

speedsbull Center core of fiber cables is made from glass or

plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage

bull Outer insulating jacket made of teflon or PVC

Fiber Optic Cabling

bull Two types of fiber cables

bull Single mode

bull Multimode

bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation

bull Both cables provide high bandwidth at high speeds

bull Single mode can provide more distance but it is more expensive

Fast Ethernetbull Higher frequency used in Fast Ethernet

standard is prone to attenuation

bull Cable distance is more limited than in old Ethernet 10Base-T

bull If encoding scheme of traditional Ethernet were used with Fast Ethernet

bull High-end frequency would be above 200 Mhz

bull Double maximum frequency rating of Category 5 cable

bull New encoding schemes were implemented to allow higher-frequency transmissions

Encoding Schemes for Ethernet

bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by

physical layer

bull Recall Manchester encoding

bull 0 is indicated by a 0 to 1 transition at center of bit

bull 1 is indicated by a 1 to 0 transition at center of bit

bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit

bull Manchester Encodingbull Up transition = 1

bull Down transition = 0

Manchester EncodingStandard Ethernet

Manchester EncodingStandard Ethernet

bull Drawbackbull Manchester encoding can consume up to

approximately twice bandwidth of original signal (20 MHz)

bull Penalty for introducing frequent transitions

bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz

bull Additional bandwidth is not significant issue for coaxial cable transmission but

bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method

Fast Ethernet Encoding

bull 4B5B encoding is a type of Block coding

bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)

bull Group of 4 bits encoded so that an extra 5th bit is added

bull 4B5B encoding (Frame Encoding ndash shorthand)

bull All data is encoded prior to transmission

bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)

bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur

bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used

bull Multi-Level Transmit-3 levels

bull No transition = 0

bull Any transition (up or down) = 1

bull Reduces frequency of signal

Fast Ethernet Encoding

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

bull Ethernet was designed by Bob _________ in 1973 at the Xerox Company in Palo Alto CA

bull Since the 1970s Ethernet has become fasterbull Why

Ethernet

1 Changes in physical medium Coaxial UTP cables Fiber optic

2 Improved media access control methods CSMA to CSMACD to none needed

3 Improved signal encoding methods Manchester encoding to 4B5B 8B10B and more

4 Cables to hubs to switches

5 Mandating Full Duplex

Ethernet Speedup

History of Ethernet

7

An Introduction of Ethernet

bull The History of Ethernet Technology

ndash 1973 Metcalfe developed Ethernet at Palo Alto

ndash 1980 Digital Intel and Xerox developed the standard of 10Mpbs Ethernet

ndash 1992 the Grand Junction Network Company brought up the structure of 100Mbps Ethernet

ndash 1998 addressed the standard of Gigabit Ethernet

ndash 2002 10 Gigabit standard httpwwwtrendcommscommultimediatrainingbroadband

20networkswebmainethernetthemechapter1EnetIntroductionhtml

Classical or Standard Ethernet

9

Categories of Standard Ethernet

Ethernet Recap

bull Classic Ethernet bull One long cable 500 meter max segmentbull Snaked around building as single long cablebull All computers attached

bull Thick Ethernetbull Began as thick yellow cable marked every

25 meters to show computer attachments

bull Thin Ethernetbull Thinner bent more easily connections with

BNC connectorsbull Cheaper to install 185 meter max segment

11

10Base5 implementation

Ethernet segment length

12

10Base2 Implementation

Ethernet segment length

13

bull Coaxial cable has single copper conductor at its center

bull A plastic layer provides insulation between center conductor and a braided metal shield

bull Metal shield helps to block any outside interference from fluorescent lights motors and other computers

bull Resistant to signal interference and can support greater cable lengths between network devices than twisted pair cable

bull Only half-duplex is possible with coaxial cable

EfficiencyCoaxial Cable

A outer plastic sheathB woven copper shieldC inner dielectric insulatorD copper core

14

10Base-T implementation

UTP = Unshielded Twisted Pair

15

Efficiency Twisted Pairbull Twisted pair cabling comes in two varieties

Shielded and Unshielded Unshielded twisted pair (UTP) is the most popular bull Cable has four pairs of wires inside jacketbull Each pair twisted with different number of

twists per inchbull Eliminate interference from adjacent pairs

and other electrical devicesbull Tighter twisting higher supported

transmission rate and greater cost per footbull Most important

bull Two connections for each host Full duplex is now possible

2 Pairs of Wires in a UTP Cable Are Always Used

No matter whether the device is a hub or a switch 2 pairs of wires in a UTP cable are always used to connect a host to the device

2 pairs

12- 16

17

Efficiency Twisted Pair

Category Speed Use

1 1 Mbps Voice Only (Telephone Wire)

2 4 Mbps LocalTalk amp Telephone (Rarely used)

3 16 Mbps 10BaseT Ethernet

4 20 Mbps Token Ring (Rarely used)

5 100 Mbps (2 pair) 100BaseT Ethernet

1000 Mbps (4 pair) Gigabit Ethernet

5e 1000 Mbps Gigabit Ethernet

6 10000 Mbps Gigabit Ethernet

18

Ethernet CablingThe most common kinds of Ethernet cabling

Three kinds of Ethernet cabling

(a) 10Base5 (b) 10Base2 (c) 10Base-T

Difference in Segment length

Costs Less

Ethernet Recap

bull Used Manchester encoding bull More later

bull Ethernet could contain multiple segments and multiple repeaters

bull Used CSMACD for shared media bull What does CSMACD stand for

Carrier Sense Multiple AccessCollision Detection

bull Review this

20

CSMACD Protocol

All hosts transmit amp receive on one channelPackets are of variable size

When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before

transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random

time then return to step 1 binary exponential backoff

21

Ethernet CSMACD algorithm

Algorithm1 NIC receives datagram from network

layer creates frame

2 If NIC senses channel idle starts frame transmission

If NIC senses channel busy waits until channel idle then transmits

3 If NIC transmits entire frame without detecting another transmission NIC is done with frame

Ethernet CSMACD algorithm

4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time

bull Returns to Step 2

22

Minimum Frame Size

bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)

bull Consequently small frames must be padded out to reach MFS

bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)

bull Ethernet and Fast Ethernet the MFS is 64 bytes

bull Gigabit Ethernet it is 416 or 520 bytes

bull Full duplex versions of Ethernet

bull Collisions are avoided and so MFS does not apply

Ethernet Performancebull One result of sharingldquoEtherrdquo

bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance

bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60

percent of the expected value of 10 Mbpsbull How would you increase performance

bull Fewer Collisions reduce the collision domain

Fast Ethernet

Fast Ethernet 8023u

bull When switches became popular bull 10 Mbps Ethernet was standard back in

1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE

Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u

bull Not really New - Kept everything the same

bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science

Fast Ethernetbull Primary concern of Fast Ethernet developers

bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate

bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional

Ethernet installationsbull One version of the Fast Ethernet standard

runs on older Category 3 cable installations

Fast Ethernet

bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps

could coexist

bull How bull A Fast Ethernet-compatible hub does speed

matching when exchanging framesbull Has auto-negotiate feature

bull Devices detect speed of incoming transmissions and adjust appropriately

29

IEEE 8023u - Fast Ethernet

bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard

bull Transmission rate is 100 Mbps

bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)

bull Uses category 3 and category 5 UTP STP and fibre cables

Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5

data-grade twisted-pair wire max distance 100 meters between hub and workstation

bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation

bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration

bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics

Fiber Optic Cablingbull Fiber optic cabling consists of center glass

core surrounded by layers of

protective materials bull Fiber optic cable transmits signals over longer

distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater

speedsbull Center core of fiber cables is made from glass or

plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage

bull Outer insulating jacket made of teflon or PVC

Fiber Optic Cabling

bull Two types of fiber cables

bull Single mode

bull Multimode

bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation

bull Both cables provide high bandwidth at high speeds

bull Single mode can provide more distance but it is more expensive

Fast Ethernetbull Higher frequency used in Fast Ethernet

standard is prone to attenuation

bull Cable distance is more limited than in old Ethernet 10Base-T

bull If encoding scheme of traditional Ethernet were used with Fast Ethernet

bull High-end frequency would be above 200 Mhz

bull Double maximum frequency rating of Category 5 cable

bull New encoding schemes were implemented to allow higher-frequency transmissions

Encoding Schemes for Ethernet

bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by

physical layer

bull Recall Manchester encoding

bull 0 is indicated by a 0 to 1 transition at center of bit

bull 1 is indicated by a 1 to 0 transition at center of bit

bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit

bull Manchester Encodingbull Up transition = 1

bull Down transition = 0

Manchester EncodingStandard Ethernet

Manchester EncodingStandard Ethernet

bull Drawbackbull Manchester encoding can consume up to

approximately twice bandwidth of original signal (20 MHz)

bull Penalty for introducing frequent transitions

bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz

bull Additional bandwidth is not significant issue for coaxial cable transmission but

bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method

Fast Ethernet Encoding

bull 4B5B encoding is a type of Block coding

bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)

bull Group of 4 bits encoded so that an extra 5th bit is added

bull 4B5B encoding (Frame Encoding ndash shorthand)

bull All data is encoded prior to transmission

bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)

bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur

bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used

bull Multi-Level Transmit-3 levels

bull No transition = 0

bull Any transition (up or down) = 1

bull Reduces frequency of signal

Fast Ethernet Encoding

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

1 Changes in physical medium Coaxial UTP cables Fiber optic

2 Improved media access control methods CSMA to CSMACD to none needed

3 Improved signal encoding methods Manchester encoding to 4B5B 8B10B and more

4 Cables to hubs to switches

5 Mandating Full Duplex

Ethernet Speedup

History of Ethernet

7

An Introduction of Ethernet

bull The History of Ethernet Technology

ndash 1973 Metcalfe developed Ethernet at Palo Alto

ndash 1980 Digital Intel and Xerox developed the standard of 10Mpbs Ethernet

ndash 1992 the Grand Junction Network Company brought up the structure of 100Mbps Ethernet

ndash 1998 addressed the standard of Gigabit Ethernet

ndash 2002 10 Gigabit standard httpwwwtrendcommscommultimediatrainingbroadband

20networkswebmainethernetthemechapter1EnetIntroductionhtml

Classical or Standard Ethernet

9

Categories of Standard Ethernet

Ethernet Recap

bull Classic Ethernet bull One long cable 500 meter max segmentbull Snaked around building as single long cablebull All computers attached

bull Thick Ethernetbull Began as thick yellow cable marked every

25 meters to show computer attachments

bull Thin Ethernetbull Thinner bent more easily connections with

BNC connectorsbull Cheaper to install 185 meter max segment

11

10Base5 implementation

Ethernet segment length

12

10Base2 Implementation

Ethernet segment length

13

bull Coaxial cable has single copper conductor at its center

bull A plastic layer provides insulation between center conductor and a braided metal shield

bull Metal shield helps to block any outside interference from fluorescent lights motors and other computers

bull Resistant to signal interference and can support greater cable lengths between network devices than twisted pair cable

bull Only half-duplex is possible with coaxial cable

EfficiencyCoaxial Cable

A outer plastic sheathB woven copper shieldC inner dielectric insulatorD copper core

14

10Base-T implementation

UTP = Unshielded Twisted Pair

15

Efficiency Twisted Pairbull Twisted pair cabling comes in two varieties

Shielded and Unshielded Unshielded twisted pair (UTP) is the most popular bull Cable has four pairs of wires inside jacketbull Each pair twisted with different number of

twists per inchbull Eliminate interference from adjacent pairs

and other electrical devicesbull Tighter twisting higher supported

transmission rate and greater cost per footbull Most important

bull Two connections for each host Full duplex is now possible

2 Pairs of Wires in a UTP Cable Are Always Used

No matter whether the device is a hub or a switch 2 pairs of wires in a UTP cable are always used to connect a host to the device

2 pairs

12- 16

17

Efficiency Twisted Pair

Category Speed Use

1 1 Mbps Voice Only (Telephone Wire)

2 4 Mbps LocalTalk amp Telephone (Rarely used)

3 16 Mbps 10BaseT Ethernet

4 20 Mbps Token Ring (Rarely used)

5 100 Mbps (2 pair) 100BaseT Ethernet

1000 Mbps (4 pair) Gigabit Ethernet

5e 1000 Mbps Gigabit Ethernet

6 10000 Mbps Gigabit Ethernet

18

Ethernet CablingThe most common kinds of Ethernet cabling

Three kinds of Ethernet cabling

(a) 10Base5 (b) 10Base2 (c) 10Base-T

Difference in Segment length

Costs Less

Ethernet Recap

bull Used Manchester encoding bull More later

bull Ethernet could contain multiple segments and multiple repeaters

bull Used CSMACD for shared media bull What does CSMACD stand for

Carrier Sense Multiple AccessCollision Detection

bull Review this

20

CSMACD Protocol

All hosts transmit amp receive on one channelPackets are of variable size

When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before

transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random

time then return to step 1 binary exponential backoff

21

Ethernet CSMACD algorithm

Algorithm1 NIC receives datagram from network

layer creates frame

2 If NIC senses channel idle starts frame transmission

If NIC senses channel busy waits until channel idle then transmits

3 If NIC transmits entire frame without detecting another transmission NIC is done with frame

Ethernet CSMACD algorithm

4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time

bull Returns to Step 2

22

Minimum Frame Size

bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)

bull Consequently small frames must be padded out to reach MFS

bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)

bull Ethernet and Fast Ethernet the MFS is 64 bytes

bull Gigabit Ethernet it is 416 or 520 bytes

bull Full duplex versions of Ethernet

bull Collisions are avoided and so MFS does not apply

Ethernet Performancebull One result of sharingldquoEtherrdquo

bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance

bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60

percent of the expected value of 10 Mbpsbull How would you increase performance

bull Fewer Collisions reduce the collision domain

Fast Ethernet

Fast Ethernet 8023u

bull When switches became popular bull 10 Mbps Ethernet was standard back in

1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE

Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u

bull Not really New - Kept everything the same

bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science

Fast Ethernetbull Primary concern of Fast Ethernet developers

bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate

bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional

Ethernet installationsbull One version of the Fast Ethernet standard

runs on older Category 3 cable installations

Fast Ethernet

bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps

could coexist

bull How bull A Fast Ethernet-compatible hub does speed

matching when exchanging framesbull Has auto-negotiate feature

bull Devices detect speed of incoming transmissions and adjust appropriately

29

IEEE 8023u - Fast Ethernet

bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard

bull Transmission rate is 100 Mbps

bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)

bull Uses category 3 and category 5 UTP STP and fibre cables

Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5

data-grade twisted-pair wire max distance 100 meters between hub and workstation

bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation

bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration

bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics

Fiber Optic Cablingbull Fiber optic cabling consists of center glass

core surrounded by layers of

protective materials bull Fiber optic cable transmits signals over longer

distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater

speedsbull Center core of fiber cables is made from glass or

plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage

bull Outer insulating jacket made of teflon or PVC

Fiber Optic Cabling

bull Two types of fiber cables

bull Single mode

bull Multimode

bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation

bull Both cables provide high bandwidth at high speeds

bull Single mode can provide more distance but it is more expensive

Fast Ethernetbull Higher frequency used in Fast Ethernet

standard is prone to attenuation

bull Cable distance is more limited than in old Ethernet 10Base-T

bull If encoding scheme of traditional Ethernet were used with Fast Ethernet

bull High-end frequency would be above 200 Mhz

bull Double maximum frequency rating of Category 5 cable

bull New encoding schemes were implemented to allow higher-frequency transmissions

Encoding Schemes for Ethernet

bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by

physical layer

bull Recall Manchester encoding

bull 0 is indicated by a 0 to 1 transition at center of bit

bull 1 is indicated by a 1 to 0 transition at center of bit

bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit

bull Manchester Encodingbull Up transition = 1

bull Down transition = 0

Manchester EncodingStandard Ethernet

Manchester EncodingStandard Ethernet

bull Drawbackbull Manchester encoding can consume up to

approximately twice bandwidth of original signal (20 MHz)

bull Penalty for introducing frequent transitions

bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz

bull Additional bandwidth is not significant issue for coaxial cable transmission but

bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method

Fast Ethernet Encoding

bull 4B5B encoding is a type of Block coding

bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)

bull Group of 4 bits encoded so that an extra 5th bit is added

bull 4B5B encoding (Frame Encoding ndash shorthand)

bull All data is encoded prior to transmission

bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)

bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur

bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used

bull Multi-Level Transmit-3 levels

bull No transition = 0

bull Any transition (up or down) = 1

bull Reduces frequency of signal

Fast Ethernet Encoding

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

History of Ethernet

7

An Introduction of Ethernet

bull The History of Ethernet Technology

ndash 1973 Metcalfe developed Ethernet at Palo Alto

ndash 1980 Digital Intel and Xerox developed the standard of 10Mpbs Ethernet

ndash 1992 the Grand Junction Network Company brought up the structure of 100Mbps Ethernet

ndash 1998 addressed the standard of Gigabit Ethernet

ndash 2002 10 Gigabit standard httpwwwtrendcommscommultimediatrainingbroadband

20networkswebmainethernetthemechapter1EnetIntroductionhtml

Classical or Standard Ethernet

9

Categories of Standard Ethernet

Ethernet Recap

bull Classic Ethernet bull One long cable 500 meter max segmentbull Snaked around building as single long cablebull All computers attached

bull Thick Ethernetbull Began as thick yellow cable marked every

25 meters to show computer attachments

bull Thin Ethernetbull Thinner bent more easily connections with

BNC connectorsbull Cheaper to install 185 meter max segment

11

10Base5 implementation

Ethernet segment length

12

10Base2 Implementation

Ethernet segment length

13

bull Coaxial cable has single copper conductor at its center

bull A plastic layer provides insulation between center conductor and a braided metal shield

bull Metal shield helps to block any outside interference from fluorescent lights motors and other computers

bull Resistant to signal interference and can support greater cable lengths between network devices than twisted pair cable

bull Only half-duplex is possible with coaxial cable

EfficiencyCoaxial Cable

A outer plastic sheathB woven copper shieldC inner dielectric insulatorD copper core

14

10Base-T implementation

UTP = Unshielded Twisted Pair

15

Efficiency Twisted Pairbull Twisted pair cabling comes in two varieties

Shielded and Unshielded Unshielded twisted pair (UTP) is the most popular bull Cable has four pairs of wires inside jacketbull Each pair twisted with different number of

twists per inchbull Eliminate interference from adjacent pairs

and other electrical devicesbull Tighter twisting higher supported

transmission rate and greater cost per footbull Most important

bull Two connections for each host Full duplex is now possible

2 Pairs of Wires in a UTP Cable Are Always Used

No matter whether the device is a hub or a switch 2 pairs of wires in a UTP cable are always used to connect a host to the device

2 pairs

12- 16

17

Efficiency Twisted Pair

Category Speed Use

1 1 Mbps Voice Only (Telephone Wire)

2 4 Mbps LocalTalk amp Telephone (Rarely used)

3 16 Mbps 10BaseT Ethernet

4 20 Mbps Token Ring (Rarely used)

5 100 Mbps (2 pair) 100BaseT Ethernet

1000 Mbps (4 pair) Gigabit Ethernet

5e 1000 Mbps Gigabit Ethernet

6 10000 Mbps Gigabit Ethernet

18

Ethernet CablingThe most common kinds of Ethernet cabling

Three kinds of Ethernet cabling

(a) 10Base5 (b) 10Base2 (c) 10Base-T

Difference in Segment length

Costs Less

Ethernet Recap

bull Used Manchester encoding bull More later

bull Ethernet could contain multiple segments and multiple repeaters

bull Used CSMACD for shared media bull What does CSMACD stand for

Carrier Sense Multiple AccessCollision Detection

bull Review this

20

CSMACD Protocol

All hosts transmit amp receive on one channelPackets are of variable size

When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before

transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random

time then return to step 1 binary exponential backoff

21

Ethernet CSMACD algorithm

Algorithm1 NIC receives datagram from network

layer creates frame

2 If NIC senses channel idle starts frame transmission

If NIC senses channel busy waits until channel idle then transmits

3 If NIC transmits entire frame without detecting another transmission NIC is done with frame

Ethernet CSMACD algorithm

4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time

bull Returns to Step 2

22

Minimum Frame Size

bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)

bull Consequently small frames must be padded out to reach MFS

bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)

bull Ethernet and Fast Ethernet the MFS is 64 bytes

bull Gigabit Ethernet it is 416 or 520 bytes

bull Full duplex versions of Ethernet

bull Collisions are avoided and so MFS does not apply

Ethernet Performancebull One result of sharingldquoEtherrdquo

bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance

bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60

percent of the expected value of 10 Mbpsbull How would you increase performance

bull Fewer Collisions reduce the collision domain

Fast Ethernet

Fast Ethernet 8023u

bull When switches became popular bull 10 Mbps Ethernet was standard back in

1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE

Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u

bull Not really New - Kept everything the same

bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science

Fast Ethernetbull Primary concern of Fast Ethernet developers

bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate

bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional

Ethernet installationsbull One version of the Fast Ethernet standard

runs on older Category 3 cable installations

Fast Ethernet

bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps

could coexist

bull How bull A Fast Ethernet-compatible hub does speed

matching when exchanging framesbull Has auto-negotiate feature

bull Devices detect speed of incoming transmissions and adjust appropriately

29

IEEE 8023u - Fast Ethernet

bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard

bull Transmission rate is 100 Mbps

bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)

bull Uses category 3 and category 5 UTP STP and fibre cables

Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5

data-grade twisted-pair wire max distance 100 meters between hub and workstation

bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation

bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration

bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics

Fiber Optic Cablingbull Fiber optic cabling consists of center glass

core surrounded by layers of

protective materials bull Fiber optic cable transmits signals over longer

distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater

speedsbull Center core of fiber cables is made from glass or

plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage

bull Outer insulating jacket made of teflon or PVC

Fiber Optic Cabling

bull Two types of fiber cables

bull Single mode

bull Multimode

bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation

bull Both cables provide high bandwidth at high speeds

bull Single mode can provide more distance but it is more expensive

Fast Ethernetbull Higher frequency used in Fast Ethernet

standard is prone to attenuation

bull Cable distance is more limited than in old Ethernet 10Base-T

bull If encoding scheme of traditional Ethernet were used with Fast Ethernet

bull High-end frequency would be above 200 Mhz

bull Double maximum frequency rating of Category 5 cable

bull New encoding schemes were implemented to allow higher-frequency transmissions

Encoding Schemes for Ethernet

bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by

physical layer

bull Recall Manchester encoding

bull 0 is indicated by a 0 to 1 transition at center of bit

bull 1 is indicated by a 1 to 0 transition at center of bit

bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit

bull Manchester Encodingbull Up transition = 1

bull Down transition = 0

Manchester EncodingStandard Ethernet

Manchester EncodingStandard Ethernet

bull Drawbackbull Manchester encoding can consume up to

approximately twice bandwidth of original signal (20 MHz)

bull Penalty for introducing frequent transitions

bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz

bull Additional bandwidth is not significant issue for coaxial cable transmission but

bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method

Fast Ethernet Encoding

bull 4B5B encoding is a type of Block coding

bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)

bull Group of 4 bits encoded so that an extra 5th bit is added

bull 4B5B encoding (Frame Encoding ndash shorthand)

bull All data is encoded prior to transmission

bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)

bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur

bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used

bull Multi-Level Transmit-3 levels

bull No transition = 0

bull Any transition (up or down) = 1

bull Reduces frequency of signal

Fast Ethernet Encoding

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

7

An Introduction of Ethernet

bull The History of Ethernet Technology

ndash 1973 Metcalfe developed Ethernet at Palo Alto

ndash 1980 Digital Intel and Xerox developed the standard of 10Mpbs Ethernet

ndash 1992 the Grand Junction Network Company brought up the structure of 100Mbps Ethernet

ndash 1998 addressed the standard of Gigabit Ethernet

ndash 2002 10 Gigabit standard httpwwwtrendcommscommultimediatrainingbroadband

20networkswebmainethernetthemechapter1EnetIntroductionhtml

Classical or Standard Ethernet

9

Categories of Standard Ethernet

Ethernet Recap

bull Classic Ethernet bull One long cable 500 meter max segmentbull Snaked around building as single long cablebull All computers attached

bull Thick Ethernetbull Began as thick yellow cable marked every

25 meters to show computer attachments

bull Thin Ethernetbull Thinner bent more easily connections with

BNC connectorsbull Cheaper to install 185 meter max segment

11

10Base5 implementation

Ethernet segment length

12

10Base2 Implementation

Ethernet segment length

13

bull Coaxial cable has single copper conductor at its center

bull A plastic layer provides insulation between center conductor and a braided metal shield

bull Metal shield helps to block any outside interference from fluorescent lights motors and other computers

bull Resistant to signal interference and can support greater cable lengths between network devices than twisted pair cable

bull Only half-duplex is possible with coaxial cable

EfficiencyCoaxial Cable

A outer plastic sheathB woven copper shieldC inner dielectric insulatorD copper core

14

10Base-T implementation

UTP = Unshielded Twisted Pair

15

Efficiency Twisted Pairbull Twisted pair cabling comes in two varieties

Shielded and Unshielded Unshielded twisted pair (UTP) is the most popular bull Cable has four pairs of wires inside jacketbull Each pair twisted with different number of

twists per inchbull Eliminate interference from adjacent pairs

and other electrical devicesbull Tighter twisting higher supported

transmission rate and greater cost per footbull Most important

bull Two connections for each host Full duplex is now possible

2 Pairs of Wires in a UTP Cable Are Always Used

No matter whether the device is a hub or a switch 2 pairs of wires in a UTP cable are always used to connect a host to the device

2 pairs

12- 16

17

Efficiency Twisted Pair

Category Speed Use

1 1 Mbps Voice Only (Telephone Wire)

2 4 Mbps LocalTalk amp Telephone (Rarely used)

3 16 Mbps 10BaseT Ethernet

4 20 Mbps Token Ring (Rarely used)

5 100 Mbps (2 pair) 100BaseT Ethernet

1000 Mbps (4 pair) Gigabit Ethernet

5e 1000 Mbps Gigabit Ethernet

6 10000 Mbps Gigabit Ethernet

18

Ethernet CablingThe most common kinds of Ethernet cabling

Three kinds of Ethernet cabling

(a) 10Base5 (b) 10Base2 (c) 10Base-T

Difference in Segment length

Costs Less

Ethernet Recap

bull Used Manchester encoding bull More later

bull Ethernet could contain multiple segments and multiple repeaters

bull Used CSMACD for shared media bull What does CSMACD stand for

Carrier Sense Multiple AccessCollision Detection

bull Review this

20

CSMACD Protocol

All hosts transmit amp receive on one channelPackets are of variable size

When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before

transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random

time then return to step 1 binary exponential backoff

21

Ethernet CSMACD algorithm

Algorithm1 NIC receives datagram from network

layer creates frame

2 If NIC senses channel idle starts frame transmission

If NIC senses channel busy waits until channel idle then transmits

3 If NIC transmits entire frame without detecting another transmission NIC is done with frame

Ethernet CSMACD algorithm

4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time

bull Returns to Step 2

22

Minimum Frame Size

bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)

bull Consequently small frames must be padded out to reach MFS

bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)

bull Ethernet and Fast Ethernet the MFS is 64 bytes

bull Gigabit Ethernet it is 416 or 520 bytes

bull Full duplex versions of Ethernet

bull Collisions are avoided and so MFS does not apply

Ethernet Performancebull One result of sharingldquoEtherrdquo

bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance

bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60

percent of the expected value of 10 Mbpsbull How would you increase performance

bull Fewer Collisions reduce the collision domain

Fast Ethernet

Fast Ethernet 8023u

bull When switches became popular bull 10 Mbps Ethernet was standard back in

1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE

Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u

bull Not really New - Kept everything the same

bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science

Fast Ethernetbull Primary concern of Fast Ethernet developers

bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate

bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional

Ethernet installationsbull One version of the Fast Ethernet standard

runs on older Category 3 cable installations

Fast Ethernet

bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps

could coexist

bull How bull A Fast Ethernet-compatible hub does speed

matching when exchanging framesbull Has auto-negotiate feature

bull Devices detect speed of incoming transmissions and adjust appropriately

29

IEEE 8023u - Fast Ethernet

bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard

bull Transmission rate is 100 Mbps

bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)

bull Uses category 3 and category 5 UTP STP and fibre cables

Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5

data-grade twisted-pair wire max distance 100 meters between hub and workstation

bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation

bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration

bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics

Fiber Optic Cablingbull Fiber optic cabling consists of center glass

core surrounded by layers of

protective materials bull Fiber optic cable transmits signals over longer

distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater

speedsbull Center core of fiber cables is made from glass or

plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage

bull Outer insulating jacket made of teflon or PVC

Fiber Optic Cabling

bull Two types of fiber cables

bull Single mode

bull Multimode

bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation

bull Both cables provide high bandwidth at high speeds

bull Single mode can provide more distance but it is more expensive

Fast Ethernetbull Higher frequency used in Fast Ethernet

standard is prone to attenuation

bull Cable distance is more limited than in old Ethernet 10Base-T

bull If encoding scheme of traditional Ethernet were used with Fast Ethernet

bull High-end frequency would be above 200 Mhz

bull Double maximum frequency rating of Category 5 cable

bull New encoding schemes were implemented to allow higher-frequency transmissions

Encoding Schemes for Ethernet

bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by

physical layer

bull Recall Manchester encoding

bull 0 is indicated by a 0 to 1 transition at center of bit

bull 1 is indicated by a 1 to 0 transition at center of bit

bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit

bull Manchester Encodingbull Up transition = 1

bull Down transition = 0

Manchester EncodingStandard Ethernet

Manchester EncodingStandard Ethernet

bull Drawbackbull Manchester encoding can consume up to

approximately twice bandwidth of original signal (20 MHz)

bull Penalty for introducing frequent transitions

bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz

bull Additional bandwidth is not significant issue for coaxial cable transmission but

bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method

Fast Ethernet Encoding

bull 4B5B encoding is a type of Block coding

bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)

bull Group of 4 bits encoded so that an extra 5th bit is added

bull 4B5B encoding (Frame Encoding ndash shorthand)

bull All data is encoded prior to transmission

bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)

bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur

bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used

bull Multi-Level Transmit-3 levels

bull No transition = 0

bull Any transition (up or down) = 1

bull Reduces frequency of signal

Fast Ethernet Encoding

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

Classical or Standard Ethernet

9

Categories of Standard Ethernet

Ethernet Recap

bull Classic Ethernet bull One long cable 500 meter max segmentbull Snaked around building as single long cablebull All computers attached

bull Thick Ethernetbull Began as thick yellow cable marked every

25 meters to show computer attachments

bull Thin Ethernetbull Thinner bent more easily connections with

BNC connectorsbull Cheaper to install 185 meter max segment

11

10Base5 implementation

Ethernet segment length

12

10Base2 Implementation

Ethernet segment length

13

bull Coaxial cable has single copper conductor at its center

bull A plastic layer provides insulation between center conductor and a braided metal shield

bull Metal shield helps to block any outside interference from fluorescent lights motors and other computers

bull Resistant to signal interference and can support greater cable lengths between network devices than twisted pair cable

bull Only half-duplex is possible with coaxial cable

EfficiencyCoaxial Cable

A outer plastic sheathB woven copper shieldC inner dielectric insulatorD copper core

14

10Base-T implementation

UTP = Unshielded Twisted Pair

15

Efficiency Twisted Pairbull Twisted pair cabling comes in two varieties

Shielded and Unshielded Unshielded twisted pair (UTP) is the most popular bull Cable has four pairs of wires inside jacketbull Each pair twisted with different number of

twists per inchbull Eliminate interference from adjacent pairs

and other electrical devicesbull Tighter twisting higher supported

transmission rate and greater cost per footbull Most important

bull Two connections for each host Full duplex is now possible

2 Pairs of Wires in a UTP Cable Are Always Used

No matter whether the device is a hub or a switch 2 pairs of wires in a UTP cable are always used to connect a host to the device

2 pairs

12- 16

17

Efficiency Twisted Pair

Category Speed Use

1 1 Mbps Voice Only (Telephone Wire)

2 4 Mbps LocalTalk amp Telephone (Rarely used)

3 16 Mbps 10BaseT Ethernet

4 20 Mbps Token Ring (Rarely used)

5 100 Mbps (2 pair) 100BaseT Ethernet

1000 Mbps (4 pair) Gigabit Ethernet

5e 1000 Mbps Gigabit Ethernet

6 10000 Mbps Gigabit Ethernet

18

Ethernet CablingThe most common kinds of Ethernet cabling

Three kinds of Ethernet cabling

(a) 10Base5 (b) 10Base2 (c) 10Base-T

Difference in Segment length

Costs Less

Ethernet Recap

bull Used Manchester encoding bull More later

bull Ethernet could contain multiple segments and multiple repeaters

bull Used CSMACD for shared media bull What does CSMACD stand for

Carrier Sense Multiple AccessCollision Detection

bull Review this

20

CSMACD Protocol

All hosts transmit amp receive on one channelPackets are of variable size

When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before

transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random

time then return to step 1 binary exponential backoff

21

Ethernet CSMACD algorithm

Algorithm1 NIC receives datagram from network

layer creates frame

2 If NIC senses channel idle starts frame transmission

If NIC senses channel busy waits until channel idle then transmits

3 If NIC transmits entire frame without detecting another transmission NIC is done with frame

Ethernet CSMACD algorithm

4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time

bull Returns to Step 2

22

Minimum Frame Size

bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)

bull Consequently small frames must be padded out to reach MFS

bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)

bull Ethernet and Fast Ethernet the MFS is 64 bytes

bull Gigabit Ethernet it is 416 or 520 bytes

bull Full duplex versions of Ethernet

bull Collisions are avoided and so MFS does not apply

Ethernet Performancebull One result of sharingldquoEtherrdquo

bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance

bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60

percent of the expected value of 10 Mbpsbull How would you increase performance

bull Fewer Collisions reduce the collision domain

Fast Ethernet

Fast Ethernet 8023u

bull When switches became popular bull 10 Mbps Ethernet was standard back in

1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE

Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u

bull Not really New - Kept everything the same

bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science

Fast Ethernetbull Primary concern of Fast Ethernet developers

bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate

bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional

Ethernet installationsbull One version of the Fast Ethernet standard

runs on older Category 3 cable installations

Fast Ethernet

bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps

could coexist

bull How bull A Fast Ethernet-compatible hub does speed

matching when exchanging framesbull Has auto-negotiate feature

bull Devices detect speed of incoming transmissions and adjust appropriately

29

IEEE 8023u - Fast Ethernet

bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard

bull Transmission rate is 100 Mbps

bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)

bull Uses category 3 and category 5 UTP STP and fibre cables

Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5

data-grade twisted-pair wire max distance 100 meters between hub and workstation

bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation

bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration

bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics

Fiber Optic Cablingbull Fiber optic cabling consists of center glass

core surrounded by layers of

protective materials bull Fiber optic cable transmits signals over longer

distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater

speedsbull Center core of fiber cables is made from glass or

plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage

bull Outer insulating jacket made of teflon or PVC

Fiber Optic Cabling

bull Two types of fiber cables

bull Single mode

bull Multimode

bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation

bull Both cables provide high bandwidth at high speeds

bull Single mode can provide more distance but it is more expensive

Fast Ethernetbull Higher frequency used in Fast Ethernet

standard is prone to attenuation

bull Cable distance is more limited than in old Ethernet 10Base-T

bull If encoding scheme of traditional Ethernet were used with Fast Ethernet

bull High-end frequency would be above 200 Mhz

bull Double maximum frequency rating of Category 5 cable

bull New encoding schemes were implemented to allow higher-frequency transmissions

Encoding Schemes for Ethernet

bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by

physical layer

bull Recall Manchester encoding

bull 0 is indicated by a 0 to 1 transition at center of bit

bull 1 is indicated by a 1 to 0 transition at center of bit

bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit

bull Manchester Encodingbull Up transition = 1

bull Down transition = 0

Manchester EncodingStandard Ethernet

Manchester EncodingStandard Ethernet

bull Drawbackbull Manchester encoding can consume up to

approximately twice bandwidth of original signal (20 MHz)

bull Penalty for introducing frequent transitions

bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz

bull Additional bandwidth is not significant issue for coaxial cable transmission but

bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method

Fast Ethernet Encoding

bull 4B5B encoding is a type of Block coding

bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)

bull Group of 4 bits encoded so that an extra 5th bit is added

bull 4B5B encoding (Frame Encoding ndash shorthand)

bull All data is encoded prior to transmission

bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)

bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur

bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used

bull Multi-Level Transmit-3 levels

bull No transition = 0

bull Any transition (up or down) = 1

bull Reduces frequency of signal

Fast Ethernet Encoding

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

9

Categories of Standard Ethernet

Ethernet Recap

bull Classic Ethernet bull One long cable 500 meter max segmentbull Snaked around building as single long cablebull All computers attached

bull Thick Ethernetbull Began as thick yellow cable marked every

25 meters to show computer attachments

bull Thin Ethernetbull Thinner bent more easily connections with

BNC connectorsbull Cheaper to install 185 meter max segment

11

10Base5 implementation

Ethernet segment length

12

10Base2 Implementation

Ethernet segment length

13

bull Coaxial cable has single copper conductor at its center

bull A plastic layer provides insulation between center conductor and a braided metal shield

bull Metal shield helps to block any outside interference from fluorescent lights motors and other computers

bull Resistant to signal interference and can support greater cable lengths between network devices than twisted pair cable

bull Only half-duplex is possible with coaxial cable

EfficiencyCoaxial Cable

A outer plastic sheathB woven copper shieldC inner dielectric insulatorD copper core

14

10Base-T implementation

UTP = Unshielded Twisted Pair

15

Efficiency Twisted Pairbull Twisted pair cabling comes in two varieties

Shielded and Unshielded Unshielded twisted pair (UTP) is the most popular bull Cable has four pairs of wires inside jacketbull Each pair twisted with different number of

twists per inchbull Eliminate interference from adjacent pairs

and other electrical devicesbull Tighter twisting higher supported

transmission rate and greater cost per footbull Most important

bull Two connections for each host Full duplex is now possible

2 Pairs of Wires in a UTP Cable Are Always Used

No matter whether the device is a hub or a switch 2 pairs of wires in a UTP cable are always used to connect a host to the device

2 pairs

12- 16

17

Efficiency Twisted Pair

Category Speed Use

1 1 Mbps Voice Only (Telephone Wire)

2 4 Mbps LocalTalk amp Telephone (Rarely used)

3 16 Mbps 10BaseT Ethernet

4 20 Mbps Token Ring (Rarely used)

5 100 Mbps (2 pair) 100BaseT Ethernet

1000 Mbps (4 pair) Gigabit Ethernet

5e 1000 Mbps Gigabit Ethernet

6 10000 Mbps Gigabit Ethernet

18

Ethernet CablingThe most common kinds of Ethernet cabling

Three kinds of Ethernet cabling

(a) 10Base5 (b) 10Base2 (c) 10Base-T

Difference in Segment length

Costs Less

Ethernet Recap

bull Used Manchester encoding bull More later

bull Ethernet could contain multiple segments and multiple repeaters

bull Used CSMACD for shared media bull What does CSMACD stand for

Carrier Sense Multiple AccessCollision Detection

bull Review this

20

CSMACD Protocol

All hosts transmit amp receive on one channelPackets are of variable size

When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before

transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random

time then return to step 1 binary exponential backoff

21

Ethernet CSMACD algorithm

Algorithm1 NIC receives datagram from network

layer creates frame

2 If NIC senses channel idle starts frame transmission

If NIC senses channel busy waits until channel idle then transmits

3 If NIC transmits entire frame without detecting another transmission NIC is done with frame

Ethernet CSMACD algorithm

4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time

bull Returns to Step 2

22

Minimum Frame Size

bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)

bull Consequently small frames must be padded out to reach MFS

bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)

bull Ethernet and Fast Ethernet the MFS is 64 bytes

bull Gigabit Ethernet it is 416 or 520 bytes

bull Full duplex versions of Ethernet

bull Collisions are avoided and so MFS does not apply

Ethernet Performancebull One result of sharingldquoEtherrdquo

bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance

bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60

percent of the expected value of 10 Mbpsbull How would you increase performance

bull Fewer Collisions reduce the collision domain

Fast Ethernet

Fast Ethernet 8023u

bull When switches became popular bull 10 Mbps Ethernet was standard back in

1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE

Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u

bull Not really New - Kept everything the same

bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science

Fast Ethernetbull Primary concern of Fast Ethernet developers

bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate

bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional

Ethernet installationsbull One version of the Fast Ethernet standard

runs on older Category 3 cable installations

Fast Ethernet

bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps

could coexist

bull How bull A Fast Ethernet-compatible hub does speed

matching when exchanging framesbull Has auto-negotiate feature

bull Devices detect speed of incoming transmissions and adjust appropriately

29

IEEE 8023u - Fast Ethernet

bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard

bull Transmission rate is 100 Mbps

bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)

bull Uses category 3 and category 5 UTP STP and fibre cables

Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5

data-grade twisted-pair wire max distance 100 meters between hub and workstation

bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation

bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration

bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics

Fiber Optic Cablingbull Fiber optic cabling consists of center glass

core surrounded by layers of

protective materials bull Fiber optic cable transmits signals over longer

distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater

speedsbull Center core of fiber cables is made from glass or

plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage

bull Outer insulating jacket made of teflon or PVC

Fiber Optic Cabling

bull Two types of fiber cables

bull Single mode

bull Multimode

bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation

bull Both cables provide high bandwidth at high speeds

bull Single mode can provide more distance but it is more expensive

Fast Ethernetbull Higher frequency used in Fast Ethernet

standard is prone to attenuation

bull Cable distance is more limited than in old Ethernet 10Base-T

bull If encoding scheme of traditional Ethernet were used with Fast Ethernet

bull High-end frequency would be above 200 Mhz

bull Double maximum frequency rating of Category 5 cable

bull New encoding schemes were implemented to allow higher-frequency transmissions

Encoding Schemes for Ethernet

bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by

physical layer

bull Recall Manchester encoding

bull 0 is indicated by a 0 to 1 transition at center of bit

bull 1 is indicated by a 1 to 0 transition at center of bit

bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit

bull Manchester Encodingbull Up transition = 1

bull Down transition = 0

Manchester EncodingStandard Ethernet

Manchester EncodingStandard Ethernet

bull Drawbackbull Manchester encoding can consume up to

approximately twice bandwidth of original signal (20 MHz)

bull Penalty for introducing frequent transitions

bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz

bull Additional bandwidth is not significant issue for coaxial cable transmission but

bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method

Fast Ethernet Encoding

bull 4B5B encoding is a type of Block coding

bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)

bull Group of 4 bits encoded so that an extra 5th bit is added

bull 4B5B encoding (Frame Encoding ndash shorthand)

bull All data is encoded prior to transmission

bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)

bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur

bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used

bull Multi-Level Transmit-3 levels

bull No transition = 0

bull Any transition (up or down) = 1

bull Reduces frequency of signal

Fast Ethernet Encoding

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

Ethernet Recap

bull Classic Ethernet bull One long cable 500 meter max segmentbull Snaked around building as single long cablebull All computers attached

bull Thick Ethernetbull Began as thick yellow cable marked every

25 meters to show computer attachments

bull Thin Ethernetbull Thinner bent more easily connections with

BNC connectorsbull Cheaper to install 185 meter max segment

11

10Base5 implementation

Ethernet segment length

12

10Base2 Implementation

Ethernet segment length

13

bull Coaxial cable has single copper conductor at its center

bull A plastic layer provides insulation between center conductor and a braided metal shield

bull Metal shield helps to block any outside interference from fluorescent lights motors and other computers

bull Resistant to signal interference and can support greater cable lengths between network devices than twisted pair cable

bull Only half-duplex is possible with coaxial cable

EfficiencyCoaxial Cable

A outer plastic sheathB woven copper shieldC inner dielectric insulatorD copper core

14

10Base-T implementation

UTP = Unshielded Twisted Pair

15

Efficiency Twisted Pairbull Twisted pair cabling comes in two varieties

Shielded and Unshielded Unshielded twisted pair (UTP) is the most popular bull Cable has four pairs of wires inside jacketbull Each pair twisted with different number of

twists per inchbull Eliminate interference from adjacent pairs

and other electrical devicesbull Tighter twisting higher supported

transmission rate and greater cost per footbull Most important

bull Two connections for each host Full duplex is now possible

2 Pairs of Wires in a UTP Cable Are Always Used

No matter whether the device is a hub or a switch 2 pairs of wires in a UTP cable are always used to connect a host to the device

2 pairs

12- 16

17

Efficiency Twisted Pair

Category Speed Use

1 1 Mbps Voice Only (Telephone Wire)

2 4 Mbps LocalTalk amp Telephone (Rarely used)

3 16 Mbps 10BaseT Ethernet

4 20 Mbps Token Ring (Rarely used)

5 100 Mbps (2 pair) 100BaseT Ethernet

1000 Mbps (4 pair) Gigabit Ethernet

5e 1000 Mbps Gigabit Ethernet

6 10000 Mbps Gigabit Ethernet

18

Ethernet CablingThe most common kinds of Ethernet cabling

Three kinds of Ethernet cabling

(a) 10Base5 (b) 10Base2 (c) 10Base-T

Difference in Segment length

Costs Less

Ethernet Recap

bull Used Manchester encoding bull More later

bull Ethernet could contain multiple segments and multiple repeaters

bull Used CSMACD for shared media bull What does CSMACD stand for

Carrier Sense Multiple AccessCollision Detection

bull Review this

20

CSMACD Protocol

All hosts transmit amp receive on one channelPackets are of variable size

When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before

transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random

time then return to step 1 binary exponential backoff

21

Ethernet CSMACD algorithm

Algorithm1 NIC receives datagram from network

layer creates frame

2 If NIC senses channel idle starts frame transmission

If NIC senses channel busy waits until channel idle then transmits

3 If NIC transmits entire frame without detecting another transmission NIC is done with frame

Ethernet CSMACD algorithm

4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time

bull Returns to Step 2

22

Minimum Frame Size

bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)

bull Consequently small frames must be padded out to reach MFS

bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)

bull Ethernet and Fast Ethernet the MFS is 64 bytes

bull Gigabit Ethernet it is 416 or 520 bytes

bull Full duplex versions of Ethernet

bull Collisions are avoided and so MFS does not apply

Ethernet Performancebull One result of sharingldquoEtherrdquo

bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance

bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60

percent of the expected value of 10 Mbpsbull How would you increase performance

bull Fewer Collisions reduce the collision domain

Fast Ethernet

Fast Ethernet 8023u

bull When switches became popular bull 10 Mbps Ethernet was standard back in

1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE

Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u

bull Not really New - Kept everything the same

bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science

Fast Ethernetbull Primary concern of Fast Ethernet developers

bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate

bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional

Ethernet installationsbull One version of the Fast Ethernet standard

runs on older Category 3 cable installations

Fast Ethernet

bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps

could coexist

bull How bull A Fast Ethernet-compatible hub does speed

matching when exchanging framesbull Has auto-negotiate feature

bull Devices detect speed of incoming transmissions and adjust appropriately

29

IEEE 8023u - Fast Ethernet

bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard

bull Transmission rate is 100 Mbps

bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)

bull Uses category 3 and category 5 UTP STP and fibre cables

Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5

data-grade twisted-pair wire max distance 100 meters between hub and workstation

bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation

bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration

bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics

Fiber Optic Cablingbull Fiber optic cabling consists of center glass

core surrounded by layers of

protective materials bull Fiber optic cable transmits signals over longer

distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater

speedsbull Center core of fiber cables is made from glass or

plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage

bull Outer insulating jacket made of teflon or PVC

Fiber Optic Cabling

bull Two types of fiber cables

bull Single mode

bull Multimode

bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation

bull Both cables provide high bandwidth at high speeds

bull Single mode can provide more distance but it is more expensive

Fast Ethernetbull Higher frequency used in Fast Ethernet

standard is prone to attenuation

bull Cable distance is more limited than in old Ethernet 10Base-T

bull If encoding scheme of traditional Ethernet were used with Fast Ethernet

bull High-end frequency would be above 200 Mhz

bull Double maximum frequency rating of Category 5 cable

bull New encoding schemes were implemented to allow higher-frequency transmissions

Encoding Schemes for Ethernet

bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by

physical layer

bull Recall Manchester encoding

bull 0 is indicated by a 0 to 1 transition at center of bit

bull 1 is indicated by a 1 to 0 transition at center of bit

bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit

bull Manchester Encodingbull Up transition = 1

bull Down transition = 0

Manchester EncodingStandard Ethernet

Manchester EncodingStandard Ethernet

bull Drawbackbull Manchester encoding can consume up to

approximately twice bandwidth of original signal (20 MHz)

bull Penalty for introducing frequent transitions

bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz

bull Additional bandwidth is not significant issue for coaxial cable transmission but

bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method

Fast Ethernet Encoding

bull 4B5B encoding is a type of Block coding

bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)

bull Group of 4 bits encoded so that an extra 5th bit is added

bull 4B5B encoding (Frame Encoding ndash shorthand)

bull All data is encoded prior to transmission

bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)

bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur

bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used

bull Multi-Level Transmit-3 levels

bull No transition = 0

bull Any transition (up or down) = 1

bull Reduces frequency of signal

Fast Ethernet Encoding

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

11

10Base5 implementation

Ethernet segment length

12

10Base2 Implementation

Ethernet segment length

13

bull Coaxial cable has single copper conductor at its center

bull A plastic layer provides insulation between center conductor and a braided metal shield

bull Metal shield helps to block any outside interference from fluorescent lights motors and other computers

bull Resistant to signal interference and can support greater cable lengths between network devices than twisted pair cable

bull Only half-duplex is possible with coaxial cable

EfficiencyCoaxial Cable

A outer plastic sheathB woven copper shieldC inner dielectric insulatorD copper core

14

10Base-T implementation

UTP = Unshielded Twisted Pair

15

Efficiency Twisted Pairbull Twisted pair cabling comes in two varieties

Shielded and Unshielded Unshielded twisted pair (UTP) is the most popular bull Cable has four pairs of wires inside jacketbull Each pair twisted with different number of

twists per inchbull Eliminate interference from adjacent pairs

and other electrical devicesbull Tighter twisting higher supported

transmission rate and greater cost per footbull Most important

bull Two connections for each host Full duplex is now possible

2 Pairs of Wires in a UTP Cable Are Always Used

No matter whether the device is a hub or a switch 2 pairs of wires in a UTP cable are always used to connect a host to the device

2 pairs

12- 16

17

Efficiency Twisted Pair

Category Speed Use

1 1 Mbps Voice Only (Telephone Wire)

2 4 Mbps LocalTalk amp Telephone (Rarely used)

3 16 Mbps 10BaseT Ethernet

4 20 Mbps Token Ring (Rarely used)

5 100 Mbps (2 pair) 100BaseT Ethernet

1000 Mbps (4 pair) Gigabit Ethernet

5e 1000 Mbps Gigabit Ethernet

6 10000 Mbps Gigabit Ethernet

18

Ethernet CablingThe most common kinds of Ethernet cabling

Three kinds of Ethernet cabling

(a) 10Base5 (b) 10Base2 (c) 10Base-T

Difference in Segment length

Costs Less

Ethernet Recap

bull Used Manchester encoding bull More later

bull Ethernet could contain multiple segments and multiple repeaters

bull Used CSMACD for shared media bull What does CSMACD stand for

Carrier Sense Multiple AccessCollision Detection

bull Review this

20

CSMACD Protocol

All hosts transmit amp receive on one channelPackets are of variable size

When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before

transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random

time then return to step 1 binary exponential backoff

21

Ethernet CSMACD algorithm

Algorithm1 NIC receives datagram from network

layer creates frame

2 If NIC senses channel idle starts frame transmission

If NIC senses channel busy waits until channel idle then transmits

3 If NIC transmits entire frame without detecting another transmission NIC is done with frame

Ethernet CSMACD algorithm

4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time

bull Returns to Step 2

22

Minimum Frame Size

bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)

bull Consequently small frames must be padded out to reach MFS

bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)

bull Ethernet and Fast Ethernet the MFS is 64 bytes

bull Gigabit Ethernet it is 416 or 520 bytes

bull Full duplex versions of Ethernet

bull Collisions are avoided and so MFS does not apply

Ethernet Performancebull One result of sharingldquoEtherrdquo

bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance

bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60

percent of the expected value of 10 Mbpsbull How would you increase performance

bull Fewer Collisions reduce the collision domain

Fast Ethernet

Fast Ethernet 8023u

bull When switches became popular bull 10 Mbps Ethernet was standard back in

1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE

Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u

bull Not really New - Kept everything the same

bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science

Fast Ethernetbull Primary concern of Fast Ethernet developers

bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate

bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional

Ethernet installationsbull One version of the Fast Ethernet standard

runs on older Category 3 cable installations

Fast Ethernet

bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps

could coexist

bull How bull A Fast Ethernet-compatible hub does speed

matching when exchanging framesbull Has auto-negotiate feature

bull Devices detect speed of incoming transmissions and adjust appropriately

29

IEEE 8023u - Fast Ethernet

bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard

bull Transmission rate is 100 Mbps

bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)

bull Uses category 3 and category 5 UTP STP and fibre cables

Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5

data-grade twisted-pair wire max distance 100 meters between hub and workstation

bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation

bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration

bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics

Fiber Optic Cablingbull Fiber optic cabling consists of center glass

core surrounded by layers of

protective materials bull Fiber optic cable transmits signals over longer

distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater

speedsbull Center core of fiber cables is made from glass or

plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage

bull Outer insulating jacket made of teflon or PVC

Fiber Optic Cabling

bull Two types of fiber cables

bull Single mode

bull Multimode

bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation

bull Both cables provide high bandwidth at high speeds

bull Single mode can provide more distance but it is more expensive

Fast Ethernetbull Higher frequency used in Fast Ethernet

standard is prone to attenuation

bull Cable distance is more limited than in old Ethernet 10Base-T

bull If encoding scheme of traditional Ethernet were used with Fast Ethernet

bull High-end frequency would be above 200 Mhz

bull Double maximum frequency rating of Category 5 cable

bull New encoding schemes were implemented to allow higher-frequency transmissions

Encoding Schemes for Ethernet

bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by

physical layer

bull Recall Manchester encoding

bull 0 is indicated by a 0 to 1 transition at center of bit

bull 1 is indicated by a 1 to 0 transition at center of bit

bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit

bull Manchester Encodingbull Up transition = 1

bull Down transition = 0

Manchester EncodingStandard Ethernet

Manchester EncodingStandard Ethernet

bull Drawbackbull Manchester encoding can consume up to

approximately twice bandwidth of original signal (20 MHz)

bull Penalty for introducing frequent transitions

bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz

bull Additional bandwidth is not significant issue for coaxial cable transmission but

bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method

Fast Ethernet Encoding

bull 4B5B encoding is a type of Block coding

bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)

bull Group of 4 bits encoded so that an extra 5th bit is added

bull 4B5B encoding (Frame Encoding ndash shorthand)

bull All data is encoded prior to transmission

bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)

bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur

bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used

bull Multi-Level Transmit-3 levels

bull No transition = 0

bull Any transition (up or down) = 1

bull Reduces frequency of signal

Fast Ethernet Encoding

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

12

10Base2 Implementation

Ethernet segment length

13

bull Coaxial cable has single copper conductor at its center

bull A plastic layer provides insulation between center conductor and a braided metal shield

bull Metal shield helps to block any outside interference from fluorescent lights motors and other computers

bull Resistant to signal interference and can support greater cable lengths between network devices than twisted pair cable

bull Only half-duplex is possible with coaxial cable

EfficiencyCoaxial Cable

A outer plastic sheathB woven copper shieldC inner dielectric insulatorD copper core

14

10Base-T implementation

UTP = Unshielded Twisted Pair

15

Efficiency Twisted Pairbull Twisted pair cabling comes in two varieties

Shielded and Unshielded Unshielded twisted pair (UTP) is the most popular bull Cable has four pairs of wires inside jacketbull Each pair twisted with different number of

twists per inchbull Eliminate interference from adjacent pairs

and other electrical devicesbull Tighter twisting higher supported

transmission rate and greater cost per footbull Most important

bull Two connections for each host Full duplex is now possible

2 Pairs of Wires in a UTP Cable Are Always Used

No matter whether the device is a hub or a switch 2 pairs of wires in a UTP cable are always used to connect a host to the device

2 pairs

12- 16

17

Efficiency Twisted Pair

Category Speed Use

1 1 Mbps Voice Only (Telephone Wire)

2 4 Mbps LocalTalk amp Telephone (Rarely used)

3 16 Mbps 10BaseT Ethernet

4 20 Mbps Token Ring (Rarely used)

5 100 Mbps (2 pair) 100BaseT Ethernet

1000 Mbps (4 pair) Gigabit Ethernet

5e 1000 Mbps Gigabit Ethernet

6 10000 Mbps Gigabit Ethernet

18

Ethernet CablingThe most common kinds of Ethernet cabling

Three kinds of Ethernet cabling

(a) 10Base5 (b) 10Base2 (c) 10Base-T

Difference in Segment length

Costs Less

Ethernet Recap

bull Used Manchester encoding bull More later

bull Ethernet could contain multiple segments and multiple repeaters

bull Used CSMACD for shared media bull What does CSMACD stand for

Carrier Sense Multiple AccessCollision Detection

bull Review this

20

CSMACD Protocol

All hosts transmit amp receive on one channelPackets are of variable size

When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before

transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random

time then return to step 1 binary exponential backoff

21

Ethernet CSMACD algorithm

Algorithm1 NIC receives datagram from network

layer creates frame

2 If NIC senses channel idle starts frame transmission

If NIC senses channel busy waits until channel idle then transmits

3 If NIC transmits entire frame without detecting another transmission NIC is done with frame

Ethernet CSMACD algorithm

4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time

bull Returns to Step 2

22

Minimum Frame Size

bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)

bull Consequently small frames must be padded out to reach MFS

bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)

bull Ethernet and Fast Ethernet the MFS is 64 bytes

bull Gigabit Ethernet it is 416 or 520 bytes

bull Full duplex versions of Ethernet

bull Collisions are avoided and so MFS does not apply

Ethernet Performancebull One result of sharingldquoEtherrdquo

bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance

bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60

percent of the expected value of 10 Mbpsbull How would you increase performance

bull Fewer Collisions reduce the collision domain

Fast Ethernet

Fast Ethernet 8023u

bull When switches became popular bull 10 Mbps Ethernet was standard back in

1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE

Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u

bull Not really New - Kept everything the same

bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science

Fast Ethernetbull Primary concern of Fast Ethernet developers

bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate

bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional

Ethernet installationsbull One version of the Fast Ethernet standard

runs on older Category 3 cable installations

Fast Ethernet

bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps

could coexist

bull How bull A Fast Ethernet-compatible hub does speed

matching when exchanging framesbull Has auto-negotiate feature

bull Devices detect speed of incoming transmissions and adjust appropriately

29

IEEE 8023u - Fast Ethernet

bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard

bull Transmission rate is 100 Mbps

bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)

bull Uses category 3 and category 5 UTP STP and fibre cables

Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5

data-grade twisted-pair wire max distance 100 meters between hub and workstation

bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation

bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration

bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics

Fiber Optic Cablingbull Fiber optic cabling consists of center glass

core surrounded by layers of

protective materials bull Fiber optic cable transmits signals over longer

distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater

speedsbull Center core of fiber cables is made from glass or

plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage

bull Outer insulating jacket made of teflon or PVC

Fiber Optic Cabling

bull Two types of fiber cables

bull Single mode

bull Multimode

bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation

bull Both cables provide high bandwidth at high speeds

bull Single mode can provide more distance but it is more expensive

Fast Ethernetbull Higher frequency used in Fast Ethernet

standard is prone to attenuation

bull Cable distance is more limited than in old Ethernet 10Base-T

bull If encoding scheme of traditional Ethernet were used with Fast Ethernet

bull High-end frequency would be above 200 Mhz

bull Double maximum frequency rating of Category 5 cable

bull New encoding schemes were implemented to allow higher-frequency transmissions

Encoding Schemes for Ethernet

bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by

physical layer

bull Recall Manchester encoding

bull 0 is indicated by a 0 to 1 transition at center of bit

bull 1 is indicated by a 1 to 0 transition at center of bit

bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit

bull Manchester Encodingbull Up transition = 1

bull Down transition = 0

Manchester EncodingStandard Ethernet

Manchester EncodingStandard Ethernet

bull Drawbackbull Manchester encoding can consume up to

approximately twice bandwidth of original signal (20 MHz)

bull Penalty for introducing frequent transitions

bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz

bull Additional bandwidth is not significant issue for coaxial cable transmission but

bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method

Fast Ethernet Encoding

bull 4B5B encoding is a type of Block coding

bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)

bull Group of 4 bits encoded so that an extra 5th bit is added

bull 4B5B encoding (Frame Encoding ndash shorthand)

bull All data is encoded prior to transmission

bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)

bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur

bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used

bull Multi-Level Transmit-3 levels

bull No transition = 0

bull Any transition (up or down) = 1

bull Reduces frequency of signal

Fast Ethernet Encoding

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

13

bull Coaxial cable has single copper conductor at its center

bull A plastic layer provides insulation between center conductor and a braided metal shield

bull Metal shield helps to block any outside interference from fluorescent lights motors and other computers

bull Resistant to signal interference and can support greater cable lengths between network devices than twisted pair cable

bull Only half-duplex is possible with coaxial cable

EfficiencyCoaxial Cable

A outer plastic sheathB woven copper shieldC inner dielectric insulatorD copper core

14

10Base-T implementation

UTP = Unshielded Twisted Pair

15

Efficiency Twisted Pairbull Twisted pair cabling comes in two varieties

Shielded and Unshielded Unshielded twisted pair (UTP) is the most popular bull Cable has four pairs of wires inside jacketbull Each pair twisted with different number of

twists per inchbull Eliminate interference from adjacent pairs

and other electrical devicesbull Tighter twisting higher supported

transmission rate and greater cost per footbull Most important

bull Two connections for each host Full duplex is now possible

2 Pairs of Wires in a UTP Cable Are Always Used

No matter whether the device is a hub or a switch 2 pairs of wires in a UTP cable are always used to connect a host to the device

2 pairs

12- 16

17

Efficiency Twisted Pair

Category Speed Use

1 1 Mbps Voice Only (Telephone Wire)

2 4 Mbps LocalTalk amp Telephone (Rarely used)

3 16 Mbps 10BaseT Ethernet

4 20 Mbps Token Ring (Rarely used)

5 100 Mbps (2 pair) 100BaseT Ethernet

1000 Mbps (4 pair) Gigabit Ethernet

5e 1000 Mbps Gigabit Ethernet

6 10000 Mbps Gigabit Ethernet

18

Ethernet CablingThe most common kinds of Ethernet cabling

Three kinds of Ethernet cabling

(a) 10Base5 (b) 10Base2 (c) 10Base-T

Difference in Segment length

Costs Less

Ethernet Recap

bull Used Manchester encoding bull More later

bull Ethernet could contain multiple segments and multiple repeaters

bull Used CSMACD for shared media bull What does CSMACD stand for

Carrier Sense Multiple AccessCollision Detection

bull Review this

20

CSMACD Protocol

All hosts transmit amp receive on one channelPackets are of variable size

When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before

transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random

time then return to step 1 binary exponential backoff

21

Ethernet CSMACD algorithm

Algorithm1 NIC receives datagram from network

layer creates frame

2 If NIC senses channel idle starts frame transmission

If NIC senses channel busy waits until channel idle then transmits

3 If NIC transmits entire frame without detecting another transmission NIC is done with frame

Ethernet CSMACD algorithm

4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time

bull Returns to Step 2

22

Minimum Frame Size

bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)

bull Consequently small frames must be padded out to reach MFS

bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)

bull Ethernet and Fast Ethernet the MFS is 64 bytes

bull Gigabit Ethernet it is 416 or 520 bytes

bull Full duplex versions of Ethernet

bull Collisions are avoided and so MFS does not apply

Ethernet Performancebull One result of sharingldquoEtherrdquo

bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance

bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60

percent of the expected value of 10 Mbpsbull How would you increase performance

bull Fewer Collisions reduce the collision domain

Fast Ethernet

Fast Ethernet 8023u

bull When switches became popular bull 10 Mbps Ethernet was standard back in

1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE

Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u

bull Not really New - Kept everything the same

bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science

Fast Ethernetbull Primary concern of Fast Ethernet developers

bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate

bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional

Ethernet installationsbull One version of the Fast Ethernet standard

runs on older Category 3 cable installations

Fast Ethernet

bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps

could coexist

bull How bull A Fast Ethernet-compatible hub does speed

matching when exchanging framesbull Has auto-negotiate feature

bull Devices detect speed of incoming transmissions and adjust appropriately

29

IEEE 8023u - Fast Ethernet

bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard

bull Transmission rate is 100 Mbps

bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)

bull Uses category 3 and category 5 UTP STP and fibre cables

Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5

data-grade twisted-pair wire max distance 100 meters between hub and workstation

bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation

bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration

bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics

Fiber Optic Cablingbull Fiber optic cabling consists of center glass

core surrounded by layers of

protective materials bull Fiber optic cable transmits signals over longer

distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater

speedsbull Center core of fiber cables is made from glass or

plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage

bull Outer insulating jacket made of teflon or PVC

Fiber Optic Cabling

bull Two types of fiber cables

bull Single mode

bull Multimode

bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation

bull Both cables provide high bandwidth at high speeds

bull Single mode can provide more distance but it is more expensive

Fast Ethernetbull Higher frequency used in Fast Ethernet

standard is prone to attenuation

bull Cable distance is more limited than in old Ethernet 10Base-T

bull If encoding scheme of traditional Ethernet were used with Fast Ethernet

bull High-end frequency would be above 200 Mhz

bull Double maximum frequency rating of Category 5 cable

bull New encoding schemes were implemented to allow higher-frequency transmissions

Encoding Schemes for Ethernet

bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by

physical layer

bull Recall Manchester encoding

bull 0 is indicated by a 0 to 1 transition at center of bit

bull 1 is indicated by a 1 to 0 transition at center of bit

bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit

bull Manchester Encodingbull Up transition = 1

bull Down transition = 0

Manchester EncodingStandard Ethernet

Manchester EncodingStandard Ethernet

bull Drawbackbull Manchester encoding can consume up to

approximately twice bandwidth of original signal (20 MHz)

bull Penalty for introducing frequent transitions

bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz

bull Additional bandwidth is not significant issue for coaxial cable transmission but

bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method

Fast Ethernet Encoding

bull 4B5B encoding is a type of Block coding

bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)

bull Group of 4 bits encoded so that an extra 5th bit is added

bull 4B5B encoding (Frame Encoding ndash shorthand)

bull All data is encoded prior to transmission

bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)

bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur

bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used

bull Multi-Level Transmit-3 levels

bull No transition = 0

bull Any transition (up or down) = 1

bull Reduces frequency of signal

Fast Ethernet Encoding

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

14

10Base-T implementation

UTP = Unshielded Twisted Pair

15

Efficiency Twisted Pairbull Twisted pair cabling comes in two varieties

Shielded and Unshielded Unshielded twisted pair (UTP) is the most popular bull Cable has four pairs of wires inside jacketbull Each pair twisted with different number of

twists per inchbull Eliminate interference from adjacent pairs

and other electrical devicesbull Tighter twisting higher supported

transmission rate and greater cost per footbull Most important

bull Two connections for each host Full duplex is now possible

2 Pairs of Wires in a UTP Cable Are Always Used

No matter whether the device is a hub or a switch 2 pairs of wires in a UTP cable are always used to connect a host to the device

2 pairs

12- 16

17

Efficiency Twisted Pair

Category Speed Use

1 1 Mbps Voice Only (Telephone Wire)

2 4 Mbps LocalTalk amp Telephone (Rarely used)

3 16 Mbps 10BaseT Ethernet

4 20 Mbps Token Ring (Rarely used)

5 100 Mbps (2 pair) 100BaseT Ethernet

1000 Mbps (4 pair) Gigabit Ethernet

5e 1000 Mbps Gigabit Ethernet

6 10000 Mbps Gigabit Ethernet

18

Ethernet CablingThe most common kinds of Ethernet cabling

Three kinds of Ethernet cabling

(a) 10Base5 (b) 10Base2 (c) 10Base-T

Difference in Segment length

Costs Less

Ethernet Recap

bull Used Manchester encoding bull More later

bull Ethernet could contain multiple segments and multiple repeaters

bull Used CSMACD for shared media bull What does CSMACD stand for

Carrier Sense Multiple AccessCollision Detection

bull Review this

20

CSMACD Protocol

All hosts transmit amp receive on one channelPackets are of variable size

When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before

transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random

time then return to step 1 binary exponential backoff

21

Ethernet CSMACD algorithm

Algorithm1 NIC receives datagram from network

layer creates frame

2 If NIC senses channel idle starts frame transmission

If NIC senses channel busy waits until channel idle then transmits

3 If NIC transmits entire frame without detecting another transmission NIC is done with frame

Ethernet CSMACD algorithm

4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time

bull Returns to Step 2

22

Minimum Frame Size

bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)

bull Consequently small frames must be padded out to reach MFS

bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)

bull Ethernet and Fast Ethernet the MFS is 64 bytes

bull Gigabit Ethernet it is 416 or 520 bytes

bull Full duplex versions of Ethernet

bull Collisions are avoided and so MFS does not apply

Ethernet Performancebull One result of sharingldquoEtherrdquo

bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance

bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60

percent of the expected value of 10 Mbpsbull How would you increase performance

bull Fewer Collisions reduce the collision domain

Fast Ethernet

Fast Ethernet 8023u

bull When switches became popular bull 10 Mbps Ethernet was standard back in

1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE

Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u

bull Not really New - Kept everything the same

bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science

Fast Ethernetbull Primary concern of Fast Ethernet developers

bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate

bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional

Ethernet installationsbull One version of the Fast Ethernet standard

runs on older Category 3 cable installations

Fast Ethernet

bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps

could coexist

bull How bull A Fast Ethernet-compatible hub does speed

matching when exchanging framesbull Has auto-negotiate feature

bull Devices detect speed of incoming transmissions and adjust appropriately

29

IEEE 8023u - Fast Ethernet

bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard

bull Transmission rate is 100 Mbps

bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)

bull Uses category 3 and category 5 UTP STP and fibre cables

Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5

data-grade twisted-pair wire max distance 100 meters between hub and workstation

bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation

bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration

bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics

Fiber Optic Cablingbull Fiber optic cabling consists of center glass

core surrounded by layers of

protective materials bull Fiber optic cable transmits signals over longer

distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater

speedsbull Center core of fiber cables is made from glass or

plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage

bull Outer insulating jacket made of teflon or PVC

Fiber Optic Cabling

bull Two types of fiber cables

bull Single mode

bull Multimode

bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation

bull Both cables provide high bandwidth at high speeds

bull Single mode can provide more distance but it is more expensive

Fast Ethernetbull Higher frequency used in Fast Ethernet

standard is prone to attenuation

bull Cable distance is more limited than in old Ethernet 10Base-T

bull If encoding scheme of traditional Ethernet were used with Fast Ethernet

bull High-end frequency would be above 200 Mhz

bull Double maximum frequency rating of Category 5 cable

bull New encoding schemes were implemented to allow higher-frequency transmissions

Encoding Schemes for Ethernet

bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by

physical layer

bull Recall Manchester encoding

bull 0 is indicated by a 0 to 1 transition at center of bit

bull 1 is indicated by a 1 to 0 transition at center of bit

bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit

bull Manchester Encodingbull Up transition = 1

bull Down transition = 0

Manchester EncodingStandard Ethernet

Manchester EncodingStandard Ethernet

bull Drawbackbull Manchester encoding can consume up to

approximately twice bandwidth of original signal (20 MHz)

bull Penalty for introducing frequent transitions

bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz

bull Additional bandwidth is not significant issue for coaxial cable transmission but

bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method

Fast Ethernet Encoding

bull 4B5B encoding is a type of Block coding

bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)

bull Group of 4 bits encoded so that an extra 5th bit is added

bull 4B5B encoding (Frame Encoding ndash shorthand)

bull All data is encoded prior to transmission

bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)

bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur

bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used

bull Multi-Level Transmit-3 levels

bull No transition = 0

bull Any transition (up or down) = 1

bull Reduces frequency of signal

Fast Ethernet Encoding

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

15

Efficiency Twisted Pairbull Twisted pair cabling comes in two varieties

Shielded and Unshielded Unshielded twisted pair (UTP) is the most popular bull Cable has four pairs of wires inside jacketbull Each pair twisted with different number of

twists per inchbull Eliminate interference from adjacent pairs

and other electrical devicesbull Tighter twisting higher supported

transmission rate and greater cost per footbull Most important

bull Two connections for each host Full duplex is now possible

2 Pairs of Wires in a UTP Cable Are Always Used

No matter whether the device is a hub or a switch 2 pairs of wires in a UTP cable are always used to connect a host to the device

2 pairs

12- 16

17

Efficiency Twisted Pair

Category Speed Use

1 1 Mbps Voice Only (Telephone Wire)

2 4 Mbps LocalTalk amp Telephone (Rarely used)

3 16 Mbps 10BaseT Ethernet

4 20 Mbps Token Ring (Rarely used)

5 100 Mbps (2 pair) 100BaseT Ethernet

1000 Mbps (4 pair) Gigabit Ethernet

5e 1000 Mbps Gigabit Ethernet

6 10000 Mbps Gigabit Ethernet

18

Ethernet CablingThe most common kinds of Ethernet cabling

Three kinds of Ethernet cabling

(a) 10Base5 (b) 10Base2 (c) 10Base-T

Difference in Segment length

Costs Less

Ethernet Recap

bull Used Manchester encoding bull More later

bull Ethernet could contain multiple segments and multiple repeaters

bull Used CSMACD for shared media bull What does CSMACD stand for

Carrier Sense Multiple AccessCollision Detection

bull Review this

20

CSMACD Protocol

All hosts transmit amp receive on one channelPackets are of variable size

When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before

transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random

time then return to step 1 binary exponential backoff

21

Ethernet CSMACD algorithm

Algorithm1 NIC receives datagram from network

layer creates frame

2 If NIC senses channel idle starts frame transmission

If NIC senses channel busy waits until channel idle then transmits

3 If NIC transmits entire frame without detecting another transmission NIC is done with frame

Ethernet CSMACD algorithm

4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time

bull Returns to Step 2

22

Minimum Frame Size

bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)

bull Consequently small frames must be padded out to reach MFS

bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)

bull Ethernet and Fast Ethernet the MFS is 64 bytes

bull Gigabit Ethernet it is 416 or 520 bytes

bull Full duplex versions of Ethernet

bull Collisions are avoided and so MFS does not apply

Ethernet Performancebull One result of sharingldquoEtherrdquo

bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance

bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60

percent of the expected value of 10 Mbpsbull How would you increase performance

bull Fewer Collisions reduce the collision domain

Fast Ethernet

Fast Ethernet 8023u

bull When switches became popular bull 10 Mbps Ethernet was standard back in

1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE

Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u

bull Not really New - Kept everything the same

bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science

Fast Ethernetbull Primary concern of Fast Ethernet developers

bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate

bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional

Ethernet installationsbull One version of the Fast Ethernet standard

runs on older Category 3 cable installations

Fast Ethernet

bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps

could coexist

bull How bull A Fast Ethernet-compatible hub does speed

matching when exchanging framesbull Has auto-negotiate feature

bull Devices detect speed of incoming transmissions and adjust appropriately

29

IEEE 8023u - Fast Ethernet

bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard

bull Transmission rate is 100 Mbps

bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)

bull Uses category 3 and category 5 UTP STP and fibre cables

Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5

data-grade twisted-pair wire max distance 100 meters between hub and workstation

bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation

bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration

bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics

Fiber Optic Cablingbull Fiber optic cabling consists of center glass

core surrounded by layers of

protective materials bull Fiber optic cable transmits signals over longer

distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater

speedsbull Center core of fiber cables is made from glass or

plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage

bull Outer insulating jacket made of teflon or PVC

Fiber Optic Cabling

bull Two types of fiber cables

bull Single mode

bull Multimode

bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation

bull Both cables provide high bandwidth at high speeds

bull Single mode can provide more distance but it is more expensive

Fast Ethernetbull Higher frequency used in Fast Ethernet

standard is prone to attenuation

bull Cable distance is more limited than in old Ethernet 10Base-T

bull If encoding scheme of traditional Ethernet were used with Fast Ethernet

bull High-end frequency would be above 200 Mhz

bull Double maximum frequency rating of Category 5 cable

bull New encoding schemes were implemented to allow higher-frequency transmissions

Encoding Schemes for Ethernet

bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by

physical layer

bull Recall Manchester encoding

bull 0 is indicated by a 0 to 1 transition at center of bit

bull 1 is indicated by a 1 to 0 transition at center of bit

bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit

bull Manchester Encodingbull Up transition = 1

bull Down transition = 0

Manchester EncodingStandard Ethernet

Manchester EncodingStandard Ethernet

bull Drawbackbull Manchester encoding can consume up to

approximately twice bandwidth of original signal (20 MHz)

bull Penalty for introducing frequent transitions

bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz

bull Additional bandwidth is not significant issue for coaxial cable transmission but

bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method

Fast Ethernet Encoding

bull 4B5B encoding is a type of Block coding

bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)

bull Group of 4 bits encoded so that an extra 5th bit is added

bull 4B5B encoding (Frame Encoding ndash shorthand)

bull All data is encoded prior to transmission

bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)

bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur

bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used

bull Multi-Level Transmit-3 levels

bull No transition = 0

bull Any transition (up or down) = 1

bull Reduces frequency of signal

Fast Ethernet Encoding

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

2 Pairs of Wires in a UTP Cable Are Always Used

No matter whether the device is a hub or a switch 2 pairs of wires in a UTP cable are always used to connect a host to the device

2 pairs

12- 16

17

Efficiency Twisted Pair

Category Speed Use

1 1 Mbps Voice Only (Telephone Wire)

2 4 Mbps LocalTalk amp Telephone (Rarely used)

3 16 Mbps 10BaseT Ethernet

4 20 Mbps Token Ring (Rarely used)

5 100 Mbps (2 pair) 100BaseT Ethernet

1000 Mbps (4 pair) Gigabit Ethernet

5e 1000 Mbps Gigabit Ethernet

6 10000 Mbps Gigabit Ethernet

18

Ethernet CablingThe most common kinds of Ethernet cabling

Three kinds of Ethernet cabling

(a) 10Base5 (b) 10Base2 (c) 10Base-T

Difference in Segment length

Costs Less

Ethernet Recap

bull Used Manchester encoding bull More later

bull Ethernet could contain multiple segments and multiple repeaters

bull Used CSMACD for shared media bull What does CSMACD stand for

Carrier Sense Multiple AccessCollision Detection

bull Review this

20

CSMACD Protocol

All hosts transmit amp receive on one channelPackets are of variable size

When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before

transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random

time then return to step 1 binary exponential backoff

21

Ethernet CSMACD algorithm

Algorithm1 NIC receives datagram from network

layer creates frame

2 If NIC senses channel idle starts frame transmission

If NIC senses channel busy waits until channel idle then transmits

3 If NIC transmits entire frame without detecting another transmission NIC is done with frame

Ethernet CSMACD algorithm

4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time

bull Returns to Step 2

22

Minimum Frame Size

bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)

bull Consequently small frames must be padded out to reach MFS

bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)

bull Ethernet and Fast Ethernet the MFS is 64 bytes

bull Gigabit Ethernet it is 416 or 520 bytes

bull Full duplex versions of Ethernet

bull Collisions are avoided and so MFS does not apply

Ethernet Performancebull One result of sharingldquoEtherrdquo

bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance

bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60

percent of the expected value of 10 Mbpsbull How would you increase performance

bull Fewer Collisions reduce the collision domain

Fast Ethernet

Fast Ethernet 8023u

bull When switches became popular bull 10 Mbps Ethernet was standard back in

1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE

Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u

bull Not really New - Kept everything the same

bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science

Fast Ethernetbull Primary concern of Fast Ethernet developers

bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate

bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional

Ethernet installationsbull One version of the Fast Ethernet standard

runs on older Category 3 cable installations

Fast Ethernet

bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps

could coexist

bull How bull A Fast Ethernet-compatible hub does speed

matching when exchanging framesbull Has auto-negotiate feature

bull Devices detect speed of incoming transmissions and adjust appropriately

29

IEEE 8023u - Fast Ethernet

bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard

bull Transmission rate is 100 Mbps

bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)

bull Uses category 3 and category 5 UTP STP and fibre cables

Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5

data-grade twisted-pair wire max distance 100 meters between hub and workstation

bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation

bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration

bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics

Fiber Optic Cablingbull Fiber optic cabling consists of center glass

core surrounded by layers of

protective materials bull Fiber optic cable transmits signals over longer

distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater

speedsbull Center core of fiber cables is made from glass or

plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage

bull Outer insulating jacket made of teflon or PVC

Fiber Optic Cabling

bull Two types of fiber cables

bull Single mode

bull Multimode

bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation

bull Both cables provide high bandwidth at high speeds

bull Single mode can provide more distance but it is more expensive

Fast Ethernetbull Higher frequency used in Fast Ethernet

standard is prone to attenuation

bull Cable distance is more limited than in old Ethernet 10Base-T

bull If encoding scheme of traditional Ethernet were used with Fast Ethernet

bull High-end frequency would be above 200 Mhz

bull Double maximum frequency rating of Category 5 cable

bull New encoding schemes were implemented to allow higher-frequency transmissions

Encoding Schemes for Ethernet

bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by

physical layer

bull Recall Manchester encoding

bull 0 is indicated by a 0 to 1 transition at center of bit

bull 1 is indicated by a 1 to 0 transition at center of bit

bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit

bull Manchester Encodingbull Up transition = 1

bull Down transition = 0

Manchester EncodingStandard Ethernet

Manchester EncodingStandard Ethernet

bull Drawbackbull Manchester encoding can consume up to

approximately twice bandwidth of original signal (20 MHz)

bull Penalty for introducing frequent transitions

bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz

bull Additional bandwidth is not significant issue for coaxial cable transmission but

bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method

Fast Ethernet Encoding

bull 4B5B encoding is a type of Block coding

bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)

bull Group of 4 bits encoded so that an extra 5th bit is added

bull 4B5B encoding (Frame Encoding ndash shorthand)

bull All data is encoded prior to transmission

bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)

bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur

bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used

bull Multi-Level Transmit-3 levels

bull No transition = 0

bull Any transition (up or down) = 1

bull Reduces frequency of signal

Fast Ethernet Encoding

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

17

Efficiency Twisted Pair

Category Speed Use

1 1 Mbps Voice Only (Telephone Wire)

2 4 Mbps LocalTalk amp Telephone (Rarely used)

3 16 Mbps 10BaseT Ethernet

4 20 Mbps Token Ring (Rarely used)

5 100 Mbps (2 pair) 100BaseT Ethernet

1000 Mbps (4 pair) Gigabit Ethernet

5e 1000 Mbps Gigabit Ethernet

6 10000 Mbps Gigabit Ethernet

18

Ethernet CablingThe most common kinds of Ethernet cabling

Three kinds of Ethernet cabling

(a) 10Base5 (b) 10Base2 (c) 10Base-T

Difference in Segment length

Costs Less

Ethernet Recap

bull Used Manchester encoding bull More later

bull Ethernet could contain multiple segments and multiple repeaters

bull Used CSMACD for shared media bull What does CSMACD stand for

Carrier Sense Multiple AccessCollision Detection

bull Review this

20

CSMACD Protocol

All hosts transmit amp receive on one channelPackets are of variable size

When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before

transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random

time then return to step 1 binary exponential backoff

21

Ethernet CSMACD algorithm

Algorithm1 NIC receives datagram from network

layer creates frame

2 If NIC senses channel idle starts frame transmission

If NIC senses channel busy waits until channel idle then transmits

3 If NIC transmits entire frame without detecting another transmission NIC is done with frame

Ethernet CSMACD algorithm

4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time

bull Returns to Step 2

22

Minimum Frame Size

bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)

bull Consequently small frames must be padded out to reach MFS

bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)

bull Ethernet and Fast Ethernet the MFS is 64 bytes

bull Gigabit Ethernet it is 416 or 520 bytes

bull Full duplex versions of Ethernet

bull Collisions are avoided and so MFS does not apply

Ethernet Performancebull One result of sharingldquoEtherrdquo

bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance

bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60

percent of the expected value of 10 Mbpsbull How would you increase performance

bull Fewer Collisions reduce the collision domain

Fast Ethernet

Fast Ethernet 8023u

bull When switches became popular bull 10 Mbps Ethernet was standard back in

1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE

Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u

bull Not really New - Kept everything the same

bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science

Fast Ethernetbull Primary concern of Fast Ethernet developers

bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate

bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional

Ethernet installationsbull One version of the Fast Ethernet standard

runs on older Category 3 cable installations

Fast Ethernet

bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps

could coexist

bull How bull A Fast Ethernet-compatible hub does speed

matching when exchanging framesbull Has auto-negotiate feature

bull Devices detect speed of incoming transmissions and adjust appropriately

29

IEEE 8023u - Fast Ethernet

bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard

bull Transmission rate is 100 Mbps

bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)

bull Uses category 3 and category 5 UTP STP and fibre cables

Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5

data-grade twisted-pair wire max distance 100 meters between hub and workstation

bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation

bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration

bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics

Fiber Optic Cablingbull Fiber optic cabling consists of center glass

core surrounded by layers of

protective materials bull Fiber optic cable transmits signals over longer

distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater

speedsbull Center core of fiber cables is made from glass or

plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage

bull Outer insulating jacket made of teflon or PVC

Fiber Optic Cabling

bull Two types of fiber cables

bull Single mode

bull Multimode

bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation

bull Both cables provide high bandwidth at high speeds

bull Single mode can provide more distance but it is more expensive

Fast Ethernetbull Higher frequency used in Fast Ethernet

standard is prone to attenuation

bull Cable distance is more limited than in old Ethernet 10Base-T

bull If encoding scheme of traditional Ethernet were used with Fast Ethernet

bull High-end frequency would be above 200 Mhz

bull Double maximum frequency rating of Category 5 cable

bull New encoding schemes were implemented to allow higher-frequency transmissions

Encoding Schemes for Ethernet

bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by

physical layer

bull Recall Manchester encoding

bull 0 is indicated by a 0 to 1 transition at center of bit

bull 1 is indicated by a 1 to 0 transition at center of bit

bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit

bull Manchester Encodingbull Up transition = 1

bull Down transition = 0

Manchester EncodingStandard Ethernet

Manchester EncodingStandard Ethernet

bull Drawbackbull Manchester encoding can consume up to

approximately twice bandwidth of original signal (20 MHz)

bull Penalty for introducing frequent transitions

bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz

bull Additional bandwidth is not significant issue for coaxial cable transmission but

bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method

Fast Ethernet Encoding

bull 4B5B encoding is a type of Block coding

bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)

bull Group of 4 bits encoded so that an extra 5th bit is added

bull 4B5B encoding (Frame Encoding ndash shorthand)

bull All data is encoded prior to transmission

bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)

bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur

bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used

bull Multi-Level Transmit-3 levels

bull No transition = 0

bull Any transition (up or down) = 1

bull Reduces frequency of signal

Fast Ethernet Encoding

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

18

Ethernet CablingThe most common kinds of Ethernet cabling

Three kinds of Ethernet cabling

(a) 10Base5 (b) 10Base2 (c) 10Base-T

Difference in Segment length

Costs Less

Ethernet Recap

bull Used Manchester encoding bull More later

bull Ethernet could contain multiple segments and multiple repeaters

bull Used CSMACD for shared media bull What does CSMACD stand for

Carrier Sense Multiple AccessCollision Detection

bull Review this

20

CSMACD Protocol

All hosts transmit amp receive on one channelPackets are of variable size

When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before

transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random

time then return to step 1 binary exponential backoff

21

Ethernet CSMACD algorithm

Algorithm1 NIC receives datagram from network

layer creates frame

2 If NIC senses channel idle starts frame transmission

If NIC senses channel busy waits until channel idle then transmits

3 If NIC transmits entire frame without detecting another transmission NIC is done with frame

Ethernet CSMACD algorithm

4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time

bull Returns to Step 2

22

Minimum Frame Size

bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)

bull Consequently small frames must be padded out to reach MFS

bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)

bull Ethernet and Fast Ethernet the MFS is 64 bytes

bull Gigabit Ethernet it is 416 or 520 bytes

bull Full duplex versions of Ethernet

bull Collisions are avoided and so MFS does not apply

Ethernet Performancebull One result of sharingldquoEtherrdquo

bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance

bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60

percent of the expected value of 10 Mbpsbull How would you increase performance

bull Fewer Collisions reduce the collision domain

Fast Ethernet

Fast Ethernet 8023u

bull When switches became popular bull 10 Mbps Ethernet was standard back in

1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE

Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u

bull Not really New - Kept everything the same

bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science

Fast Ethernetbull Primary concern of Fast Ethernet developers

bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate

bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional

Ethernet installationsbull One version of the Fast Ethernet standard

runs on older Category 3 cable installations

Fast Ethernet

bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps

could coexist

bull How bull A Fast Ethernet-compatible hub does speed

matching when exchanging framesbull Has auto-negotiate feature

bull Devices detect speed of incoming transmissions and adjust appropriately

29

IEEE 8023u - Fast Ethernet

bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard

bull Transmission rate is 100 Mbps

bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)

bull Uses category 3 and category 5 UTP STP and fibre cables

Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5

data-grade twisted-pair wire max distance 100 meters between hub and workstation

bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation

bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration

bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics

Fiber Optic Cablingbull Fiber optic cabling consists of center glass

core surrounded by layers of

protective materials bull Fiber optic cable transmits signals over longer

distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater

speedsbull Center core of fiber cables is made from glass or

plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage

bull Outer insulating jacket made of teflon or PVC

Fiber Optic Cabling

bull Two types of fiber cables

bull Single mode

bull Multimode

bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation

bull Both cables provide high bandwidth at high speeds

bull Single mode can provide more distance but it is more expensive

Fast Ethernetbull Higher frequency used in Fast Ethernet

standard is prone to attenuation

bull Cable distance is more limited than in old Ethernet 10Base-T

bull If encoding scheme of traditional Ethernet were used with Fast Ethernet

bull High-end frequency would be above 200 Mhz

bull Double maximum frequency rating of Category 5 cable

bull New encoding schemes were implemented to allow higher-frequency transmissions

Encoding Schemes for Ethernet

bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by

physical layer

bull Recall Manchester encoding

bull 0 is indicated by a 0 to 1 transition at center of bit

bull 1 is indicated by a 1 to 0 transition at center of bit

bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit

bull Manchester Encodingbull Up transition = 1

bull Down transition = 0

Manchester EncodingStandard Ethernet

Manchester EncodingStandard Ethernet

bull Drawbackbull Manchester encoding can consume up to

approximately twice bandwidth of original signal (20 MHz)

bull Penalty for introducing frequent transitions

bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz

bull Additional bandwidth is not significant issue for coaxial cable transmission but

bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method

Fast Ethernet Encoding

bull 4B5B encoding is a type of Block coding

bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)

bull Group of 4 bits encoded so that an extra 5th bit is added

bull 4B5B encoding (Frame Encoding ndash shorthand)

bull All data is encoded prior to transmission

bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)

bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur

bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used

bull Multi-Level Transmit-3 levels

bull No transition = 0

bull Any transition (up or down) = 1

bull Reduces frequency of signal

Fast Ethernet Encoding

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

Ethernet Recap

bull Used Manchester encoding bull More later

bull Ethernet could contain multiple segments and multiple repeaters

bull Used CSMACD for shared media bull What does CSMACD stand for

Carrier Sense Multiple AccessCollision Detection

bull Review this

20

CSMACD Protocol

All hosts transmit amp receive on one channelPackets are of variable size

When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before

transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random

time then return to step 1 binary exponential backoff

21

Ethernet CSMACD algorithm

Algorithm1 NIC receives datagram from network

layer creates frame

2 If NIC senses channel idle starts frame transmission

If NIC senses channel busy waits until channel idle then transmits

3 If NIC transmits entire frame without detecting another transmission NIC is done with frame

Ethernet CSMACD algorithm

4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time

bull Returns to Step 2

22

Minimum Frame Size

bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)

bull Consequently small frames must be padded out to reach MFS

bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)

bull Ethernet and Fast Ethernet the MFS is 64 bytes

bull Gigabit Ethernet it is 416 or 520 bytes

bull Full duplex versions of Ethernet

bull Collisions are avoided and so MFS does not apply

Ethernet Performancebull One result of sharingldquoEtherrdquo

bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance

bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60

percent of the expected value of 10 Mbpsbull How would you increase performance

bull Fewer Collisions reduce the collision domain

Fast Ethernet

Fast Ethernet 8023u

bull When switches became popular bull 10 Mbps Ethernet was standard back in

1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE

Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u

bull Not really New - Kept everything the same

bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science

Fast Ethernetbull Primary concern of Fast Ethernet developers

bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate

bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional

Ethernet installationsbull One version of the Fast Ethernet standard

runs on older Category 3 cable installations

Fast Ethernet

bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps

could coexist

bull How bull A Fast Ethernet-compatible hub does speed

matching when exchanging framesbull Has auto-negotiate feature

bull Devices detect speed of incoming transmissions and adjust appropriately

29

IEEE 8023u - Fast Ethernet

bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard

bull Transmission rate is 100 Mbps

bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)

bull Uses category 3 and category 5 UTP STP and fibre cables

Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5

data-grade twisted-pair wire max distance 100 meters between hub and workstation

bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation

bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration

bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics

Fiber Optic Cablingbull Fiber optic cabling consists of center glass

core surrounded by layers of

protective materials bull Fiber optic cable transmits signals over longer

distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater

speedsbull Center core of fiber cables is made from glass or

plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage

bull Outer insulating jacket made of teflon or PVC

Fiber Optic Cabling

bull Two types of fiber cables

bull Single mode

bull Multimode

bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation

bull Both cables provide high bandwidth at high speeds

bull Single mode can provide more distance but it is more expensive

Fast Ethernetbull Higher frequency used in Fast Ethernet

standard is prone to attenuation

bull Cable distance is more limited than in old Ethernet 10Base-T

bull If encoding scheme of traditional Ethernet were used with Fast Ethernet

bull High-end frequency would be above 200 Mhz

bull Double maximum frequency rating of Category 5 cable

bull New encoding schemes were implemented to allow higher-frequency transmissions

Encoding Schemes for Ethernet

bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by

physical layer

bull Recall Manchester encoding

bull 0 is indicated by a 0 to 1 transition at center of bit

bull 1 is indicated by a 1 to 0 transition at center of bit

bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit

bull Manchester Encodingbull Up transition = 1

bull Down transition = 0

Manchester EncodingStandard Ethernet

Manchester EncodingStandard Ethernet

bull Drawbackbull Manchester encoding can consume up to

approximately twice bandwidth of original signal (20 MHz)

bull Penalty for introducing frequent transitions

bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz

bull Additional bandwidth is not significant issue for coaxial cable transmission but

bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method

Fast Ethernet Encoding

bull 4B5B encoding is a type of Block coding

bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)

bull Group of 4 bits encoded so that an extra 5th bit is added

bull 4B5B encoding (Frame Encoding ndash shorthand)

bull All data is encoded prior to transmission

bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)

bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur

bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used

bull Multi-Level Transmit-3 levels

bull No transition = 0

bull Any transition (up or down) = 1

bull Reduces frequency of signal

Fast Ethernet Encoding

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

20

CSMACD Protocol

All hosts transmit amp receive on one channelPackets are of variable size

When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before

transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random

time then return to step 1 binary exponential backoff

21

Ethernet CSMACD algorithm

Algorithm1 NIC receives datagram from network

layer creates frame

2 If NIC senses channel idle starts frame transmission

If NIC senses channel busy waits until channel idle then transmits

3 If NIC transmits entire frame without detecting another transmission NIC is done with frame

Ethernet CSMACD algorithm

4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time

bull Returns to Step 2

22

Minimum Frame Size

bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)

bull Consequently small frames must be padded out to reach MFS

bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)

bull Ethernet and Fast Ethernet the MFS is 64 bytes

bull Gigabit Ethernet it is 416 or 520 bytes

bull Full duplex versions of Ethernet

bull Collisions are avoided and so MFS does not apply

Ethernet Performancebull One result of sharingldquoEtherrdquo

bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance

bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60

percent of the expected value of 10 Mbpsbull How would you increase performance

bull Fewer Collisions reduce the collision domain

Fast Ethernet

Fast Ethernet 8023u

bull When switches became popular bull 10 Mbps Ethernet was standard back in

1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE

Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u

bull Not really New - Kept everything the same

bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science

Fast Ethernetbull Primary concern of Fast Ethernet developers

bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate

bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional

Ethernet installationsbull One version of the Fast Ethernet standard

runs on older Category 3 cable installations

Fast Ethernet

bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps

could coexist

bull How bull A Fast Ethernet-compatible hub does speed

matching when exchanging framesbull Has auto-negotiate feature

bull Devices detect speed of incoming transmissions and adjust appropriately

29

IEEE 8023u - Fast Ethernet

bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard

bull Transmission rate is 100 Mbps

bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)

bull Uses category 3 and category 5 UTP STP and fibre cables

Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5

data-grade twisted-pair wire max distance 100 meters between hub and workstation

bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation

bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration

bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics

Fiber Optic Cablingbull Fiber optic cabling consists of center glass

core surrounded by layers of

protective materials bull Fiber optic cable transmits signals over longer

distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater

speedsbull Center core of fiber cables is made from glass or

plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage

bull Outer insulating jacket made of teflon or PVC

Fiber Optic Cabling

bull Two types of fiber cables

bull Single mode

bull Multimode

bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation

bull Both cables provide high bandwidth at high speeds

bull Single mode can provide more distance but it is more expensive

Fast Ethernetbull Higher frequency used in Fast Ethernet

standard is prone to attenuation

bull Cable distance is more limited than in old Ethernet 10Base-T

bull If encoding scheme of traditional Ethernet were used with Fast Ethernet

bull High-end frequency would be above 200 Mhz

bull Double maximum frequency rating of Category 5 cable

bull New encoding schemes were implemented to allow higher-frequency transmissions

Encoding Schemes for Ethernet

bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by

physical layer

bull Recall Manchester encoding

bull 0 is indicated by a 0 to 1 transition at center of bit

bull 1 is indicated by a 1 to 0 transition at center of bit

bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit

bull Manchester Encodingbull Up transition = 1

bull Down transition = 0

Manchester EncodingStandard Ethernet

Manchester EncodingStandard Ethernet

bull Drawbackbull Manchester encoding can consume up to

approximately twice bandwidth of original signal (20 MHz)

bull Penalty for introducing frequent transitions

bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz

bull Additional bandwidth is not significant issue for coaxial cable transmission but

bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method

Fast Ethernet Encoding

bull 4B5B encoding is a type of Block coding

bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)

bull Group of 4 bits encoded so that an extra 5th bit is added

bull 4B5B encoding (Frame Encoding ndash shorthand)

bull All data is encoded prior to transmission

bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)

bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur

bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used

bull Multi-Level Transmit-3 levels

bull No transition = 0

bull Any transition (up or down) = 1

bull Reduces frequency of signal

Fast Ethernet Encoding

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

21

Ethernet CSMACD algorithm

Algorithm1 NIC receives datagram from network

layer creates frame

2 If NIC senses channel idle starts frame transmission

If NIC senses channel busy waits until channel idle then transmits

3 If NIC transmits entire frame without detecting another transmission NIC is done with frame

Ethernet CSMACD algorithm

4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time

bull Returns to Step 2

22

Minimum Frame Size

bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)

bull Consequently small frames must be padded out to reach MFS

bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)

bull Ethernet and Fast Ethernet the MFS is 64 bytes

bull Gigabit Ethernet it is 416 or 520 bytes

bull Full duplex versions of Ethernet

bull Collisions are avoided and so MFS does not apply

Ethernet Performancebull One result of sharingldquoEtherrdquo

bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance

bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60

percent of the expected value of 10 Mbpsbull How would you increase performance

bull Fewer Collisions reduce the collision domain

Fast Ethernet

Fast Ethernet 8023u

bull When switches became popular bull 10 Mbps Ethernet was standard back in

1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE

Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u

bull Not really New - Kept everything the same

bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science

Fast Ethernetbull Primary concern of Fast Ethernet developers

bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate

bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional

Ethernet installationsbull One version of the Fast Ethernet standard

runs on older Category 3 cable installations

Fast Ethernet

bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps

could coexist

bull How bull A Fast Ethernet-compatible hub does speed

matching when exchanging framesbull Has auto-negotiate feature

bull Devices detect speed of incoming transmissions and adjust appropriately

29

IEEE 8023u - Fast Ethernet

bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard

bull Transmission rate is 100 Mbps

bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)

bull Uses category 3 and category 5 UTP STP and fibre cables

Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5

data-grade twisted-pair wire max distance 100 meters between hub and workstation

bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation

bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration

bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics

Fiber Optic Cablingbull Fiber optic cabling consists of center glass

core surrounded by layers of

protective materials bull Fiber optic cable transmits signals over longer

distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater

speedsbull Center core of fiber cables is made from glass or

plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage

bull Outer insulating jacket made of teflon or PVC

Fiber Optic Cabling

bull Two types of fiber cables

bull Single mode

bull Multimode

bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation

bull Both cables provide high bandwidth at high speeds

bull Single mode can provide more distance but it is more expensive

Fast Ethernetbull Higher frequency used in Fast Ethernet

standard is prone to attenuation

bull Cable distance is more limited than in old Ethernet 10Base-T

bull If encoding scheme of traditional Ethernet were used with Fast Ethernet

bull High-end frequency would be above 200 Mhz

bull Double maximum frequency rating of Category 5 cable

bull New encoding schemes were implemented to allow higher-frequency transmissions

Encoding Schemes for Ethernet

bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by

physical layer

bull Recall Manchester encoding

bull 0 is indicated by a 0 to 1 transition at center of bit

bull 1 is indicated by a 1 to 0 transition at center of bit

bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit

bull Manchester Encodingbull Up transition = 1

bull Down transition = 0

Manchester EncodingStandard Ethernet

Manchester EncodingStandard Ethernet

bull Drawbackbull Manchester encoding can consume up to

approximately twice bandwidth of original signal (20 MHz)

bull Penalty for introducing frequent transitions

bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz

bull Additional bandwidth is not significant issue for coaxial cable transmission but

bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method

Fast Ethernet Encoding

bull 4B5B encoding is a type of Block coding

bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)

bull Group of 4 bits encoded so that an extra 5th bit is added

bull 4B5B encoding (Frame Encoding ndash shorthand)

bull All data is encoded prior to transmission

bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)

bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur

bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used

bull Multi-Level Transmit-3 levels

bull No transition = 0

bull Any transition (up or down) = 1

bull Reduces frequency of signal

Fast Ethernet Encoding

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

Ethernet CSMACD algorithm

4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time

bull Returns to Step 2

22

Minimum Frame Size

bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)

bull Consequently small frames must be padded out to reach MFS

bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)

bull Ethernet and Fast Ethernet the MFS is 64 bytes

bull Gigabit Ethernet it is 416 or 520 bytes

bull Full duplex versions of Ethernet

bull Collisions are avoided and so MFS does not apply

Ethernet Performancebull One result of sharingldquoEtherrdquo

bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance

bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60

percent of the expected value of 10 Mbpsbull How would you increase performance

bull Fewer Collisions reduce the collision domain

Fast Ethernet

Fast Ethernet 8023u

bull When switches became popular bull 10 Mbps Ethernet was standard back in

1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE

Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u

bull Not really New - Kept everything the same

bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science

Fast Ethernetbull Primary concern of Fast Ethernet developers

bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate

bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional

Ethernet installationsbull One version of the Fast Ethernet standard

runs on older Category 3 cable installations

Fast Ethernet

bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps

could coexist

bull How bull A Fast Ethernet-compatible hub does speed

matching when exchanging framesbull Has auto-negotiate feature

bull Devices detect speed of incoming transmissions and adjust appropriately

29

IEEE 8023u - Fast Ethernet

bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard

bull Transmission rate is 100 Mbps

bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)

bull Uses category 3 and category 5 UTP STP and fibre cables

Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5

data-grade twisted-pair wire max distance 100 meters between hub and workstation

bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation

bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration

bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics

Fiber Optic Cablingbull Fiber optic cabling consists of center glass

core surrounded by layers of

protective materials bull Fiber optic cable transmits signals over longer

distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater

speedsbull Center core of fiber cables is made from glass or

plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage

bull Outer insulating jacket made of teflon or PVC

Fiber Optic Cabling

bull Two types of fiber cables

bull Single mode

bull Multimode

bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation

bull Both cables provide high bandwidth at high speeds

bull Single mode can provide more distance but it is more expensive

Fast Ethernetbull Higher frequency used in Fast Ethernet

standard is prone to attenuation

bull Cable distance is more limited than in old Ethernet 10Base-T

bull If encoding scheme of traditional Ethernet were used with Fast Ethernet

bull High-end frequency would be above 200 Mhz

bull Double maximum frequency rating of Category 5 cable

bull New encoding schemes were implemented to allow higher-frequency transmissions

Encoding Schemes for Ethernet

bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by

physical layer

bull Recall Manchester encoding

bull 0 is indicated by a 0 to 1 transition at center of bit

bull 1 is indicated by a 1 to 0 transition at center of bit

bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit

bull Manchester Encodingbull Up transition = 1

bull Down transition = 0

Manchester EncodingStandard Ethernet

Manchester EncodingStandard Ethernet

bull Drawbackbull Manchester encoding can consume up to

approximately twice bandwidth of original signal (20 MHz)

bull Penalty for introducing frequent transitions

bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz

bull Additional bandwidth is not significant issue for coaxial cable transmission but

bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method

Fast Ethernet Encoding

bull 4B5B encoding is a type of Block coding

bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)

bull Group of 4 bits encoded so that an extra 5th bit is added

bull 4B5B encoding (Frame Encoding ndash shorthand)

bull All data is encoded prior to transmission

bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)

bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur

bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used

bull Multi-Level Transmit-3 levels

bull No transition = 0

bull Any transition (up or down) = 1

bull Reduces frequency of signal

Fast Ethernet Encoding

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

Minimum Frame Size

bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)

bull Consequently small frames must be padded out to reach MFS

bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)

bull Ethernet and Fast Ethernet the MFS is 64 bytes

bull Gigabit Ethernet it is 416 or 520 bytes

bull Full duplex versions of Ethernet

bull Collisions are avoided and so MFS does not apply

Ethernet Performancebull One result of sharingldquoEtherrdquo

bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance

bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60

percent of the expected value of 10 Mbpsbull How would you increase performance

bull Fewer Collisions reduce the collision domain

Fast Ethernet

Fast Ethernet 8023u

bull When switches became popular bull 10 Mbps Ethernet was standard back in

1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE

Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u

bull Not really New - Kept everything the same

bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science

Fast Ethernetbull Primary concern of Fast Ethernet developers

bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate

bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional

Ethernet installationsbull One version of the Fast Ethernet standard

runs on older Category 3 cable installations

Fast Ethernet

bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps

could coexist

bull How bull A Fast Ethernet-compatible hub does speed

matching when exchanging framesbull Has auto-negotiate feature

bull Devices detect speed of incoming transmissions and adjust appropriately

29

IEEE 8023u - Fast Ethernet

bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard

bull Transmission rate is 100 Mbps

bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)

bull Uses category 3 and category 5 UTP STP and fibre cables

Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5

data-grade twisted-pair wire max distance 100 meters between hub and workstation

bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation

bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration

bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics

Fiber Optic Cablingbull Fiber optic cabling consists of center glass

core surrounded by layers of

protective materials bull Fiber optic cable transmits signals over longer

distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater

speedsbull Center core of fiber cables is made from glass or

plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage

bull Outer insulating jacket made of teflon or PVC

Fiber Optic Cabling

bull Two types of fiber cables

bull Single mode

bull Multimode

bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation

bull Both cables provide high bandwidth at high speeds

bull Single mode can provide more distance but it is more expensive

Fast Ethernetbull Higher frequency used in Fast Ethernet

standard is prone to attenuation

bull Cable distance is more limited than in old Ethernet 10Base-T

bull If encoding scheme of traditional Ethernet were used with Fast Ethernet

bull High-end frequency would be above 200 Mhz

bull Double maximum frequency rating of Category 5 cable

bull New encoding schemes were implemented to allow higher-frequency transmissions

Encoding Schemes for Ethernet

bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by

physical layer

bull Recall Manchester encoding

bull 0 is indicated by a 0 to 1 transition at center of bit

bull 1 is indicated by a 1 to 0 transition at center of bit

bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit

bull Manchester Encodingbull Up transition = 1

bull Down transition = 0

Manchester EncodingStandard Ethernet

Manchester EncodingStandard Ethernet

bull Drawbackbull Manchester encoding can consume up to

approximately twice bandwidth of original signal (20 MHz)

bull Penalty for introducing frequent transitions

bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz

bull Additional bandwidth is not significant issue for coaxial cable transmission but

bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method

Fast Ethernet Encoding

bull 4B5B encoding is a type of Block coding

bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)

bull Group of 4 bits encoded so that an extra 5th bit is added

bull 4B5B encoding (Frame Encoding ndash shorthand)

bull All data is encoded prior to transmission

bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)

bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur

bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used

bull Multi-Level Transmit-3 levels

bull No transition = 0

bull Any transition (up or down) = 1

bull Reduces frequency of signal

Fast Ethernet Encoding

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

Ethernet Performancebull One result of sharingldquoEtherrdquo

bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance

bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60

percent of the expected value of 10 Mbpsbull How would you increase performance

bull Fewer Collisions reduce the collision domain

Fast Ethernet

Fast Ethernet 8023u

bull When switches became popular bull 10 Mbps Ethernet was standard back in

1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE

Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u

bull Not really New - Kept everything the same

bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science

Fast Ethernetbull Primary concern of Fast Ethernet developers

bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate

bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional

Ethernet installationsbull One version of the Fast Ethernet standard

runs on older Category 3 cable installations

Fast Ethernet

bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps

could coexist

bull How bull A Fast Ethernet-compatible hub does speed

matching when exchanging framesbull Has auto-negotiate feature

bull Devices detect speed of incoming transmissions and adjust appropriately

29

IEEE 8023u - Fast Ethernet

bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard

bull Transmission rate is 100 Mbps

bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)

bull Uses category 3 and category 5 UTP STP and fibre cables

Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5

data-grade twisted-pair wire max distance 100 meters between hub and workstation

bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation

bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration

bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics

Fiber Optic Cablingbull Fiber optic cabling consists of center glass

core surrounded by layers of

protective materials bull Fiber optic cable transmits signals over longer

distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater

speedsbull Center core of fiber cables is made from glass or

plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage

bull Outer insulating jacket made of teflon or PVC

Fiber Optic Cabling

bull Two types of fiber cables

bull Single mode

bull Multimode

bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation

bull Both cables provide high bandwidth at high speeds

bull Single mode can provide more distance but it is more expensive

Fast Ethernetbull Higher frequency used in Fast Ethernet

standard is prone to attenuation

bull Cable distance is more limited than in old Ethernet 10Base-T

bull If encoding scheme of traditional Ethernet were used with Fast Ethernet

bull High-end frequency would be above 200 Mhz

bull Double maximum frequency rating of Category 5 cable

bull New encoding schemes were implemented to allow higher-frequency transmissions

Encoding Schemes for Ethernet

bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by

physical layer

bull Recall Manchester encoding

bull 0 is indicated by a 0 to 1 transition at center of bit

bull 1 is indicated by a 1 to 0 transition at center of bit

bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit

bull Manchester Encodingbull Up transition = 1

bull Down transition = 0

Manchester EncodingStandard Ethernet

Manchester EncodingStandard Ethernet

bull Drawbackbull Manchester encoding can consume up to

approximately twice bandwidth of original signal (20 MHz)

bull Penalty for introducing frequent transitions

bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz

bull Additional bandwidth is not significant issue for coaxial cable transmission but

bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method

Fast Ethernet Encoding

bull 4B5B encoding is a type of Block coding

bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)

bull Group of 4 bits encoded so that an extra 5th bit is added

bull 4B5B encoding (Frame Encoding ndash shorthand)

bull All data is encoded prior to transmission

bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)

bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur

bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used

bull Multi-Level Transmit-3 levels

bull No transition = 0

bull Any transition (up or down) = 1

bull Reduces frequency of signal

Fast Ethernet Encoding

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

Fast Ethernet

Fast Ethernet 8023u

bull When switches became popular bull 10 Mbps Ethernet was standard back in

1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE

Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u

bull Not really New - Kept everything the same

bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science

Fast Ethernetbull Primary concern of Fast Ethernet developers

bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate

bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional

Ethernet installationsbull One version of the Fast Ethernet standard

runs on older Category 3 cable installations

Fast Ethernet

bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps

could coexist

bull How bull A Fast Ethernet-compatible hub does speed

matching when exchanging framesbull Has auto-negotiate feature

bull Devices detect speed of incoming transmissions and adjust appropriately

29

IEEE 8023u - Fast Ethernet

bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard

bull Transmission rate is 100 Mbps

bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)

bull Uses category 3 and category 5 UTP STP and fibre cables

Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5

data-grade twisted-pair wire max distance 100 meters between hub and workstation

bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation

bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration

bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics

Fiber Optic Cablingbull Fiber optic cabling consists of center glass

core surrounded by layers of

protective materials bull Fiber optic cable transmits signals over longer

distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater

speedsbull Center core of fiber cables is made from glass or

plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage

bull Outer insulating jacket made of teflon or PVC

Fiber Optic Cabling

bull Two types of fiber cables

bull Single mode

bull Multimode

bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation

bull Both cables provide high bandwidth at high speeds

bull Single mode can provide more distance but it is more expensive

Fast Ethernetbull Higher frequency used in Fast Ethernet

standard is prone to attenuation

bull Cable distance is more limited than in old Ethernet 10Base-T

bull If encoding scheme of traditional Ethernet were used with Fast Ethernet

bull High-end frequency would be above 200 Mhz

bull Double maximum frequency rating of Category 5 cable

bull New encoding schemes were implemented to allow higher-frequency transmissions

Encoding Schemes for Ethernet

bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by

physical layer

bull Recall Manchester encoding

bull 0 is indicated by a 0 to 1 transition at center of bit

bull 1 is indicated by a 1 to 0 transition at center of bit

bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit

bull Manchester Encodingbull Up transition = 1

bull Down transition = 0

Manchester EncodingStandard Ethernet

Manchester EncodingStandard Ethernet

bull Drawbackbull Manchester encoding can consume up to

approximately twice bandwidth of original signal (20 MHz)

bull Penalty for introducing frequent transitions

bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz

bull Additional bandwidth is not significant issue for coaxial cable transmission but

bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method

Fast Ethernet Encoding

bull 4B5B encoding is a type of Block coding

bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)

bull Group of 4 bits encoded so that an extra 5th bit is added

bull 4B5B encoding (Frame Encoding ndash shorthand)

bull All data is encoded prior to transmission

bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)

bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur

bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used

bull Multi-Level Transmit-3 levels

bull No transition = 0

bull Any transition (up or down) = 1

bull Reduces frequency of signal

Fast Ethernet Encoding

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

Fast Ethernet 8023u

bull When switches became popular bull 10 Mbps Ethernet was standard back in

1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE

Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u

bull Not really New - Kept everything the same

bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science

Fast Ethernetbull Primary concern of Fast Ethernet developers

bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate

bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional

Ethernet installationsbull One version of the Fast Ethernet standard

runs on older Category 3 cable installations

Fast Ethernet

bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps

could coexist

bull How bull A Fast Ethernet-compatible hub does speed

matching when exchanging framesbull Has auto-negotiate feature

bull Devices detect speed of incoming transmissions and adjust appropriately

29

IEEE 8023u - Fast Ethernet

bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard

bull Transmission rate is 100 Mbps

bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)

bull Uses category 3 and category 5 UTP STP and fibre cables

Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5

data-grade twisted-pair wire max distance 100 meters between hub and workstation

bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation

bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration

bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics

Fiber Optic Cablingbull Fiber optic cabling consists of center glass

core surrounded by layers of

protective materials bull Fiber optic cable transmits signals over longer

distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater

speedsbull Center core of fiber cables is made from glass or

plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage

bull Outer insulating jacket made of teflon or PVC

Fiber Optic Cabling

bull Two types of fiber cables

bull Single mode

bull Multimode

bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation

bull Both cables provide high bandwidth at high speeds

bull Single mode can provide more distance but it is more expensive

Fast Ethernetbull Higher frequency used in Fast Ethernet

standard is prone to attenuation

bull Cable distance is more limited than in old Ethernet 10Base-T

bull If encoding scheme of traditional Ethernet were used with Fast Ethernet

bull High-end frequency would be above 200 Mhz

bull Double maximum frequency rating of Category 5 cable

bull New encoding schemes were implemented to allow higher-frequency transmissions

Encoding Schemes for Ethernet

bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by

physical layer

bull Recall Manchester encoding

bull 0 is indicated by a 0 to 1 transition at center of bit

bull 1 is indicated by a 1 to 0 transition at center of bit

bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit

bull Manchester Encodingbull Up transition = 1

bull Down transition = 0

Manchester EncodingStandard Ethernet

Manchester EncodingStandard Ethernet

bull Drawbackbull Manchester encoding can consume up to

approximately twice bandwidth of original signal (20 MHz)

bull Penalty for introducing frequent transitions

bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz

bull Additional bandwidth is not significant issue for coaxial cable transmission but

bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method

Fast Ethernet Encoding

bull 4B5B encoding is a type of Block coding

bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)

bull Group of 4 bits encoded so that an extra 5th bit is added

bull 4B5B encoding (Frame Encoding ndash shorthand)

bull All data is encoded prior to transmission

bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)

bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur

bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used

bull Multi-Level Transmit-3 levels

bull No transition = 0

bull Any transition (up or down) = 1

bull Reduces frequency of signal

Fast Ethernet Encoding

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

Fast Ethernetbull Primary concern of Fast Ethernet developers

bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate

bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional

Ethernet installationsbull One version of the Fast Ethernet standard

runs on older Category 3 cable installations

Fast Ethernet

bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps

could coexist

bull How bull A Fast Ethernet-compatible hub does speed

matching when exchanging framesbull Has auto-negotiate feature

bull Devices detect speed of incoming transmissions and adjust appropriately

29

IEEE 8023u - Fast Ethernet

bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard

bull Transmission rate is 100 Mbps

bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)

bull Uses category 3 and category 5 UTP STP and fibre cables

Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5

data-grade twisted-pair wire max distance 100 meters between hub and workstation

bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation

bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration

bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics

Fiber Optic Cablingbull Fiber optic cabling consists of center glass

core surrounded by layers of

protective materials bull Fiber optic cable transmits signals over longer

distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater

speedsbull Center core of fiber cables is made from glass or

plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage

bull Outer insulating jacket made of teflon or PVC

Fiber Optic Cabling

bull Two types of fiber cables

bull Single mode

bull Multimode

bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation

bull Both cables provide high bandwidth at high speeds

bull Single mode can provide more distance but it is more expensive

Fast Ethernetbull Higher frequency used in Fast Ethernet

standard is prone to attenuation

bull Cable distance is more limited than in old Ethernet 10Base-T

bull If encoding scheme of traditional Ethernet were used with Fast Ethernet

bull High-end frequency would be above 200 Mhz

bull Double maximum frequency rating of Category 5 cable

bull New encoding schemes were implemented to allow higher-frequency transmissions

Encoding Schemes for Ethernet

bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by

physical layer

bull Recall Manchester encoding

bull 0 is indicated by a 0 to 1 transition at center of bit

bull 1 is indicated by a 1 to 0 transition at center of bit

bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit

bull Manchester Encodingbull Up transition = 1

bull Down transition = 0

Manchester EncodingStandard Ethernet

Manchester EncodingStandard Ethernet

bull Drawbackbull Manchester encoding can consume up to

approximately twice bandwidth of original signal (20 MHz)

bull Penalty for introducing frequent transitions

bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz

bull Additional bandwidth is not significant issue for coaxial cable transmission but

bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method

Fast Ethernet Encoding

bull 4B5B encoding is a type of Block coding

bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)

bull Group of 4 bits encoded so that an extra 5th bit is added

bull 4B5B encoding (Frame Encoding ndash shorthand)

bull All data is encoded prior to transmission

bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)

bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur

bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used

bull Multi-Level Transmit-3 levels

bull No transition = 0

bull Any transition (up or down) = 1

bull Reduces frequency of signal

Fast Ethernet Encoding

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

Fast Ethernet

bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps

could coexist

bull How bull A Fast Ethernet-compatible hub does speed

matching when exchanging framesbull Has auto-negotiate feature

bull Devices detect speed of incoming transmissions and adjust appropriately

29

IEEE 8023u - Fast Ethernet

bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard

bull Transmission rate is 100 Mbps

bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)

bull Uses category 3 and category 5 UTP STP and fibre cables

Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5

data-grade twisted-pair wire max distance 100 meters between hub and workstation

bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation

bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration

bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics

Fiber Optic Cablingbull Fiber optic cabling consists of center glass

core surrounded by layers of

protective materials bull Fiber optic cable transmits signals over longer

distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater

speedsbull Center core of fiber cables is made from glass or

plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage

bull Outer insulating jacket made of teflon or PVC

Fiber Optic Cabling

bull Two types of fiber cables

bull Single mode

bull Multimode

bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation

bull Both cables provide high bandwidth at high speeds

bull Single mode can provide more distance but it is more expensive

Fast Ethernetbull Higher frequency used in Fast Ethernet

standard is prone to attenuation

bull Cable distance is more limited than in old Ethernet 10Base-T

bull If encoding scheme of traditional Ethernet were used with Fast Ethernet

bull High-end frequency would be above 200 Mhz

bull Double maximum frequency rating of Category 5 cable

bull New encoding schemes were implemented to allow higher-frequency transmissions

Encoding Schemes for Ethernet

bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by

physical layer

bull Recall Manchester encoding

bull 0 is indicated by a 0 to 1 transition at center of bit

bull 1 is indicated by a 1 to 0 transition at center of bit

bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit

bull Manchester Encodingbull Up transition = 1

bull Down transition = 0

Manchester EncodingStandard Ethernet

Manchester EncodingStandard Ethernet

bull Drawbackbull Manchester encoding can consume up to

approximately twice bandwidth of original signal (20 MHz)

bull Penalty for introducing frequent transitions

bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz

bull Additional bandwidth is not significant issue for coaxial cable transmission but

bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method

Fast Ethernet Encoding

bull 4B5B encoding is a type of Block coding

bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)

bull Group of 4 bits encoded so that an extra 5th bit is added

bull 4B5B encoding (Frame Encoding ndash shorthand)

bull All data is encoded prior to transmission

bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)

bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur

bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used

bull Multi-Level Transmit-3 levels

bull No transition = 0

bull Any transition (up or down) = 1

bull Reduces frequency of signal

Fast Ethernet Encoding

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

29

IEEE 8023u - Fast Ethernet

bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard

bull Transmission rate is 100 Mbps

bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)

bull Uses category 3 and category 5 UTP STP and fibre cables

Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5

data-grade twisted-pair wire max distance 100 meters between hub and workstation

bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation

bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration

bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics

Fiber Optic Cablingbull Fiber optic cabling consists of center glass

core surrounded by layers of

protective materials bull Fiber optic cable transmits signals over longer

distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater

speedsbull Center core of fiber cables is made from glass or

plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage

bull Outer insulating jacket made of teflon or PVC

Fiber Optic Cabling

bull Two types of fiber cables

bull Single mode

bull Multimode

bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation

bull Both cables provide high bandwidth at high speeds

bull Single mode can provide more distance but it is more expensive

Fast Ethernetbull Higher frequency used in Fast Ethernet

standard is prone to attenuation

bull Cable distance is more limited than in old Ethernet 10Base-T

bull If encoding scheme of traditional Ethernet were used with Fast Ethernet

bull High-end frequency would be above 200 Mhz

bull Double maximum frequency rating of Category 5 cable

bull New encoding schemes were implemented to allow higher-frequency transmissions

Encoding Schemes for Ethernet

bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by

physical layer

bull Recall Manchester encoding

bull 0 is indicated by a 0 to 1 transition at center of bit

bull 1 is indicated by a 1 to 0 transition at center of bit

bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit

bull Manchester Encodingbull Up transition = 1

bull Down transition = 0

Manchester EncodingStandard Ethernet

Manchester EncodingStandard Ethernet

bull Drawbackbull Manchester encoding can consume up to

approximately twice bandwidth of original signal (20 MHz)

bull Penalty for introducing frequent transitions

bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz

bull Additional bandwidth is not significant issue for coaxial cable transmission but

bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method

Fast Ethernet Encoding

bull 4B5B encoding is a type of Block coding

bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)

bull Group of 4 bits encoded so that an extra 5th bit is added

bull 4B5B encoding (Frame Encoding ndash shorthand)

bull All data is encoded prior to transmission

bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)

bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur

bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used

bull Multi-Level Transmit-3 levels

bull No transition = 0

bull Any transition (up or down) = 1

bull Reduces frequency of signal

Fast Ethernet Encoding

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5

data-grade twisted-pair wire max distance 100 meters between hub and workstation

bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation

bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration

bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics

Fiber Optic Cablingbull Fiber optic cabling consists of center glass

core surrounded by layers of

protective materials bull Fiber optic cable transmits signals over longer

distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater

speedsbull Center core of fiber cables is made from glass or

plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage

bull Outer insulating jacket made of teflon or PVC

Fiber Optic Cabling

bull Two types of fiber cables

bull Single mode

bull Multimode

bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation

bull Both cables provide high bandwidth at high speeds

bull Single mode can provide more distance but it is more expensive

Fast Ethernetbull Higher frequency used in Fast Ethernet

standard is prone to attenuation

bull Cable distance is more limited than in old Ethernet 10Base-T

bull If encoding scheme of traditional Ethernet were used with Fast Ethernet

bull High-end frequency would be above 200 Mhz

bull Double maximum frequency rating of Category 5 cable

bull New encoding schemes were implemented to allow higher-frequency transmissions

Encoding Schemes for Ethernet

bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by

physical layer

bull Recall Manchester encoding

bull 0 is indicated by a 0 to 1 transition at center of bit

bull 1 is indicated by a 1 to 0 transition at center of bit

bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit

bull Manchester Encodingbull Up transition = 1

bull Down transition = 0

Manchester EncodingStandard Ethernet

Manchester EncodingStandard Ethernet

bull Drawbackbull Manchester encoding can consume up to

approximately twice bandwidth of original signal (20 MHz)

bull Penalty for introducing frequent transitions

bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz

bull Additional bandwidth is not significant issue for coaxial cable transmission but

bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method

Fast Ethernet Encoding

bull 4B5B encoding is a type of Block coding

bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)

bull Group of 4 bits encoded so that an extra 5th bit is added

bull 4B5B encoding (Frame Encoding ndash shorthand)

bull All data is encoded prior to transmission

bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)

bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur

bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used

bull Multi-Level Transmit-3 levels

bull No transition = 0

bull Any transition (up or down) = 1

bull Reduces frequency of signal

Fast Ethernet Encoding

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

Fiber Optic Cablingbull Fiber optic cabling consists of center glass

core surrounded by layers of

protective materials bull Fiber optic cable transmits signals over longer

distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater

speedsbull Center core of fiber cables is made from glass or

plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage

bull Outer insulating jacket made of teflon or PVC

Fiber Optic Cabling

bull Two types of fiber cables

bull Single mode

bull Multimode

bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation

bull Both cables provide high bandwidth at high speeds

bull Single mode can provide more distance but it is more expensive

Fast Ethernetbull Higher frequency used in Fast Ethernet

standard is prone to attenuation

bull Cable distance is more limited than in old Ethernet 10Base-T

bull If encoding scheme of traditional Ethernet were used with Fast Ethernet

bull High-end frequency would be above 200 Mhz

bull Double maximum frequency rating of Category 5 cable

bull New encoding schemes were implemented to allow higher-frequency transmissions

Encoding Schemes for Ethernet

bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by

physical layer

bull Recall Manchester encoding

bull 0 is indicated by a 0 to 1 transition at center of bit

bull 1 is indicated by a 1 to 0 transition at center of bit

bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit

bull Manchester Encodingbull Up transition = 1

bull Down transition = 0

Manchester EncodingStandard Ethernet

Manchester EncodingStandard Ethernet

bull Drawbackbull Manchester encoding can consume up to

approximately twice bandwidth of original signal (20 MHz)

bull Penalty for introducing frequent transitions

bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz

bull Additional bandwidth is not significant issue for coaxial cable transmission but

bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method

Fast Ethernet Encoding

bull 4B5B encoding is a type of Block coding

bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)

bull Group of 4 bits encoded so that an extra 5th bit is added

bull 4B5B encoding (Frame Encoding ndash shorthand)

bull All data is encoded prior to transmission

bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)

bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur

bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used

bull Multi-Level Transmit-3 levels

bull No transition = 0

bull Any transition (up or down) = 1

bull Reduces frequency of signal

Fast Ethernet Encoding

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

Fiber Optic Cabling

bull Two types of fiber cables

bull Single mode

bull Multimode

bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation

bull Both cables provide high bandwidth at high speeds

bull Single mode can provide more distance but it is more expensive

Fast Ethernetbull Higher frequency used in Fast Ethernet

standard is prone to attenuation

bull Cable distance is more limited than in old Ethernet 10Base-T

bull If encoding scheme of traditional Ethernet were used with Fast Ethernet

bull High-end frequency would be above 200 Mhz

bull Double maximum frequency rating of Category 5 cable

bull New encoding schemes were implemented to allow higher-frequency transmissions

Encoding Schemes for Ethernet

bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by

physical layer

bull Recall Manchester encoding

bull 0 is indicated by a 0 to 1 transition at center of bit

bull 1 is indicated by a 1 to 0 transition at center of bit

bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit

bull Manchester Encodingbull Up transition = 1

bull Down transition = 0

Manchester EncodingStandard Ethernet

Manchester EncodingStandard Ethernet

bull Drawbackbull Manchester encoding can consume up to

approximately twice bandwidth of original signal (20 MHz)

bull Penalty for introducing frequent transitions

bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz

bull Additional bandwidth is not significant issue for coaxial cable transmission but

bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method

Fast Ethernet Encoding

bull 4B5B encoding is a type of Block coding

bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)

bull Group of 4 bits encoded so that an extra 5th bit is added

bull 4B5B encoding (Frame Encoding ndash shorthand)

bull All data is encoded prior to transmission

bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)

bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur

bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used

bull Multi-Level Transmit-3 levels

bull No transition = 0

bull Any transition (up or down) = 1

bull Reduces frequency of signal

Fast Ethernet Encoding

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

Fast Ethernetbull Higher frequency used in Fast Ethernet

standard is prone to attenuation

bull Cable distance is more limited than in old Ethernet 10Base-T

bull If encoding scheme of traditional Ethernet were used with Fast Ethernet

bull High-end frequency would be above 200 Mhz

bull Double maximum frequency rating of Category 5 cable

bull New encoding schemes were implemented to allow higher-frequency transmissions

Encoding Schemes for Ethernet

bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by

physical layer

bull Recall Manchester encoding

bull 0 is indicated by a 0 to 1 transition at center of bit

bull 1 is indicated by a 1 to 0 transition at center of bit

bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit

bull Manchester Encodingbull Up transition = 1

bull Down transition = 0

Manchester EncodingStandard Ethernet

Manchester EncodingStandard Ethernet

bull Drawbackbull Manchester encoding can consume up to

approximately twice bandwidth of original signal (20 MHz)

bull Penalty for introducing frequent transitions

bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz

bull Additional bandwidth is not significant issue for coaxial cable transmission but

bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method

Fast Ethernet Encoding

bull 4B5B encoding is a type of Block coding

bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)

bull Group of 4 bits encoded so that an extra 5th bit is added

bull 4B5B encoding (Frame Encoding ndash shorthand)

bull All data is encoded prior to transmission

bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)

bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur

bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used

bull Multi-Level Transmit-3 levels

bull No transition = 0

bull Any transition (up or down) = 1

bull Reduces frequency of signal

Fast Ethernet Encoding

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

Encoding Schemes for Ethernet

bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by

physical layer

bull Recall Manchester encoding

bull 0 is indicated by a 0 to 1 transition at center of bit

bull 1 is indicated by a 1 to 0 transition at center of bit

bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit

bull Manchester Encodingbull Up transition = 1

bull Down transition = 0

Manchester EncodingStandard Ethernet

Manchester EncodingStandard Ethernet

bull Drawbackbull Manchester encoding can consume up to

approximately twice bandwidth of original signal (20 MHz)

bull Penalty for introducing frequent transitions

bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz

bull Additional bandwidth is not significant issue for coaxial cable transmission but

bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method

Fast Ethernet Encoding

bull 4B5B encoding is a type of Block coding

bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)

bull Group of 4 bits encoded so that an extra 5th bit is added

bull 4B5B encoding (Frame Encoding ndash shorthand)

bull All data is encoded prior to transmission

bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)

bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur

bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used

bull Multi-Level Transmit-3 levels

bull No transition = 0

bull Any transition (up or down) = 1

bull Reduces frequency of signal

Fast Ethernet Encoding

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

bull Manchester Encodingbull Up transition = 1

bull Down transition = 0

Manchester EncodingStandard Ethernet

Manchester EncodingStandard Ethernet

bull Drawbackbull Manchester encoding can consume up to

approximately twice bandwidth of original signal (20 MHz)

bull Penalty for introducing frequent transitions

bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz

bull Additional bandwidth is not significant issue for coaxial cable transmission but

bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method

Fast Ethernet Encoding

bull 4B5B encoding is a type of Block coding

bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)

bull Group of 4 bits encoded so that an extra 5th bit is added

bull 4B5B encoding (Frame Encoding ndash shorthand)

bull All data is encoded prior to transmission

bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)

bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur

bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used

bull Multi-Level Transmit-3 levels

bull No transition = 0

bull Any transition (up or down) = 1

bull Reduces frequency of signal

Fast Ethernet Encoding

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

Manchester EncodingStandard Ethernet

bull Drawbackbull Manchester encoding can consume up to

approximately twice bandwidth of original signal (20 MHz)

bull Penalty for introducing frequent transitions

bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz

bull Additional bandwidth is not significant issue for coaxial cable transmission but

bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method

Fast Ethernet Encoding

bull 4B5B encoding is a type of Block coding

bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)

bull Group of 4 bits encoded so that an extra 5th bit is added

bull 4B5B encoding (Frame Encoding ndash shorthand)

bull All data is encoded prior to transmission

bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)

bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur

bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used

bull Multi-Level Transmit-3 levels

bull No transition = 0

bull Any transition (up or down) = 1

bull Reduces frequency of signal

Fast Ethernet Encoding

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

Fast Ethernet Encoding

bull 4B5B encoding is a type of Block coding

bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)

bull Group of 4 bits encoded so that an extra 5th bit is added

bull 4B5B encoding (Frame Encoding ndash shorthand)

bull All data is encoded prior to transmission

bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)

bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur

bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used

bull Multi-Level Transmit-3 levels

bull No transition = 0

bull Any transition (up or down) = 1

bull Reduces frequency of signal

Fast Ethernet Encoding

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

bull 4B5B encoding (Frame Encoding ndash shorthand)

bull All data is encoded prior to transmission

bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)

bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur

bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used

bull Multi-Level Transmit-3 levels

bull No transition = 0

bull Any transition (up or down) = 1

bull Reduces frequency of signal

Fast Ethernet Encoding

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

Fast Ethernet Encodingbull Thus 100 Mbps transmission

bull Uses a 4b5b MLT code

bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth

bull Gigabit Ethernet

bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth

bull 1 Gbps within 100 MHz of bandwidth

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

Fast Ethernetbull Fast Ethernet supports Full-Duplex switched

mode to provide even better performancebull A full-duplex nonshared link

bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions

can be disabled bull If both end systems are transmitting at

same time combined data rate is 200 Mbps

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

All Gigabit Ethernet

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

Gigabit Ethernetbull Yet more speed

bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP

bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks

and service provider networksbull Can be used to tie together existing 10 and 100

Mbps Ethernet networksbull Gigabit Ethernet competes with ATM

(Asynchronous Transfer Mode) as core networking technology

bull Many ISPs use Gigabit Ethernet in their data centers

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes

1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense

to have larger framesbull Transmitting larger frames means fewer

CPU interrupts and more data getting through instead of more headers

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

Gigabit Ethernet Extensions

bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely

bull So flow control is supported

bull One end sends control frame telling it to pause for a time

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

Pause Function

bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames

12- 45

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

10 Gigabit Ethernet

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

47

Easy Migration to Higher Performancebull 10 Gigabit Ethernet

ndash Is simplest way to scale enterprise and service provider (SP) networks

ndash Leverages installed base of more 300 million Ethernet switch ports

ndash Supports all data servicesndash Supports local metro and wide area

networks

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

48

Easy Migration to Higher Performance

ndash Is faster cheaper and simpler than alternatives

ndash Optionally matches MANWAN backbone speed of OC-192

bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone

bull SONET Synchronous Optical NETwork

bull SDH equivalent Synchronous Digital Hierarchy network

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

49

Low Cost of Ownership

bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation

bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous

Ethernet linkndash SONETSDH is difficult expensive to

implement timing and jitter requirement

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

50

Ethernet Economics

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

51

Application for 10 Gigabit Ethernet

bull 10 Gigabit Ethernet in LAN

bull 10 Gigabit Ethernet in MAN

bull 10 Gigabit Ethernet in WAN

bull 10 Gigabit Ethernet in SAN

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

52

10 Gigabit Ethernet in LAN

bull Campus Backbonendash Higher speed links

bull Inter-Campusndash Long distance connectivity

bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from

servers

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

53

10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks

ndash Meeting SAN QoS requirements across WANs

bull Removal of LAN bottlenecks

bull Eliminate of 1Gbps link aggregation issues

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

54

10 Gigabit Ethernet in LAN(cont)

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

55

10 Gigabit Ethernet in MAN

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

56

10 Gigabit Ethernet in WAN

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

57

10 Gigabit Ethernet in WAN(cont)

bull Seamless access to the optical infrastructure

bull Simple very high speed low cost interintra-PoP connection

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

References

Encoding Schemes (very thorough)httpgbenthiennetencodingpdf

Cablinghttpfcitusfedunetworkchap4chap4htm

Ethernet Encoding SchemeshttpfengnetcombookCNF

ch02lev1sec1html

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

Summary

bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding

changing Media Access has allowed Ethernet to change with changes in technology

bull Managed to maintain its cost-effectiveness in the face of competing technologies

60

bull Assignmentbull Problems from the Book

60

bull Assignmentbull Problems from the Book