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CommServ – Education Division Datacom Networking Introduction-1
Data Communication Transport
CommServ – Education Division Datacom Networking Introduction-2
Introduction
• Name, Company and Location
• Job Title and Responsibilities
• Related Work Experience
• Course Expectations
CommServ – Education Division Datacom Networking Introduction-3
Course Prerequisites
• There are no prerequisites for this course.
CommServ – Education Division Datacom Networking Introduction-4
Course Materials
• Course Manual
• Evaluation Form
• Reference Materials
CommServ – Education Division Datacom Networking Introduction-5
Course Objectives
• To gain a solid understanding of modern data
communications technologies and concepts
• Technologies covered:
– TCP/IP, Ethernet, ATM, Frame Relay, X.25, PPP, Modems,
ISDN, xDSL, SDH/SONET, Packet-over-SONET, MPLS
CommServ – Education Division Datacom Networking Introduction-6
Course Schedule
•Day 1: PRE-TEST, Standards, Physical Media, Datacom Concepts
& Traffic Cases
•Day 2: Ethernet Concepts, Ethernet Frame Types & Devices
Fast & Gigabit Ethernet
•Day 3: WAN Concepts, ATM and Frame Relay
•Day 4: WAN Concepts, X.25, Point-to-Point Protocol, Modems,
ISDN, xDSL, PDH/SDH/SONET, Packet-Over-SONET, MPLS
•Day 5: Internet Architecture & Applications, Transport Layer,
Protocols, Internet Protocol & IP Addressing, Internet Routing &
Dynamic Routing
POST TEST
CommServ – Education Division Datacom Networking Introduction-7
Modern Datacom Networking
CommServ – Education Division Datacom Networking Standard-8
Datacom Networking 2. Standardization and the OSI Model
Chapter Objectives
–Identify the standards bodies associated with data
communications
–Describe in detail the OSI reference model
CommServ – Education Division Datacom Networking Standard-9
Standard Bodies
Frame Relay Forum
IEEE
ITU
ISO
ANSI
IETF
ATM Forum
ETSI
CommServ – Education Division Datacom Networking Standard-10
International Telecommunications Union (ITU)
ITU-R
Study Group Study Group
ITU-T ITU-D
ITU
CommServ – Education Division Datacom Networking Standard-11
ITU-T Recommendations
Function Series
Public data communication network X-
Digital communication over the telephone network V-
Telephone switching and signalling networks Q-
ISDN I-
International telephone connections and circuits G-
Telephone network and ISDN E-
CommServ – Education Division Datacom Networking Standard-12
Standards Organizations
• International Telecommunications Union
– www.itu.int
• International Standards Organisation
– www.iso.ch
• American National Standards Institute
– www.ansi.org
• European Telecommunications Standards Institute
– www.etsi.org
• Electronic Industries Alliance
– www.eia.org
• Internet Engineering Task Force
– www.ietf.org
CommServ – Education Division Datacom Networking Standard-13
Standards Organizations
• Frame Relay Forum
– www.frforum.com
• Institute of Electrical and Electronics Engineers
– www.ieee.org
• International Multimedia Teleconferencing Consortium
– www.imtc.org
CommServ – Education Division Datacom Networking Standard-14
OSI Reference Model
• The Open System Interconnection (OSI) Reference Model is a concept that describes how data communications should take place
• It divides the process into seven groups, called layers
• Protocol standards developed by the ISO and other standards bodies are fitted into these layers
• The OSI model is not a single definition of how data communications actually takes place in the real world, Numerous protocols may exist at each layer
• The OSI model is old, but it’s important because modern functionality is defined using the language of the OSI model, for example “layer 2 forwarding”
CommServ – Education Division Datacom Networking Standard-15
OSI Reference Model Layers
Transmits and receives on the network medium Physical 1
Transfers units of information to the other end
of the physical link Data Link 2
Switches and routes information to the
appropriate network device Network 3
Provides end-to-end data integrity and reliable
delivery of data Transport 4
Co-ordinates interaction between end-to-end
application processes Session 5
Provides code conversion and data
reformatting Presentation 6
Interfaces directly with application programs
running on the devices Application 7
CommServ – Education Division Datacom Networking Standard-16
The Physical Layer
TDM / FDM / WDM Multiplexing
Baseband
Broadband Bandwidth Usage
Asynchronous
Synchronous
Bit
Synchronisation
Current State Signalling
Bus, Ring, Cellular Physical Topology
P-2-P , P-2-MP Connection Types
Physical
Methods Function Layer
CommServ – Education Division Datacom Networking Standard-17
The Datalink Layer
DLC
Physical
device Addressing
Contention
Token passing
Media access
services
Bus
Ring Logical topology
MAC
Flow control
Error control Connection services
Asynchronous
Synchronous
Transmission
Synchronisation LLC
Methods Function Sub layer
CommServ – Education Division Datacom Networking Standard-18
Network Layer
Static
Dynamic Route Selection
Distance Vector
Link State Route Discovery
Packet Switching Switching
Logical Network
Services Addressing
Network
Method Function Layer
CommServ – Education Division Datacom Networking Standard-19
Routing
6 5 4
3
2
3
3 2
1 1
1
3
2
3 2 4
5 6 1
4
5
6
CommServ – Education Division Datacom Networking Standard-20
Transport Layer
Service requester
initiated
Address/Name
Resolution
Segment sequencing
Error control
End-2-End flow control
Connection services
Segmentation and
Reassembly (SAR) Segment development
Connection identifier
Transaction identifier Addressing Methods
Transport
Method Function Layer
CommServ – Education Division Datacom Networking Standard-21
Session Layer
• Session layer facilitates and controls communication sessions between service providers and service requesters
• The session layer has functions to establish maintain, synchronise and manage communication sessions
• Often, it also helps the upper layers identify and connect to the services available on the network.
• The two main session layer tasks are:
• Dialogue control
• Session administration
• This includes the control and management of multiple bidirectional messages so that the application can be notified if only some of a series of messages are completed.
• For example, an Automated Teller Machine transaction in which you get cash out of your checking account should not debit your account and fail before handing you the cash, and then record the transaction even though you did not receive money.
• RPC, SQL, NFS, NetBios names, AppleTalk ASP, DECnet SCP
CommServ – Education Division Datacom Networking Standard-22
Presentation Layer
• This layer’s main purpose is defining data formats, such as ASCII text, EBCDIC text, binary, BCD, and JPEG.
• Encryption is also defined by OSI as a presentation layer service.
• For example, FTP allows you to choose binary or ASCII transfer. If binary, the sender and receiver do not modify the contents of the file. If ASCII is chosen, the sender translates the text from the sender’s character set to a standard ASCII and sends the data. The receiver translates back from the standard ASCII to the character set used on the receiving computer.
• Example: TIFF, GIF, JPEG, PICT, ASCII, EBCDIC, encryption, MPEG, MIDI, HTML
CommServ – Education Division Datacom Networking Standard-23
Presentation Layer
The presentation layer’s main functions are:
• Translation • Code conventions
• Bit/Byte order
• File syntax
• Encryption / Decryption
CommServ – Education Division Datacom Networking Standard-24
Application Layer
• Provides interface to end user process and applications
• Takes care of all the requests made by the running applications
• An application that communicates with other computers is implementing OSI application layer concepts. The application layer refers to communications services to applications. For example, a word processor that lacks communications capabilities would not implement code for communications, and word processor programmers would not be concerned about OSI Layer 7. However, if an option for transferring a file were added, then the word processor would need to implement OSI Layer 7 (or the equivalent layer in another protocol specification).
• Examples: FTP, WWW browsers, Telnet, NFS, SMTP gateways (Eudora, CC:mail), SNMP, X.400 mail, FTAM
CommServ – Education Division Datacom Networking Standard-25
Data Transmission
Bits
S-Data unit
T-Data unit
Packet
Frame
Bits
P-Data unit
A-Data unit Data A
Data
Physical
Data Link
Network
Transport
Session
Presentation
Application
Data A P
Data A P S
S Data A P T
T S Data A P N
N T S Data A P D D
101101111000101011010010101010
Pro
toco
l S
tack
Data unit
CommServ – Education Division Datacom Networking Standard-26
Example: HTTP
Web Browser
Physical
Data Link
Network
Transport
Session
Presentation
Application
Ethernet
IP
TCP
HTTP
Web Server
Ethernet
IP
TCP
HTTP
CommServ – Education Division Datacom Networking Standard-27
OSI and Network Devices
Physical
Data Link
Network
Transport
Session
Presentation
Application
Physical
Data Link
Network
Transport
Session
Presentation
Application
Repeater
Bridge
Router
Hub
Switch
Router
User
Application
User
Application
CommServ – Education Division Datacom Networking Standard-28
OSI and Network Devices
CommServ – Education Division Datacom Networking Standard-29
OSI Layers: Network Interaction
Physical
Data Link
Network
Transport
Session
Presentation
Application
Physical
Data Link
Network
Transport
Session
Presentation
Application
User
Application
User
Application
CommServ – Education Division Datacom Networking Standard-30
OSI Model Summary
Concerned with transmission of unstructured bit stream over physical medium; deals with the mechanical, electrical, functional and procedural characteristics to access the physical medium.
1) Physical
Provides for the reliable transfer of information across the physical link.
Establishes a physical link, sends blocks of data (frames) in the proper
format, along with the necessary synchronization, error control, and flow
control.
2) Data Link
Provides upper-layers with independence from the data transmission and switching technology used to connect systems. Concerned with routing packets, congestion control, fragmentation, and reassembly.
3) Network
Provides reliable, transparent transfer of data between end points.
Provides end-to-end error recovery and flow control. 4) Transport
Provides the control structure for communication between applications.
Establishes, manages and terminates connections (sessions) between
applications. 5) Session
Provides data representation (Syntax) independence to the
application process. 6) Presentation
Access to the OSI environment for user applications and processes. 7) Application
CommServ – Education Division Datacom Networking Physical Media
-31
Datacom Networking 3. Physical Media
Chapter Objectives –Describe the characteristics of coaxial cable, UTP, STP and optical fiber
–Describe the terms DCE and DTE
–Describe the characteristics of RS232, RS422, V.35, V.36 and X.21
CommServ – Education Division Datacom Networking Physical Media
-32
Physical Media
• Co-axial
• Twisted Pair
– Unshielded
– Shielded
• Optical Fiber
– Single Mode
– Multimode
CommServ – Education Division Datacom Networking Physical Media
-33
Typical Coaxial Cable
BNC Connectors
CommServ – Education Division Datacom Networking Physical Media
-34
BNC T-Connector
CommServ – Education Division Datacom Networking Physical Media
-35
Characteristics of Coax
• Medium cable costs
• Simple to install
• Moderate installation costs
• Moderate EMI
• High bandwidth
• Often used as backbone cable
CommServ – Education Division Datacom Networking Physical Media
-36
Unshielded Twisted Pair
CommServ – Education Division Datacom Networking Physical Media
-37
Characteristics of UTP
• Lowest cost
• Very simple to install
• Low installation costs
• Highest electromagnetic interference (EMI)
• Lowest in bandwidth
• Used in more than 99% of LANs
CommServ – Education Division Datacom Networking Physical Media
-38
Categories of UTP for Networks
• Category 3 (Cat 3)
– Bandwidth 16 Mhz
– Data transmission function
– 11.5 dB attenuation
– 100 ohms Impedience
– Used with 10baseT (10Mbps), IBM token ring (4Mbps), ARCnet, 100VG-AnyLAN (100 Mbps)
• Category 4 (Cat 4)
– 20 MHz Bandwidth
– Data transmission function
– 7.5 dB Attenuation
– 100 ohms Impedance
– Used with 10baseT (10Mbps), IBM Token ring, ARCnet, 100VG-AnyLan (100 Mbps)
CommServ – Education Division Datacom Networking Physical Media
-39
Categories of UTP for Networks (2)
• Category 5 (Cat 5)
– 100 MHz Bandwidth
– Used for high-speed data transmission
– 24.0 dB Attenuation
– 100 ohms Impedance
– Used with 10BaseT (10 Mbps), IBM Token ring, Fast Ethernet, (100 Mbps), Gigabit Ethernet (1000 Mbps), ATM (155 Mbps)
• Category 5 Enhanced (Cat 5E)
– 100 MHz Bandwidth
– Transmits high-speed data
– 24.0 dB Attenuation
– 100 ohms Impedance
– Used with 10BaseT (10 Mbps), IBM Token Ring, Fast Ethernet (100 Mbps), Gigabit Ethernet (1000 Mbps), ATM (155 Mbps)
CommServ – Education Division Datacom Networking Physical Media
-40
Categories of UTP for Networks (3)
• Category 6 (Cat 6)
– 250 MHz Bandwidth
– Transmits high-speed data
– 19.8 dB Attenuation
– 100 ohms Impedance
– Used with 10BaseT (10 Mbps), IBM Token Ring, Fast Ethernet (100 Mbps), Gigabit Ethernet (1000 Mbps), ATM (155 Mbps)
• Category 6 Enhanced (Cat 6E)
– 250 MHz Bandwidth
– Transmits high-speed data
– 19.8 dB Attenuation
– 100 ohms Impedance
– Used with 10BaseT (10 Mbps), IBM Token Ring, Fast Ethernet (100 Mbps), Gigabit Ethernet (1000 Mbps), ATM (155 Mbps)
• Category 7 (Cat 7-NOT YET APPROVED)
– 600 MHz Bandwidth
– Transmits high-speed data
CommServ – Education Division Datacom Networking Physical Media
-41
Shielded Twisted Pair
CommServ – Education Division Datacom Networking Physical Media
-42
CommServ – Education Division Datacom Networking Physical Media
-43
Characteristics of STP
• Medium cable costs expense
• Simple to moderate installation difficulty
• Moderate installation costs
• Moderately low EMI
• Moderate band width
• Usually found in older networks
CommServ – Education Division Datacom Networking Physical Media
-44
Optical Fiber
CommServ – Education Division Datacom Networking Physical Media
-45
Single Mode and Multimode Fiber
• Single Mode Fiber
– Small core diameter which only allows one mode (ray) of light to propagate through the fiber
– Used for applications with long transmission distances (carrier core networks)
• Multimode Fiber
– Larger core diameter which allows many modes of light to propagate through the fiber
– Larger core diameter facilitates use of cheaper components
– Used primarily for applications with short (<2Km) transmission distances (campus backbones)
CommServ – Education Division Datacom Networking Physical Media
-46
Characteristics of Fiber
• Highest cable costs
• Difficult to install
• Highest installation costs
• No EMI
• Very high bandwidth
• Uses light rather than electrical signals
CommServ – Education Division Datacom Networking Physical Media
-47
DCE Vs DTE
DCE DCE
DTE DTE
V.24,
V.28,
Client/Calling Server/Called/ Modem Answer Modem
PSTN
V.24,
V.28,
V.90/V.34/V.32
V.42/V.42bis
CommServ – Education Division Datacom Networking Physical Media
-48
Physical Layer Standards
RS-232C (EIA) / V.24 (ITU)
generator receiver A
B common ground pin 7
RS232C (V.24, V.28)
CommServ – Education Division Datacom Networking Physical Media
-49
Physical Layer Standards (contd)
generator receiver
A
B
RS422 (V.11, X.27) R
RS-422 (EIA) / V.11 (ITU)
CommServ – Education Division Datacom Networking Physical Media
-50
Data Rate vs. Cable Length
100
1k
10k
cable
length
(feet)
50
10
Data Rate - bps
100 1k 10k 100k 1M 10M
RS-232
4k
RS-422
CommServ – Education Division Datacom Networking Physical Media
-51
V.24/V.28, RS232c Interface
ISO 2110 Connector
1 13
14 25
CommServ – Education Division Datacom Networking Physical Media
-52
9 - 25 pin D Cable
PC 9 Pin Modem 25 Pin Function in the PC
3 2 TxD Transit Data
2 3 RxD Receive Data
7 4 RTS Request to Send
8 5 CTS Clear to Send
6 6 DSR Data Set Ready
5 7 SG Signal Ground
1 8 DCD Carrier Detect
4 20 DTR Data Terminal Ready
9 22 RI Ring Indicator
CommServ – Education Division Datacom Networking Physical Media
-53
V.24 Interface Circuits Pin V.24 RS232c DTE DCE EIA Description
1 101 AA FG Protective Ground
2 103 BA X TxD Transmit Data
3 104 BB X RxD Receive Data
4 105 CA X RTS Request to Send
5 106 CB X CTS Clear to Send
6 107 CC X DSR Data Set Ready
7 102 AB SG Common Return / Signal
Ground
8 109 CF X DCD Data Carrier Detect
15 114 DB X TC Transmit Timing Clock
17 115 DD X RC Receive Timing Clock
20 108 CD X DTR Data Terminal Ready
22 125 CE X RI Ring Indicator
24 113 DA X TC External Transmit Timing
Clock
Other pins not shown used used in some modem circuits only.
CommServ – Education Division Datacom Networking Physical Media
-54
Null Modem Cable 25 pin to 25 pin D
Pin Signal
7 Signal
Ground
2 Transmit
3 Receive
4 RTS
5 CTS
20 DTR
6 DSR
8 DCD
Signal Pin
Signal Ground
7
Transmit 2
Receive 3
RTS 4
CTS 5
DTR 20
DSR 6
DCD 8
CommServ – Education Division Datacom Networking Physical Media
-55
Pin Signal
5 Signal
Ground
3 Transmit
2 Receive
7 RTS
8 CTS
4 DTR
6 DSR
1 DCD
Signal Pin
Signal Ground
5
Transmit 3
Receive 2
RTS 7
CTS 8
DTR 4
DSR 6
DCD 1
Null Modem Cable 9 pin to 9 pin D
CommServ – Education Division Datacom Networking Physical Media
-56
V.35 Interface
KK EE AA W S M H C
MM HH CC Y U P K E A
LL FF BB X T N J D
DD JJ NN Z V R L F B
ISO 2593 Connector
CommServ – Education Division Datacom Networking Physical Media
-57
V.35 Interface (contd)
ITU-T No. Circuit Pin Number Source Source Designation
DTE DCE
102 GND B Signal Ground
103 TXD P , S X Transmit Data a,b
104 RXD R , T X Receive Data a,b
105 RTS C X Request to Send
106 CTS D X Clear to Send
107 DSR E X Data Set Ready
108.1 DTR H X Data Terminal Ready
109 DCD F X Data Carrier Detect
113 TCX U , W X Transmit Signal timing a,b from DTE
114 TXC Y , AA X Transmit Signal timing a,b to DTE
115 RXC V , X X Receive Signal timing a,b to DTE
140 RL N X Remote Digital Loop
141 LL L X Local Loop
142 TST NN X Test Indicator
CommServ – Education Division Datacom Networking Physical Media
-58
V.36 Interface
1 19
37 20
ISO 4902 Connector
CommServ – Education Division Datacom Networking Physical Media
-59
X.21 Interface
1 8
9 15
ISO 4903 Connector
ITU-T. Pin Number Source Source Designation
circuit DTE DCE
G 8 Signal Ground
T 2, 9 X Transmit Data a,b
R 4, 11 X Receive Data a,b
C 3, 10 X Control a, b
I 5, 12 X Indication a, b
S 6, 13 X Signal element timing a, b
CommServ – Education Division Datacom Networking Physical Media
-60
RJ 45 Ethernet
Pin Name Description 568A 568B
1 TD + Transmit Data + White/Green White/Orange
2 TD - Transmit Data - Green Orange
3 RD + Receive Data + White/Orange White/Green
4 n/c Not connected Blue Blue
5 n/c Not connected White/Blue White/Blue
6 RD - Receive Data - Orange Green
7 n/c Not connected White/Brown White/Brown
8 n/c Not connected Brown Brown
Note 1 Cable has four pairs. White/Green and Green are a pair etc.
Note 2 TD & RD are swapped on Hub's.
CommServ – Education Division Datacom Networking Physical Media
-61
Pin Function Required
TE NT
1 Power source 3 + Power sink + No
2 Power source 3 - Power sink - No
3 Transmit +
4 Receive +
5 Receive -
6 Transmit -
7 Power sink 2 - Power source 3 - No
8 Power sink 2 + Power source 3 + No
Note: Power source 2 and 3 are not mandatory and may only be
available from some NT or TE devices.
RJ 45 ISDN BRI s/t Interface
CommServ – Education Division Datacom Networking Physical Media
-62
RJ 48c
Pin Description
1 Receive Ring
2 Receive Tip
3 Not connected
4 Transmit Ring
5 Transmit Tip
6 Not connected
7 ground for transmit screen
8 ground for receive screen
E1 / T1 Balanced/Unbalanced
CommServ – Education Division Datacom Networking Physical Media
-63
SC Connectors
CommServ – Education Division Datacom Networking Physical Media
-64
ST Connectors
CommServ – Education Division Datacom Networking Physical Media
-65
LC FC
MTRJ
Mini-Gbic plus LC, MRTJ and FC Connector
Mini-Gbic
CommServ – Education Division Datacom Networking Fundamental -
66
Datacom Networking 4. Datacom Fundamental
Chapter Objectives –Define LANs and WANs
–Identify multiplexing, transmission, and error control methods
–Describe common network topologies
CommServ – Education Division Datacom Networking Fundamental -
67
Network Definition - LAN / WAN
Local Area Networks
(LANs)
Router A Router B
Wide Area Network
(WAN)
Token Ring
CommServ – Education Division Datacom Networking Fundamental -
68
Bandwidth Usage
• Baseband
all the available bandwidth is used to derive a single transmission path
• Broadband
the total available bandwidth of the cable is divided into a number of lower bit rate channels, which can transmit many simultaneous signals
CommServ – Education Division Datacom Networking Fundamental -
69
Modulation / Demodulation
• Amplitude Modulation
where the Amplitude of the signal is varied
• Frequency Modulation
where the Frequency of the signal is varied
• Phase Modulation
where the Phase of the signal is shifted
CommServ – Education Division Datacom Networking Fundamental -
70
Digitization
• Is the Process of Converting an Analog Signal to Digital Format
• A COder-DECoder performs this operation by applying Pulse Code Modulation algorithm
• The CODEC may be placed at any point
• A logarithmic (com-panding) scale is used to map the amplitude to its digital value
• The PCM companding rules define:
255 amplitude levels, -law, in USA, Canada and Japan
256 amplitude levels, A-law, almost rest of the world
CommServ – Education Division Datacom Networking Fundamental -
71
Multiplexing Techniques
• Time Division Multiplexing (TDM)
– Conventional
• Bit-Interleaved
• Byte-Interleaved – Statistical (STDM)
T S - 1
t
f
T S - 2 T S - 3 T S - 4 T S - 1 T S - 2 T S - 3 T S - 4 T S - 1 T S - 2 T S - 3 T S - 4TDM
CommServ – Education Division Datacom Networking Fundamental -
72
Multiplexing Techniques
• Frequency Division Multiplexing (FDM) (CATV is a good example)
• Wavelength Division Multiplexing (WDM)
(often used in optical data transmission)
t
f
F C - 1
F C - 2
F C - 3
F C - 4
FDM
CommServ – Education Division Datacom Networking Fundamental -
73
Communication Modes
• Simplex
– data is transmitted in one direction only
• Half Duplex
– Data can be transmitted in both directions, but only in one direction at any given time
• Full Duplex
– Data is transmitted in both directions simultaneously
CommServ – Education Division Datacom Networking Fundamental -
74
Transmission Modes
SYN character Bit stream of many characters
Asynchronous
Synchronous
SYN character
Stop bit Character Start bit
CommServ – Education Division Datacom Networking Fundamental -
75
Asynchronous communications
CommServ – Education Division Datacom Networking Fundamental -
76
Synchronous Transmission
• The complete block of data is transmitted as a contiguous bit stream in frames
• To enable the receiving device to stay in sync data is carefully encoded (bit sync)
• frames are preceded by a reserved byte to ensure correct interpretation on byte boundaries (byte sync)
• frames are preceded by synchronization bytes (frame sync)
CommServ – Education Division Datacom Networking Fundamental -
77
Error Control
• Parity Bit Method
– an additional bit is added to each tansmitted character to detect single bit errors
• Even / Odd parity
• Block sum check algorithms
– two additional bits are added (row / column) to detect errors
– two bit errors that escape the row parity checking, will be detected by this method
CommServ – Education Division Datacom Networking Fundamental -
78
Error Control
Frame to be transmitted Calculated CRC value
f Input data Output data
Input
poly
nom
ial
CommServ – Education Division Datacom Networking Fundamental -
79
Data Compression
• Packed Decimal
– Reduce the number of transmitted data (numbers 0-9 all have 011 in msb position)
• Relative Encoding
– Data that has only small differences between successive values, (send only the d-magnitude)
• Character Suppression
– Used for more general case
• Huffman Coding
– Statistical coding
CommServ – Education Division Datacom Networking Fundamental -
80
Network Topologies
CommServ – Education Division Datacom Networking Fundamental -
81
Protocols
• A protocol is a set of rules that govern the behaviour of communicating parties
• Protocols handle:
Format of the exchanged data
Type and order of the information
Timing
Sequencing
Error control
Flow Control
CommServ – Education Division Datacom Networking Traffic Case-82
Datacom Networking 5. Traffic Case
Chapter Objectives
–Describe at a high level the path a packet may take through a
network
CommServ – Education Division Datacom Networking Traffic Case-83
So, what happens when you do this?
CommServ – Education Division Datacom Networking Traffic Case-84
Upper Layer Protocol into IP
• This is the File Transfer Protocol (FTP), which is a higher-
layer protocol (layers 5,6 & 7 of OSI model)
• FTP is carried within an Internet Protocol (IP) packet
CommServ – Education Division Datacom Networking Traffic Case-85
Local Area Network Technologies
• Your PC is connected to your office Local Area Network
(LAN), through a Network Interface Card (NIC)
• Typically, the LAN technology used is Ethernet
CommServ – Education Division Datacom Networking Traffic Case-86
Adapting IP to Ethernet
• The information (IP) needs to be adapted to the network technology
• In this case the information must be transmitted in Ethernet frames
CommServ – Education Division Datacom Networking Traffic Case-87
The Hub
• Likely the first device your frame will encounter is a hub – an Ethernet repeater
• This hub simply repeats the signal and sends it on
CommServ – Education Division Datacom Networking Traffic Case-88
The LAN Switch
• Likely the next device your frame will encounter is an Ethernet switch, also called a LAN switch
• This LAN switch forwards on your Ethernet frame intelligently on the basis of it’s Ethernet address
CommServ – Education Division Datacom Networking Traffic Case-89
A Typical Office Network
CommServ – Education Division Datacom Networking Traffic Case-90
The Router
• A router’s job is to take in IP packets and work out the next
best hop for that packet based on the router’s internal
routing tables
CommServ – Education Division Datacom Networking Traffic Case-91
IP Forwarding
CommServ – Education Division Datacom Networking Traffic Case-92
Layer 3 – Layer 2 Interaction
• Consider a router with Ethernet and ATM interfaces
CommServ – Education Division Datacom Networking Traffic Case-93
Destination Server
The final router knows
that the destination
IP device is directly
connected to it
The server will return
the requested files to
the source – the same
process in reverse
CommServ – Education Division Datacom Networking Ethernet
Concept-94
Datacom Networking 7. Ethernet Concept
Chapter Objectives –Describe naming conventions used with Ethernet
–Describe the structure of a MAC address
–Describe the CSMA/CD principle
CommServ – Education Division Datacom Networking Ethernet
Concept-95
LAN Technologies
• Ethernet
– By far the most widely used LAN technology today (95%+)
– Available in 10Mbps, 100Mbps and 1000Mbps flavours
• Token Ring
– Old IBM standard
– Workstations connected to rings, token passing concept
– Rings were available at speeds of 4Mbit/s and 16Mbit/s
• Fiber Distributed Data Interface (FDDI)
– LAN Fiber backbone technology, used 100Mbit/s ring
– No longer likely to be implemented in a new network
• Asynchronous Transfer Mode (ATM)
– Extensively deployed WAN technology, can be deployed in LANs
– However, Ethernet is a far more cost effective LAN technology
CommServ – Education Division Datacom Networking Ethernet
Concept-96
Ethernet Evolution
Ethernet Design Goals
– Simplicity
– Efficient use of shared resources
– Ease of reconfiguration and
maintenance
– Compatibility
– Low cost
1972 1996
Gigabit standard (802.3z) VLANs
(802.1Q) 1000BaseT (802.3ab)
1980
EthernetV1 DIX - V2 in 82
1983 1990
10Base-T
(802.3i)
10BaseF (Fiber)
1993
802.3z study group formed to standardize
Gigabit Ethernet
1998 1985
IBM ships first
Token Ring LAN
IEEE
802.3
Standard
81-83
Fast
Ethernet
(802.3u)
1995 1997
Full
Duplex
(802.3x)
1973
Invention accredited to Robert Metcalfe-
Patent 1977
CommServ – Education Division Datacom Networking Ethernet
Concept-97
IEEE 802 Family Architecture
IEEE 802.3 IEEE 802.4 IEEE 802.5 IEEE 802.6 Physical
IEEE 802.2
Internet
Transport
Upper
IEEE 802.x
Link
802.1 Internetworking
802.2 Logical Link Control (LLC)
802.3 CSMA\CD
802.4 Token Bus
802.5 Token Ring
802.6 Metropolitan Area
Networks
802.7 Broadband Tech Advisory Group
802.8 Fiber Optic Tech Advisory Group
802.9 Integrated Voice&Data Networks
802.10 Network Security
802.11 Wireless Networks
802.12 Demand Priority Access LAN's
CommServ – Education Division Datacom Networking Ethernet
Concept-98
Ethernet Naming Conventions
CommServ – Education Division Datacom Networking Ethernet
Concept-99
10BaseT Specifications
• 10BaseT
– 2 pairs of Cat 3 UTP
– By far the most widely used specification
• 10BaseF
– 2 strands of MMF
• 10Base2
– Thin coaxial or “Thinnet” (Dead)
• 10Base5
– Thick coaxial or “Thicknet” (Dead)
• 10Broad36
– Coaxial (Dead)
CommServ – Education Division Datacom Networking Ethernet
Concept-100
MAC Address Format
7 0 - 7 0 - 7 0 - 7 0 - 7 0 - 7 0 -
octet order bit order
CommServ – Education Division Datacom Networking Ethernet
Concept-101
Ethernet Principle – CSMA/CD
• CS = Carrier Sense
– Listen until no carrier is sensed, then transmit after a delay
• MA = Multiple Access
– Designed for a broadcast environment
– Every station hears every frame
• CD = Collision Detection
– Listen for a collision while you transmit
CommServ – Education Division Datacom Networking Ethernet
Concept-102
Ethernet Operation – CSMA
CommServ – Education Division Datacom Networking Ethernet
Concept-103
Ethernet Operation – CD
CommServ – Education Division Datacom Networking Ethernet
Concept-104
Ethernet Collisions – More Detail
The adapters have to hear the collision while they
are still transmitting
They then transmit a 32-bit jam signal
They wait a random time before retransmission
If there are repeated collisions the adapter tries
again, up to a a maximum of 16 times
– Uses ―truncated binary exponential backoff‖ algorithm
CommServ – Education Division Datacom Networking Ethernet
Concept-105
Ethernet, Logical vs Physical
CommServ – Education Division Datacom Networking Ethernet
Frame-106
Datacom Networking 8. Ethernet Frame
Chapter Objectives –Identify the characteristics of the following Ethernet frame types:
•Ethernet Version 2
•IEEE 802.3 Novell Raw
•IEEE 802.3 Standard (with LLC)
•IEEE 802.3 SNAP
CommServ – Education Division Datacom Networking Ethernet
Frame-107
Chapter Objectives
• After completing this chapter you will be able to:
– Identify the characteristics of the following Ethernet frame types:
• Ethernet Version 2
• IEEE 802.3 Novell Raw
• IEEE 802.3 Standard (with LLC)
• IEEE 802.3 SNAP
CommServ – Education Division Datacom Networking Ethernet
Frame-108
Ethernet Version 2 Frame (DIX) Network
Data Link Control
Physical
CommServ – Education Division Datacom Networking Ethernet
Frame-109
Examples of Ethernet Types
E-Type Value
NetWare 8137
XNS 0600, 0807
IP 0800
IP (VINES) 0BAD, 80C4
ARP 0806
RARP 8035
DRP 6003
LAT 6004
LAVC 6007
ARP (ATalk) 80F3
CommServ – Education Division Datacom Networking Ethernet
Frame-110
IEEE 802.3 Frame - Novell ―RAW‖
CommServ – Education Division Datacom Networking Ethernet
Frame-111
IEEE 802.3 Frame – with LLC (Standard Frame)
Network
Logical Link Control
Physical
Media Access Control
CommServ – Education Division Datacom Networking Ethernet
Frame-112
IEEE 802.3 Frame – SNAP Network
SNAP
Physical
LLC
MAC
CommServ – Education Division Datacom Networking Ethernet
Frame-113
Ethernet Frames Compared
CommServ – Education Division Datacom Networking Ethernet
Frame-114
Determining Ethernet Frame Types
CommServ – Education Division Datacom Networking Ethernet
Device-115
Datacom Networking 9. Ethernet Device
Chapter Objectives –Describe collision domains and broadcast domains
–Describe how a hub, bridge and switch operate
–Identify where a crossover cable is used
–Describe the concept of Virtual LANs (VLANs)
CommServ – Education Division Datacom Networking Ethernet
Device-116
Chapter Objectives
• After completing this chapter you will:
– Describe collision domains and broadcast domains
– Describe how a hub, bridge and switch operate
– Identify where a crossover cable is used
– Describe the concept of Virtual LANs (VLANs)
CommServ – Education Division Datacom Networking Ethernet
Device-117
Broadcasts
Ethernet inherently supports broadcasts
Broadcast mechanism is used frequently
Example ARP – Address Resolution Protocol
A Broadcast Domain is all devices that will see a
broadcast frame
CommServ – Education Division Datacom Networking Ethernet
Device-118
Ethernet Devices
CommServ – Education Division Datacom Networking Ethernet
Device-119
Hubs
A hub is a simple OSI layer 1 device: a hub just
repeats the incoming signal
CommServ – Education Division Datacom Networking Ethernet
Device-120
CommServ – Education Division Datacom Networking Ethernet
Device-121
CommServ – Education Division Datacom Networking Ethernet
Device-122
Crossover Cables
A ―crossover‖ or ―crossed‖ cable may be used to
directly connect two Ethernet devices
– Transmit/Receive reversed at one end
– Crossover cables can be made or bought
CommServ – Education Division Datacom Networking Ethernet
Device-123
Connecting Hubs
Hubs may be connected or ―cascaded‖
– Connected hubs behave like one ―big‖ hub
CommServ – Education Division Datacom Networking Ethernet
Device-124
Transparent Bridging
CommServ – Education Division Datacom Networking Ethernet
Device-125
Bridges and Switches
CommServ – Education Division Datacom Networking Ethernet
Device-126
CommServ – Education Division Datacom Networking Ethernet
Device-127
CommServ – Education Division Datacom Networking Ethernet
Device-128
CommServ – Education Division Datacom Networking Ethernet
Device-129
CommServ – Education Division Datacom Networking Ethernet
Device-130
LAN Switch Operation
• Flooding
• Learning
• Forwarding
• Filtering
• User filtering
CommServ – Education Division Datacom Networking Ethernet
Device-131
LAN Switch Operation
• Having learned about destination addresses on the network the switch will forward frames intelligently on the basis of their MAC address
CommServ – Education Division Datacom Networking Ethernet
Device-132
Full-Duplex Ethernet
CommServ – Education Division Datacom Networking Ethernet
Device-133
CommServ – Education Division Datacom Networking Ethernet
Device-134
CommServ – Education Division Datacom Networking Ethernet
Device-135
CommServ – Education Division Datacom Networking Ethernet
Device-136
CommServ – Education Division Datacom Networking Ethernet
Device-137
Virtual LANs (VLANs)
• A VLAN is a logical grouping of nodes (clients and servers) residing in a common broadcast domain
• The broadcast domain has been artificially created within a LAN switch
– standard 802.3ac
LAN Switch
OFF
ON
OFF
ON
VLAN #1 - 5 workstations or repeaters
VLAN #2 - 11 workstations or repeaters
VLAN #3 - 6 workstations or repeaters
VLAN #4 - 10 workstations or repeaters
CommServ – Education Division Datacom Networking Ethernet
Device-138
VLAN Example -1
CommServ – Education Division Datacom Networking Ethernet
Device-139
VLAN Example -2
CommServ – Education Division Datacom Networking Ethernet
Device-140
CommServ – Education Division Datacom Networking Ethernet
Device-141
CommServ – Education Division Datacom Networking Ethernet
Device-142
CommServ – Education Division Datacom Networking Ethernet
Device-143
CommServ – Education Division Datacom Networking Fast Ethernet-
144
Datacom Networking 10. Fast Ethernet
Chapter Objectives –Identify the physical specifications for Fast Ethernet
–Define auto-negotiation
–Understand how to interwork 10Mbit/s Ethernet and Fast Ethernet
CommServ – Education Division Datacom Networking Fast Ethernet-
145
Fast Ethernet Essentials
• 10BaseT and 100BaseT
– Both use CSMA/CD
– Frame formats and frame lengths the same
– Usually deployed over Category 5 UTP
– Interconnections made with hubs, switches, routers etc.
– Standard defined by IEEE 802.3u
CommServ – Education Division Datacom Networking Fast Ethernet-
146
Fast Ethernet vs 10BaseT Ethernet
• 10BaseT vs 100BaseT
– Transmits 10 times as much data in the same time
– New physical standards
– Interframe gap .96 microseconds instead of 9.6 microseconds (unchanged at 96 bit times)
CommServ – Education Division Datacom Networking Fast Ethernet-
147
100BaseT Specifications
• 100BaseTX
– 2 pairs of Cat 5 UTP or Cat 1 STP
– By far the most widely used specification (95%+)
• 100BaseFX
– 2 strands of SMF or MMF
• 100BaseT4
– 4 pairs of Cat 3/4/5 UTP
• 100BaseT2
– 2 pairs of Cat 3/4/5 UTP
CommServ – Education Division Datacom Networking Fast Ethernet-
148
Matching Interfaces
CommServ – Education Division Datacom Networking Fast Ethernet-
149
Auto-Negotiation
10 or 100?
Full or half?
Then,
AUTO-NEGOTIATE!
Useful if unsure what
you‘re plugging in to
- AND when
upgrading to a
100BASE-T hub
??
Switch or
Hub
Algorithm used to negotiate common data service
Common RJ-45 connector for 1 of 8 services
Fast link pulses (FLP) similar to link integrity (LI)
Hub/NIC adjust speed to highest common mode
Order:
1. 1000BaseT FDX
2. 100BaseT2 FDX
3. 100BaseT2 HDX
4. 100BaseTX FDX
5. 100BaseT4
6. 100BaseTX
7. 10BaseT FDX
8. 10BaseT
CommServ – Education Division Datacom Networking Fast Ethernet-
150
Flow Control
HDX - Switch generates collision
FDX - Switch generates pause
frame
CommServ – Education Division Datacom Networking Gigabit
Ethernet-151
Datacom Networking 11. Gigabit Ethernet
Chapter Objectives –Identify the physical specifications for Gigabit Ethernet
–Describe carrier extend
–Describe frame bursting
CommServ – Education Division Datacom Networking Gigabit
Ethernet-152
Gigabit Ethernet Essentials
• Latest extension to Ethernet
• 1000 Mbit/s - 10 times faster than fast Ethernet
• Compatible with existing Ethernet
CommServ – Education Division Datacom Networking Gigabit
Ethernet-153
Gigabit Carrier Extend
P DA SA L/T Data F SS DS LLC Carrier Extend 448 bytes
64 previous minimum
+ 448 carrier extend
= 512 minimum frame size
Minimum frame size = 512 bytes
CommServ – Education Division Datacom Networking Gigabit
Ethernet-154
Frame Bursting
• Frame Bursting is a means to reduce the Inefficiency of Carrier Extension
• The first frame is transmitted using the normal procedures for gigabit Ethernet.
• A frame burst timer is started to allow transmissions of up to 64 Kbits.
• If additional frames are queued for transmission and the 64 Kbit timer has not expired, two things happen
– The first frame is followed by carrier extend
– The next frame is transmitted
CommServ – Education Division Datacom Networking Gigabit
Ethernet-155
Gigabit Ethernet Specifications
• 1000BaseLX
– 2 strands of SMF or MMF
• 1000BaseSX
– 2 strands of SMF
• 1000BaseCX
– 2 pairs of twinax
• 1000BaseT
– 4 pairs of Cat 5 UTP
CommServ – Education Division Datacom Networking Gigabit
Ethernet-156
Ethernet Comparison
512 Bytes
64 Bytes
64 Bytes Min Frame
Size
1518 Bytes 1518 Bytes 1518 Bytes Max Frame
Size
16 tries 16 tries 16 tries Attempt
Limit
96 bit times 96 bit times 96 bit times Inter Frame
Gap
Fast Ethernet
802.3u
Ethernet,
802.3
Parameter Gigabit
Ethernet,
802.3z
48 bits 48 bits 48 bits Address
Size
CommServ – Education Division Datacom Networking WAN-157
Datacom Networking 13. WAN Concepts
Chapter Objectives –Define circuit switching and packet switching
–Define SVCs and PVCs
–Identify HDLC protocols and describe where they are used
CommServ – Education Division Datacom Networking WAN-158
Circuit Switching and Packet Switching
• Circuit Switching
– In a circuit switched network, a dedicated communications path is established between two terminals through the nodes of the network and for information transfer
• Packet Switching
– In this case it is not necessary to dedicate transmission capacity along a path through the network. Rather, data is sent out in a sequence of small chunks, called packets. Each packet is passed through the network from node to node along some path leading from the source to the destination.
CommServ – Education Division Datacom Networking WAN-159
A B
A B
A B
A B
A B
A B
A B
Circuit Switching Packet Switching
Info
Info
Info
Info
CS vs. PS for different applications
CommServ – Education Division Datacom Networking WAN-160
Leased Line and Dial-up
• Leased line
– With a leased line connection, a data user has a permanent dedicated transmission path which can be end to end across the network, locally, nationally or internationally.
• Dial-up
– This method is used for modem to modem data communication over the public switched telephone network (PSTN). Source and destination must have compatible modems.
CommServ – Education Division Datacom Networking WAN-161
Virtual Circuits, PVC and SVC
• Virtual Circuit
– Appears to be a separate physical circuit to the user, but in fact is part of a shared pool of resources
• Permanent Virtual Circuit (PVC)
– PVC is a continuously dedicated virtual circuit
• Switched Virtual Circuit (SVC)
– SVC is a temporary virtual circuit established and maintained only for the duration of a data transfer session
CommServ – Education Division Datacom Networking WAN-162
Datalink Layer Review
• A data link layer protocol only provides services on a point-to-point,
physical link.
• It’s up to a higher layer protocol to provide end-to-end services.
CommServ – Education Division Datacom Networking WAN-163
HDLC, Derivatives and Variations
Used by Frame Relay
technology LAPF
Error-correcting modems
(specified as part of V.42) LAPM
ISDN D channel and Frame
Relay LAPD
Current X.25 implementations LAPB
Early X.25 implementations LAP
Uses HDLC Subset
CommServ – Education Division Datacom Networking ATM-164
Datacom Networking 14. ATM
Chapter Objectives –Understand the concept of ATM
–Describe how an ATM switch works
–Describe where ATM is used in a Network
CommServ – Education Division Datacom Networking ATM-165
ATM Essentials
• Flexible bearer technology (2Mbit/s – 2.5Gbit/s)
• Connection-orientated
• Uses fixed-size cells
• Able to guarantee Quality of Service (QoS)
• A multiservice technology: both voice and data traffic can be carried on an ATM network
CommServ – Education Division Datacom Networking ATM-166
ATM connections
• In ATM a connection must be set up from source to destination before traffic can flow
CommServ – Education Division Datacom Networking ATM-167
The ATM Cell
• Fixed cell size
• ATM switches read the cell header only, any information in the payload flows through the network transparently
CommServ – Education Division Datacom Networking ATM-168
channel
1
channel
5
channel
1
empty
cell
channel
1
channel
7
channel
1
channel
2
Cell
Labelled multiplexing
CommServ – Education Division Datacom Networking ATM-169
Asynchronous? Transfer Mode
CommServ – Education Division Datacom Networking ATM-170
The principle of ATM switching
ATM
payload A 2
payload B 7
payload B 14
payload A 18
CommServ – Education Division Datacom Networking ATM-171
ATM Multiplexing
CommServ – Education Division Datacom Networking ATM-172
Constant
bit rate
Data
bursts
Variable
bit rate
Segmentation Addressing Multiplexing
Cell buffers
Segmentation and Multiplexing of different Broadband Services
CommServ – Education Division Datacom Networking ATM-173
ATM Connections
• Many ways of setting up the connections:
– Permanent Virtual Circuit (PVC)
– Switched Virtual Circuit (SVC)
• Many types of connections:
– Constant Bit Rate (CBR)
– Variable Bit Rate (VBR)
– Available Bit Rate (ABR)
– Unspecified Bit Rate (UBR)
• Virtual connections can be of any bandwidth
CommServ – Education Division Datacom Networking ATM-174
ATM Connections
• Connections are virtual channels
– Permanent (PVC)
– Switched (SVC)
CommServ – Education Division Datacom Networking ATM-175
ATM‘s Physical Layer
ATM Layer
Physical Layer
Adaptation Layer
PMD
TC
SAR
CS
Layer two
Layer one
CommServ – Education Division Datacom Networking ATM-176
ATM Interface References Public
Networks
Private
Networks
Public
NNI
B-ICI
Public
NNI
Private
NNI
Public
UNI
Public
UNI
Private
UNI
Private
UNI
Public
UNI
Public
UNI
CommServ – Education Division Datacom Networking ATM-177
The Physical Interfaces Supported
• E1 2.048 Mbit/s, T1 1.544 Mbit/s
• E3 34 Mbit/s, DS3 45 Mbit/s
• UTP-25 25 Mbit/s
• STS-1 51.84 Mbit/s
• TAXI 100 Mbit/s
• UTP- 5 I55.52 Mbit/s
• STM-1, OC3 155.52 Mbit/s
• STM-4, OC12 622.08 Mbit/s
• STM-16, OC48 2.488 Gbit/s
• STM-64, OC192 10 Gbit/s - work in progress
CommServ – Education Division Datacom Networking ATM-178
SDH/SONET
• The base standard defined to support ATM is:
– European/world standard
• Synchronous Digital Hierarchy (SDH)
– American standard
• Synchronous Optical Network (SONET)
• The two systems are identical at transmission rates of 155 Mbps and above
CommServ – Education Division Datacom Networking ATM-179
SONET / SDH Topology
Section
ADM
Line Path
ADM ADM
Repeaters
Inserted Data
Dropped Data
Repeaters
Inserted Data
Dropped Data
CommServ – Education Division Datacom Networking ATM-180
Physical Implementation of SDH
• Physical aspects of SDH/SONET
– Fibre
• single mode
– Preferred connection to operator connection
• multimode
– Used for private ATM networks, for example, a university campus
– UTP
• Category 5
– Used among workgroups
– To replace traditional LANs with ATM
CommServ – Education Division Datacom Networking ATM-181
ATM Layer
ATM Layer
Physical Layer
Adaptation Layer
PMD
TC
SAR
CS
Layer two
Layer one
CommServ – Education Division Datacom Networking ATM-182
ATM Cell Format
VPI (high order)
VCI - 1 VPI (low order)
VCI - 2
VCI - 3 Payload type CLP
Header error control
Payload (48 octets)
bit order
CommServ – Education Division Datacom Networking ATM-183
UNI Cell Header
48-octet data field
GFC VPI
VPI VCI
VCI
VCI PTI
HEC
8 1
1st Octet
2nd Octet
3rd Octet
4th Octet
5th Octet
Bits
CLP
CommServ – Education Division Datacom Networking ATM-184
NNI Cell Header
48-octet data field
VPI
VPI VCI
VCI
VCI PTI CLP
HEC
8 1
1st Octet
2nd Octet
3rd Octet
4th Octet
5th Octet
Bits
CommServ – Education Division Datacom Networking ATM-185
Generic Flow Control
• Locally significant only (at UNI)
– Any value will be overwritten by the switch
• Two modes of operation:
– Controlled mode
– Uncontrolled mode
• Currently only uncontrolled mode is defined
– Uncontrolled GFC = 0000
48-octet data field
VPI
VPI VCI
VCI
VCI PTI CLP
HEC
GFC
CommServ – Education Division Datacom Networking ATM-186
Virtual Path Identifier
• Identifies this cell’s path
• 8 bits available at the UNI
• 12 bits available at the NNI
– 256/4096 possible simultaneous paths
– Maximum number of usable bits is negotiable between user and network
48-octet data field
VCI
VCI
VCI PTI CLP
HEC
VPI
VPI
GFC
‘Real’ physical link
VPI 57
VPI 68
CommServ – Education Division Datacom Networking ATM-187
Virtual Channel Identifier
• Identifies this cell’s channel
• 16 bits available at the UNI & NNI
– 65,536 possible simultaneous channels per path
– Maximum number of useable bits is negotiable on a per-path basis
VPI 57
VPI 68
VCI 39 VCI 40
VCI 38 VCI 39
VPI 68
VPI 68
VCI 39
VCI44
VCI 40 VCI 41
Physical Interfaces 4- octet data field
PTI CLP
HEC
VPI
VPI
GFC
VCI
VCI
VCI
CommServ – Education Division Datacom Networking ATM-188
Virtual Paths
Multiple channels destined for a common location can be quickly and simply switched by the network if they share a common VPI
channels 131 145 117
channels 131 145 117
CommServ – Education Division Datacom Networking ATM-189
Reserved Virtual Connections
• The following VPI/VCI combinations have been reserved:
– VPI = 0 VCI = 0 to 15 ITU-T
– VPI = 0 VCI = 16 to 31 ATM Forum
– VPI = ALL VCI = 1 to 5
• In practice, carriers regard VCIs 0 to 31 as reserved for all VPIs
CommServ – Education Division Datacom Networking ATM-190
Payload Type Identifier
PTI Coding (MSB first)
Interpretation
User data cell, congestion not experienced, SDU type = 0 User data cell, congestion not experienced, SDU type = 1 User data cell, congestion experienced, SDU type = 0 User data cell, congestion experienced, SDU type = 1 Segment OAM F5 flow-related cell End-to-end OAM F5 flow-related cell Resource management cell Reserved for future functions
000
001
010
011
100
101
110
111
48-octet data field
VPI
VPI VCI
VCI
VCI CLP
HEC
GFC
PTI
CommServ – Education Division Datacom Networking ATM-191
Congestion Control
• Bit 2 of the PTI may be used to indicate to the destination that
congestion has taken place in the network
• The bit is called Explicit Forward Congestion Indicator (EFCI)
• This will occur when switches are discarding cells with CLP =1
48-byte data field
VPI
VPI VCI
VCI
VCI CLP
HEC
GFC
PTI
EFCI
CommServ – Education Division Datacom Networking ATM-192
Cell Loss Priority
• CLP operates independently on each active VPI/VCI
• A switch may flip CLP from 0 to 1, for example, if traffic on
a VPI/VCI exceeds the maximum agreed sustainable cell
rate
CLP = 0
CLP = 0 CLP = 1 CLP = 1
Private UNI Private NNI Public UNI Public NNI
48-octet data field
VPI
VPI VCI
VCI
VCI
HEC
GFC
PTI CLP
CommServ – Education Division Datacom Networking ATM-193
Header Error Check
• The HEC is performed on the header only
– Supports forward correction of single-bit errors
– Supports detection of multiple-bit errors
• Faulty cells are discarded
– At the UNI:
• Error detection is mandatory
• Error correction is optional
• The HEC is generated/verified at the TC part of the physical layer
48-octet data field
VPI
VPI VCI
VCI
VCI CLP
GFC
PTI
HEC
CommServ – Education Division Datacom Networking ATM-194
Virtual Paths and Channels ATM Switch
Virtual Channel Switch
Virtual Path Switch
VCI1 VCI2 VCI3 VCI4
VCI1
VCI2
VCI3
VCI4
VCIa
VCIb
VCIa
VCIb
VPI1
VPI2
VPI3
VPI1
VPI2
VPI4
VPI5
VPI5
CommServ – Education Division Datacom Networking ATM-195
The Switch Map
ATM Cell ATM Cells
VPI/VCI = A/B VPI/VCI = X/Y
1 2
Switch Map (1) VPI VCI Interface VPI VCI
A B 2 X Y
- - - - -
VPI/VCI is of
LOCAL Significance
Only
CommServ – Education Division Datacom Networking ATM-196
ATM Switching
• ATM cells are being switched along a predefined connection
CommServ – Education Division Datacom Networking ATM-197
CommServ – Education Division Datacom Networking ATM-198
CommServ – Education Division Datacom Networking ATM-199
The Adaptation Layer
ATM Layer
Physical Layer
Adaptation Layer
PMD
TC
SAR
CS
Layer two
Layer one
CommServ – Education Division Datacom Networking ATM-200
QoS Service Catagories
• CBR Constant Bit Rate
• VBR-RT Variable Bit Rate - Real Time
• VBR-NRT Variable Bit Rate - Non-Real Time
• ABR Available Bit Rate
• UBR Unspecified Bit Rate
• GFR Guaranteed Frame Rate (later)
CommServ – Education Division Datacom Networking ATM-201
ATM Service Classes
• Classes as defined by ITU-T rec. I 362
Class A Class B Class C Class D
Timing between
source and destination Required Not required
Bit rate Constant Variable
Connection mode Connection-oriented Connectionless
AAL 1 AAL 2 AAL 3 AAL 4
AAL 5
Relevant Adaptation Layer
CommServ – Education Division Datacom Networking ATM-202
General Principles of Adaptation
Adaptation Layer
SAR
CS
Higher layer data
H H
The use of a CS is not required by all AALs Etc.
H T H T H T
CommServ – Education Division Datacom Networking ATM-203
Usage of Adaptation Layer
• AAL is used to adapt a source application to ATM
– ATM switching takes place in the ATM Layer.
CommServ – Education Division Datacom Networking ATM-204
AAL1 Segmentation and Reassembly sublayer
Protocol Data Unit (SAR PDU)
Payload, 47 bytes (376 bits) Header, 5 bytes
SNP SN
44
SN, Sequence Number, 3 bits are used
to detect loss of cells
SNP, Sequence Number Protection
CommServ – Education Division Datacom Networking ATM-205
ATM Adaptation Layer type 1
Payload
Information for:
•Lost cell detection
•Synchronization
•Support of structured Circuit Emulation
1 octet47 octets
Real time, constant bit rate stream (e.g. PCM Speech)
CommServ – Education Division Datacom Networking ATM-206
AAL 1
CommServ – Education Division Datacom Networking ATM-207
AAL 2
CommServ – Education Division Datacom Networking ATM-208
AAL 2
CommServ – Education Division Datacom Networking ATM-209
AAL2 Segmentation And Reassemble sublayer
Protocol Data Unit (SAR PDU)
Header, 5 bytes
LI CID
8
CID, Channel Identity
LI, Length Indicator
UUI, User-to-user Indicator
HEC, Header Error Control
PayloadPayloadPayload
UUIHEC
8
STF
655
STF, Start Field
CommServ – Education Division Datacom Networking ATM-210
AAL2 demultiplexed to AAL2U
Header, 5 bytesPayloadPayloadPayload
Payload
Payload
Payload
AAL2
AAL 2U
CommServ – Education Division Datacom Networking ATM-211
AAL5 (SEAL)
CommServ – Education Division Datacom Networking ATM-212
AAL5, variable bit rate
CommServ – Education Division Datacom Networking ATM-213
AAL5 Trailer
CommServ – Education Division Datacom Networking ATM-214
AAL5 Transmission
• AAL5 makes use of the PTI field in ATM cell header
– Bit 1 = 1 indicates this cell carries the AAL5 trailer
48-byte data field
VPI
VPI VCI
VCI
VCI CLP
HEC
GFC
PTI
CommServ – Education Division Datacom Networking ATM-215
The use of AALs
ATM
AAL1ATM
AAL5
PCM (voice)
IP (64KB max.)
48 octet
ATM SDUs 53 octet
ATM PDUs
AAL1ATM
AAL5
AAL
ATM ATM ATM
AAL
ATM
CommServ – Education Division Datacom Networking ATM-216
ATM Applications – Large Core Networks
CommServ – Education Division Datacom Networking ATM-217
Site 2
Site 1
Transport Layer
Network Control Layer
Signaling
User Plane
RNC
TDM
Network
PCM
64 kbps
AMR coding
12 kbps
WCDMA Transport
• Aggregation of server nodes in the Control Layer
TSC
Server
MSC
Server Q.BICC
N-ISUP RANAP
Iu
MGW
GCP GCP
TRA
• M-MGw build the Transport Layer
AAL2
Switch
AAL2
Switches
Q.AAL2
Q.AAL2
• Bandwidth efficient transport using “Codec at the edge” • Local Switching
TDM
Network
CommServ – Education Division Datacom Networking ATM-218
ATM Based Signaling
MAP-ATM
TCAP
MAP/CAP
SCCP
MTP3b
SSCF-NNI
ATM
L1
AAL5
SSCOP
SGSN <---> HLR
3G MSC <--> HLR
HLR <--> VLR
MSC <--> MSC
RANAP-ATM
RANAP
SCCP
MTP3b
SSCF-NNI
ATM
L1
AAL5
SSCOP
MSC MA <--> RNC
MSC server <--> RNC
SGSN <---> RNC
Q.AAL2-ATM
Q.AAL2
MTP3b
SSCF-NNI
ATM
L1
AAL5
SSCOP
GCP-ATM
GCP
MTP3b
SSCF-NNI
ATM
L1
AAL5
SSCOP
MSC server <---> MGW
BICC/ISUP-ATM
BICC/ISUP
MTP3b
SSCF-NNI
ATM
L1
AAL5
SSCOP
MSC server <---> MSC server
TSC server <--> PSTN
MSC MA <---> RNC
C-MGw <--> RNC
C-MGw <--> C-MGw
RNC <--> RNC
RNSAP-ATM
RNSAP
SCCP
MTP3b
SSCF-NNI
ATM
L1
AAL5
SSCOP
RNC <---> RNC
CommServ – Education Division Datacom Networking Frame Relay-
219
Datacom Networking 15. Frame Relay
Chapter Objectives –Understand the concept of Frame Relay
–Describe how a Frame Relay switch works
–Describe where Frame Relay is used in a Network
CommServ – Education Division Datacom Networking Frame Relay-
220
Frame Relay Essentials
• WAN packet switching technology, preceded ATM
• Typically implemented at speeds from 56kbit/s to 2Mbit/s (Can go to speeds of 45Mbit/s)
• Supports PVCs (SVCs are supported, but generally not used)
• Uses variable-length frames to transfer data
• Has some built in traffic control mechanisms
CommServ – Education Division Datacom Networking Frame Relay-
221
Frame (LAPF) Format
CommServ – Education Division Datacom Networking Frame Relay-
222
CommServ – Education Division Datacom Networking
Frame Relay Terms
DLCI 21
DLCI 23
DLCI 22
DLCI 31
DLCI 32
DLCI 33
S 0
Frame Relay
Switch
Token Ring
SDLC FRAD
Definitions
DLCI: Data Link Connection Identifier
CIR : Committed Information Rate
Bc : Committed burst in bits
Be : Excess burst in bits
FECN: Forward Explicit Congestion Notify
BECN: Backward Explicit Congestion Notify
DE: Discard Eligible
Router
Frame Relay Switch
Maps DLCIs to form a PVC
Controls each PVC‘s CIR, Bc, Be Congestion Notification: FECN, BECN
Provides Accounting and Monitoring
Router
CommServ – Education Division Datacom Networking Frame Relay-
224
Frame Relay Switching
• Frame Relay Frames are being switched along a predefined connection
CommServ – Education Division Datacom Networking Frame Relay-
225
Congestion Control
• FECN – Forward Explicit Congestion Notification
• BECN – Backward Explicit Congestion Notification
• DE – Discard Eligibility
8 7 6 5 4 3 2 1 8 7 6 5 4 3 2 1
Byte 1 Byte 2
DLCI(msb) DLCI(lsb) C/R EA EA DE
F
E
C
N
B
E
C
N
CommServ – Education Division Datacom Networking Frame Relay-
226
Congestion Notification
CommServ – Education Division Datacom Networking Frame Relay-
227
Network Congestion Recovery
Committed Information Rate (CIR)
Maximum Information
Rate
Guaranteed transmission
Transmit if possible DE =
1
Discard all excess
CommServ – Education Division Datacom Networking
Frame Relay Illustration
• Committed Information Rate (CIR)
• Port speed (PIR)
• Permanent Virtual Circuits (PVCs)
Free if
Available
Traffic
Time
Peak
CIR What
You Pay
for {
{
CommServ – Education Division Datacom Networking Frame Relay-
229
Performance Model
Frame 1
DE=0
Frame 2
DE=0
Frame 3
DE=0
Frame 1
DE=0
Frame 2
DE=0
Frame 3
DE=0
Frame 4
DE=1
Frame 1
DE=0
Frame 2
DE=0
Frame 3
DE=1
Frame 4
DISCARDED
Time Time Time
Number of
bits
transmitte
d
Number of
bits
transmitte
d
Number of
bits
transmitte
d
Discard region
DE = 1 region
DE = 0 region
Discard region
DE = 1 region
DE = 0 region
Discard region
DE = 1 region
DE = 0 region
Bc+Be
Bc
Bc+Be
Bc
Bc+Be
Bc
CommServ – Education Division Datacom Networking Frame Relay-
230
FR Applications – Corporate LAN Interconnect
CommServ – Education Division Datacom Networking Frame Relay-
231
CommServ – Education Division Datacom Networking
interface s 0 encapsulation frame-relay ! interface s 0.1 point-to-point ip address 172.16.1.1 255.255.255.0 frame-relay interface-dlci 42 ! interface s 0.2 point-to-point ip address 172.16.4.1 255.255.255.0 frame-relay interface-dlci 53 ! Interface s 0.3 point-to-point ip address 172.16.2.10 255.255.255.0 frame-relay interface-dlci 59
interface s 0 encapsulation frame-relay ! interface s 0.1 point-to-point ip address 172.16.2.18 255.255.255.0 frame-relay interface-dlci 36 ! interface s 0.2 point-to-point ip address 172.16.3.25 frame-relay interface-dlci 46
Frame Relay Configuration Example
DLCI 36
Frame Relay
Network 172.16.3.0
B A
DLCI 42
172.16.1.0 DLCI 59
172.16.2.0
DLCI 53 172.16.4.0
DLCI 46
CommServ – Education Division Datacom Networking
interface s 0 encapsulation frame-relay ! interface s 0.1 multipoint ip address 172.16.1.1 255.255.255.0 frame-relay interface-dlci 300 frame-relay interface-dlci 212 frame-relay interface-dlci 437
interface s 0 encapsulation frame-relay ! interface s 0.1 point-to-point ip address 172.16.1.18 255.255.255.0 frame-relay interface-dlci 36
Frame Relay
B A
172.16.1.2
172.16.1.3
D
C
DLCI 36
Frame Relay Multipoint Example
CommServ – Education Division Datacom Networking Frame Relay-
234
CommServ – Education Division Datacom Networking X25-235
Datacom Networking 16. X25
Chapter Objectives •Understand the concept X.25
•Describe the structure of a LAPB frame
•Describe the structure of an X.25 packet
CommServ – Education Division Datacom Networking X25-236
X.25 Essentials
Old WAN packet switching technology, preceded both
Frame Relay and ATM
Designed to run over error-prone physical links so
contains extensive error checking mechanisms
X.25 typically implemented over low speed links <64K
- (low speed by today‘s standards)
X.25 used extensively with older proprietary systems
- banking terminals, control links for telephone exchanges
CommServ – Education Division Datacom Networking X25-237
X.25 and OSI Reference Model
Application
Presentation
Session
Transport
Network
Data Link
Physical Physical
Frame
Packet X.25 Protocol
Suite
Upper
Layer
Protocols
CommServ – Education Division Datacom Networking X25-238
X.25 Interface
User
Process
Packet
Link
Access
Link
Access
Physical Physical
User
Process
Packet
Multi-channel
Logical Interface
LAPB Link Level
Logical Interface
Physical Interface Physical
DLC
Network
OSI-RM User Data
User Data Layer 3
Header
X.25 Packet
LAPB
Header
Layer 3
Header User Data FCS
LAPB Frame
10101110111......
Node-A Node-B
Flag
CommServ – Education Division Datacom Networking X25-239
X.25 WAN
DTE DCE DCE
Packet Switching Network
Leased line
Physical DTE
Physical DCE
CommServ – Education Division Datacom Networking X25-240
X.25 WAN (contd)
DTE
Packet Switching Network
X 25 context is between
DTE and Packet switched network (DCE)
DTE
DTE
X 25
X 25
Logical DCE
at layer 2 / 3
Logical DTE
at layer 2 / 3
DCE DCE
Transparent at layer 2 / 3
Logical DTE
at layer 2 / 3
CommServ – Education Division Datacom Networking
Flag Address Information FCS Flag Control
0 1 1 1 1 1 1 0 0 1 1 1 1 1 1 0
Flag
Flags
CommServ – Education Division Datacom Networking
Flag Address Information FCS Flag Control
0 N(R) N(S) I:
7 6 5 4 3 2 1 0
F P
S: N(R) 0 1
7 6 5 4 3 2 1 0
U: P F X X 1 1
7 6 5 4 3 2 1 0
P F
X X X
X X
01 or 03
Address and Control
CommServ – Education Division Datacom Networking X25-243
Information frames
I Information nr p ns 0
Supervisory frames
RR Receiver Ready nr p/f 0 0 0 1
RNR Receiver Not Ready nr p/f 0 1 0 1
REJ Reject nr p/f 1 0 0 1
Unnumbered frames
SABM Set asynchronous balanced mode 0 0 1 p 1 1 1 1
UA Unnumbered acknowledgement 0 1 1 f 0 0 1 1
DISC Disconnect 0 1 0 p 0 0 1 1
DM Disconnected mode 0 0 0 f 1 1 1 1
FRMR Frame Reject 1 0 0 f 0 1 1 1
LAPB Commands and Responses
CommServ – Education Division Datacom Networking X25-244
LAPB Operation 1
SABM
SABM
UA UA
Info nr=0 ns=0
Info nr=0 ns=0
Info nr=1 ns=0
Info nr=1 ns=2
Info nr=1 ns=1
Info nr=1 ns=0
Info nr=1 ns=1
Info nr=1 ns=3 Info nr=1 ns=2
Info nr=1 ns=3
RR nr=4 RR nr=4
Info nr=4 ns=1 Info nr=4 ns=1
DCE
DTE
Info nr=2 ns=4 Info nr=2 ns=4
CommServ – Education Division Datacom Networking X25-245
LAPB Operation 2
Info nr=2 ns=7
Info nr=2 ns=7
REJ nr=6
DCE
DTE
Info nr=2 ns=5
Info nr=2 ns=4
Info nr=2 ns=6 Info nr=2 ns=5
Info nr=2 ns=4
Ignored as
CRC incorrect
Info nr=2 ns=0
Info nr=2 ns=0
REJ nr=6
Info nr=2 ns=6
Info nr=2 ns=6 Info nr=2 ns=7
Info nr=2 ns=0
Info nr=2 ns=0
Info nr=2 ns=7
Info nr=1 ns=2
Info nr=1 ns=2
REJ frame
acknowledges
up to frame 5
XX
CommServ – Education Division Datacom Networking X25-246
LAPB Operation 3
Info nr=2 ns=7 p=0
Info nr=2 ns=7 p=0
DCE DTE
Info nr=2 ns=5 p=0
Info nr=2 ns=4 p=0
Info nr=2 ns=6 p=0 Info nr=2 ns=5 p=0
Info nr=2 ns=4 p=0
Info nr=2 ns=4 p=1
Info nr=2 ns=4 p=1
T1
timer
T1
timer
Info nr=2 ns=4 p=1
Info nr=2 ns=4 p=1
Info nr=2 ns=4 p=1
Info nr=2 ns=6 p=0
T1
timer
N 2 times Info nr=2 ns=4 p=1
CommServ – Education Division Datacom Networking
Logical Channel Numbers (LCNs)
LCN LCN
LCN LCN
Logical DTE
Logical DCE
Logical DTE Logical DTE
Logical DCE
Logical DTE
CommServ – Education Division Datacom Networking
LCNs (contd)
LCN 5 LCN 8
LCN 45
LCN 19
LCN 9 LCN 9
CommServ – Education Division Datacom Networking
General Format Identifier
Q D
01 Modulo 8 10 Modulo 128 11 Extensions 00 Reserved
8 7 6 5 4 3 2 1 Bits
Byte 1 LCGN Modulo
GFI normal
L D
Long Address indicator Call Request packets only
8 7 6 5 4 3 2 1 Bits
Byte 1 LCGN Modulo
GFI Extended addressing
CommServ – Education Division Datacom Networking
Byte 1
2
3
1 2 3 4 5 6 7 8
Logical Channel Number
GFI
Bits
Packet Type Identifier
Logical Channel Group Number
Packet Layer Header
16 Logical Channel Group Numbers
256 Logical Channel Numbers in each group
A Logical channel may be identified by LCN or by LCGN + LCN
Logical channel 0 = LCGN 0 , LCN 0
Logical channel 1025 = LCGN 4 , LCN 1
CommServ – Education Division Datacom Networking
Packet Header
Call request / incoming call 0 0 0 0 1 0 1 1
Call accept / call connected 0 0 0 0 1 1 1 1
Clear request / Clear indication 0 0 0 1 0 0 1 1
Clear confirmation 0 0 0 1 0 1 1 1
Data pr m ps 0
RR pr 0 0 0 0 1
RNR pr 0 0 1 0 1
REJ pr 0 1 0 0 1
Interrupt 0 0 1 0 0 0 1 1
Interrupt confirmation 0 0 1 0 0 1 1 1
Reset request / Reset indication 0 0 0 1 1 0 1 1
Reset confirmation 0 0 0 1 1 1 1 1
Restart request/restart indication 1 1 1 1 1 0 1 1
Restart confirmation 1 1 1 1 1 1 1 1
Diagnostic 1 1 1 1 0 0 0 1
CommServ – Education Division Datacom Networking
Call Setup
Call request Incoming Call
Call Accept Call connected
CommServ – Education Division Datacom Networking
General Format Identifier Logical Channel Group Number
Logical Channel Number
Packet Type Identifier
Calling DTE Address Length Called DTE Address Length
Called DTE Address Field BCD - 2 digits / octet Variable length (15 digits max)
Facility Field Length
1 2 3 4 5 6 7 8 Bits
Call Request, Incoming call, Call Accepted, Call Connected
Facility Field codes and values Variable length
Calling DTE Address Field BCD - 2 digits / octet Variable length (15 digits max)
CommServ – Education Division Datacom Networking X25-254
X.25 Operation
DTE A DTE B A Initiates a
virtual call to B
Incoming Call
Call Accepted
Data pr=0 ps=0
Data pr=0 ps=1
Data pr=2 ps=0
RR pr = 1
Call Request
Call Connected
Data pr=0 ps=0
Data pr=0 ps=1
Data pr=3 ps=0
Network
RR pr=1
RR pr=2
Data pr=1 ps=3
Data pr=1 ps=2
Data pr=1 ps=3
Data pr=1 ps=2
Acknowledgement
from local DCE
Acknowledgement
from local node
Call established
Data transfer stage
Acknowledgement
changed by local
node for packet
with ps=2
Packet delayed at local node
until ACK has been received
from remote DTE
CommServ – Education Division Datacom Networking X25-255
X.121 Addressing
DNIC Data Network Identification Code (DCC + NI)
DCC Data Country Code (3 digits)
NI Network Identifier (1 digit)
NTN Network Terminal Number (max10 digits incl SA)
SA Sub-address
234 2 19201005
234 2 19201004 74
240 2 00451
272 4 30000200
310 6 000715
DNIC NI NTN SA
CommServ – Education Division Datacom Networking PPP-256
Datacom Networking 17. PPP
Chapter Objectives –Describe how a PPP frame structure
–Describe the function of the Link Control Protocol (LCP)
–Describe the function of the Network Control Protocol (NCP)
–Describe where PPP is used in a Network
CommServ – Education Division Datacom Networking PPP-257
PPP Essentials
• Very widely-used standard for transporting layer 3 datagrams (especially IP) over point-to-point links (rfc 1661)
• PPP replaces the older Serial Line Interface Protocol (SLIP)
• PPP is comprised of: – Encapsulation method
– Link Control Protocol (LCP)
– Network Control Protocol (NCP)
• Often referred to as “self-configuring”
CommServ – Education Division Datacom Networking PPP-258
CommServ – Education Division Datacom Networking PPP-259
PPP Frame Format
CommServ – Education Division Datacom Networking PPP-260
CommServ – Education Division Datacom Networking PPP-261
Link Control Protocol (LCP) Functions
• Determine encapsulation format options
• Negotiate optimal packet size
• Terminate the link
• Authenticate the identity of the peer on the link [ PAP or CHAP ]
(optional)
• Negotiate PPP Multilink data compression (optional)
• Link quality monitoring (optional)
CommServ – Education Division Datacom Networking PPP-262
Network Control Protocols (NCPs)
• NCPs are a series of independently-defined protocols that
encapsulate network layer protocols
• Examples: TCP/IP, DECnet, AppleTalk, IPX…
CommServ – Education Division Datacom Networking PPP-263
PPP Logical Flow
LCP
Link DEAD
Start
Up State
NCP Negotiate Options
Bind NCP
Last
Last
Terminate Data Exchange
Fail authentication
Open LCP phase
NCP phase
Open State
CommServ – Education Division Datacom Networking PPP-264
CommServ – Education Division Datacom Networking PPP-265
CommServ – Education Division Datacom Networking PPP-266
PPP Applications
CommServ – Education Division Datacom Networking Modems-267
Datacom Networking 18. Modems
Chapter Objectives –Describe the function of a modem
–Identify modem standards and associated speeds
–Describe where modems are used in a Network
CommServ – Education Division Datacom Networking Modems-268
Chapter Objectives
• After completing this chapter you will be able to:
– Describe the function of a modem
– Identify modem standards and associated speeds
– Describe where modems are used in a Network
CommServ – Education Division Datacom Networking Modems-269
Modem – MOdulation and DEModulation
CommServ – Education Division Datacom Networking Modems-270
Modem Standards Rec. Speed (bit/s) Transmission
ModePSTN LL
2WLL4W
Back-upvia PSTN
Mod.Method
V.21 300 Asynchronous (A) FD FD FSK
V.23 1200/600 A and S HD HD FD * FSK
V.22 1200/600 A and S FD FD * DPSK
V.22bis
V.22f.bk
2400/1200 A and S FD FD * QAM
V.26bis 2400/1200 Synchronous (S) HD HD FD * DPSK
V.26ter 2400/1200 A and S FD FD * DPSK
V.27ter
V.26bisf.bk
4800/2400 S HD HD FD * DPSK
V.29 9600/7200/4800 A and S FD QAM
V.32 9600/4800 A and S FD FD * QAM/TCM
V.33 14400/12000 S FD QAM/TCM
V.34 28800 S FD TCM
V.34bis 28800/31200/33600 S FD TCM
Baseband 2400/1800/1200
7200/4800/3600
19200/14400/9600
A and S HD FD
V.90 56000 to the end user33600 from the end user
S Asymetric PCM
CommServ – Education Division Datacom Networking Modems-271
LAPM Frame Format
CommServ – Education Division Datacom Networking Modems-272
Modem Applications
CommServ – Education Division Datacom Networking ISDN-273
Datacom Networking 19. ISDN
Chapter Objectives –Describe the concept of ISDN
–Identify the reference points in an ISDN network
–Identify the differences between primary and basic rate ISDN
–Describe where ISDN is used in network
CommServ – Education Division Datacom Networking ISDN-274
ISDN Essentials
• Full services, digital, end-to-end network
• Narrowband ISDN and Broadband ISDN (B-ISDN is ATM-based)
• ISDN based on 64Kbit/s channels
• Two channel types: Bearer (B) Channel and Data (D) Channel
– B channel for user traffic, uses PPP
– D channel signalling and control, uses LAPD
CommServ – Education Division Datacom Networking ISDN-275
ISDN BRI Reference Model
TE1
NT2 NT1
Terminal Adapter
U
Interface
T
Interface
S
Interface
R
Interface
To Telco
To Telco TE2
CommServ – Education Division Datacom Networking ISDN-276
PRI Frame Format for E1/T1
7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0 0
B1 D-Channel B31 Framing
7 6 5 4 3 2 1
256 bits/125 microseconds (2.048Mbps)
E1
Signaling
+31 +0 +1 +16
Data Data
F
7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0
B1 B2 B23 D-Channel
24th Channel
193 bits/125 microseconds (1.544Mbps)
T1
CommServ – Education Division Datacom Networking ISDN-277
Basic Rate Interface (BRI)
B1
B2
D
64Kbs
64Kbs
16Kbs
2B + 1D
CommServ – Education Division Datacom Networking ISDN-278
Primary Rate Interface (PRI)
64Kbs
64Kbs
: :
B1 64Kbs
64Kbs
64Kbs
: B2
D
23B + 1D (USA)
30B + 1D (EISDN)
B22 or
29 B23 or
30
CommServ – Education Division Datacom Networking ISDN-279
LAPD Format
CommServ – Education Division Datacom Networking ISDN-280
Types of ISDN Connections
• Circuit Switched
• Packet Switched
• Frame Mode
• Semi-permanent
CommServ – Education Division Datacom Networking ISDN-281
ISDN Applications
CommServ – Education Division Datacom Networking xDSL-282
Datacom Networking 20. xDSL
Chapter Objectives –Describe the concept of xDSL
–Identify the speeds of common xDSL standards
–Describe where xDSL is used in a network
CommServ – Education Division Datacom Networking xDSL-283
Copper Access
CommServ – Education Division Datacom Networking xDSL-284
xDSL Technologies
• Asymmetric Digital Subscriber Line (ADSL)
• Rate Adaptive Digital Subscriber Line (RADSL)
• High-bit-rate Digital Subscriber Line (HDSL)
• Symmetrical Digital Subscriber Line (SDSL)
• Very-high-data-rate Digital Subscriber Line (VDSL)
CommServ – Education Division Datacom Networking xDSL-285
DSL Types
Technology Data Rate Mode Distance (ft) Distance (m)
ISDL/ISDN 128Kbps
Duplex 18000 5400
HDSL 2.048Mbps
1.544Mbps
Duplex
Duplex
12000 3600
SDSL 2.048Mbps
1.544Mbps
Duplex
Duplex
10000 3000
ADSL 6.144Mbps
640Kbps
Downstream
Upstream
12000 3600
RADSL 0.32-9Mbps Downstream Depends on data
rate
VDSL 12.96Mbps
25.92Mbps
51.84Mbps
1.5 – 6Mbps
Downstream
Upstream
4500
3000
1000
1350
900
300
CommServ – Education Division Datacom Networking xDSL-286
ADSL standards and bandwidth
8,1 / 1,5 Mbps
Annex A (POTS)
8,1 / 1,8 Mbps Annex B (ISDN)
8 / 3.4 Mbps ‗Annex J‘ (POTS)
Scenario ...
ADSL ADSL2 ADSL2+ ADSL2++
VDSL1/2 DMT
13,4 / 1,6 Mbps Annex A (POTS)
11,5 / 1,9 Mbps Annex B (ISDN)
5,7 / 1,0 Mbps Annex L (POTS)
11,5 / 3,5 Mbps
Annex M (POTS)
28,7 / 1,6 Mbps Annex A (POTS)
26,8 / 1,9 Mbps Annex B (ISDN)
26,8 / 3,5 Mbps
Annex M (POTS)
CommServ – Education Division Datacom Networking xDSL-287
ITU G.992.1 - ADSL
• ITU G.992.1 (ADSL) is implemented from EDA 1.1
• The following ADSL annexes are available:
ISDN DS ADSL
Annex B f
[kHz]
ADSL
Annex A f
[kHz]
DS
PO
TS
US
US
Variable frequency spectrum
PO
TS
f
[kHz]
DS ADSL
Annex M US
25 80 138 276 1104 552
CommServ – Education Division Datacom Networking xDSL-288
ITU G.992.3 - ADSL2
• ITU G.992.3 (ADSL2) is implemented from EDA 1.3
• The following ADSL2 annexes are available:
ISDN DS ADSL2
Annex B f
[kHz]
ADSL2
Annex A f
[kHz]
DS
PO
TS
US
US
Variable frequency spectrum
PO
TS
f
[kHz]
DS ADSL2
Annex M US
25 80 138 276 1104
DS
PO
TS
US
552
f
[kHz]
ADSL2
Annex L
CommServ – Education Division Datacom Networking xDSL-289
ITU G.992.5 - ADSL2+
• ITU G.992.5 (ADSL2+) is implemented from EDA 2.0
• New frequency spectrum compared with G992.1 & G992.3
• The following ADSL2+ annexes are available:
ISDN DS ADSL2+
Annex B f
[kHz] PO
TS
f
[kHz]
ADSL2+
Annex A f
[kHz]
DS
DS
PO
TS
US
ADSL2+
Annex M US
25 80 138 276 2208
US
Variable frequency spectrum
CommServ – Education Division Datacom Networking xDSL-290
ADSL2/ADSL2+ Facts
• ADSL2 Boosts performance
– 13 Mbps / 3 Mbps (DS/US)
• ADSL2 provides service over longer loop lengths
– Approx. 500 m more compared with G992.1
– Annex L even more on long loop lengths
• ADSL2+ Boosts performance even more
– 28 Mbps / 3 Mbps (DS/US)
• ADSL2+ relevant for loop lengths up to 2 km
Length, Km 1 Km 2 Km 3 Km 4 Km 5 Km 6 Km
8
13
ADSL2
ADSL2+
28
Data Rate, Mbps
Annex L is
relevant here
7 Km
ADSL
CommServ – Education Division Datacom Networking xDSL-291
xDSL Applications
CommServ – Education Division Datacom Networking xDSL-292
Multiple downstream
tunnels with same content
Video service via PPP tunnels
Channel 1
Channel 2
Set-top Box
Channel 1
Set-top Box
Channel 2
Set-top Box
Channel 2
Router/
BRAS
Video
Service
Provider
IP
DSLAM
CommServ – Education Division Datacom Networking xDSL-293
Video service via IGMP
Supports
IGMP snooping
Supports
IP Multicast
Only one downstream
for each channel
Channel 1
Channel 2
Set-top Box
Channel 1
Set-top Box
Channel 2
Set-top Box
Channel 2
Router/
BRAS
Video
Service
Provider
IP
DSLAM
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294
Datacom Networking 21. SDH & SONET
Chapter Objectives –Describe the differences between PDH and SDH/SONET
–Identify the speeds associated with SDH/SONET
–Describe where SDH/SONET is used in a Network
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295
PDH Systems
DS0 @ 64k
1.5Mb 6Mb 45Mb 274Mb X 4 X 7 X 6
2Mb 8Mb 34Mb 565Mb 140Mb
X 3
0
X 4 X 4 X 4
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296
PDH Multiplexing and Demultiplexing
• With PDH everything must be de-multiplexed to extract a single signal!
– Motivation for development of SDH/SONET
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297
PDH/SDH and SONET
SDH/SONET
– Higher bandwidth, easier to manage, backwards-
compatible with PDH
CommServ – Education Division Datacom Networking SDH SONET-
298
SONET and SDH Frames
CommServ – Education Division Datacom Networking SDH SONET-
299
SONET and SDH Frames – Overhead
CommServ – Education Division Datacom Networking SDH SONET-
300
CommServ – Education Division Datacom Networking SDH SONET-
301
Overhead Layers
ADM
or
DCS REG REG PTE PTE
Section Section Section Section
Line Line
Path
Path
Termination
Section
Termination Line
Termination
Section
Termination Path
Termination
Service (DS1, DS3 ..)
Mapping and
Demapping
Service
Mapping and
Demapping
PTE Path Terminating Element
REG Regenerator
ADM Add-Drop Multiplexer
DCS Digital Cross-Connect System
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SDH Multiplexing Structure
Pointer
SOH
SOH
STM-1
VC-4
C-4
260
9
P
O
H
140 Mbit/s C-4 VC-4 STM-1
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303
SDH Multiplexing Structure
x 1
x 3
x 1
x 7
x 3
x 1 x N
STM-N
AUG AU4 VC4 C4
C3
C2
C12
C11
139,264
kbit /s
44,736 34,368
kbit /s
6,312
kbit /s
2,048
kbit /s
1,544
kbit /s
VC3
VC2
VC12
VC11
TU3
TU2
TU12
TUG2
TUG3
Aligning
Mapping
Multiplexing STM Synchronous Transport Mode
AUG Administrative Unit Group
AU Administrative Unit
TUG Tributary Unit Group
TU Tributary Unit VC Virtual Container
C Container
AU3 VC3
x 3
x 7
TU11 TU11
x 4
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305
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306
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307
SDH/SONET Equipment
• Add-drop multiplexer
– A multiplexer capable or extracting or inserting lower rate signals from a higher rate multiplexed signal without completely demultiplexing the signal
• Digital Cross Connect
– An electronic cross-connect which has access to lower-rate channels in higher-rate multiplexed signals and can cross-connect those channels
• Regenerator (Repeater)
– Device that restores a degraded digital signal for continued transmission
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308
SDH / SONET Acronyms
This Graphic is the Property
of Quill Training Services
9953.280
2488.320
622.080
155.520
51.840
STS-192
STS-48
STS-12
STS-3
STS-1
OC-192
OC-48
OC-12
OC-3
OC-1
STM-64
STM-16
STM-4
STM-1
SDH-64
SDH-16
SDH-4
SDH-1
Format Frame
Level SDH
( Mbps ) Line Rate
Format Frame
Carrier Level Optical
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310
Applications of SDH/SONET
CommServ – Education Division Datacom Networking POS-311
Datacom Networking 22. POS
Chapter Objectives –Describe the concept of Packet Over SONET (POS)
–Describe where POS is used in a Network
CommServ – Education Division Datacom Networking POS-312
CommServ – Education Division Datacom Networking POS-313
Packet Over SONET (POS) Essentials
• POS = Packet over SONET or Packet over SDH
• A standard for transmitting packets (primarily IP) over high speed SONET/SDH links
• Consists of PPP over SONET or SDH
– IP is carried within PPP
• Works with all speed of SONET/SDH
• Attractive solution for large ISP cores
CommServ – Education Division Datacom Networking POS-314
IP over PPP over SDH/SONET
CommServ – Education Division Datacom Networking POS-315
CommServ – Education Division Datacom Networking POS-316
CommServ – Education Division Datacom Networking POS-317
POS Applications – Large Core ISP Networks
CommServ – Education Division Datacom Networking POS-318
CommServ – Education Division Datacom Networking MPLS-319
Datacom Networking 23. MPLS
Chapter Objectives –Describe the concept of Multiprotocol Label Switching (MPLS)
–Describe how MPLS devices work
–Identify how MPLS is implemented with different technologies
–Describe where MPLS is used in a Network
CommServ – Education Division Datacom Networking MPLS-320
Multiprotocol Label Switching Essentials
• MPLS is an Internet Engineering Task Force (IETF) forwarding standard
• Concept:
– Packets entering the network are analysed and put into a forward equivalence class (FEC)
– Forward equivalence classes are mapped to connections through the network
– The packet is labelled according to which path it should take through the network
– Packet is transferred though the network by switching on the label
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CommServ – Education Division Datacom Networking MPLS-324
MPLS Network Components
Label Switching Router (LSR) deployed in
the core of the network to perform high
speed label switching
Label Edge Router (LER) deployed at the
edge of the network for connectivity to user
networks. Also called ingress and egress
LSRs.
CommServ – Education Division Datacom Networking MPLS-325
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CommServ – Education Division Datacom Networking MPLS-327
CommServ – Education Division Datacom Networking MPLS-328
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CommServ – Education Division Datacom Networking MPLS-330
CommServ – Education Division Datacom Networking MPLS-331
MPLS in Operation
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MPLS in Operation
CommServ – Education Division Datacom Networking MPLS-333
LER Functions
CommServ – Education Division Datacom Networking MPLS-334
LSR Functions
CommServ – Education Division Datacom Networking MPLS-335
MPLS Implementation
• MPLS can be implemented as:
• A Layer 3 (or “Pure IP”) solution
– The Label is extra information attached to the IP header
– LERs are edge routers running MPLS software
– LSRs are core routers running MPLS software
• An ATM solution
– The Label is the VPI/VCI
– LERs are edge routers running MPLS software
– LSRs are ATM switches running MPLS software
CommServ – Education Division Datacom Networking MPLS-336
MPLS Label in a ―Pure IP‖ Solution
CommServ – Education Division Datacom Networking MPLS-337
CommServ – Education Division Datacom Networking MPLS-338
MPLS Label in an IP over ATM Solution
CommServ – Education Division Datacom Networking MPLS-339
CommServ – Education Division Datacom Networking MPLS-340
CommServ – Education Division Datacom Networking MPLS-341
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MPLS Applications – Large Backbone
Networks
CommServ – Education Division Datacom Networking MPLS-349
CommServ – Education Division Datacom Networking MPLS-350
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CommServ – Education Division Datacom Networking Internet
Architecture-
352
Datacom Networking 25. Internet Architecture
Chapter Objectives
–Describe the structure of the TCP/IP protocol suite
CommServ – Education Division Datacom Networking Internet
Architecture-
353
Internet Protocols
TCP
IP
Transport Layer
RARP
UDP OSPF EGP
BGP
ICMP IGMP
RIP
TELNET, FTP, TFTP, BOOTP, SMTP, HTTP, SNMP, NFS, NTP, , ,
Internet Layer ARP
Type Code
Protocol Number
Port Number
IEEE 802.2, PPP, LAPB, Ethernet, RS232, 802.3, 802.5,
Upper Layer
Link/Physical Layer
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Architecture-
354
Upper-Layer Protocols: End User and Utility
Functions
TCP
IP
Transport Layer
RARP
UDP OSPF EGP
BGP
ICMP IGMP
RIP
TELNET, FTP, TFTP, HTTP, SMTP
SNMP, BOOTP/DHCP, DNS, NTP, RADIUS
Internet Layer
ARP
Type Code
Protocol Number
Port Number
IEEE 802.2, PPP, LAPB, Ethernet, RS232, 802.3, 802.5,
Upper Layer
Link/Physical Layer
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Architecture-
355
Transport Layer Protocols
TCP
IP
Transport Layer
RARP
UDP OSPF EGP
BGP
ICMP IGMP
RIP
SNMP, BOOTP/DHCP, DNS, NTP, RADIUS, , , ,
Internet Layer
ARP
Type Code
Protocol Number
Port Number
IEEE 802.2, PPP, LAPB, Ethernet, RS232, 802.3, 802.5,
Upper Layer
Link/Physical Layer
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Architecture-
356
Internet Layer Protocol: Internet Protocol
TCP
IP
Transport Layer
RARP
UDP OSPF EGP
BGP
ICMP IGMP
RIP
SNMP, BOOTP/DHCP, DNS, NTP, RADIUS, , , ,
Internet Layer
ARP
Type Code
Protocol Number
Port Number
IEEE 802.2, PPP, LAPB, Ethernet, RS232, 802.3, 802.5,
Upper Layer
Link/Physical Layer
CommServ – Education Division Datacom Networking Internet
Architecture-
357
Anomalies
TCP
IP
Transport Layer
RARP
UDP OSPF EGP
BGP
ICMP IGMP
RIP
SNMP, BOOTP/DHCP, DNS, NTP, RADIUS, , , ,
Internet Layer ARP
Type Code
Protocol Number
Port Number
IEEE 802.2, PPP, LAPB, Ethernet, RS232, 802.3, 802.5,
Upper Layer
Link/Physical Layer
CommServ – Education Division Datacom Networking Internet
Architecture-
358
Sending and Receiving a Message
Application specify:
Upper Layer Protocol Internet address
Upper Layer protocol:
Build header for peer to describe format Specify Port number to select Application
Transport Layer protocol:
Build Header for peer to describe format Specify Protocol number to select proper
Internet Layer (IP):
Build header for peer to describe format Source and destination IP addresses
Link Layer (unique for physical connection):
Build header for peer to describe format Identify IP stack with Type Code number
at IP address
Transport Layer protocol
CommServ – Education Division Datacom Networking Internet
Architecture-
359
Internet Society (ISOC) Specifications
• All Internet standards specified by the IETF, a division of ISOC
• Standards are called Request for Comments (RFCs) and are sequentially numbered
• All standards available free from http://www.ietf.org
• RFC search facility available at http://www.rfc-editor.org/
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Datacom Networking 26. Internet Applications
Chapter Objectives –Describe how the Hypertext Transfer Protocol (HTTP) works
–Describe how the Domain Name Service (DNS) works
–Describe how the Simple Network Management Protocol (SNMP) works
–Describe how the File Transfer Protocol (FTP) works
–Describe how Telnet works
CommServ – Education Division Datacom Networking Internet Apps-
361
Hypertext Transfer Protocol
Architecture
HTTP
TCP
IP
Protocol 6
HTTP
TCP
IP
Protocol 6
Server Client
Port 80 Port 80
CommServ – Education Division Datacom Networking Internet Apps-
362
HTTP Operation
Web client
browser TCP port 80
hypertext
links
Web
server
CommServ – Education Division Datacom Networking Internet Apps-
363
Uniform Resource Locator (URL)
scheme = http://, ftp://, telnet://,
news:, mailto: , , , , ,
http://server.name/file.type
scheme
path=domain name
or IP address
search object
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364
Domain Name Service (DNS)
root unnamed
int org net mil gov edu com uk au us
geographically based domains:
2-letter country codes
defined in ISO 3166
organizationally based domains:
defined by Internet Registry (IR)
IP
Physical network
DNS
UDP
Protocol 17
port 53
CommServ – Education Division Datacom Networking Internet Apps-
365
File Transfer Protocol
IP
Physical network
FTP
TCP
Protocol 6
port 21
CommServ – Education Division Datacom Networking Internet Apps-
366
Telnet
IP
Physical network
Telnet
TCP
Protocol 6
port 23
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367
Simple Network Management Protocol
Architecture
SNMP
UDP
IP
Protocol 17
SNMP
UDP
IP
Protocol 17
Manager Agent
Port 169 Port 169
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368
SNMP Management
Manager
Managed
Resources
Managed Node
Agent
MIB
SNMP
SNMP Operations
Set, Get, GetResponse,
GetNext, Trap
CommServ – Education Division Datacom Networking Transport
Protocol-369
Datacom Networking 27. Transport Layer Protocol
Chapter Objectives –Describe how connection may be multiplexed
–Define ports and sockets
–Describe the differences between TCP and UDP
–Describe the operation of TCP and UDP
CommServ – Education Division Datacom Networking Transport
Protocol-370
Multiplexing Connections
Internet
client server
SMTP
FTP
HTTP
SMTP
FTP
HTTP
IP address
X
IP address
Y
destination
port 25 source
port 3000
destination
port 21 source
port 3001
destination
port 80 source
port 3002
CommServ – Education Division Datacom Networking Transport
Protocol-371
Connection Components
Internet
client server
SMTP
FTP
HTTP
SMTP
FTP
HTTP
IP address
X
IP address
Y
destination
port 25 source
port 3000
destination
port 21 source
port 3001
destination
port 80 source
port 3002
socket socket
connection
CommServ – Education Division Datacom Networking Transport
Protocol-372
Transport Layer Protocols
UDP
IP
TCP
Upper Layer Protocols
Physical network
ports
6 17 protocols
CommServ – Education Division Datacom Networking Transport
Protocol-373
Transmission Control Protocol (TCP)
Segment Format
TCP Data
+0
+4
bit order
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
octet +0 octet +1 octet +2 octet +3
octet order
+8
+16
+20
source port destination port
sequence number
acknowledgement number
check sum urgent pointer
options (if any) padding
window +12 hdr
length reserved code
bits
CommServ – Education Division Datacom Networking Transport
Protocol-374
Transmission Control Protocol (TCP)
Segment Format
TCP Data
+0
+4
bit order
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
octet +0 octet +1 octet +2 octet +3
octet order
+8
+12
+16
+20
source port destination port
sequence number
acknowledgement number
hdr length window reserved
code bits
check sum urgent pointer
options (if any) padding
CommServ – Education Division Datacom Networking Transport
Protocol-375
Connection Sequence
0
Sender Receiver
SYN,seq=x
SYN/ACK,seq=y,ack=x+1
Internet
ACK, seq=x+1,ack=y+1
(SYN,seq=x)
(SYN,seq=y,ack=x+1)
(ACK, seq=x+1,ack=y+1) DATA,seq=x+1,ack=y+1
(DATA,seq=x+1,ack=y+1)
1
2
3
4
Legend:
CLOSED
LISTEN
SYN-SENT
ESTABLISHED
(received and sent)
SYN-RECEIVED
4
0
1 3
2
4
Note: ACK does not
use sequence space
CommServ – Education Division Datacom Networking Transport
Protocol-376
Closing Sequence
FIN,seq=x,ack=y
ACK,seq=y, ack=x+1
ACK, seq=x+1,ack=y+1
(ACK, seq=y,ack=x+1)
(ACK, seq=x+1,ack=y+1)
FIN/ACK,seq=y ack=x+1
(FIN/ACK, seq=y,ack=x+1)
Inform Application ->
(CLOSE ->)
(<- CLOSE)
(FIN,seq=x,ack=y)
Wait=2*MSL
ESTABLISHED
FIN-WAIT-1
FIN-WAIT-2
CLOSE-WAIT
LAST-ACK
TIME-WAIT CLOSED
Internet Sender Receiver
4 4
5
7
6
9
10
0 0
0 10
9
7 4
5
6
Legend:
CommServ – Education Division Datacom Networking Transport
Protocol-377
User Datagram Protocol (UDP)
bit order
UDP Data
UDP Destination Port
UDP Checksum UDP Message Length
UDP Source Port
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
octet +0 octet +1 octet +2 octet +3
+0
+4
Octet order
Segment Format
CommServ – Education Division Datacom Networking Internet
Protocol-378
Datacom Networking 28. Internet Protocol
Chapter Objectives –Describe IP functions and characteristics
–Describe the fields contained within an IP header
–Describe the Internet Control Message Protocol (ICMP)
CommServ – Education Division Datacom Networking Internet
Protocol-379
Internet Protocol
IP Data
+0
+4
bit order
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
octet +0 octet +1 octet +2 octet +3
octet order
datagram format
+8
+12
+16
+20
ver total length
time to live
source IP address
options (if any) padding
hdr ver length
identification flags fragment offset
header checksum protocol
destination IP address
+24
type of service
CommServ – Education Division Datacom Networking Internet
Protocol-380
Internet Protocol
IP Data
+0
+4
bit order
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
octet +0 octet +1 octet +2 octet +3
octet order
+8
+12
+16
+20
ver total length
time to live
source IP address
options (if any) padding
hdr ver length type of service
identification flags fragment offset
header checksum protocol
destination IP address
+24
datagram format
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Protocol-381
CommServ – Education Division Datacom Networking Internet
Protocol-382
Internet Protocol
IP Data
+0
+4
bit order
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
octet +0 octet +1 octet +2 octet +3
octet order
datagram format
+8
+12
+16
+20
ver total length
time to live
source IP address
options (if any) padding
hdr ver length type of service
identification flags fragment offset
header checksum protocol
destination IP address
+24
CommServ – Education Division Datacom Networking Internet
Protocol-383
Internet Protocol
datagram format
0 IP Data
+0
+4
bit order
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
octet +0 octet +1 octet +2 octet +3
octet order
+8
+12
+16
+20
ver total length
time to live
source IP address
options (if any) padding
hdr ver length type of service
identification flags fragment offset
header checksum protocol
destination IP address
+24
CommServ – Education Division Datacom Networking Internet
Protocol-384
Internet Control Message Protocol
UDP
IP
TCP
Upper Layer Protocols
Physical network
ports
6 17 protocols
ICMP
1 Utility (no ports)
Ping
CommServ – Education Division Datacom Networking Internet
Protocol-385
Ping Command
Usage: ping [-t] [-a] [-n count] [-l size] [-f] [-i TTL] [-v TOS]
[-r count] [-s count] [[-j host-list] | [-k host-list]]
[-w timeout] destination-list
Options:
-t Ping the specified host until interrupted.
-a Resolve addresses to hostnames.
-n count Number of echo requests to send.
-l size Send buffer size.
-f Set Don't Fragment flag in packet.
-i TTL Time To Live.
-v TOS Type Of Service.
-r count Record route for count hops.
-s count Timestamp for count hops.
-j host-list Loose source route along host-list.
-k host-list Strict source route along host-list.
-w timeout Timeout in milliseconds to wait for reply.
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386
Datacom Networking 29. IP Addressing
Chapter Objectives –Describe the structure of an IP address
–Identify different address classes
–Describe the function of a subnet mask
CommServ – Education Division Datacom Networking IP Addressing-
387
IP Address Function
Router 1 Router 2
Router 3
A B
C D
E
G
H
K J
M L
Host 1
Host 2
Host 3
N
P
F
CommServ – Education Division Datacom Networking IP Addressing-
388
CommServ – Education Division Datacom Networking IP Addressing-
389
CommServ – Education Division Datacom Networking IP Addressing-
390
IP Address Format
Class A
Class B
Class C
Class D
bit order
Host Network
octet order
0
Host 1
Host 1
Multicast Address
Network 0
Network 1 0
1 1 0 1
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
octet +0 octet +1 octet +2 octet +3
CommServ – Education Division Datacom Networking IP Addressing-
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392
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393
IP Address Notation
binary format
bit order octet order
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
octet +0 octet +1 octet +2 octet +3
0-255 0-255 0-255 0-255
0-255 0-255 0-255 0-255
128 129 64 192
dotted decimal format
dotted decimal example
CommServ – Education Division Datacom Networking IP Addressing-
394
IP Addresses in Decimal
Class Valid Network Numbers
A 1 through 126
B 128.1 through 191.254
C 192.0.1 through 223.255.254
D 224.0.0.1 through 239.255.255.255
E 240 through 255.255.255.255
Valid Host Numbers
Not applicable
1 through 255.255.254
1 through 255.254
1 through 254
Reserved
CommServ – Education Division Datacom Networking IP Addressing-
395
CommServ – Education Division Datacom Networking IP Addressing-
396
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397
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398
CommServ – Education Division Datacom Networking IP Addressing-
399
Class B Subnet Mask
user’s
IP address 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1
Subnet 1
Mask 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0
bit order octet order
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
octet +0 octet +1 octet +2 octet +3
Host Class B
1 Network 0 format
Network Subnet Host
Subnet 1
IP address 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0
1 0
CommServ – Education Division Datacom Networking IP Addressing-
400
Multicast Addressing
• Class D addresses are Multicast addresses
• Range 224.0.0.1 through 239.255.255.255 is available
Class D IP multicast address 1 1 0 1
7 0 - 7 0 - 7 0 - 7 0 - IP
CommServ – Education Division Datacom Networking IP Addressing-
401
IP Addressing Problem
Over 4 billion address space
ABC Ltd.
London, England
129.1.0.0
RST Co.
New York, U.S.
129.2.0.0
MNO Ltd.
London, England
170.1.0.0
JKL Co.
New York, U.S.
170.2.0.0
CommServ – Education Division Datacom Networking IP Addressing-
402
CIDR Addressing
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 1 1 1 0 0 0 0 0
subnet supernet
host Class C network
mask
In dotted decimal notation, supernet mask = 255.255.248.0 In CIDR notation, supernet mask = /21
CommServ – Education Division Datacom Networking IP Addressing-
403
CommServ – Education Division Datacom Networking IP Addressing-
404
CommServ – Education Division Datacom Networking IP Addressing-
405
CommServ – Education Division Datacom Networking IP Addressing-
406
CommServ – Education Division Datacom Networking IP Addressing-
407
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408
CommServ – Education Division Datacom Networking IP Addressing-
409
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410
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411
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412
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Datacom Networking 30. Internet Routing
Chapter Objectives –Describe the concept of IP routing
–Identify the information contained within a typical routing table
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Routing-414
IP Forwarder Architecture
Physical
Link
Internet
Physical
Link
Internet
IP Routing
Source
router
Intermediate
router
Destination
router
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Sample IP Route Table (RT)
Destination Route Mask Next Hop Port Metric Type Source Age
0.0.0.0 0.0.0.0 129.192.64.28 J4.1 0 DIR Static 0
129.192.16.0 255.255.0.0 129.192.16.3 J3 2 REM RIP 19477560
129.192.17.0 255.255.0.0 129.192.16.6 J4.2 3 REM OSPF 1422605
129.192.18.0 255.255.0.0 129.192.18.3 J3 2 REM BGP 4933
129.192.64.0 255.255.0.0 129.192.40.3 J4.3 2 REM BGP 4933
172.20.1.3 255.255.255.255 129.192.40.3 J4.3 2 DIR LOC 1949913
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Routing Table
One Forwarding Table
198.113.181.0 [170/304793] 192.150.42.177 02:03:50 D
198.113.178.0
192.168.96.0
192.168.97.0
[110/9936] 192.150.42.177 02:03:50 O
192.150.42.177 00:00:20 R
C
[120/3]
Ethernet0
Ethernet0
Ethernet0
Ethernet0
Age Source Network # Interface Next Hop Metric
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Routing-418
Default Gateway
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Routing-420
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Selection Criteria
r X
s Y
t Z
1
2
n
Hops Address J
Route
Table
J1
J2
Jn
?
?
?
m X
n Y
0 Z
1
2
3
Hops J
Route Table
J1
J2
J3
Z
Address
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Simplified Routing Example
J1
J2 J3
J1 J1
J1 J2
J1
J2 J3
J1 J1
11.0.0.1
12.0.0.1
12.0.0.2
11.0.0.2
10.0.0.1 14.0.0.1
10.0.0.3 10.0.0.2
13.0.0.1
13.0.0.3 13.0.0.2
14.0.0.2
A
C
B D
E F G
0 0.0.0.0 1
Hops Address J
0 10.0.0.3 1
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Routing-424
Simplified Routing Example
J1
J2 J3
J1 J1
J1 J2
J1
J2 J3
J1 J1
11.0.0.1
12.0.0.1
12.0.0.2
11.0.0.2
10.0.0.1 14.0.0.1
10.0.0.3 10.0.0.2
13.0.0.1
13.0.0.3 13.0.0.2
14.0.0.2
A
C
B D
E F G
0 10.0.0.2
0 10.0.0.3
1 13.0.0.2
1 13.0.0.3
2 13.0.0.2
2 13.0.0.3
3
3
2
2
1
1
Address J
Route
Table
1 10.0.0.2
1 10.0.0.3
1 13.0.0.2
1 13.0.0.3
1
1
2
2
Hops Address J
0 0.0.0.0 1
Hops Address J
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Simplified Routing Example
J1
J2 J3
J1 J1
J1 J2
J1
J2 J3
J1 J1
11.0.0.1
12.0.0.1
12.0.0.2
11.0.0.2
10.0.0.1 14.0.0.1
10.0.0.3 10.0.0.2
13.0.0.1
13.0.0.3 13.0.0.2
14.0.0.2
A
C
B D
E F G
0 10.0.0.2
0 10.0.0.3
1 13.0.0.2
1 13.0.0.3
2 13.0.0.2
2 13.0.0.3
3
3
2
2
1
1
Address J
Route
Table
1 10.0.0.2
1 10.0.0.3
1 13.0.0.2
1 13.0.0.3
1
1
2
2
Hops Address J
0 0.0.0.0 1
Hops Address J
0 13.0.0.2
0 13.0.0.3
1 10.0.0.2
1 10.0.0.3
2 10.0.0.2
2 10.0.0.3
3
3
2
2
1
1
Hops Address J
Route
Table
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Datacom Networking 31. Dynamic Routing
Chapter Objectives –Describe routing protocol categories
–Briefly describe the following routing protocols:
•Routing Information Protocol (RIP)
•Open Shortest Path First (OSPF)
•Border Gateway Protocol (BGP)
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Dynamic Routing Categories
Dynamic Routing
Interior Exterior
Vector Distance (RIP)
Link State (OSPF)
BGP EGP
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Scope of Dynamic Routing Protocols
area-1
area-2
area-3
area-0
OSPF
area-0
OSPF
Internet
RIP
BGP
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RIP Architecture
RIP
UDP
IP
Port 520
Protocol 17
RIP
UDP
IP
Port 520
Protocol 17
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Routing-431
RIP Operation
LAN or WAN neighbors
route table
route table
update update update
update update
30 seconds
(minimum)
180 seconds
(maximum)
120 seconds
(delay)
>180, set inactive
purge from RT
update
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RIP—Distance Vector
Send Routing Table to Neighbors
Net A
Net B Net C
Net D
E0 S0 S0 S1 S0 E0
R1 R2 R3
A E0
B S0
B
C
S0
S1
C
D
S0
E0
A S0 B S0
A S0 D S1 S0 D
S0 C
Network Interface Network Interface Network Interface
CommServ – Education Division Datacom Networking Dynamic Routing-433
• Update = 1x 30 sec
• Invalid = 3x 90 sec
• Holddown = 3x 90 sec
• Flush = 7x 210 sec
RIP Timers
Net A
Net B Net C
Net D
E0 S0 S0 S1 S0 E0
R1 R2 R3
A E0
B S0
B
C
S0
S1
C
D
S0
E0
A S0 B S0
A S0 D S1 S0 D
S0 C
Network Interface Network Interface Network Interface
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Routing-434
RIP Metric
R1
R2
R3
T1
56k
T1
0 Hops
1 Hop
Path A
Path B
Hops
CommServ – Education Division Datacom Networking Dynamic Routing-435
Count to Infinity
• Hop count max = 15
• 16 = infinity
Net A
Net B Net C
Net D
E0 S0 S0 S1 S0 E0
R1 R2 R3
X
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Routing-436
Count to Infinity
A = 4 Hop
A = 5 Hop
A = 6 Hop
A = 7 Hop
Net A
Net B Net C
Net D
E0 S0 S0 S1 S0 E0
R1 R2 R3
X
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Routing-437
Split Horizon
Do not send routing
updates back in the
direction from
which it came
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Routing-438
OSPF Architecture
OSPF
IP
Protocol 9
OSPF
IP
Protocol 9
Link and Physical Layers
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OSPF
• Dynamic routing protocol
• Link state or SPF technology
• Developed by OSPF working group of IETF (RFC 1253)
• Intra-autonomous system (IGP)
• Designed expressly for TCP/IP Internet environment
• Fast convergence
• Variable-length subnet masks
• Discontiguous subnets
• No periodic updates
• Route authentication
• Delivered two years after IGRP
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Link State Routing
• Neighbor discovery
• Constructing an LSP
• Distribute LSP
• Compute routes
• On network failure
– New LSPs flooded
– All routers recompute routing tables
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OSPF Link State Database
LSD
LSD LSD
LSD
identical
interface
Metric = 100,000,000/link bit rate
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Topology/Link State Database
• A router has a separate LS database for each area to which it belongs
• All routers belonging to the same area have identical database
• SPF calculation is performed separately for each area
• LSA flooding is bounded by area
• Router ID determined by interface or command
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OSPF Metric
• Derived from bandwidth
–100 ÷ bandwidth
– 56-kbps serial link = 1785 64-kbps serial link = 1562
– T1 (1.544-Mbps serial link) = 65 E1 (2.048-Mbps serial link) = 48
– 4-Mbps Token Ring = 25 16-Mbps Token Ring = 6
– Ethernet = 10 Fast Ethernet / FDDI = 1
• Configured via
–Interface sub-command: bandwidth
–Interface sub-command: ip ospf cost
–Router sub-command:
–ospf auto-cost reference-bandwidth
–Default = 108
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Routing-445
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Routing-446
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Routing-447
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Routing-451
Simplified Routing Example
1.544 Mbps
Route
Table
J1
J2 J3
J1 J1
J1 J2
J1
J2 J3
J1 J1
10.0.0.11
11.0.0.2
12.0.0.11
11.0.0.1
10.0.0.1 10.0.0.12
10.0.0.3 10.0.0.2
12.0.0.1
12.0.0.3 12.0.0.2
12.0.0.12
65 10.0.0.2
65 10.0.0.3
65 12.0.0.2
65 12.0.0.3
1
1
2
2
Metric Address J
0 12.0.0.2
0 12.0.0.3
3125 10.0.0.2
3125 10.0.0.3
130 10.0.0.2
130 10.0.0.3
3
3
2
2
1
1
Metric Address J
Route
Table
0 0.0.0.0 1
Hops Address J
A
C
B D
E F G
1.544 Mbps
64 Kbps
0 10.0.0.2
0 10.0.0.3
3125 12.0.0.2
3125 12.0.0.3
130 12.0.0.2
130 12.0.0.3
3
3
2
2
1
1
Metric Address J
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Routing-452
BGP Architecture
BGP
TCP
IP
Port 179
Protocol 6
BGP
TCP
IP
Port 179
Protocol 6
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Routing Information Bases (RIBs)
BGP speaker
to/from other BGP speakers
I-RIB
L-RIB
O-RIB
received
sent
used
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BGP Basics
• Runs over TCP
• Path vector protocol
• Incremental update
AS 100 AS 101
AS 102
A
Peering
D
E
B
C
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Routing-455
BGP General Operation
• Learns multiple paths via internal and external BGP speakers
• Picks the best path and installs in the IP forwarding table
• Policies applied by influencing the best path selection
CommServ – Education Division Datacom Networking Dynamic Routing-456
Internal BGP Peering
• BGP peer within the same AS
• Not required to be directly connected
• IBGP neighbors should be fully meshed
• Few BGP speakers in corporate network
AS 100
A
E
D
B
CommServ – Education Division Datacom Networking Dynamic Routing-457
External BGP Peering
C
A
• Between BGP speakers in different AS
• Should be directly connected
B
AS 100 AS 101
CommServ – Education Division Datacom Networking Dynamic Routing-458
• Representative of most BGP configurations
BGP Configuration Example
15.1.1.0 15.0.0.0 19.0.0.0
15.1.1.1 15.1.1.2
Configuration for A Configuration for B
A B AS 100 AS 200
router bgp 100
network 19.0.0.0
neighbor 15.1.1.2 remote-as 200
router bgp 200
network 15.0.0.0
neighbor 15.1.1.1 remote-as 100
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Routing-459
Route Aggregation
1.544 Mbps
Route
Table
J1
J2 J3
J1 J1
J1 J2
J1
J2 J3
J1 J1
11.0.0.1
12.0.0.1
12.0.0.2
11.0.0.2
10.0.0.1 14.0.0.1
10.0.0.3 10.0.0.2
13.0.0.1
13.0.0.3 13.0.0.2
14.0.0.2
0 0.0.0.0 1
Hops Address J
A
C
B D
E F G
1.544 Mbps
64 Kbps
0 13.0.0.0
1560 10.0.0.0
1300 10.0.0.0
3
2
1
Metric Address J
Route
Table
0 10.0.0.0
1560 13.0.0.0
1300 13.0.0.0
3
2
1
Metric Address J
650 10.0.0.0
650 13.0.0.0
1
2
Metric Address J
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Routing-460