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High-Speed LANs
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IntroductionIntroduction
Fast Ethernet and Gigabit Ethernet
Fiber Channel
High-speed Wireless LANs
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Table 6.1Table 6.1
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Emergence of High-Speed LANsEmergence of High-Speed LANs
2 Significant trends
Computing power of PCs continues to grow
rapidlyNetwork computing
Examples of requirements
Centralized server farmsPower workgroups
High-speed local backbone
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Classical EthernetClassical Ethernet
Bus topology LAN
10 Mbps
CSMA/CD medium access controlprotocol
2 problems:
A transmission from any station can bereceived by all
stations
How to regulate transmission
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Solution to First ProblemSolution to First Problem
Data transmitted in blocks called frames:
User data
Frame header containing unique address ofdestination station
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Figure 6.1Figure 6.1
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CSMA/CDCSMA/CD
Carrier Sense Multiple Access/ Carrier Detection
1. If the medium is idle, transmit.
2. If the medium is busy, continue to listen untilthe channel is
idle, then transmit immediately.
3. If a collision is detected during transmission,immediately
cease transmitting.
4. After a collision, wait a random amount oftime, then attempt
to transmit again (repeatfrom step 1).
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Figure 6.2Figure 6.2
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Figure 6.3Figure 6.3
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Medium Options at 10MbpsMedium Options at 10Mbps
10Base5
10 Mbps 50-ohm coaxial cable bus
Maximum segment length 500 meters
10Base-T
Twisted pair, maximum length 100 meters
Star topology (hub or multipoint repeater at central point)
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Figure 6.4Figure 6.4
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Hubs and SwitchesHubs and Switches
Hub Transmission from a station received by central
hub and retransmitted on all outgoing linesOnly one transmission
at a time
Layer 2 Switch Incoming frame switched to one outgoing line
Many transmissions at same time
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Figure 6.5Figure 6.5
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Bridge Frame handling done
in softwareAnalyze and forward
one frame at a time
Store-and-forward
Layer 2 Switch Frame handling done
in hardwareMultiple data paths
and can handlemultiple frames at a
time Can do cut-through
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Layer 2 SwitchesLayer 2 Switches
Flat address space
Broadcast storm
Only one path between any 2 devices
Solution 1: subnetworks connected by
routersSolution 2: layer 3 switching, packet-
forwarding logic in hardware
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Figure 6.6Figure 6.6
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Figure 6.7Figure 6.7
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Figure 6.8Figure 6.8
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Figure 6.9Figure 6.9
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Figure 6.10Figure 6.10
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Figure 6.11Figure 6.11
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Benefits of 10 Gbps Ethernet overBenefits of 10 Gbps Ethernet
over
ATMATMNo expensive, bandwidth consuming
conversion between Ethernet packets and
ATM cellsNetwork is Ethernet, end to end
IP plus Ethernet offers QoS and traffic
policing capabilities approach that of ATMWide variety of
standard optical interfaces
for 10 Gbps Ethernet
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Fibre ChannelFibre Channel
2 methods of communication withprocessor:
I/O channelNetwork communications
Fibre channel combines bothSimplicity and speed of channel
communicationsFlexibility and interconnectivity of network
communications
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Figure 6.12Figure 6.12
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I/O channelI/O channel
Hardware based, high-speed, shortdistance
Direct point-to-point or multipoint
communications linkData type qualifiers for routing
payloadLink-level constructs for individual I/O
operationsProtocol specific specifications to support
e.g. SCSI
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Fibre Channel Network-OrientedFibre Channel Network-Oriented
FacilitiesFacilitiesFull multiplexing between multiple
destinations
Peer-to-peer connectivity between any pairof ports
Internetworking with other connection
technologies
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Fibre Channel RequirementsFibre Channel Requirements
Full duplex links with 2 fibres/link 100 Mbps 800 MbpsDistances
up to 10 km
Small connectors high-capacityGreater connectivity than existing
multidrop
channels
Broad availability Support for multiple cost/performance levels
Support for multiple existing interface command
sets
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Figure 6.13Figure 6.13
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Fibre Channel ProtocolFibre Channel Protocol
ArchitectureArchitectureFC-0 Physical Media
FC-1 Transmission Protocol
FC-2 Framing ProtocolFC-3 Common Services
FC-4 Mapping
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Wireless LAN RequirementsWireless LAN
RequirementsThroughputNumber of nodesConnection to backbone
Service areaBattery power consumptionTransmission robustness and
security
Collocated network operationLicense-free
operationHandoff/roamingDynamic configuration
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Figure 6.14Figure 6.14
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IEEE 802.11 ServicesIEEE 802.11 Services
Association
Reassociation
DisassociationAuthentication
Privacy
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Figure 6.15Figure 6.15
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Figure 6.16Figure 6.16
