1 unit i (contd..) high-speed lans. 2 introduction fast ethernet and gigabit ethernet fast ethernet...
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UNIT I (Contd..)UNIT I (Contd..)
High-Speed LANsHigh-Speed LANs
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Introduction Introduction
Fast Ethernet and Gigabit EthernetFast Ethernet and Gigabit Ethernet Fibre ChannelFibre Channel High-speed Wireless LANsHigh-speed Wireless LANs
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Table 6.1Table 6.1
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Emergence of High-Speed Emergence of High-Speed LANsLANs
2 Significant trends2 Significant trends Computing power of PCs continues to Computing power of PCs continues to
grow rapidlygrow rapidly Network computingNetwork computing
Examples of requirementsExamples of requirements Centralized server farmsCentralized server farms Power workgroupsPower workgroups High-speed local backboneHigh-speed local backbone
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Classical EthernetClassical Ethernet
Bus topology LANBus topology LAN 10 Mbps10 Mbps CSMA/CD medium access control CSMA/CD medium access control
protocolprotocol 2 problems:2 problems:
A transmission from any station can be A transmission from any station can be received by all stationsreceived by all stations
How to regulate transmissionHow to regulate transmission
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Solution to First ProblemSolution to First Problem
Data transmitted in blocks called Data transmitted in blocks called frames:frames: User dataUser data Frame header containing unique Frame header containing unique
address of destination stationaddress of destination station
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Figure 6.1Figure 6.1
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CSMA/CDCSMA/CD
Carrier Sense Multiple Access/ Carrier DetectionCarrier Sense Multiple Access/ Carrier Detection
1.1. If the medium is idle, transmit.If the medium is idle, transmit.2.2. If the medium is busy, continue to listen If the medium is busy, continue to listen
until the channel is idle, then transmit until the channel is idle, then transmit immediately.immediately.
3.3. If a collision is detected during If a collision is detected during transmission, immediately cease transmission, immediately cease transmitting.transmitting.
4.4. After a collision, wait a random amount After a collision, wait a random amount of time, then attempt to transmit again of time, then attempt to transmit again (repeat from step 1).(repeat from 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 Medium Options at 10Mbps10Mbps
<data rate> <signaling method> <max <data rate> <signaling method> <max length>length>
10Base510Base5 10 Mbps10 Mbps 50-ohm coaxial cable bus50-ohm coaxial cable bus Maximum segment length 500 metersMaximum segment length 500 meters
10Base-T10Base-T Twisted pair, maximum length 100 metersTwisted pair, maximum length 100 meters Star topology (hub or multipoint repeater at Star topology (hub or multipoint repeater at
central point)central point)
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Figure 6.4Figure 6.4
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Hubs and SwitchesHubs and Switches
HubHub Transmission from a station received by Transmission from a station received by
central hub and retransmitted on all central hub and retransmitted on all outgoing linesoutgoing lines
Only one transmission at a timeOnly one transmission at a time
Layer 2 SwitchLayer 2 Switch Incoming frame switched to one outgoing Incoming frame switched to one outgoing
lineline Many transmissions at same timeMany transmissions at same time
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Figure 6.5Figure 6.5
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BridgeBridge Frame handling Frame handling
done in softwaredone in software Analyze and Analyze and
forward one forward one frame at a timeframe at a time
Store-and-Store-and-forwardforward
Layer 2 SwitchLayer 2 Switch Frame handling Frame handling
done in hardwaredone in hardware Multiple data Multiple data
paths and can paths and can handle multiple handle multiple frames at a timeframes at a time
Can do cut-Can do cut-throughthrough
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Layer 2 SwitchesLayer 2 Switches
Flat address spaceFlat address space Broadcast stormBroadcast storm Only one path between any 2 devicesOnly one path between any 2 devices
Solution 1: subnetworks connected Solution 1: subnetworks connected by routersby routers
Solution 2: layer 3 switching, packet-Solution 2: layer 3 switching, packet-forwarding logic in hardwareforwarding 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 Benefits of 10 Gbps Ethernet over ATMEthernet over ATM
No expensive, bandwidth consuming No expensive, bandwidth consuming conversion between Ethernet packets conversion between Ethernet packets and ATM cellsand ATM cells
Network is Ethernet, end to endNetwork is Ethernet, end to end IP plus Ethernet offers QoS and traffic IP plus Ethernet offers QoS and traffic
policing capabilities approach that of policing capabilities approach that of ATMATM
Wide variety of standard optical Wide variety of standard optical interfaces for 10 Gbps Ethernetinterfaces for 10 Gbps Ethernet
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Fibre ChannelFibre Channel 2 methods of communication with 2 methods of communication with
processor:processor: I/O channelI/O channel Network communicationsNetwork communications
Fibre channel combines bothFibre channel combines both Simplicity and speed of channel Simplicity and speed of channel
communicationscommunications Flexibility and interconnectivity of Flexibility and interconnectivity of
network communicationsnetwork communications
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Figure 6.12Figure 6.12
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I/O channelI/O channel
Hardware based, high-speed, Hardware based, high-speed, short distanceshort distance
Direct point-to-point or multipoint Direct point-to-point or multipoint communications linkcommunications link
Data type qualifiers for routing Data type qualifiers for routing payloadpayload
Link-level constructs for individual Link-level constructs for individual I/O operationsI/O operations
Protocol specific specifications to Protocol specific specifications to support e.g. SCSIsupport e.g. SCSI
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Fibre Channel Network-Fibre Channel Network-Oriented FacilitiesOriented Facilities
Full multiplexing between multiple Full multiplexing between multiple destinationsdestinations
Peer-to-peer connectivity between Peer-to-peer connectivity between any pair of portsany pair of ports
Internetworking with other Internetworking with other connection technologiesconnection technologies
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Fibre Channel Fibre Channel RequirementsRequirements
Full duplex links with 2 fibres/linkFull duplex links with 2 fibres/link 100 Mbps – 800 Mbps100 Mbps – 800 Mbps Distances up to 10 kmDistances up to 10 km Small connectorsSmall connectors high-capacityhigh-capacity Greater connectivity than existing Greater connectivity than existing
multidrop channelsmultidrop channels Broad availabilityBroad availability Support for multiple cost/performance Support for multiple cost/performance
levelslevels Support for multiple existing interface Support for multiple existing interface
command setscommand sets
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Figure 6.13Figure 6.13
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Fibre Channel Protocol Fibre Channel Protocol ArchitectureArchitecture
FC-0 Physical MediaFC-0 Physical Media FC-1 Transmission ProtocolFC-1 Transmission Protocol FC-2 Framing ProtocolFC-2 Framing Protocol FC-3 Common ServicesFC-3 Common Services FC-4 MappingFC-4 Mapping
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Wireless LAN Wireless LAN RequirementsRequirements
ThroughputThroughput Number of nodesNumber of nodes Connection to backboneConnection to backbone Service areaService area Battery power consumptionBattery power consumption Transmission robustness and securityTransmission robustness and security Collocated network operationCollocated network operation License-free operationLicense-free operation Handoff/roamingHandoff/roaming Dynamic configurationDynamic configuration
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Figure 6.14Figure 6.14
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IEEE 802.11 ServicesIEEE 802.11 Services
Association Association ReassociationReassociation DisassociationDisassociation AuthenticationAuthentication PrivacyPrivacy
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Figure 6.15Figure 6.15
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Figure 6.16Figure 6.16
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