Chapter 7Network Architectures

Network ArchitectureOverall network structurePhysical mediaTopologyChannel access method

EthernetMost popular architectureEase of installation, Low costFrames, Baseband, CSMA/CD10/100MbpsNIC ROM address MAC address

IEEE 10Mbps 10BASE-5 Thicknet coaxial10BASE-2 Thinnet coaxial10BASE-T Unshielded twisted pair10BASE-F Fiber-optic cable

10BASE-5Standard EthernetTransceivers, vampire taps, 50 meter500 meters/segment 5 segmentsFrozen yellow garden hose5-4-3 rule

10 Base 5

5-4-3 Rule

10Base-5 Summary

10BASE-2200 meters (185)Thinnet, not TV coaxTransceiver built into NICBNC connector, terminatorsBus topology, 5-4-3 rule

10 BASE- 2

10BASE-TMost popular, Star topologyUTP, STP twisted pair, 100 metersLow cost of media and equipment5-4-3 doesn’t applyActive hubs act as repeaters

10BASE-T

10BASE-T Hub Connection

10BASE-T Specifications

10BASE-FFiber-optic cable10BASE-FL fiber to the desktop10BASE-FP passive hubs 500 meters per segment10BASEFB Fiber backbone between hubsAll use star topology

10BASE-F

100Mbps IEEE Standards100VAnyLAN, 100BASE-TFast EthernetSuited for videoCAD computer aided draftingCAM computer aided manufacturingImaging

100VG-AnyLANDemand priorityCascaded hubs

Star topologyRoot or parent hub100BASE-VG, 100VG, VG, AnyLAN

100VG-AnyLAN

100VG-AnyLAN

100BASE-TCategory 5 UTP, Cascading hubsStar topology, Modified 802.3100BASE-T4 4 pair Cat. 3,4,5 UTP100BASE-TX 2 pair Cat. 5UTP100BASE-FX 2 strand fiber-optic

100BASE-T

100BASE-T Summary

Ethernet Frame TypesFour frame types:Ethernet 802.3

Ethernet 802.2Ethernet SNAPEthernet II

Ethernet 802.3 FrameIPX/SPX Usually only Novell NetWare 2.X 3.XEthernet rawStart Frame Delimiter (SFD)Cyclic Redundancy Check (CRC)

Ethernet 802.3 Frame

Ethernet 802.2802.3 Ethernet standard compliant

Logical Link Control (LLC) OSI layerHas 3 additional LLC fieldsIEEE 802.2 group was LLC focusedNovell had chosen Ethernet raw for 802.3

Ethernet SNAPSubNetwork Address ProtocolAppleTalk Phase IIEnhanced 802.2 frameIncludes a “type” fieldNetwork protocol in data portion

Ethernet IIUsed IN TCP/IP networksSFD field included in preambleType field replaces length fieldType field identifies protocol

Ethernet II

SegmentationIncreasing numbers of computersIncreasing network trafficNetwork slows downBreak network into smaller piecesAdd bridge or router

Segmentation

Token Ring Developed by IBM IEEE 802.5 standardStar cabled, operate as logical ringToken passing channel access method

Token Ring

How Token Ring worksToken passes around ring

Receives from:Nearest Active Upstream NeighborNAUN

Transmits to:Nearest Active Downstream NeighborNADN

Each computer reads token Acts upon if addressed to itSends to NADN if not or; Attaches data if token is empty“To” addressee verifies receptionBeaconingAutomatic Token-Ring fault isolationFirst computer is active monitorEvery 7 seconds transmits packetTravels ring collecting addressesRing reconfigures avoiding inactive

Beaconing

Token-Ring HardwareHub is the IBM;Multistation Access Unit (MAU) orSmart MAU (SMAU)Ten connections, eight computersRing IN, Ring Out (RI/RO) ports

Token-Ring CablingAmerican Wire Gauge standards (AWG)Larger AWG means smaller wire diameterTypes 1, 2, 3, 5, 6, 8, 9

Token-Ring Summary

The AppleTalk EnvironmentSimple, easy to implementUses dynamic addressing schemeEtherTalk TokenTalk Local talk

Local TalkUses STPBus topologyShare devices, data in small numberTree structureConnector is three connectors

LocalTalk Connector

EtherTalk & TokenTalkEtherTalk is AppleTalk protocols running on 802.3 Ethernet 10Mbps networkTokenTalk is AppleTalk protocols running on a Token-Ring 4Mbps or 16 Mbps network

LocalTalk Summary

ARCnet EnvironmentAttached Resource Computer NetworkUp to 2.5 MbpsToken-passing channel accessOperates in a virtual ringWired as bus, star, or both

ARCnet Network

ARCnet EnvironmentTokens are passed based on SIDStation IdentifiersNIC addressee is set by dip switchesSID for next station in line NIDNext Station Identifier1-255 nodes receive token

ARCnet Environment

ARCnet HubsActive hubs are generally 8 ports

Regenerate signalHub to hub < 600 meters

Passive hubs are generally 4 ports Pass signal only from port to portPassive to active hub < 30 meters

ARCnet CablingRG-62 A/U 93 ohm coaxial BNC connectorsBus or star topologyUTP up to 121 metersFiber-optic up to 3,485 meters

FDDIFiber Distributed Data InterfaceToken-passing channel access 100Mbps, 500 nodes, 100 kmPhysical ring, no hubs Dual counter rotating rings

FDDI Network

Network AlternativesBroadband technology - Analog, Internet, cable modemsBroadcast technology - Satellite home reception, InternetGigabit technology - 1,000 Mbps, 802.3z/D2 for UTP

Chapter SummaryArchitecture defines how:Data is placed on the networkHow data is transmittedWhat transmission speedHow problems are handled

Ethernet IEEE 802.3 10 MbpsThicknet 10BASE-5Thinnnet 10 BASE-2Twisted pair 10 BASE-TFiber-optic 10BASE-F

Ethernet IEEE 802.3 100 MbpsTwisted pair Fiber-optic

100VG-AnyLANEasily bridge to other networksFDDI, Token-Ring, ATM

Token-Ring networks4 or 16 Mbps, equal network accessBeaconing to solve cabling problems, expensive

AppleTalk - Macintosh network

ARCnet - reliable, slow, not popular

FDDI - reliable, fast, secure