Zte ZXR10 5900E Series - Page 85

Chapter4
IS-ISConguration
TableofContents
IS-ISOverview...........................................................................................................4-1
ConguringtheIS-ISProtocol..................................................................................4-11
MaintainingtheIS-ISProtocol..................................................................................4-23
IS-ISCongurationExamples...................................................................................
4-28
4.1IS-ISOverview
IntroductiontoIS-IS
IntermediateSystemto-IntermediateSystem(IS-IS)islaunchedbyInternationalStandard
Organization(ISO),whichisaroutingprotocolusedforConnectionlessNetworkService
(CLNS).IS-ISisanetworklayerprotocolofOpenSystemInterconnection(OSI).By
expandingIS-ISprotocol,thesupporttoIProutingisadded,andtheintegratedIS-IS
protocolisformed.
IS-ISisalreadywidelyusedinnetworkactingasakindofInteriorGatewayProtocol(IGP).
TheworkingprincipleofIS-ISissimilartothatofOSPF.IS-ISdividesanetworkintosome
areas.Theroutersofanareaonlymanagetheroutinginformationoftheirarea.Inthis
way,theroutercostissaved.IS-IScansatisfytherequirementsformiddleandlarge-scale
network.
SincetheIS-ISprotocolisbasedonCLNS(notIP),IS-ISusesProtocolDataUnit(PDU)
denedbyISOtoimplementcommunicationbetweenrouters.ThetypesofPDUsusedin
IS-ISprotocolareasfollows:
lHelloPDU
lLinkstatePDU(LSP)
lSequenceNumberPDU(SNP)
Where,HelloPDUissimilartotheHELLOpacketinOSPFprotocol,whichisresponsible
toformadjacencybetweenrouters,discoversnewneighborsanddetectstheleavingof
anyneighbors.
IS-ISroutersusesLSAtoexchangeroutinginformation,setupandmaintainlinkstate
database.ALSPindicatestheimportantinformationrelatedtoarouter,includingthearea
andtheconnectednetwork.SNPisusedtoensurethatLSPscanbetransmittedreliably.
SNPcontainsthesummaryinformationofeveryLSPonthenetwork.Whenarouter
receivesaSNP ,itcomparestheSNPwithitslinkstatedatabase.Iftherouterlosesa
4-1
SJ-20150114102049-003|2015-01-15(R1.0)ZTEProprietaryandCondential