Chapter3
OSPFConguration
TableofContents
OSPFOverview.........................................................................................................3-1
ConguringtheOSPFProtocol..................................................................................3-8
MaintainingtheOSPFProtocol................................................................................3-38
OSPFCongurationExamples.................................................................................
3-45
3.1OSPFOverview
OpenShortestPathFirst(OSPF)isoneofthemostpopularandwidelyusedrouting
protocols.OSPFisalinkstateprotocol,whichovercomesthedisadvantagesofRIPand
otherdistancevectorprotocols.OSPFversion1isdenedbyRFC1131.Atpresent,OSPF
version2isused,whichisdenedinRFC2328.ZXR105900EsupportsOSPFversion2
completely.
OSPFhasthefollowingfeatures.
lItconvergesfast.T oensurethesynchronizationofdatabase,OSPFfastoodsthe
updatingoflinkstateandcalculatesroutingtableatthesametime.
lItdoesnothaverouteloop.ShortestPathFirst(SPF)algorithmisappliedtoguarantee
thatnoloopswillbegenerated.
lItadoptsrouteaggregation,whichreducesthesizeoftheroutingtable.
lItsupportsVariableLengthSubnetMask(VLSM)andClasslessInter-DomainRouting
(CIDR).
lItusestriggerupdatingmechanismtosendupdatingmessageonlywhennetwork
changes.
lItsupportsinterfacepacketauthenticationtoguaranteethesecurityofrouting
calculation
lItsendsupdatepacketbymulticastmode.
OSPFBasic
AnOSPFswitchgeneratestheroutingtablebysettingupalinkstatedatabase.Thelink
statedatabasesofallOSPFswitchsmustbethetotallysame.Linkstatedatabaseisbuilt
accordingtoLinkStateAdvertisements(LSAs)whicharegeneratedbyallswitchsand
spreadoverthewholeOSPFnetwork.TherearemanytypesofLSAs,andacomplete
LSAsetshowsanaccuratedistributiondiagramoverthewholenetwork.
3-1
SJ-20150114102049-003|2015-01-15(R1.0)ZTEProprietaryandCondential