Zte ZXR10 5900E Series - Chapter 3 OSPF Configuration

Chapter3OSPFConguration
2.Routerdead-interval
Therouterdead-intervalreferstothewaitingtimefromtherouterreceivingthelast
hellopackettotherouterdetectingthattheneighborisofine.Thedefaultrouter
dead-intervalisfourtimesofHELLOpacketsendinginterval,whichisapplicabletoall
networktypes.
3.PollInterval
PollintervalonlyappliestoNBMAnetwork.
OSPFNeighbors
OSPFneighborsareagroupofroutersbelongingtothesamenetwork.Theserouters
stipulatesomecongurationparameters.Theroutersmustbeneighborstoform
adjacency.T oformadjacency,theroutershavetobeneighborhood.
RoutersanalyzetheirHELLOpacketstomakesurethattherequiredparametersare
stipulatedwhentheywanttoformneighborhood.Thefollowingparametershavetobe
consistentsothattheadjacentrouterscansetupneighborhood,areaID,areaag,
authenticationinformation,HELLOpacketsendingintervalandrouterdeadinterval.
AdjacencyandDR
Whentworoutersformanadjacency,theycanexchangeroutingmessages.Whethertwo
routerscanformanadjacencydependsuponnetworktypeconnectedtorouters.The
networktypeoftheconnectingrouterdecideswhethertworouterscanformadjacency.
lThereareonlytworoutersinpoint-topointnetworkorvirtuallinks.Thetworouters
havetoexchangetherelatedroutinginformation,sotheycanformanadjacency
automatically.Apoint-to-multipointnetworkcanberegardedasasetofpoint-to-point
networks,soanadjacencyisformedbetweeneachpairofrouters.
lInabroadcastoranNBMAnetwork,anadjacencymaynotbeformedbetweentwo
neighbors.Ifadjacenciesarealreadyestablishedamongallrouters(thenumber
ofroutersis"n"forexample)onanetwork,eachrouterwillhave"(n-1)"adjacent
connectionsandthenetworkwillhave"n×(n-1)/2"adjacentconnections.
Inalargemulti-accessnetwork,therouterwillbetooheavytrafcifeveryoneneedsto
tracesomanyadjacentconnections.Furthermore,theexchangingofroutinginformation
betweeneachadjacentrouterswasteslotsofnetworkbandwidths.
Sincealargemulti-accessnetworkhasamassofredundancyinformation,OSPFdenes
aDRandaBDR.TheDRandBDRmustformanadjacencywitheachOSPFrouteron
network.EachOSPFrouteronlyformsanadjacentrelationshipswithDRandBDR.All
routersonlysendroutinginformationtoDR,andDRsendstheinformationtootherrouters
inthesamenetworksegment.Thetworouters(neitherDRnorBDR)donotestablishan
adjacencybetweeneachotherandneitherwilltheyexchangeroutinginformation.Ifthe
DRstopsworking,theBDRwillbecomeaDR.
3-3
SJ-20150114102049-003|2015-01-15(R1.0)ZTEProprietaryandCondential