Enterasys Matrix DFE-Gold Series User Manual

redistribute Configuring OSPF
Enterasys Matrix DFE-Gold Series Configuration Guide 21-19
Configuring OSPF
Understanding Graceful Restart
OSPFgracefulrestart,sometimesreferredtoasnon‐stopforwarding,providesforanOSPFrouter
toremainontheforwardingpathduringarestartofitsOSPFsoftware.Graceful‐restarthasfour
elementstoitsconfiguration:enabling,helperrouter,restartinterval,andstrictLSAchecking.
Enablinggracefulrestartinstructsthefirmware
toperformagracefulrestart,ratherthana
standardOSPFrestart.Restartisonlyinitiatedbyafail‐over.GraceLSAsaresentwhenOSPFis
restartedonanothermodule.Whetherthefailoverisintentionalornot,thefailedrouterprotocol
isrestartedonanothermodule,anduponstartup,OSPFsends
graceLSAsouttoitsneighbors
usingexistinglinkaggregationgroups.Usethegraceful‐restartenablecommandtoenablethe
gracefulrestartabilityonthisrouter.
Thehelperrelationshipwiththerestartingrouterisonapernetworksegmentbasis.Thehelper
monitorsthenetworkfortopologychanges.Ifnochanges
occur,thehelperroutercontinuesto
advertiseitsLSAsasthoughnorestartwasoccurring.Iftherestartingrouterwasthedesignated
router,thehelpercontinuestotreatitassuch.Ifatopologychangedoesoccur,gracefulrestartis
terminatedontherestartingrouterandastandardrestartoccurs.
Helpermodecanbedisabledon
arestartingrouterneighborusingthegraceful‐restarthelper‐disabledcommand.Iftherestarting
routerreceivesanLSAindicatingadisabledhelper,thegracefulrestartterminatesandastandard
restartoccurs.
Arestartintervalprovidesforamaximumtimeinsecondsafterwhichthegraceful
restartwill
terminateshoulditnotcompleteorterminateforotherreasonswithintheinterval.Usethe
graceful‐restartrestart‐intervalcommandtochangetherestartintervalsetting.
StrictLSAcheckingassuresthatgracefulrestartwillterminateifthereisachangetoanLSAthat
wouldbefloodedtothe 
restartingrouter.StrictLSAcheckingcanbedisabled.Ifdisabled,a
changetoanLSAthatwouldbefloodedtotherestartingrouterwillnotcausethegracefulrestart
toterminate.Usethegraceful‐restartstrict‐lsa‐checking‐disabledcommandtodisablestrictLSA
checking.
ViewtherouterOSPFsectionof
theshowrunning‐configdisplaytoverifyanynon‐default
gracefulrestartsettings.
Graceful Restart and High Availability
TheDFEsupportssinglerouterhighavailabilityfailoverusingthefollowingcomponents:
•OSPFgracefulrestart
•Non‐stoprouterframeforwardingoneachmodule
•Singlerouterconfiguration
•Routerprotocolprocessfailovertoanothermodule
•LinkAggregateGroup(LAG)connectivitytoneighboringrouters
TheDFEisadistributedroutingsystem.Theroutingprotocolprocessresides
onasinglerouter
module.Informationsuchasaccesslistrules,policyroutingrules,interfaceconfigurationandbest
routesarecalculatedbytheprotocolprocessanddistributedtoallmodules.Eachmodulehasits
Important Notice
OSPF is an advanced routing feature that must be enabled with a license key. If you have purchased an
advanced license key, and have enabled routing on the device, you must activate your license as described
back in “Activating Licensed Features” on page 2-58 in order to enable the OSPF command set. If you wish to
purchase an advanced routing license, contact Enterasys Networks Sales.

Enterasys Matrix DFE-Gold Series Specifications

General

Brand	Enterasys
Model	Matrix DFE-Gold Series
Category	Switch
Language	English