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WideAreaNetworkingProtocols
1Overview1.0WideAreaNetworks2.0High-LevelData-LinkControlProtocol(HDLC)3.0Point-to-PointProtocol(PPP)4.0FrameRelay5.0IntegratedServicesDigitalNetwork6.0Dial-onDemandRouting(DDR)
21.0WideAreaNetworks1.1IntroductiontoWideAreaServices1.2DefiningWANTerms1.2WANConnectionTypes1.3WANProtocols
31.1IntroductiontoWideAreaServicesToextendLANstootherLANsatremotesitesConnectingsitestogethersoinformationcanbeexchangedServiceprovidersleaseorsharetheiralreadyinstalledconnections
41.2DefiningWANTerms(WANServiceProviders)CustomerPremisesEquipment(CPE)Equipmentthatisownedandlocatedatthesubscriber’spremisesDemarcation(demarc)TheplacewheretheCPEendsandthelocalloopportionoftheservicebegins(usuallyinthe“phone-closet”)LocalLoopConnectsthedemarctotheclosestswitchingoffice(CO)CentralOffice(CO)/PointofPresence(POP)Connectsthecustomerstotheprovider’sswitchingnetwork.TollNetworkTheswitchesandfacilities,(trunks),insidetheWANprovider’s“cloud”.
5SynchronousserialAsynchronousserial,ISDNSynchronousserial1.3WANConnectionTypesDedicatedLeasedlines(PointtoPointConnection)Apre-establishedWANcommunicationspathfromtheCPE,throughtheDCEswitch,totheCPEoftheremotesite,allowingDTEnetworkstocommunicateatanytimewithnosetupproceduresbeforetransmittingdata.CircuitSwitchingSetsuplinelikeaphonecall.Nodatacantransferbeforetheend-to-endconnectionisestablished.Usedial-upmodemsandISDN.Itisusedforlow-bandwidthdatatransfers.PacketSwitchingSharebandwidthwithothercompaniestosavemoney.Fornotconstantlydatatransmission(otherwiseusingleasedline)TelephoneCompanyServiceProviderSpeedupto45MbpsLow-bandwidthdatatransfersSpeedrangefrom56Kto2.048M
61.4WANProtocolsFrameRelayPacket-switchedtechnologywithDataLinkandPhysicalLayerspecificationProvideDynamic-bandwidthallocationandcongestioncontrolISDN(IntegratedServicesDigitalNetwork)VoiceandDatatransmissionoverexistingphonelinesHigherspeedthananalogdial-uplink;goodchoiceasabackuplinkLAPB(LinkAccessProcedure,Balanced)Aconnection-orientedprotocolattheDataLinklayerforusewithX.25Veryhighoverhead;onlyusediflinkisveryerrorproneHDLC(High-LevelDataLinkControl)DerivedfromSynchronousDataLinkControl(SDLC)createdbyIBMAconnection-orientedprotocolattheDataLinkLayer,lowoverheadEachvendor’sHDLCisproprietaryfortheirequipmentPPP(Point-to-PointProtocol)Anindustry-standardprotocol,tocreatepoint-to-pointlinksbetweendifferentvendor’sequipmentAllowauthenticationandmulti-linkconnections,runoverasyn.&syn.links
72.0High-LevelData-LinkControlProtocol(HDLC)ISOstandard,bit-orientedDataLinklayerprotocolApoint-to-pointprotocolusedonleasedlinesDefaultencapsulationusedbyCiscoroutersoversynchronousseriallinks;ortypethefollowingcommandsRouter(config-if)#EncapsulationhdlcEachvendorhasadifferentwayfortheHDLCprotocoltocommunicatewiththeNetworklayerprotocolNoauthenticationSynchronousPhysicalMediaHDLCIPIPXAppleTalkBit-orientedprotocolsusesinglebitascontrolinformation(byte-orienteduseentirebyte)
83.0Point-to-PointProtocol3.1IntroductiontoPPP3.2Point-to-pointProtocolStack3.3LinkControlProtocol(LCP)ConfigurationOptions3.4PPPSessionEstablishment3.5PPPAuthenticationMethods3.6ConfiguringPPPonCiscoRouters3.7VerifyingPPPEncapsulation
93.1IntroductiontoPPPAData-link,point-to-pointprotocolusedOverasynchronousserial(dialup)Oversynchronousserial(ISDN,Leasedline)LCP(LinkControlProtocol)tobuildandmaintaindata-linkconnectionsUsetotransportlayer-3packetsacrossaData-linklayerComponents:EIT/TIA-232-C(formerlyRS-232)–physicallayerinternationalstandardforserialcommunicationHDLC–AmethodforencapsulatingdatagramsoverseriallinksLCP–Amethodofestablishing,configuring,maintaining,andterminatingthepoint-to-pointconnectionNCP–EncapsulatingdifferentNetworklayerprotocolacrossaPPPdatalink
103.2Point-to-pointProtocolStackNetworkLayerIPIPXOthers,e.g.AppleTalkIPCPIPXCPOthers…DataLinkLayerNetworkControlProtocol(NCP)LinkControlProtocol(LCP)Authentication,otheroptionsHigh-LevelDataLinkControlProtocol(HDLC)PhysicalLayerSynchronousorAsynchronousPhysicalMedia(suchasEIA/TIA-232,V.24,V.35,ISDN)PPPServiceProviderTCP/IPAppleTalkPPPEncapsulationTCP/IPIPXAppleTalkIPX
113.3LinkControlProtocol(LCP)ConfigurationOptionsLCPoffersPPPthefollowingoptions:AuthenticationPAP&CHAPCompressiontoincreasethethroughputofPPPconnection(Stacker&Predictor)ErrorDetectionQuality&MagicNumberMulti-linkstartinginIOS11.1SplitstheloadforPPPovertwoormoreparallelcircuits(bundle)
123.4PPPSessionEstablishmentThreephasesofsessionestablishmentLink-establishmentphaseLCPpacketsaresentbyeachPPdevicetoconfigureandtestthelinkAuthenticationphase(optional)CHAPorPAPisusedtoauthenticatealinkNetwork-layerprotocolphaseNCPtoencapsulatemultipleNetwork-layerprotocolsandthensendoveraPPPdatalink
133.5PPPAuthenticationMethodsPasswordAuthenticationProtocol(PAP)LesssecurePasswordsaresentincleartextOnlyperformupontheinitiallinkestablishmentWhenthePPPlinkisfirstestablished,theremotenodesentbacktheusernameandpasswordforauthenticationatthesendingrouterChallengeAuthenticationProtocol(CHAP)UsedattheinitialstartupofalinkandatperiodiccheckupachallengerequestAvaluecalculatedwithMD5Checkthevalue,ifnotmatch->terminateatonce!*MD5isaone-wayhashfunction
143.6ConfiguringPPPonCiscoRoutersRouter(config-if)#EncapsulationpppConfiguringPPPencapsulationonaninterface(serial)Router(config)#HostnameUsernamepasswordCase-sensitiveandPlain-textpasswordThepasswordonbothroutersmustbethesameBoththelocalandremoteroutermustbeconfiguredRouter(config-if)#pppauthenticaiton{chap|pap}Configuringtheauthenticationtypeonaninterface(serial)Ifbotharechosen,thefirstonewillbeused.Ifthefirstonefailed,thesecondonewillbeused.
153.7VerifyingPPPEncapsulationRouter#Showints0Showtheencapsulationmethod,protocolsupport,etc.Router#DebugpppauthenticationVerifythePPPauthenticationconfiguration
164.0FrameRelay4.1IntroductiontoFrameRelay4.2FrameRelayTerminology4.3DataLinkConnectionIdentifiers(DLCIs)4.4LocalManagementInterface(LMI)4.5Sub-interface4.6MappingFrameRelay4.7FrameRelayConfigurationTasks4.8FrameRelayCongestionControl4.9CommittedInformationRate(CIR)4.10MonitoringFrameRelay
174.1IntroductiontoFrameRelayFrameRelayworksonphysicalanddatalinklayer.FrameRelayprovidesconnection-oriented,DataLinklayercommunicationviavirtualcircuitsjustasX.25does.ThesevirtualcircuitsarelogicalconnectionscreatedbetweentwoDTEsacrossapacket-switchednetwork,whichisidentifiedbyaDLCI,orDataLinkConnectionIdentifier.FrameRelayismoreefficientandfasterthanX.25becauseitassumeserrorcheckingwillbedonethroughhigher-layerprotocolsandapplicationservices.Also,likeX.25,FrameRelayusesbothPVCs(PermanentVirtualCircuits)andSVCs(SwitchedVirtualCircuits),althoughmostFrameRelaynetworksuseonlyPVCs.Thisvirtualcircuitprovidesthecompletepathtothedestinationnetworkpriortothesendingofthefirstframe.FrameRelayisusedoveravarietyofnetworkprotocols.FrameRelayinterfacebetweentheuserandthenetworkequipmentwilltransmitandreceiveframesusingfirst-infirst-outqueuingonastatisticallymultiplexedcircuit
184.2FrameRelayTerminologyHub/SwitchDSU/CSURouterDLCI16DSU/CSUUserDemarcCentralOfficeDemarcDSU/CSUHub/SwitchRouterDLCI17DSU/CSUUserFrameactuallytransversethisPVCRouterseethisUseronlyseethisFrameRelaynetworkallowuserstocommunicatebetweentwoDTEdevicesthroughDCEdevices.123456Rememberthatbeforedataissentthroughthecloud,thevirtualcircuitiscreatedfromendtoend.CentralOfficeWAN78
194.3DataLinkConnectionIdentifier(DLCI)AssignmentFrameRelayvirtualcircuits(PVCs)areidentifiedbyDLCIs.FrameRelayprovidersetsuptheDLCInumberstobeusedbytheroutersforestablishingPVCsFortheIPdevicesateachendofavirtualcircuittocommunicate,theirIPaddressesneedtobemappedtoDLCIs.Thismappingcanfunctionasamultipointdevice—onethatcanidentifytotheFrameRelaynetworktheappropriatedestinationvirtualcircuitforeachpacketthatissentoverthesinglephysicalinterface.ThemappingscanbedonedynamicallythroughIARPormanuallythroughtheFrameRelaymapcommand.EachDLCIislocallysignificant.ThatmeansDLCInumbersdonotnecessarilyneedtobeunique.TwoDLCInumberscanbethesameondifferentsidesofalinkbecauseFrameRelaymapsalocalDLCInumbertoavirtualcircuitoneachinterfaceoftheswitch.EachremoteofficecanhaveitsownDLCInumberandcommunicatewiththecorporateofficeusinguniqueDLCInumbers.DLCIstartat16.DLCI1023isspecificforLMIuse,DLCIs1019to1022addressmulticastMapentryindicatesstaticroutetodestination
204.4LocalManagementInterface(LMI)TheLMIisasignalingstandardbetweenaCPEdevice(router)andaframeswitch.TheLMIisresponsibleformanagingandmaintainingstatusbetweenthesedevices.LMImessagesprovideinformationaboutthefollowing:KeepalivesVerifydataisflowingMulticastingProvidesalocalDLCIPVCMulticastaddressingProvidesglobalsignificanceStatusofvirtualcircuitsProvidesDLCIstatusTherearethreestandardLMIsignalingformatsaresupported:CiscoLMIdefinedbytheGangofFour(default)ANSIAnnexDdefinedbyANSIstandardT1.617ITU-T(q933a)AnnexAdefinedbyQ.933RoutersreceiveLMIinformationonaframe-encapsulatedinterfaceandupdatethevirtualcircuitstatustooneofthreedifferentstates:ActivestateEverythingisupandrouterscanexchangeinformation.InactivestateTherouter’sinterfaceisupandworkingwithaconnectiontotheswitchingoffice,buttheremoterouterisnotworking.DeletedstateThismeansthatnoLMIinformationisbeingreceivedontheinterfacefromtheswitch.Itcouldbeamappingproblemoralinefailure.
214.5SubinterfacesCreatingSubinterfacesinordertohavemultiplevirtualcircuitsonasingleserialinterfaceandyettreateachasaseparateinterface(withdifferentconfiguration).Defineslogicalsub-interfacesontheseriallineEachsub-interfaceusesaDLCItorepresentsthedestinationsforFrameRelayPVCnetworkEachsub-interfaceusesitsownsub-networkWorkforPartialmeshFrameRelaynetworkConfiguringsubinterfacesactuallyworkstosubdividetheFrameRelaynetworkintosmallersubnetworks.Subinterfacesalsosolvetheproblemwithroutingprotocolsthatusesplithorizon.Therearetwotypesofsubinterfaces:Point-to-pointUsedwhenasinglevirtualcircuitconnectsoneroutertoanother.Eachpoint-to-pointsubinterfacerequiresitsownsubnet.MultipointUsedwhentherouteristhecenterofastarofvirtualcircuits.Usesasinglesubnetforallrouters’serialinterfacesconnectedtotheframeswitch.
224.6MappingFrameRelayInorderforIPdevicesattheendsofvirtualcircuitstocommunicate,theiraddressesmustbemappedtotheDLCIs.Therearetwowaystomakethismappinghappen:UsetheFrameRelaymapcommandformanuallymapping.ThisisalsotheonlywaytoconfiguremultipleframeencapsulationtypesonaninterfaceUsetheinverse-arp(bydefaultenable)functiontoperformdynamicmappingoftheIPaddresstotheDLCInumberbutit’snotasstableasusingthemapcommand-becausevirtualcircuitscanbeinsidiouslyanddynamicallymappedtounknowndevices.
234.7FrameRelayConfigurationTasks(1)Router(config-if#encapsulationframe-relay[cisco|ietf]Setsframerelayencapsulationforconnectiontonon-CiscoRouters(thedefaultencapsulationisforsameCiscoRouters)Router(config-if)#frame-relaylmi-type[ansi|cisco|q933a]SelectsLMItypeBeginningwithIOSversion11.2,theLMItypeisauto-sensed.ThisenablestheinterfacetodeterminetheLMItypesupportedbytheswitch.Router(config-if)#frame-relaymapprotocol-address[cisco|ietf][broadcast]DefineshowtoreachadestinationThebroadcastkeywordattheendtellstheroutertoforwardbroadcastsforthisinterfacetothisspecificvirtualcircuit.RememberthatFrameRelayisanonbroadcastmultiaccess(NBMA)encapsulationmethod,whichwillnotbroadcastroutingprotocolsbydefault.
244.7FrameRelayConfigurationTasks(2)Router(config)#interface.sub-interface-number{point-to-point|multipoint}Createsthelogicalsub-interfaceforFrameRelayGenerallythesubinterfacenumbermatchestheDLCInumberbutthisisnotarequirement–itonlyhelpsintheadministrationoftheinterfaces.Router(config-if)#frame-relayinterface-dlciAssignsaDLCItotheFrameRelaysub-interfaceontherouter
254.8FrameRelayCongestionControlFrameRelayswitchcontrolcongestionasfollows:DE(DiscardEligibility)WhenaFrameRelayrouterdetectscongestionontheFrameRelaynetwork,itwillturntheDEbitoninaFrameRelaypacketheader.Iftheswitchiscongested,theFrameRelayswitchwilldiscardthepacketswiththeDEbitsetfirst.IfyourbandwidthisconfiguredwithaCIRofzero,theDEwillalwaysbeon.FECN(Forward-ExplicitCongestionNotification)WhentheFrameRelaynetworkrecognizescongestioninthecloud,theswitchwillsettheFECNbitto1inaFrameRelaypacketheader.ThiswillindicatetothedestinationDCEthatthepathjusttraversediscongested.BECN(Backward-ExplicitCongestionNotification)WhentheswitchdetectscongestionintheFrameRelaynetwork,itwillsettheBECNbitinaFrameRelaypacketandsendittothesourcerouter,tellingittoslowdowntherateatwhichitistransmittingpackets.
264.9CommittedInformationControl(CIR)FrameRelayisbasedontheassumptionthatnotallcustomersneedtotransmitconstantdataallatthesametime.FrameRelayworksbestwithburstytraffic.FrameRelayprovidersallowcustomerstobuyaloweramountofbandwidththanwhattheyreallymightneed.ThisiscalledtheCommittedInformationRate(CIR).TheCIRspecifiesthataslongasthedatainputbyadevicetotheFrameRelaynetworkisbeloworequaltotheCIR,thenthenetworkwillcontinuetoforwarddataforthePVC.However,ifdataratesexceedtheCIR,itisnotguaranteed.YoucanuseazeroCIRtosavemoneyifretransmissionofpacketsisacceptable.However,understandthattheDEbitwillalwaysbeturnedonineveryframe.
274.10MonitoringFrameRelayshowframe-relaylmicommandwillgiveyoutheLMItrafficstatisticsexchangedbetweenthelocalrouterandtheFrameRelayswitch.showframepvccommandwilllistallconfiguredPVCsandDLCInumbers.thestatusofeachPVCconnectionandtrafficstatisticsthenumberofBECNandFECNpacketsreceivedontheroutershowinterfacecommanddisplaysline,protocol,DLCI,andLMIinformationshowframemapcommandwillshowyoutheNetworklayer–to–DLCImappingsdebugframelmicommandwillshowoutputontherouterconsolesbydefault.TheinformationfromthiscommandwillallowyoutoverifyandtroubleshoottheFrameRelayconnectionbyhelpingyoutodeterminewhethertherouterandswitchareexchangingthecorrectLMIinformation
285.0IntegratedServicesDigitalNetwork(ISDN)5.1IntroductiontoISDN5.2ISDNComponents5.3BasicRateInterface(BRI)5.4PrimaryRateInterface(PRI)5.5ISDNwithCiscoRouters5.6ISDNConfigurationTasks5.7ISDNConfigurationExample
295.1IntroductiontoISDNAsetofcommunicationprotocolsproposedbytelephonecompanyallowingdigitalservicesrunoverexistingtelephonenetworksSupportdata,text,voice,music,graphicandvideotransmissionsimultaneously,e.g.High-speedimageapplicationsHigh-speedfiletransferVideo-conferencingMultiplelinksintohomesoftelecommutersReferencedbyasuiteofITU-TstandardsthatencompasstheOSImodel’sphysical,DataLinkandNetworklayersPPPistypicallyusedwithISDNtoprovidedataencapsulation,linkintegrityandauthentication.Benefits:Cancarryvoice,video,anddatasimultaneouslyHasfastercallsetupthanamodemHasfasterdataratesthanamodemconnectionTwoTransferInterfaces:BasicRateInterfaceandPrimaryRateInterface
305.2ISDNComponents(1)ISDNTerminalEquipmentTypes:NT1–(NetworkTermination1)ConvertBRIsignalsintoaformusedbytheISDNdigitallineNT2–switchorISDNPBX(typicallyaprovider’sequipment)TE1–(TerminalEquipment1)understandISDNstandardsTE2–Non-ISDNdevice,predateISDNstandards,requireaTATA–(TerminalAdapter),e.g.ISDNmodemwhichconvertV.35,andothersignalsintoBRIsignalsReferencePointsdescribetheinterfacebetween:R–non-ISDNandTAS–userterminalsandNT2T–NT1andNT2devicesU–NT1andlineterminationTANT1US/TRTE2NT1US/TTE1Routerwithbuilt-inNT1ISDNSwitchserviceUReferencepointsareaseriesofspecificationdefiningtheconnectionbetweenthevariousequipmentusedinanISDNnetworkL1L1-L3L4–L7L4–L7
315.2ISDNComponents(2)ISDNProtocolsseries(definedbytheITU)ISDNSwitchTypesTheswitchtypesandthecorrespondingkeywordusedwiththeisdnswitch-typecommandtoconfiguretherouterconnectedtoSwitchTypeKeywordAT&TbasicrateswitchBasic-5essNortelDMS-100basicrateswitchBasic-dms100NationalISDN-1SwitchBasic-nilAT&T4ESS(ISDNPRIonly)Primary-4essAT&T5ESS(ISDNPRIonly)Primary-5essNortelDMS-100(ISDNPRIonly)Primary-dms100IssueProtocolsKeyExamplesTelephonenetworkandISDNE-seriesE.163—InternationaltelephonenumberingplanE.164—InternationalISDNaddressingConcepts,aspects,andinterfacesI-seriesI.100series—Concepts,structures,terminologyI.400series—UserNetworkInterfaces(UNIs)SwitchingandsignalingQ-seriesQ.921—LAPD(LinkAccessProcedureontheD-channel)Q.931—ISDNnetworklayerbetweenterminalandswitch
325.3BasicRateInterface(BRI)-1ISDNBRIserviceprovides:2Bchannelsoperateat64Kbps,carrydataEachchannelshouldhaveaSPID(ServiceProfileIdentifier)1Dchanneloperatesat16Kbps,carrycontrolandsignalinginformationtosetupandcontrolcallsWorkwithLAPDatheDataLinklayer;protocolsspanacrossOSI’sPhysical,DataLinkandNetworklayersAlsousedforotherfunctions(e.g.alarmsystemforabuilding)whichdoesn’tneedmuchbandwidth
335.3BasicRateInterface(BRI)-2SetupprocedureforaBRIcall:DchannelbetweenrouterandISDNswitchcomesupISDNswitchusestheSS7signalingtechniquetosetupapathtoaremoteswitchTheremoteswitchsetsuptheD-channellinktotheremoterouterTheBchannelsoflocalandremoteroutersarethenconnectedend-to-endRouterwithbuilt-inNT1ISDNSwitchserviceUNT2-ISDN SwitchatProviderNT2-ISDN SwitchatProviderRouterwithbuilt-inNT1LOCALREMOTEU
345.4PrimaryRateInterface(PRI)ProvidehighertransferrateMainlyuseinBusinessorPBX(PrivateBranchExchange)InNorthAmericaandJapanISDNPRIprovides23B(64K)+1D(64K)serviceTotalbitrateupto1.544MbpsInEurope,AustraliaISDNPRIprovides30B(64K)+1D(64K)serviceTotalbitrateupto2.048Mbps
355.5ISDNwithCiscoRoutersRoutershouldhavebuilt-inNT1oranISDNmodemforISDNAccessWhenconfiguringISDNyou’llneedtoknowthetypeofswitchwhatyourserviceproviderisusing(differentmanufacturerhasaproprietaryprotocolforsignaling)Needtoseewhichswitchestherouterwillsupportbyusingcommandisdnswitch-type?NT1US/TTE2Routerwithbuilt-inNT1(ISDNUport)ISDNSwitchserviceUNT2-ISDNSwitchatProviderNT1UTA(ISDNModem)TE1RouterwithISDNS/Tport
365.6ISDNConfigurationTasksRouter(config)#isdnswitch-typeORRouter(config-if)#isdnswitch-typeRouter(config)#interfacebriSelectstheinterfaceforISDNBRIoperationRouter(config-if)#encapsulation[ppp|hdlc]SelectsframingforISDNBRIRouter(config-if)#isdnspid1spid-number[ldn]SetsaBchannelServiceProfileIdentifier(SPID)requiresbymanyserviceprovidersRouter(config-if)#isdnspid2spid-number[ldn]SetsaSPIDforthesecondBchannelSpid-numberisprovidedbytheISDNprovidertoidentifyyouontheswitchLdn=localdialnumber
375.7ISDNConfigurationExampleExampleRouterA(config)#isdnwitch-typebasic-nelRouterA(config)#intbri0RouterA(config-if)#encapppp(optional)RouterA(config-if)#isdnspid10865066101008650661RouterA(config-if)#isdnspid20865066201008650662Theisdnswitch-typecommandcanbeconfiguredeitherin:Globalconfigurationmode–settheswitchtypeforallBRIintherouterInterfaceconfigurationmode–settheswitchtypeforindividualinterface
386.0Dial-on-DemandRouting(DDR)6.1IntroductiontoDDR6.2ConfiguringDDR6.2aConfiguringStaticRoutes6.2bSpecifyingInterestTraffic6.2cConfiguringtheDialerInformation6.3OptionalCommands6.4VerifyingtheISDNOperationRouter1CorporateIntranetRemoteNetworkModemPSTN,ISDN,InternetModemRouter1
396.1IntroductiontoDDRDial-on-demandrouting(DDR)isusedtoallowtwoormoreCiscorouterstodialanISDNdial-upconnectiononanas-neededbasis.DDRisonlyusedforlow-volume,periodicnetworkconnectionsusingeitheraPublicSwitchedTelephoneNetwork(PSTN)orISDN.ThiswasdesignedtoreduceWANcostsifyouhavetopayonaper-minuteorper-packetbasis.DDRworkswhenapacketreceivedonaninterfacemeetstherequirementsofanaccesslistdefinedbyanadministrator,whichdefinesinterestingtraffic.ThefollowingfivestepsgiveabasicdescriptionofhowDDRworkswhenaninterestingpacketisreceivedinarouterinterface:Routetothedestinationnetworkisdetermined.InterestingpacketsdictateaDDRcall.Dialerinformationislookedup.Trafficistransmitted.Callisterminatedwhennomoretrafficisbeingtransmittedoveralinkandtheidle-timeoutperiodends.
406.2DDRConfigurationTasksToconfigurelegacyDDR,youneedtoperformthreetasks:1.Definestaticroutes,whichdefinehowtogettotheremotenetworksandwhatinterfacetousetogetthere.2.Specifythetrafficthatisconsideredinterestingtotherouter.3.Configurethedialerinformationthatwillbeusedtodialtheinterfacetogettotheremotenetwork.CommandsdefininginterestingtrafficDialerGroupS0orBRI0CommandssetDDRcallparametersCommandsdirectcallandtraffictogroupinterfaceDDRinterface
416.2aConfiguringStaticRoutesToforwardtrafficacrosstheISDNlink,youconfigurestaticroutes(notdynamic)ineachoftherouters.KeepthefollowinginmindwhencreatingstaticroutesDDR:Allparticipatingroutersmusthavestaticroutesdefiningallroutesofknownnetworks.Defaultroutingcanbeusedifthenetworkisastubnetwork.AnexampleofstaticroutingwithISDNisshownbelow:RouterA(config)#iproute172.16.50.0255.255.255.0172.16.60.2RouterA(config)#iproute172.16.60.2255.255.255.255bri0Thefirstlinetellstherouterhowtogettonetwork172.16.50.0,whichisthrough172.16.60.2.Thesecondlinetellstherouterhowtogetto172.16.60.2.
426.2bSpecifyingInterestingTrafficSpecifyinginterestingtrafficmeanstoconfiguretheroutertodeterminewhatbringsuptheISDNline.Anadministratorusingthedialer-listglobalconfigurationcommanddefinesinterestingpackets.Router(config)#dialer-listprotocol{permit|deny|list|}Todefineadial-on-demandrouting(DDR)dialerlistfordialingbyProtocolAcombinationofaprotocolandapreviouslydefinedaccesslistUsethedialer-groupcommandtoassociateinterfacewiththedialerlistExampleshowingthecommandstoturnonallIPtraffic:Router(config)#dialer-list1protocolippermitRouter(config)#intbri0Router(config-if)#dialer-group1
436.2cConfiguringtheDialerInformationTherearefivestepsintheconfigurationofthedialerinformation.1.Choosetheinterface.2.SettheIPaddress.3.Configuretheencapsulationtype.4.Linkinterestingtraffictotheinterface.5.ConfigurethenumbertodialbyusingthedialerstringcommandHereisanexampleofhowtoconfigurethefivesteps:Router(config)#intbri0Router(config-if)#ipaddress172.16.60.1255.255.255.0Router(config-if)#encapsulationpppRouter(config-if)#dialer-group1Router(config-if)#dialerstring8350661ToconfigureaserialinterfaceorISDNinterfacetocalloneormultiplesitesortoreceivecallsfrommultiplesites,usethedialermapcommandRouter(config-if)#dialermapip172.16.60.2nameRouter28350661
446.3OptionalCommands(1)Router(config-if)#dialermap[namehostname][speed56/64][broadcast][dialer-string]DefineshowtoreachaDDRdestinationRecipient’sprotocoladdress(Optional)Hostnameofremotesystem(Optional)LinespeedforTDMcircuit(Optional)Indicatesbroadcastsareforwarded(Optional)Phonenumberofnexthopsenttothedialingdeviceforinterestingtrafficdialermapmustbeusedwithdialer-groupcommand
456.3OptionalCommands(2)Router(config-if)#dialerwait-for-carrier-timeSpecifiestimetowaitforcarriertocomeupRouter(config-if)#dialerload-threshold[outbound|inbound|either]SpecifybandwidthondemandbysettingthemaximumloadbeforethedialerplacesanothercalltoadestinationInterfaceusedtodeterminewhethertoinitiateanothercallortodropalinktothedestination.Thisargumentrepresentsautilizationpercentage;itisanumberbetween1and255,where255is100%Thesecondoptionforthatcommandisin,out,oreither.Thiscalculatestheactualloadontheinterfaceeitheronoutboundtraffic,inboundtraffic,orcombined.Thedefaultisoutbound.Router(config-if)#dialeridle-timeoutsecondsSpecifiesidletimebeforecircuitdisconnect.Thedefaultis120seconds
466.4VerifyingtheISDNOperationShowcontrollerbri0DisplayBandDchannelphysical-layerstatusShowdialerGivesgoodinformationaboutyourdialerdiagnosticinformationandshowsthenumberoftimesthedialerstringhasbeenreached,theidle-timeoutvaluesofeachBchannel,thelengthofcal,andthenameoftheroutertowhichtheinterfaceisconnected.ShowisdnactiveShowsthenumbercalledandwhetheracallisinprogress.Showisdnstatusisagoodcommandtousebeforetryingtodial.ShowsifyourSPIDsarevalidandifyouareconnectedandcommunicatingwithlayers1through3informationtotheprovider’sswitch.Debugisdnq921Isusedtoseelayer-2informationonly.Debugisdnq931Isusedtoseelayer-3information,includingcallsetupandteardown.DebugdialerGivesyoucall-setupandteardownactivity.Isdndisconnectintbri0Clearstheinterfaceanddropstheconnection.Performingashutdownontheinterfacecangiveyouthesameresults.
