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IP Routing on Cisco IOS, IOS XE, and IOS XR: An Essential Guide to Understanding and Implementing IP Routing Protocols

by Brad Edgeworth, Aaron Foss, Ramiro Garza Rios

December 2014

Intermediate to advanced

1200 pages

35h 34m

English

Cisco Press

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Who Should Read This Book?How This Book Is Organized
IOS, IOS XE, and IOS XR Software ArchitectureIOSKernel and OS SchedulingMemory ManagementSoftware PackagingIOS XEKernel and OS SchedulingMemory ManagementIOS XRKernel and OS SchedulingMemory ManagementSoftware PackagingDebuggingCLI and ConfigurationIOSUser ModePrivileged ModeGlobal Configuration ModeConfiguration ArchivingConfiguration ReplaceIOS XRViewing Changes in the SysDBCommit LabelCommit ReplaceFailed CommitsConfiguration RollbackCommit ConfirmedMultiple Commit OptionsLoading Files for ChangesHierarchical ConfigurationPWDRootSummaryReferences in This Chapter
IP FundamentalsUnderstanding BinaryAddress ClassesSubnet Masks and SubnettingSubnet Mask PurposeCalculating Usable IP AddressesNetwork Prefix NotationSubnettingSubnet FieldSubnet MathSubnet DesignClassless Interdomain RoutingClassful Versus Classless RoutingClassful RoutingClassless RoutingVariable-Length Subnet MasksSummarizationPrivate IP AddressingSpecial IP AddressesIPv4 Address ConfigurationWildcard Subnet MasksSummaryReferences in This Chapter
IP RoutingDistance Vector AlgorithmsEnhanced Distance Vector AlgorithmLink-State AlgorithmsPath Vector AlgorithmRouting TablePrefix LengthAdministrative DistanceMetricsVirtual Routing and ForwardingIP Packet SwitchingProcess SwitchingCisco Express ForwardingSoftware CEFHardware CEFPlanes of OperationSummaryReferences in This Chapter
Connected NetworksSecondary Connected NetworksStatic Routing FundamentalsPoint-to-Point InterfacesBroadcast InterfacesDefault RouteFloating Static RoutingRecursive LookupMultihop RoutingSingle Recursive LookupMultiple Recursive LookupsProblems with Static Route RecursionNull InterfaceStatic VRF RoutesSummaryReferences in This Chapter
EIGRP FundamentalsEIGRP NeighborsInter-Router CommunicationForming EIGRP NeighborsClassic EIGRP Autonomous System ConfigurationIOS network StatementIOS XRPassive InterfacesSample Topology and ConfigurationConfirmation of InterfacesVerification of EIGRP Neighbor AdjacenciesDisplay of Installed EIGRP RoutesRouter IDEIGRP TerminologyTopology TablePath Metric CalculationCustom K ValuesInterface Delay SettingsLoad BalancingEIGRP Wide MetricsFailure Detection and TimersConvergenceStuck in ActiveStubDesign Considerations with EIGRP StubsSummarizationInterface-Specific SummarizationSummarization MetricsAdvertising a Default RouteAutomatic SummarizationAuthenticationEnabling Authentication on the interfaceKey Chain ConfigurationWAN ConsiderationsIP Bandwidth PercentSplit HorizonNext-Hop SelfEIGRP Named ConfigurationAddress Family Instance ConfigurationAddress Family Interface ConfigurationAddress Family Topology ConfigurationSummaryReferences in This Chapter
OSPF FundamentalsInter-Router CommunicationOSPF Hello PacketsRouter IDNeighborsForming OSPF Neighbor AdjacenciesBasic OSPF ConfigurationIOS network StatementIOS Interface SpecificIOS XRPassive InterfacesSample Topology and ConfigurationConfirmation of InterfacesVerification of OSPF Neighbor AdjacenciesVerification of OSPF RoutesDesignated Router and Backup Designated RouterDesignated Router ElectionsDR and BDR PlacementFailure DetectionHello TimerDead Interval TimerVerifying OSPF TimersOSPF Fast Packet HellosOSPF Network TypesBroadcastNon-BroadcastPoint-to-Point NetworksPoint-to-Multipoint NetworksLoopback NetworksReview of OSPF Network TypesOSPF Adjacency with Different OSPF Network TypesLink CostsAuthenticationIOS Support for OSPF AuthenticationIOS XR Support for OSPF AuthenticationSummaryReferences in This Chapter
AreasArea IDOSPF Route TypesExternal OSPF RoutesLink-State AnnouncementsLSA Age and FloodingLSA TypesLSA Type 1: Router LinkLSA Type 2: Network LinkLSA Type 3: Summary LinkLSA Type 5: External RoutesLSA Type 4: ASBR SummaryLSA Type 7: NSSA External SummaryLSA Type SummaryOSPF Path SelectionIntra-Area RoutesInterarea RoutesExternal Route SelectionE1 and N1 External RoutesE2 and N2 External RoutesEqual Cost Multi-PathSummarization of RoutesInterarea SummarizationExternal SummarizationDefault RouteOSPF Stubby AreasStub AreasTotally Stubby AreasNot-So-Stubby AreasTotally NSSA AreasVirtual LinksDiscontiguous NetworkMulti-Area AdjacencyPrefix SuppressionSummaryReferences in This Chapter
IS-IS FundamentalsAreasOSI AddressingInter-Domain PartDomain Specific PartNET AddressingInter-Router CommunicationIS Protocol HeaderTLVsIS PDU AddressingHello PacketsLink-State PacketsLSP LifetimeLSP IDLSP SequenceAttribute FieldsLSP Packet and TLVsIS-IS NeighborEthernetPoint-to-PointBasic IS-IS ConfigurationIOSIOS XRSample Topology and ConfigurationConfirmation of IS-IS InterfacesVerification of IS-IS Neighbor AdjacenciesVerification of IS-IS RoutesDesignated Intermediate SystemDIS ElectionsDIS PlacementPoint-to-Point Adjacency on Broadcast MediaLink State Packet DatabaseViewing the LSPDBNon-Pseudonode LSPsPseudonode LSPsBuilding the TopologyViewing the TopologySPF CalculationsPassive InterfacesRemoval of Hello PaddingFailure DetectionHello TimerHello Multiplier and Holding TimerAuthenticationIS-IS Hello AuthenticationIS-IS LSP AuthenticationSummaryReferences in This Chapter
Advanced IS-IS RoutingRoute LeakingBackbone ContinuityLoop PreventionRouter-Specific IS-IS LevelsInterface Specific IS-IS LevelsPath SelectionEqual Cost Multi-PathInterface MetricsOverload BitSummarizationDefault RoutesPrefix SuppressionSummaryReferences in This Chapter
BGP FundamentalsAutonomous System NumbersPath AttributesLoop PreventionAddress FamiliesInter-Router CommunicationOpen MessagesHold TimeBGP IdentifierKeepalive MessagesUpdate MessagesNotification MessagesBGP SessionsBGP Neighbor StatesIdle StateConnect StateActive StateOpenSent StateOpenConfirm StateEstablished StateBasic BGP ConfigurationIOSIOS XRVerification of BGP SessionsPrefix AdvertisementReceiving and Viewing RoutesiBGPiBGP Full-Mesh RequirementPeering via Loopback AddresseseBGPeBGP and iBGP TopologiesNext-Hop ManipulationiBGP ScalabilityRoute ReflectorsLoop Prevention in Route ReflectorsOut-of-Band Route ReflectorsConfederationsFailure DetectionSecurityeBGP MultihopTTL SecuritySummaryReferences in This Chapter
Access Control ListsStandard ACLsExtended ACLsIGP Network SelectionBGP Network SelectionPrefix MatchingPrefix ListsPrefix SetsRegular Expressions_ (Underscore)^ (Caret)$ (Dollar Sign)[ ] (Brackets)- (Hyphen)[^] (Caret in Brackets)( ) (Parentheses and | Pipe). (Period)+ (Plus Sign)? (Question Mark)* (Asterisk)Looking Glass and Route ServersAS_Path Access ListIOS XR AS_Path Selection Optionsis-locallengthunique-lengthpasses-throughneighbor-isoriginates-fromAS Path SetRoute MapsConditional MatchingMultiple Conditional Match ConditionsComplex MatchingOptional ActionsContinueRoute Map ExamplesRouting Policy LanguageRoute Policy StructureMatch StatementsAttribute ModificationCommon Route Policy StructureBoolean OperatorsNegationConjunctionDisjunctionOrder of ProcessingComparing Prefix Sets to Prefix ListsParameterizationRoute Policy NestingOriginal ValueEditorsRPL ExamplesRPL VerificationRedistribution RPL VerificationBGP RPL VerificationSummaryReferences in This Chapter
Conditional Routing of PacketsPolicy-Based Routing ConfigurationAccess-List-Based Forwarding ConfigurationLocal PBRAdministrative DistanceModifying EIGRP ADModifying OSPF ADModifying IS-IS ADModifying BGP ADRoute Filtering and ManipulationEIGRP Filtering by PrefixEIGRP Filtering by Hop CountEIGRP Offset ListsOSPF Filtering (Local)OSPF Filtering (Area)IS-IS Filtering (Local)BGP FilteringClearing BGP ConnectionsSummaryReferences in This Chapter
Redistribution BasicsRedistribution Is Not TransitiveSequential Protocol RedistributionRoutes Must Exist in the RIBMetricsProtocol-Specific ConfigurationSource-Specific BehaviorsConnected NetworksIS-ISBGPDestination-Specific BehaviorsEIGRPOSPFIS-ISBGPChallenges with RedistributionRoute FeedbackSuboptimal RoutingInvalid Routing TablesRouting LoopsMethods to Avoid Routing LoopsPrefix FilteringTaggingIncrease Seed MetricsAdministrative DistanceSummarization on Redistributing RouterSolutions to Redistribution ChallengesSummaryReferences in This Chapter
BGP CommunitiesEnabling BGP Community SupportWell-Known CommunitiesInternetNo_ExportNo_AdvertiseNo_Export_SubConfedConditionally Matching BGP CommunitiesCommunity SetInlineSetting Private BGP CommunitiesRoute SummarizationAggregate AddressFlexible Route SuppressionSelective Prefix SuppressionLeaking Suppressed RoutesAtomic AggregateRoute Aggregation with AS_SETRoute Aggregation with Selective Advertisement of AS_SetDefault Route AdvertisementDefault Route Advertisement Per NeighborConditional Route AdvertisementOutbound Route FilteringBackdoor NetworksMaximum Autonomous SystemMaximum PrefixRemove Private Autonomous SystemAllow Autonomous SystemLocal Autonomous SystemConfiguration ScalabilityIOS Peer GroupsIOS Peer TemplatesIOS XR Configuration TemplatesSummaryReferences in This Chapter
BGP Best Path OverviewWeightLocal PreferenceLocally Originated via Network or Aggregate AdvertisementAccumulated Interior Gateway ProtocolShortest AS_PathOrigin TypeMulti-Exit DiscriminatorMissing MED behaviorAlways Compare MedBGP Deterministic MEDeBGP over iBGPLowest IGP MetricPrefer the Oldest EBGP PathRouter IDMinimum Cluster List LengthLowest Neighbor AddressBGP ECMPeBGP and iBGP MultipatheiBGP MultipathR1R2XR3XR4XR5AS_Path RelaxSuboptimal Routing with Route ReflectorsAdditional Route ReflectorShadow Route ReflectorShadow Session Route ReflectorBGP Add-PathSummaryFurther ReadingReferences in This Chapter
Multicast FundamentalsMulticast AddressingLayer 2 Multicast AddressesInternet Group Management ProtocolIGMP SnoopingIGMPv2IGMPv3Multicast Distribution TreesSource TreesShared TreesProtocol Independent MulticastPIM Dense ModePIM Sparse ModePIM Shared and Source Path TreesShared Tree JoinSource RegistrationPIM SPT SwitchoverDesignated RoutersRendezvous PointsStatic RPAuto-RPCandidate RPsRP Mapping AgentsPIM Bootstrap RouterCandidate RPsReverse Path ForwardingPIM ForwarderBasic Multicast ConfigurationConfigure Rendezvous PointsStatic RPAuto-RPBSRMulticast VerificationBidirectional PIMBidir-PIM Designated ForwarderSummaryReferences in This Chapter
Interdomain Multicast RoutingMultiprotocol BGPMulticast Source Discovery ProtocolMSDP Source Active Message TypesSA MessagesKeepalive MessagesMSDP PeersMSDP VerificationMSDP Stub NetworksRendezvous Point RedundancyAuto-RP with Multiple RPsAuto-RP Group FilteringBSR with Multiple RPsBSR Group FilteringBSR RP Hash AlgorithmStatic RP with Multiple RPsAnycast RPSource Specific MulticastSSM MappingDNS SSM MappingStatic SSM MappingMulticast SecurityAuto-RP ScopingMulticast BoundariesAdministratively Scoped BoundariesAuto-RP Multicast BoundariesBSR Multicast BoundariesAuto-RP Cisco-RP-Announce Message FilteringPIM-SM Source Registration FilteringPIM-SM Accept RPPIM Neighbor ControlPIM Register Rate LimitMulticast Traffic EngineeringRPF RulesStatic MroutesMBGPStatic IGMP JoinsMulticast TroubleshootingMtraceSummaryReferences in This Chapter
IPv6 Address StructureText Representation Address AbbreviationIPv6 Hexadecimal to Binary ConversionIPv6 Address TypesUnicastGlobal UnicastUnique Local UnicastLink-Local UnicastAnycastMulticastSpecial IPv6 AddressesNeighbor Discovery ProtocolRouter, Prefix, and Parameter Discovery.RedirectIPv6 Stateless Address AutoconfigurationExtended Unique IdentifierSLAAC Router ConfigurationRA Options for DNSStateless DHCPv6IOS Stateless DHCPv6 ConfigurationIOS XR Stateless DHCPv6 ConfigurationStateless DHCPv6 VerificationStateful DHCPv6, Relay Agent, and Relay ProxyIOS Relay Agent ConfigurationIOS Relay Agent VerificationIOS XR Proxy Agent ConfigurationIOS XR Proxy Agent VerificationIOS Stateful DHCPv6 Server ConfigurationIOS XR Stateful DHCPv6 Server ConfigurationStateful DHCPv6 Server VerificationIPv6 Address Resolution and Neighbor Unreachability DetectionDuplicate Address DetectionSummaryReferences in This Chapter
Static RoutingStatic Route ConfigurationStatic Route Reference Chart for IPv6EIGRPv6EIGRPv6 Inter-Router CommunicationEIGRPv6 ConfigurationIOS EIGRPv6 Autonomous System Configuration (Classic)IOS EIGRPv6 Hierarchical Configuration (Named Mode)IOS XR EIGRPv6 ConfigurationEIGRPv6 VerificationSummarizationDefault RouteRoute FilteringEIGRP Configuration Command Reference Chart for IPv6OSPFv3OSPFv3 Inter-Router CommunicationOSPFv3 Link-State AdvertisementOSPFv3 LSA Flooding ScopeOSPFv3 ConfigurationIOS OSPFv3 ConfigurationIOS XR OSPFv3 ConfigurationOSPFv3 VerificationOSPFv3 AuthenticationOSPFv3 Multiple InstancesOSPFv3 Configuration Command Reference Chart for IPv6Integrated IS-IS for IPv6IS-IS Inter-Router CommunicationIS-IS Type-Length-ValueIS-IS Topology ModesIS-IS ConfigurationIOS Base ConfigurationIOS XR Base ConfigurationIOS Topology Mode ConfigurationIOS XR Topology Mode ConfigurationVerificationIS-IS Configuration Reference Chart for IPv6Multiprotocol BGP for IPv6Inter-Router CommunicationBGP ConfigurationIOS Base ConfigurationIOS XR Base ConfigurationBGP VerificationIPv6 over IPv4 BGP SessionsBGP Configuration Command Reference Chart for IPv6IPv6 Route RedistributionSummaryReferences in This Chapter
IPv6 Multicast Routing OverviewIPv6 Multicast Address Mapping into MAC AddressEnabling Multicast RoutingMulticast Listener DiscoveryProtocol Independent MulticastPIM Sparse ModeStatic RPBootstrap RouterEmbedded RPIPv6 Multicast Verification CommandsReverse Path ForwardingMulticast Boundary ScopePIM Source Specific MulticastSummaryReferences in This Chapter
Network Convergence OverviewContinuous ForwardingStateful SwitchoverNonstop Forwarding and Graceful RestartOSPFIS-ISEIGRPBGPNonstop RoutingNSR for OSPFNSR for IS-ISNSR for BGPNonstop Forwarding and Nonstop Routing TogetherFailure AvoidanceRoute Flap DampeningIP Event DampeningBGP DampeningEvent-Driven Failure DetectionCarrier DelayBFDAsynchronous Mode Without EchoAsynchronous Mode with EchoBFD Configuration for OSPF, IS-IS, and EIGRPBFD Configuration for BGPBFD Configuration for BGP MultihopBFD Configuration for Static RoutesFast Routing ConvergenceIS-IS Convergence TuningOSPF Convergence TuningSPF Prefix PrioritizationBGP Convergence TuningNext-Hop TrackingMinimum Route Advertisement IntervalTCP PerformanceFast RerouteLoop-Free Alternate Fast RerouteLoop-Free Condition RulesLFA Protection ModesOSPF LFA FRRIS-IS LFA FRRShared Risk Link GroupBGP Prefix-Independent ConvergenceBGP PIC CoreBGP PIC EdgeBGP PIC Edge Link and Node ProtectionBGP PIC Edge with Next-Hop-SelfBGP Advertise Best ExternalBGP Additional PathSummaryReferences in This Chapter

Content preview from IP Routing on Cisco IOS, IOS XE, and IOS XR: An Essential Guide to Understanding and Implementing IP Routing Protocols

Chapter 15. BGP Best Path Selection

This chapter covers the following topics:

BGP best path

BGP multipath

Route reflector considerations

In Border Gateway Protocol (BGP), route advertisements consist of the network layer reachability information (NLRI) and the path attributes (PAs). The NLRI consists of the network prefix and prefix length, and the BGP attributes such as AS_Path, origin, and so on are stored in the PAs. A BGP route may contain multiple ...

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ISBN: 9780133846751Purchase book