【正文】 planeCLISNMPXMLNetflowAlarmPerf. mgmt.SSHManagement planeMemoryprotected microkernel Distributed subsystems/processesSystem servicesControl plane169。2/ 64Version Fault Tolerance and IsolationLayered rather than monolithic architectureFault isolation and protection between the planesCisco IOS XRDataplaneControlplaneManagementplane169。2/ 66Version ProcessLevel RedundancyStandbyprocessActiveprocessActive serviceproviding processStandby processActive process uses a checkpoint database to share running state with standbyClientClientClientClients use active serviceproviding process169。2/ 68Version PRINT ONLY!!!!!1. Active process failsClientClientClient5. Clients use new active serviceproviding process4. New active starts sending updates to standby processActiveprocessStandbyprocessNew activeprocess3. New standby process is started2. Standby process bees active169。BProcessD111Active card Standby card2234Checkptprocess Checkptprocess169。2/ 71Version RP and DRP FailoverActive RPStandby RPCheckpointedRP failureIf no standby DRP exists, no checkpointingActive DRPStandby DRPActive DRPDRP failureCheckpointedNotcheckpointed169。2/ 73Version PRINT ONLY!!? Paired RPs or DRPs? Each LC has dedicated packet forwarding hardware (PSE)? Packet forwarding is not affected by: ISIS, OSPF, BGP, MPLS, Multicast process restartInfrastructure process restartsRP failoverLC LCRP RPControlupdatesinterruptedBut…FwdingOk!Active Active169。2/ 75Version Adjacency ManagementAdjacency InformationBaseModular services card (MSC)ARP/MaptablesInterface managerRP169。2/ 77Version Forwarding Information TablesMSCCPURP or DRPOSPFISISStaticroutesRIBBGPHardwareFIBSwitch fabricMSCPSEFIBprocessAIB Ifmgr169。2/ 79Version Distributed Configuration ManagementRPConfiguration managerL2/L3 applications and H/W driversMSCHardwareConfiguration managerL2/L3 applications and H/W driversMSCHardwareConfiguration manager169。2/ 81Version RP “disk0:”Running configplus changesIOS XRConfiguration File SystemNew binary configuration created。Essentials—ModuleEssentials—ModuleCRS1CRS1CRS1CRS1Essentials—ModuleEssentials—Module2/ 80Version Running configConfig databaseSecond stageFirst stagemitTargetconfigConfig changes New running configConfig agentsCLI/XML+TwoStage ConfigurationRouter Config t=? Stage 1: Make configuration changesCreate new target config by entering config? Stage 2: Make changes persistentRunning config169。2/ 78Version Interface driverMSCDistributed Interface ManagementRPInterface managerInterface driverMSCInterface manager Interface managerInterfaces InterfacesInterface manager global databaseInterface driver169。2/ 76Version TwoStage ForwardingWhat is twostage forwarding?? Forwarding lookup is done twice? Ingress side – Lookup returns information to forward packet to correct outbound MSC and physical interface? Egress side – Lookup gets correct interface and adjacency informationWhy twostage forwarding?? Scaling? With the number of cards/interfaces in a CRS1, the amount of forwarding information for each MSC must be limited? Entire Layer 2 adjacency information is not required on all cards? Example: Feature scalingInput ACLs on ingress cardsOutput ACLs on egress cards169。2/ 74Version Scalability Features?Adjacency management?Forwarding Information Base tables?Distributed interface management?Distributed configuration management?Twostage forwarding169。2/ 72Version Nonstop Forwarding? Paired RPs or DRPs? Each LC has dedicated packet forwarding hardware (PSE)? Packet forwarding is not affected by: ISIS, OSPF, BGP, MPLS, Multicast process restartInfrastructure process restartsRP failoverLC LCRP RPControlupdatesinterruptedBut…FwdingOk!Active ActiveStandby169。2/ 70Version RP and DRP Failover (for print)Active RPStandby RPCheckpointedRP failureIf no standby DRP exists, no checkpointingActive DRPStandby DRPActive DRPDRP failureCheckpointedNotcheckpointed169。B180。2/ 69Version Process Restart and Recovery—RP Failure 1. Process A: checkpoint data sent to standby peer continually2. Process B: checkpoint data mirrored to standby card3. Process C: no checkpointing process C39。2/ 67Version ProcessLevel Redundancy (Cont.)1. Active process failsClientClientClient5. Clients use new active serviceproviding process4. New active starts sending updates to standby processActiveprocessStandbyprocessNew activeprocess3. New standby process is started2. Standby process bees active169。2/ 65Version Checkpoint Support for Process RestartProcessCheckpoint shared memory storeUpdates of running stateNew instance of process(Process fails)Recover stateActive RP/DRP169。2/ 63Version Fault Tolerance and Isolation (For Print)Layered rather than monolithic architectureFault isolation and protection between the planesCisco IOS XRDataplaneControlplaneManagementplane169。2/ 61Version Kernel?Memoryprotection, messagepassing, preemptive?Modular software design?All basic OS and router functionality implemented as processes?Process model with separate, protected address spacesMicrokernel:ThreadsSchedulingDebugTimersMessage queuesSynchronizationDistributed processingFile systemLightweight messagingEvent managementCISC OPOSIXApplications169。2/ 59Version Cisco IOS XR ArchitectureCisco IOS XR kernelDistributed infrastructureRoutingmodules(BGP, OSPF)Pro