OSPFv3 Fast Convergence: LSA and SPF Throttling

The Open Shortest Path First version 3 (OSPFv3) link-state advertisement (LSAs) and shortest-path first (SPF) throttling feature provides a dynamic mechanism to slow down link-state advertisement updates in OSPFv3 during times of network instability. It also allows faster OSPFv3 convergence by providing LSA rate limiting in milliseconds.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/​go/​cfn. An account on Cisco.com is not required.

Information About OSPFv3 Fast Convergence: LSA and SPF Throttling

Fast Convergence: LSA and SPF Throttling

The OSPFv3 LSA and SPF throttling feature provides a dynamic mechanism to slow down link-state advertisement updates in OSPFv3 during times of network instability. It also allows faster OSPFv3 convergence by providing LSA rate limiting in milliseconds.

OSPFv3 can use static timers for rate-limiting SPF calculation and LSA generation. Although these timers are configurable, the values used are specified in seconds, which poses a limitation on OSPFv3 convergence. LSA and SPF throttling achieves subsecond convergence by providing a more sophisticated SPF and LSA rate-limiting mechanism that is able to react quickly to changes and also provide stability and protection during prolonged periods of instability.

How to Configure OSPFv3 Fast Convergence: LSA and SPF Throttling

Tuning LSA and SPF Timers for OSPFv3 Fast Convergence

This task can be performed in Cisco IOS Release 15.1(3)S and 15.2(1)T and later releases.

SUMMARY STEPS

    1.    enable

    2.    configure terminal

    3.    router ospfv3 [process-id]

    4.    timers lsa arrival milliseconds

    5.    timers pacing flood milliseconds

    6.    timers pacing lsa-group seconds

    7.    timers pacing retransmission milliseconds


DETAILED STEPS
      Command or Action Purpose
    Step 1 enable


    Example: 
    Device> enable
     

    Enables privileged EXEC mode.

    • Enter your password if prompted.
     
    Step 2 configure terminal


    Example: 
    Device# configure terminal
     

    Enters global configuration mode.

     
    Step 3 router ospfv3 [process-id]


    Example: 
    Device(config)# router ospfv3 1
     

    Enables OSPFv3 router configuration mode for the IPv4 or IPv6 address family.

     
    Step 4 timers lsa arrival milliseconds


    Example: 
    Device(config-rtr)# timers lsa arrival 300
     

    Sets the minimum interval at which the software accepts the same LSA from OSPFv3 neighbors.

     
    Step 5 timers pacing flood milliseconds


    Example: 
    Device(config-rtr)# timers pacing flood 30
     

    Configures LSA flood packet pacing.

     
    Step 6 timers pacing lsa-group seconds


    Example: 
    Device(config-router)# timers pacing lsa-group 300
     

    Changes the interval at which OSPFv3 LSAs are collected into a group and refreshed, checksummed, or aged.

     
    Step 7 timers pacing retransmission milliseconds


    Example: 
    Device(config-router)# timers pacing retransmission 100
     

    Configures LSA retransmission packet pacing in IPv4 OSPFv3.

     

    Configuring LSA and SPF Throttling for OSPFv3 Fast Convergence

    This task can be performed in releases prior to Cisco IOS Release 15.1(3)S and 15.2(1)T.

    SUMMARY STEPS

      1.    enable

      2.    configure terminal

      3.    ipv6 router ospf process-id

      4.    timers throttle spf spf-start spf-hold spf-max-wait

      5.    timers throttle lsa start-interval hold-interval max-interval

      6.    timers lsa arrival milliseconds

      7.    timers pacing flood milliseconds


    DETAILED STEPS
        Command or Action Purpose
      Step 1 enable


      Example: 
      Device> enable
       

      Enables privileged EXEC mode.

      • Enter your password if prompted.
       
      Step 2 configure terminal


      Example: 
      Device# configure terminal
       

      Enters global configuration mode.

       
      Step 3 ipv6 router ospf process-id


      Example: 
      Device(config)# ipv6 router ospf 1
       

      Enables OSPFv3 router configuration mode.

       
      Step 4 timers throttle spf spf-start spf-hold spf-max-wait


      Example: 
      Device(config-rtr)# timers throttle spf 200 200 200
       

      Turns on SPF throttling.

       
      Step 5 timers throttle lsa start-interval hold-interval max-interval


      Example: 
      Device(config-rtr)# timers throttle lsa 300 300 300
       

      Sets rate-limiting values for OSPFv3 LSA generation.

       
      Step 6 timers lsa arrival milliseconds


      Example: 
      Device(config-rtr)# timers lsa arrival 300
       

      Sets the minimum interval at which the software accepts the same LSA from OSPFv3 neighbors.

       
      Step 7 timers pacing flood milliseconds


      Example: 
      Device(config-rtr)# timers pacing flood 30
       

      Configures LSA flood packet pacing.

       

      Configuration Examples for OSPFv3 Fast Convergence: LSA and SPF Throttling

      Example: Configuring LSA and SPF Throttling for OSPFv3 Fast Convergence

      The following example show how to display the configuration values for SPF and LSA throttling timers: 

      Device# show ipv6 ospf 

Routing Process "ospfv3 1" with ID 10.9.4.1
Event-log enabled, Maximum number of events: 1000, Mode: cyclic
 It is an autonomous system boundary router
 Redistributing External Routes from, 
    ospf 2  
 Initial SPF schedule delay 5000 msecs 
 Minimum hold time between two consecutive SPFs 10000 msecs 
 Maximum wait time between two consecutive SPFs 10000 msecs 
 Minimum LSA interval 5 secs
 Minimum LSA arrival 1000 msecs

      Additional References

      Related Documents

      Related Topic

      Document Title

      IPv6 addressing and connectivity

      IPv6 Configuration Guide

      Cisco IOS commands

      Cisco IOS Master Commands List, All Releases

      IPv6 commands

      Cisco IOS IPv6 Command Reference

      Cisco IOS IPv6 features

      Cisco IOS IPv6 Feature Mapping

      OSPFv3 Fast Convergence: LSA and SPF Throttling

      “OSPF Link-State Advertisement Throttling ” module

      Standards and RFCs

      Standard/RFC

      Title

      RFCs for IPv6

      IPv6 RFCs

      MIBs

      MIB

      MIBs Link

      To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:

      http:/​/​www.cisco.com/​go/​mibs

      Technical Assistance

      Description

      Link

      The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

      http:/​/​www.cisco.com/​cisco/​web/​support/​index.html

      Feature Information for OSPFv3 Fast Convergence: LSA and SPF Throttling

      The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

      Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/​go/​cfn. An account on Cisco.com is not required.

      Table 1 Feature Information for OSPFv3 Fast Convergence: LSA and SPF Throttling

      Feature Name

      Releases

      Feature Information

      OSPFv3 Fast Convergence: LSA and SPF Throttling

      Cisco IOS XE Release 2.1

      The OSPFv3 LSA and SPF throttling feature provides a dynamic mechanism to slow down link-state advertisement updates in OSPFv3 during times of network instability.