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 Tooland 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.

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 Shortest Path First 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

12.2(33)SRC

15.0(1)SY

15.0(1)M

15.1(1)SY

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.

The following commands were introduced or modified: ipv6 router ospf , router ospfv3 , timers lsa arrival , timers pacing flood , timers pacing lsa-group , timers pacing retransmission , timers throttle lsa , timers throttle spf .