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OSPF Link-State Advertisement (LSA) Throttling
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OSPF Link-State Advertisement Throttling

Table Of Contents

OSPF Link-State Advertisement Throttling

Finding Feature Information

Contents

Prerequisites for OSPF LSA Throttling

Information About OSPF LSA Throttling

Benefits of OSPF LSA Throttling

How OSPF LSA Throttling Works

How to Customize OSPF LSA Throttling

Customizing OSPF LSA Throttling

Configuration Examples for OSPF LSA Throttling

Example: OSPF LSA Throttling

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Feature Information for OSPF Link-State Advertisement Throttling


OSPF Link-State Advertisement Throttling


First Published: April 15, 2003

Last Updated: February 26, 2010

The OSPF Link-State Advertisement Throttling feature provides a dynamic mechanism to slow down link-state advertisement (LSA) updates in Open Shortest Path First (OSPF) during times of network instability. It also allows faster OSPF convergence by providing LSA rate limiting in milliseconds.

Finding Feature Information

For the latest feature information and caveats, see 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 for OSPF Link-State Advertisement Throttling" section.

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

Contents

Prerequisites for OSPF LSA Throttling

Information About OSPF LSA Throttling

How to Customize OSPF LSA Throttling

Configuration Examples for OSPF LSA Throttling

Additional References

Feature Information for OSPF Link-State Advertisement Throttling

Prerequisites for OSPF LSA Throttling

It is presumed that you have OSPF configured in your network.

Information About OSPF LSA Throttling

Before you enable OSPF LSA Throttling, you should understand the following concepts:

Benefits of OSPF LSA Throttling

How OSPF LSA Throttling Works

Benefits of OSPF LSA Throttling

Prior to the OSPF LSA Throttling feature, LSA generation was rate-limited for 5 seconds. That meant that changes in an LSA could not be propagated in milliseconds, so the OSPF network could not achieve millisecond convergence.

The OSPF LSA Throttling feature is enabled by default and allows faster OSPF convergence (in milliseconds). This feature can be customized. One command controls the generation (sending) of LSAs, and another command controls the receiving interval. This feature also provides a dynamic mechanism to slow down the frequency of LSA updates in OSPF during times of network instability.

How OSPF LSA Throttling Works

The timers throttle lsa all command controls the generation (sending) of LSAs. The first LSA is always generated immediately upon an OSPF topology change, and the next LSA generated is controlled by the minimum start interval. The subsequent LSAs generated for the same LSA are rate-limited until the maximum interval is reached. The "same LSA" is defined as an LSA instance that contains the same LSA ID number, LSA type, and advertising router ID.

The timers lsa arrival command controls the minimum interval for accepting the same LSA. If an instance of the same LSA arrives sooner than the interval that is set, the LSA is dropped. It is recommended that the arrival interval be less than or equal to the hold-time interval of the timers throttle lsa all command.

How to Customize OSPF LSA Throttling

Customizing OSPF LSA Throttling

SUMMARY STEPS

1. enable

2. configure terminal

3. router ospf process-id

4. timers throttle lsa all start-interval hold-interval max-interval

5. timers lsa arrival milliseconds

6. end

7. show ip ospf timers rate-limit

8. show ip ospf

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

Enter your password if prompted.

Step 2 

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3 

router ospf process-id

Example:

Router(config)# router ospf 1

Configures an OSPF routing process.

Step 4 

timers throttle lsa all start-interval hold-interval max-interval

Example:

Router(config-router)# timers throttle lsa all 100 10000 45000

(Optional) Sets the rate-limiting values (in milliseconds) for LSA generation.

The default values are as follows:

start-interval is 0 milliseconds.

hold-interval is 5000 milliseconds.

max-interval is 5000 milliseconds.

Step 5 

timers lsa arrival milliseconds

Example:

Router(config-router)# timers lsa arrival 2000

(Optional) Sets the minimum interval (in milliseconds) between instances of receiving the same LSA.

The default value is 1000 milliseconds.

We suggest you keep the milliseconds value of the LSA arrival timer less than or equal to the neighbors' hold-interval value of the timers throttle lsa all command.

Step 6 

end

Example:

Router(config-router)# end

Exits router configuration mode.

Step 7 

show ip ospf timers rate-limit

Example:

Router# show ip ospf timers rate-limit


LSAID: 10.1.1.1    Type: 1   Adv Rtr: 172.16.2.2 Due in: 00:00:00.028

LSAID: 192.168.4.1   Type: 3   Adv Rtr: 172.17.2.2 Due in: 00:00:00.028

(Optional) Displays a list of the LSAs in the rate limit queue (about to be generated).

The example shows two LSAs in the queue. Each LSA is identified by LSA ID number, Type (of LSA), Advertising router ID, and the time in hours:minutes:seconds (to the milliseconds) when the LSA is due to be generated.

Step 8 

show ip ospf

Example:

Router# show ip ospf


Routing Process "ospf 4" with ID 10.10.24.4
 Supports only single TOS(TOS0) routes
 Supports opaque LSA
 Supports Link-local Signaling (LLS)
 Initial SPF schedule delay 5000 msecs
 Minimum hold time between two consecutive SPFs 10000 
msecs
 Maximum wait time between two consecutive SPFs 10000 
msecs
 Incremental-SPF disabled
 Initial LSA throttle delay 100 msecs
 Minimum hold time for LSA throttle 10000 msecs
 Maximum wait time for LSA throttle 45000 msecs
Minimum LSA arrival 1000 msecs
 LSA group pacing timer 240 secs
 Interface flood pacing timer 33 msecs
 Retransmission pacing timer 66 msecs
 Number of external LSA 0. Checksum Sum 0x0     
 Number of opaque AS LSA 0. Checksum Sum 0x0     
 Number of DCbitless external and opaque AS LSA 0
 Number of DoNotAge external and opaque AS LSA 0
 Number of areas in this router is 1. 1 normal 0 stub 
0 nssa
 External flood list length 0
    Area 24
        Number of interfaces in this area is 2
        Area has no authentication
        SPF algorithm last executed 04:28:18.396 ago
        SPF algorithm executed 8 times
        Area ranges are
        Number of LSA 4. Checksum Sum 0x23EB9 
        Number of opaque link LSA 0. Checksum Sum 0x0     
        Number of DCbitless LSA 0
        Number of indication LSA 0
        Number of DoNotAge LSA 0
        Flood list length 0

(Optional) Displays information about OSPF.

The output lines that specify initial throttle delay, minimum hold time for LSA throttle, and maximum wait time for LSA throttle indicate the LSA throttling values.

Configuration Examples for OSPF LSA Throttling

Example: OSPF LSA Throttling

This example customizes OSPF LSA throttling so that the start interval is 200 milliseconds, the hold interval is 10,000 milliseconds, and the maximum interval is 45,000 milliseconds. The minimum interval between instances of receiving the same LSA is 2000 milliseconds.

router ospf 1
 log-adjacency-changes
 timers throttle lsa all 200 10000 45000
 timers lsa arrival 2000
 network 10.10.4.0 0.0.0.255 area 24
 network 10.10.24.0 0.0.0.255 area 24

Additional References

The following sections provide references related to OSPF LSA throttling.

Related Documents

Related Topic
Document Title

Cisco IOS commands

Cisco IOS Master Commands List, All Releases

OSPF commands

Cisco IOS IP Routing: OSPF Command Reference

Configuring OSPF

"Configuring OSPF"


Standards

Standard
Title

None


MIBs

MIB
MIBs Link

No new or modified MIBs are supported by this feature, and support for existing MIBs has not been modified by this feature.

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

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


RFCs

RFC
Title

None


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 OSPF Link-State Advertisement Throttling

Table 1 lists the release history for this feature.

Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which Cisco IOS XE software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.


Note Table 1 lists only the Cisco IOS XE software release that introduced support for a given feature in a given Cisco IOS XE software release train. Unless noted otherwise, subsequent releases of that Cisco IOS XE software release train also support that feature.


Table 1 Feature Information for OSPF Link-State Advertisement Throttling

Feature Name
Releases
Feature Information

OSPF Link-State Advertisement Throttling

Cisco IOS XE
Release 2.1
Cisco IOS XE
Release 2.6

The OSPF Link-State Advertisement Throttling feature provides a dynamic mechanism to slow down link-state advertisement (LSA) updates in OSPF during times of network instability. It also allows faster OSPF convergence by providing LSA rate limiting in milliseconds.

The following commands are introduced or modified in the feature documented in this module:

debug ip ospf database-timer rate-limit

show ip ospf

show ip ospf timers rate-limit

timers lsa arrival

timers throttle lsa all