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

OSPF LSA Throttling: Example

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Feature Information for OSPF Link-State Advertisement Throttling

OSPF Link-State Advertisement Throttling

---

Last Updated: May 4, 2009

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 Open Shortest Path First (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

This section contains the following optional procedure:

•Customizing OSPF LSA Throttling (optional)

Customizing OSPF LSA Throttling

This task describes how to customize OSPF LSA throttling if you prefer to set values other than the defaults.

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 shown in bold in the example indicate the LSA throttling values.

Configuration Examples for OSPF LSA Throttling

This section contains an example of customizing OSPF LSA throttling:

•OSPF LSA Throttling: Example

OSPF LSA Throttling: Example

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
Configuring OSPF	"Configuring OSPF" chapter in the Cisco IOS XE IP Routing Protocols Configuration Guide, Release 2
OSPF commands	Cisco IOS IP Routing Protocols Command Reference
Cisco IOS master command list, all releases	Cisco IOS Master Command List, All Releases

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 website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies. To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds. Access to most tools on the Cisco Support website requires a Cisco.com user ID and password.

http://www.cisco.com/techsupport

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	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

---

CCDE, CCSI, CCENT, Cisco Eos, Cisco HealthPresence, the Cisco logo, Cisco Lumin, Cisco Nexus, Cisco Nurse Connect, Cisco Stackpower, Cisco StadiumVision, Cisco TelePresence, Cisco WebEx, DCE, and Welcome to the Human Network are trademarks; Changing the Way We Work, Live, Play, and Learn and Cisco Store are service marks; and Access Registrar, Aironet, AsyncOS, Bringing the Meeting To You, Catalyst, CCDA, CCDP, CCIE, CCIP, CCNA, CCNP, CCSP, CCVP, Cisco, the Cisco Certified Internetwork Expert logo, Cisco IOS, Cisco Press, Cisco Systems, Cisco Systems Capital, the Cisco Systems logo, Cisco Unity, Collaboration Without Limitation, EtherFast, EtherSwitch, Event Center, Fast Step, Follow Me Browsing, FormShare, GigaDrive, HomeLink, Internet Quotient, IOS, iPhone, iQuick Study, IronPort, the IronPort logo, LightStream, Linksys, MediaTone, MeetingPlace, MeetingPlace Chime Sound, MGX, Networkers, Networking Academy, Network Registrar, PCNow, PIX, PowerPanels, ProConnect, ScriptShare, SenderBase, SMARTnet, Spectrum Expert, StackWise, The Fastest Way to Increase Your Internet Quotient, TransPath, WebEx, and the WebEx logo are registered trademarks of Cisco Systems, Inc. and/or its affiliates in the United States and certain other countries.

All other trademarks mentioned in this document or website are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company. (0903R)

Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be actual addresses and phone numbers. Any examples, command display output, and figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses or phone numbers in illustrative content is unintentional and coincidental.

© 2008-2009 Cisco Systems, Inc. All rights reserved.