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Table Of Contents
Related Features and Technologies
Setting OSPF Retransmission Limits
OSPF Retransmissions Limit
Feature History
This feature module describes the change in how the Open Shortest Path First (OSPF) protocol handles retransmissions and includes the following sections:
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Related Features and Technologies
Feature Overview
Cisco IOS Release 12.2(4)T added a limit to the number of retransmissions of database exchange and update packets for both demand and non-demand circuits. The retransmission of these packets stops once this retry limit is reached, thus preventing unnecessary use of the link in continual retransmission of the packets if, for some reason, a neighbor is not responding during adjacency forming.
The limit for both demand circuit and non-demand circuit retransmissions is 24.
The limit-retransmissions command allows you to either remove (disable) the limit or change the maximum number of retransmissions to be a number from 1 to 255.
Benefits
The limit-retransmissions command provides for backward compatibility for previous or other releases of Cisco IOS or other routers that do not have this feature.
Restrictions
The limit to the number of retransmissions does not apply for update packets on nonbroadcast multiaccess (NBMA) point-to-multipoint direct circuits. In this situation, the dead timer is used to end communication with non-responding neighbors and thus stop the retransmissions.
Related Features and Technologies
This feature is an extension of the OSPF routing protocol. For more information about configuring OSPF and configuring route summarization and filtering, refer to the "Configuring OSPF" chapter of the Cisco IOS IP Configuration Guide and the Cisco IOS IP Command Reference, Volume 2 of 3: Routing Protocols.
Supported Platforms
The limit-retransmissions command is supported for the following platforms in Cisco IOS Release 12.2(11)T:
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Determining Platform Support Through Cisco Feature Navigator
Cisco IOS software is packaged in feature sets that are supported on specific platforms. To get updated information regarding platform support for this feature, access Cisco Feature Navigator. Cisco Feature Navigator dynamically updates the list of supported platforms as new platform support is added for the feature.
Cisco Feature Navigator is a web-based tool that enables you to determine which Cisco IOS software images support a specific set of features and which features are supported in a specific Cisco IOS image. You can search by feature or release. Under the release section, you can compare releases side by side to display both the features unique to each software release and the features in common.
To access Cisco Feature Navigator, you must have an account on Cisco.com. If you have forgotten or lost your account information, send a blank e-mail to cco-locksmith@cisco.com. An automatic check will verify that your e-mail address is registered with Cisco.com. If the check is successful, account details with a new random password will be e-mailed to you. Qualified users can establish an account on Cisco.com by following the directions found at this URL:
Cisco Feature Navigator is updated regularly when major Cisco IOS software releases and technology releases occur. For the most current information, go to the Cisco Feature Navigator home page at the following URL:
Availability of Cisco IOS Software Images
Platform support for particular Cisco IOS software releases is dependent on the availability of the software images for those platforms. Software images for some platforms may be deferred, delayed, or changed without prior notice. For updated information about platform support and availability of software images for each Cisco IOS software release, refer to the online release notes or, if supported, Cisco Feature Navigator.
Configuration Tasks
See the following sections for configuration tasks for the OSPF retransmission limits feature. Each task in the list is identified as either required or optional:
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Setting OSPF Retransmission Limits
To set OSPF retransmission limits, use the following commands beginning in router configuration mode:
Command Reference
This section documents the new limit retransmissions command that changes or removes the limit in the number of retransmissions of database exchange and update packets for both demand and non-demand circuits. All other commands used with this feature are documented in the Cisco IOS Release 12.2 command reference publications.
limit retransmissions
To change or remove the limit in the number of retransmissions of database exchange and update packets for both demand and non-demand circuits, use the limit retransmissions command in router configuration mode. To reset the maximum number of retransmissions back to the default value of 24, use the no form of this command.
limit retransmissions {[dc {max-number | disable}] [non-dc {max-number | disable}]}
no limit transmissions [dc | non-dc]
Syntax Description
Defaults
Maximum number of retransmissions is 24.
Command Modes
Router configuration
Command History
Usage Guidelines
Cisco IOS Release 12.2(4)T added a limit to the number of retransmissions of database exchange and update packets for both demand and non-demand circuits. The retransmission of these packets stops once this retry limit is reached, thus preventing unnecessary use of the link in continual retransmission of the packets if, for some reason, a neighbor is not responding during adjacency forming.
The limit for both demand circuit and non-demand circuit retransmissions is 24.
The limit-retransmissions command allows you to either remove (disable) the limit or change the maximum number of retransmissions to be a number from 1 to 255. This provides for backward compatibility for previous or other releases of Cisco IOS or other routers that do not have this feature.
Note
Examples
The following example shows how to set the maximum number of demand circuit retransmissions to 10:
limit retransmissions dc 10The following example shows how to remove the limit for the number of demand circuit retransmissions:
limit retransmissions dc disableThe following example shows how to set the maximum number of demand circuit retransmissions to 10 and to set the maximum number of non-demand circuit retransmissions to 20:
limit retransmissions dc 10 non-dc 20The following example shows how to set the maximum number of demand circuit retransmissions to 10, and to remove the limit for the number of non-demand circuit retransmissions:
limit retransmissions dc 10 non-dc disableThe following example shows how to reset both the demand circuit and non-demand circuit maximum number of retransmissions back to the default of 24:
no limit retransmissionsRelated Commands
