Table Of Contents

OSPF Area Transit Capability

Finding Feature Information in This Module

Contents

Information About OSPF Area Transit Capability

How the OSPF Area Transit Capability Feature Works

How to Disable OSPF Area Transit Capability

Disabling OSPF Area Transit Capability on an Area Border Router

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Command Reference

Feature Information for OSPF Area Transit Capability

OSPF Area Transit Capability

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First Published: January 27, 2004

Last Updated: May 2, 2008

The OSPF Area Transit Capability feature provides an OSPF Area Border Router (ABR) with the ability to discover shorter paths through the transit area for forwarding traffic that would normally need to travel through the virtual-link path. This functionality allows Cisco IOS software to be compliant with RFC 2328.

Finding Feature Information in This Module

Your software release may not support all the features documented in this module. 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 Area Transit Capability" section.

Use Cisco Feature Navigator to find information about platform support and Cisco IOS and Catalyst OS 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

•Information About OSPF Area Transit Capability

•How to Disable OSPF Area Transit Capability

•Additional References

•Command Reference

•Feature Information for OSPF Area Transit Capability

Information About OSPF Area Transit Capability

To use the OSPF Area Transit Capability feature, you should understand the concept in the following section:

•How the OSPF Area Transit Capability Feature Works

How the OSPF Area Transit Capability Feature Works

The OSPF Area Transit Capability feature is enabled by default. RFC 2328 defines OSPF area transit capability as the ability of the area to carry data traffic that neither originates nor terminates in the area itself. This capability enables the OSPF ABR to discover shorter paths through the transit area and forward traffic along those paths rather than using the virtual link or path, which are not as optimal.

For a detailed description of OSPF area transit capability, see RFC 2328, OSPF Version 2, at the following URL:

http://www.faqs.org/rfcs/rfc2328.html

How to Disable OSPF Area Transit Capability

This section contains the following procedure:

•Disabling OSPF Area Transit Capability on an Area Border Router (required)

Disabling OSPF Area Transit Capability on an Area Border Router

This task describes how to disable the OSPF Area Transit Capability feature on an OSPF ABR.

SUMMARY STEPS

1. enable

2. configure terminal

3. router ospf process-id [vrf vpn-name]

4. no capability transit

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 [vrf vpn-name] Example: Router(config)# router ospf 100	Enables OSPF routing and enters router configuration mode. •The process-id argument identifies the OSPF process.
Step 4	no capability transit Example: Router(config-router)# no capability transit	Disables OSPF area capability transit on all areas for a router process.

Additional References

The following sections provide references related to the OSPF Area Transit Capability feature.

Related Documents

Related Topic	Document Title
Configuring OSPF	Cisco IOS IP Routing Protocols Configuration Guide

Standards

Standard	Title
None	—

MIBs

MIB	MIBs Link
None	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

RFCs

RFC	Title
RFC 2328	OSPF Version 2

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

Command Reference

The following commands are introduced or modified in the feature or features documented in this module. For information about these commands, see the Cisco IOS IP Routing Protocols Command Reference at http://www.cisco.com/en/US/docs/ios/iproute/command/reference/irp_book.html. For information about all Cisco IOS commands, go to the Command Lookup Tool at http://tools.cisco.com/Support/CLILookup or to the Cisco IOS Master Commands List.

•capability transit

Feature Information for OSPF Area Transit Capability

Table 1 lists the release history for this feature.

Not all commands may be available in your Cisco IOS software release. For release information about a specific command, see the command reference documentation.

Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which Cisco IOS and Catalyst OS 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.

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

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Note Software images for Cisco 12000 series Internet routers have been deferred to Cisco IOS Release 12.0(27)S1.

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Table 1 Feature Information for OSPF Area Transit Capability 

Feature Name	Releases	Feature Information
OSPF Area Transit Capability	12.0(27)S 12.3(7)T 12.2(25)S 12.2(27)SBC 12.2(33)SRA 12.2(33)SXH	The OSPF Area Transit Capability feature provides an OSPF Area Border Router (ABR) the ability to discover shorter paths through the transit area for forwarding traffic that would normally need to travel through the virtual-link path. This functionality allows Cisco IOS software to be compliant with RFC 2328.

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