Re: split horizon in ospf

From: Darby Weaver (ccie.weaver@gmail.com)
Date: Tue Mar 17 2009 - 09:31:15 ART


From http://www.darbylogs.blogspot.com
================================

No Capability Transit

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, refer to 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]

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]

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.
 Posted by DARBY WEAVER'S CCIE LOGS at 8:53
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Another Reference:

http://www.cisco.com/en/US/docs/ios/12_0s/feature/guide/ospfatc.html

Blogs and organic groups at http://www.ccie.net



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