From: Pavel Bykov (slidersv@gmail.com)
Date: Tue Mar 17 2009 - 18:51:39 ART
Darby, good Info.
But I think this is seeing much more than what the question actually asked.
Of course, the question can be interpreted deeply, and then the answer would
be:
Since Inter Area OSPF behaves as distance vector, without information about
exact network location, only a vector and a distance (type3 and type 4 LSAs)
there is an architectural loop prevention, which eliminates the need for
split horizon at all.
That architectural limitation is that ALL areas have to be connected to
Backbone Area (or Area 0).
But that I think is seeing more than the question asked as well.
Therefore I would go with the others and point out that LSAs are (usually)
Flooded throughtout the area, because we want everybody to know the
information. Split horizon would be counter productive.
On Tue, Mar 17, 2009 at 1:31 PM, Darby Weaver <ccie.weaver@gmail.com> wrote:
> 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
> AM<http://darbylogs.blogspot.com/2009/02/hot-discussion-item.html> 0
> comments<
> https://www.blogger.com/comment.g?blogID=1668663710008599256&postID=
> 272188173124441502>
> <
> http://www.blogger.com/post-edit.g?blogID=1668663710008599256&postID=2721881
> 73124441502>
>
>
> 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
>
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html
>
>
>
>
>
>
>
>
-- Pavel Bykov ---------------- Don't forget to help stopping the braindumps, use of which reduces value of your certifications. Sign the petition at http://www.stopbraindumps.com/Blogs and organic groups at http://www.ccie.net
This archive was generated by hypermail 2.1.4 : Mon Apr 06 2009 - 06:44:05 ART