[21652] in North American Network Operators' Group
Re: Strange BGP announcement
daemon@ATHENA.MIT.EDU (Vijay Gill)
Tue Nov 17 18:57:39 1998
Date: Tue, 17 Nov 1998 18:03:01 -0500 (EST)
From: Vijay Gill <wrath@cs.umbc.edu>
To: I Am Not An Isp <patrick@ianai.net>
cc: nanog@merit.edu
In-Reply-To: <199811170556.AAA01476@newman.concentric.net>
On Mon, 16 Nov 1998, I Am Not An Isp wrote:
> At 01:00 AM 11/14/98 +0000, Andrew Bangs wrote:
> You really want all backbone routers to ignore AS-Path length in the BGP
> route selection process? I think I like it better the way it is now - at
> least for the near future.
>
> Hrmm.... Perhaps if the vendors covered the RFC error code type stuff at
> least, then they could add kewl, new features like "as-path length" as a
> step in the route selection process.
>
> TTFN,
> patrick
You appear to have misunderstood the problem. The issue has nothing to do
with route selection, or are you talking about FastPath(TM, Pat Pending)
here?
The issue is that an invalid as-path attribute was injected from
somewhere. The cisco as-path sanity check code failed to pick it up.
Bug ID : CSCdk63586 Project: CSC.sys Status : O 3
encls
Product : all Found : customer-use Care Update: N
Versions : 11.1CC
Headline : BGP: Tighten as-path sanity check
-- Release-note --
When the total bytes (2*seglen) of an as-path segment is equal
to the as-path attribute length, the as-path sanity check would
fail and such a bad attribute would be accepted.
The workaround is to identify and get rid of the announcement
of prefixes with the bad attributes.
/vijay
