North American Network Operators Group

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Re: That pesky AS path corruption bug...

  • From: Vijay Gill
  • Date: Tue May 23 13:31:00 2000

On Tue, 23 May 2000, Blaine Christian wrote:

> After observing a recent issue regarding a router that sent corrupted AS
> path (all names are witheld to protect the guilty).  I took a look at the
> path information that was being received and have a possible solution.
> Since the corrupted AS-path does not include the AS that the route is
> coming from (at least in the corruption that I saw) it seems to me that a
> simple solution for all is to filter on AS i.e. only allow routes that
> have the AS of your EBGP neighbor prepended to them.  I realize this does
> not cover all cases of wacky AS corruption problems but it may fix some of

This is a hack.  We do not need more cruft added on, rather, what we need
is correct behavior.  The correct behavior being - if you see a corrupt/ a
malformed update from a peer, send a notify and drop the session.  Seems
fairly simple to me. 

The above suggestion of your fails in case of route servers.

Insist on correct behavior, not on cruftery.