AS prepending

Fri Apr 8 15:35:40 UTC 2005

Philip Lavine wrote:

> Update:
> 
> I am prepending my AS 3 times to the un-preferred ISP.
> Both ISP's are my peers. The un-preferred ISP claims
> the see my advertisement yet they do not add it to
> their routing table (suggests filtering??). They claim
> all the filtering they are doing is based on the
> networks I told them over the phone that I was using
> with that AS.

I have heard of providers who filter on AS path, and filter in such a 
way that more than N prepends (for varying values of N) causes the 
route(s) to be rejected.  This could potentially be your problem.  If 
they do soft-reconfig in on their customer sessions, they may see the 
route but filter it out.

pt