AS prepending

Fri Apr 8 15:25:50 UTC 2005

On Friday 08 April 2005 16:04, Philip Lavine wrote:
> 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.
To answer your  originial question: it is not "normal" to filter routers with 
the same AS prepended 3 times. However if the ISP chose such a policy they 
could do that.

On this subject:

When they say "do not add it to their routing table" do you know if they mean 
the BGP table or the IP table?

i.e. if the ISP in question does a "sh ip bgp route <your prefix>" does it 
show in the list. Yet when they do a "sh ip route <your prefix>" it does not. 
If so then your ISP will be preferring a different route.

Are you certain that the prefix filters this ISP is using - well sounds like 
they are using - are the same as the prefixes you are announcing? It could be 
that the prefix list is misconfigured.

-- 
Cheers

Dg