AS prepending
David Gethings
davidg at pipex.net
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
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