BGP and AS loop prevention

I have a scenario labbed up where I have an discontiguous BGP AS split by
another AS, something like this: (AS100) <> (AS 200) <> (AS 100).

I am trying to get the prefixes on the AS 100 routers to show up in each
others BGP tables. I have implemented the neighbor x.x.x.x allowas-in
command on the AS 100 routers on their neighbor statements facing the AS 200
routers but it does not seem to work. When I do a SHOW IP BGP NEIGH x.x.x.x
ADVERTISED-ROUTES on the AS 200 routers, I see that the AS 200 router will
not send the route that originated in the far side AS 100.

Is there some sort of configuration needed on the AS 200 routers to allow
them to send a route with an AS PATH that contains the AS they are sending
into? I was under the impression that they do not perform an outgoing AS
PATH check.

Thanks!

Nate

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Received on Mon Oct 19 2009 - 22:12:32 ART