weird BGP cisco-ism? [problem resolved]
Barry A. Dykes
bdykes at genuity.net
Sat Jul 12 00:40:35 UTC 1997
Why don't you just tag your exportable routes and let them through,
while blocking everything else? You could then build a route-map that
places that tag on all of your inbound BGP customers. This would allow
you to export everything that they send you (allowing them to send the
more specific as Dorian stated) and use a static tag for your aggregate
routes. Then all the more specific routes on your backbone would be
filtered, unless it originated from a BGP customer - who would need to
send the more specific advertisements to each of it's providers and
allow routing to work correctly. I know, that's what we do! If you
don't have the right tag, you don't get off! And I don't have to mess
with any filters after they are set up.
Barry
> >
> >You can remove the specifics at the edges of your network either via community
> >based filtering or prefix based filtering. The former is much more flexible
> >and is the one I'd recommend.
> >
> >-dorian
> >
>
> I'd think prefix based filters would be more likely to be correct.
> Since you have to explicitly list what you think you should be announcing
> you protect against having routes you don't expect in your tables and
> against having interactions that cause unexpected routes to get tagged as
> announceable.
>
> --
>
> -Chris (cgarner at sni.net)
>
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