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Re: The Gorgon's Knot. Was: Re: Verio Peering Question
- From: Sean M. Doran
- Date: Fri Sep 28 22:36:47 2001
| > ip as-path access-list 1 permit _badguy_
| >
| > route-map fix-badguy permit 10
| > descr proxy-aggregate the networks who are "holey"
| > match as-path 1
| >
| > router bgp my-as
| > aggregate-address bad.guy.blo.ck1 255.255.224.0 as-set suppress-map fix-badguy
| > aggregate-address bad.guy.blo.ck2 255.255.224.0 as-set suppress-map fix-badguy
| > ...
|
| And one aggregates a lone /24 with what?
Oh yay, a bona fide techical question.
The answer:
ACL 1 need not match only one AS
as-set is there to deal with matches on multiple AS paths
since we want to avoid looping announcements. conveniently,
not only does it handle the case where ACL 1 matches
lots of AS paths containing _X_, it can equally handle the
case where ACL 1 matches lots of AS paths containing _Y_.
Next time I use the example I will remember to make ACL 1 longer,
and change "bad.guy.blo.ck1" (etc) into something along the lines
of "poo.rag.gre.g81", but perhaps more aesthetically pleasing.
Sean.
|
