The Gorgon's Knot. Was: Re: Verio Peering Question

> 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 as-set suppress-map fix-badguy
> aggregate-address bad.guy.blo.ck2 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.