a crude method of limiting long-prefix propagation

john heasley heas
Fri Mar 23 19:54:41 UTC 2001

Fri, Mar 23, 2001 at 03:05:56AM -0500, Joe Abley:
> Ah, I sent that out slightly prematurely:
> On Fri, Mar 23, 2001 at 02:30:17AM -0500, Joe Abley wrote:
> > 3.2 Towards the Other Edge
> > 
> >    ASes which support this convention must include additional clauses in
> >    their advertisement policy to all neighbour ASes, as follows:
> > 
> >    o  When announcing prefixes to AS A: if the community attributes
> >       EPPC_ALLOW:0 and EPPC_ALLOW:A are both present, then delete the
> >       EPPC_ALLOW:A community, and then advertise the prefix.
> In fact, I don't think there is any need to delete the :A community

then there really isnt a need for the :0 communities by matching EPPC_ALLOW:*.

> attribute. That was something we were using for an earlier idea, where
> we were considering using an empty set of EPPC_ALOW:X attributes to
> signal the end of the propagation scope.
> We didn't wind up doing that, and it makes sense to keep all the
> attributes intact so that they can be observed for troubleshooting
> purposes.
> Joe

important to note that this either makes your generic out-bound peering
policy rather long (N(peers) + ?? paragraphs) or means you can not use
peer-groups with today's limitations, which do not seem likely to change.

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