Wanted: one more well-known BGP community

[Vince Fuller <[e-mail]>]

In working with cisco's implementation of BGP communities, I've come across
what I believe is a need for an additional, well-known BGP community. The
application is that of advertising more-specific routes to an external peer
which should only be used for next-hop resolution and should not be propagated
to any other peers, either internal or external. This new community will be
called "no-propagate".

Why can't "no-export" be used for tihs? Because "no-export" indicates that a
particular route should be propagated to all internal peers but not to external
peers. For the purposes of resolving the next hop across a shared "DMZ" lan,
it is neither necessary nor desireable to propagate additional information
beyond the router on the "DMZ".

Why can't "no-advertise" be used for this? Because it doesn't really make
sense to set "no-advertise" in an outgoing update. Cisco's "route-map"
facility, for example, can't do this because when it is used to set
"no-advertise" in the BGP routing table, the route is naturally not advertised
to any neighbors. The "no-advertise" community is something that only really
makes sense when applied to incoming updates (in fact, one uses "no-propagate"
by configuring a router to set "no-advertise" on any routes received with
"no-propagate").

The "no-propagate" community requires no special semantics and no changes to
BGP implementations, it just requires a community number to be assigned so
that the keyword will (hopefully) be added to routers whose parsers recognize
the names of well-known communities.

Comments? Thoughts?

	--Vince