Scope of Communities [was: Re: Last call for bgp-redistribution]

[Jeffrey Haas]

On Thu, Jul 25, 2002 at 09:50:38AM -0500, Tom Barron wrote:
>   It seems clear to me that many communities should not be propagated
> to the general Internet.

Andrew Partan posted a nice set of rules-of-thumb to this list a while
ago on this very topic

> likewise, if I
> for some reason do not strip them, a neighboring AS would be advised to
> strip them on ingress.

That would depend.  You could leave specific communities with your AS
number on a route to indicate to the Internet that "I did *this*
to the route."

One imagined use for this is "I think this connection is congested,
I'm going to use it, but *you* might not want to".

>   But certain communities not of my own definition SHOULD be kept
> intact and be allowed to transit my AS when I readvertise routes.
> Talking to Geoff in Yokohama, I think NOPEER is an an example of
> one of these.  If I receive a route marked with NOPEER and I choose
> to readvertise it (e.g. I got it from someone who pays me for transit
> and I'm readvertising to someone I pay for transit), then I SHOULD
> leave the NOPEER community intact when I readvertise.

IMO, the well-known communities (NO_EXPORT, etc.), should be left
unmolested.  

> - Tom

-- 
Jeff Haas 
NextHop Technologies