[8381] in North American Network Operators' Group
Re: BGP4 COMMUNITY attribute
daemon@ATHENA.MIT.EDU (Paul G. Donner)
Thu Mar 27 14:48:56 1997
Date: Thu, 27 Mar 1997 14:20:09 -0800
To: "John W. Stewart III" <jstewart@isi.edu>,
Walter Towbin <Walter.Towbin@TELUS.COM>
From: "Paul G. Donner" <pdonner@cisco.com>
Cc: "'nanog@merit.edu'" <nanog@merit.edu>
Actually, along this vein (granted, this may not be the place but since
the subject came up)..
What is the general concensus about passing communities in the "community"?
See in-line below...
At 01:32 PM 3/27/97 EST, John W. Stewart III wrote:
>
>many of your questions are for MCI and not nanog
>
> > In the preparation for upcoming 2nd (multihomed) connection to Internet
> > I am looking into
> > COMMUNITY attribute of BGP4 as a way (in conjunction with my own
> > LOCAL_PREF) of load balancing
> > traffic between my two internet links (both T3). After reading CISCO
> > documentation I am still not
> > clear on some issues:
> >
> > 1. Is COMMUNITY a transitive attribute only between me and my immediate
> > upstream supplier or
> > is it being propagated further into Internet (so I can influence how
> > somebody ,say, 5 AS hops
> > away from me sees my routes) ?
>
>the attribute is defined as transitive (i.e., once associated
>with a route it *stays* associated with the route). however, in
Unless an intermediate provider deliberately changes the value, as
opposed to appending to it.
>practice, many providers are configured to not send communities
>to other providers
Is this a conscious decision or just that they have not turned on
"send-community"?
Donner
>
> > 2. If COMMUNITY propagates into big I, and I set COMMUNITY to 3561:70
> > (for MCI to set
> > LOCAL_PREF on my routes to 70) and my next hop supplier sets COMMUNITY
> > of my routes to
> > 3561:80, what happens ? what MCI is going to do ?
>
>is one of your immediate upstream provider's MCI? if so, then
>you would tag routes with 3561:70 and MCI would immediately see
>and react to that. however, you imply that your "next hop
>supplier" isn't MCI, which makes it a bit odd for you to be
>sending communities for MCI, but is doable if your "next hop
>supplier" agrees to carry your communities all the way to MCI
>
> > 3. Is COMMUNITY a CISCO only or is it part of RFC ? Has any other router
> > vendor implemented
> > this parameter ?
>
>rfc1997. i think there's a GateD with communities
>
>/jws
>
> > 4. Which major Internet providers have COMMUNITY/LOCAL_PREF implemented
> > (I am aware of MCI and Sprint) ?
> >
> > 5. Your experiences, comments, suggestions .....
> >
> >
> > Thanks in advance, Walter
> >
> >
> >
> > Walter Towbin
> > Telus Advanced Communications
> > phone: 403-543-2032, fax: 403-543-2030, cell: 403-620-0019
> > walter.towbin@telus.com
> >
>
>
