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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: BGP4 COMMUNITY attribute
Walter Towbin wrote:
>
> 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) ?
It is propagated further into the Internet. Note that only BGP routers
which are configured with specific policies will pay any attention to
any communities you set, other than the well-known communities. Unless
an ISP decides to set up its policies to handle communities, you can't
use communities to influence how it sees your routes.
>
> 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 ?
MCI will receive and act on 3561:80
>
> 3. Is COMMUNITY a CISCO only or is it part of RFC ? Has any other router
> vendor implemented
> this parameter ?
Bay Networks also supports Communities, including the well-known
communities:
NO_EXPORT (0xFFFFFF01)
All routes received carrying a communities attribute containing
this value MUST NOT be advertised outside a BGP confederation
boundary (a stand-alone autonomous system that is not part of a
confederation should be considered a confederation itself).
NO_ADVERTISE (0xFFFFFF02)
All routes received carrying a communities attribute containing
this value MUST NOT be advertised to other BGP peers.
NO_EXPORT_SUBCONFED (0xFFFFFF03)
All routes received carrying a communities attribute containing
this value MUST NOT be advertised to external BGP peers (this
>
> 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
> [email protected]
--
Paul Knight mailto:[email protected]
IP Engineering, Systems Test Office: (508) 916-7087
Bay Networks, Inc. M/S BL2-02 Lab: (508) 670-8888, x-65404
2 Federal St., Billerica, MA 01821 Fax: (508) 670-4004
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