From: Scott Morris (swm@emanon.com)
Date: Tue Mar 02 2004 - 16:59:43 GMT-3
Well, the old version was 4 bytes long as we see below from 8 hex characters
(32 bits in total). The new format BGP communities are 48 bits long but
come in different flavors.
The typcal/common AA:NN format is a 16-bit lead (usually AS#) followed by a
32-bit value as before. Another version is IP:NN where there's a 32-bit
lead based on an originating IP locale followed by a 16-bit miscellaneous
value. Depends on what you're running. Bits are bits. But you have extra
ones in the new format.
So as far as what these would look like. They're kinda sorta mostly look
the same, just a little different. :) You'd add more bits to them. RFC
2547 assisted us with all this excitement.
Scott
-----Original Message-----
From: Michael Snyder [mailto:msnyder@revolutioncomputer.com]
Sent: Tuesday, March 02, 2004 2:43 PM
To: ccielab@groupstudy.com
Cc: 'Scott Morris'
Subject: RE: BGP Community-lists
NoExport 4294967041
NoAdvertise 4294967042
NoExportSub 4294967043
If you don't speak hex.
What would they be in the new community format? I speak decimal and hex.
-----Original Message-----
From: Scott Morris [mailto:swm@emanon.com]
Sent: Tuesday, March 02, 2004 1:36 PM
To: 'Packet Man'; ccielab@groupstudy.com
Subject: RE: BGP Community-lists
All communities are known by a numerical value. This includes some of the
"well-known" communities.
Here's an excerpt from RFC 1997:
The following communities have global significance and their
operations shall be implemented in any community-attribute-aware BGP
speaker.
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 includes peers in other members autonomous
systems inside a BGP confederation).
Enjoy,
Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713, CISSP,
JNCIS, et al.
IPExpert CCIE Program Manager
IPExpert Sr. Technical Instructor
swm@emanon.com/smorris@ipexpert.net
http://www.ipexpert.net
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Packet Man
Sent: Tuesday, March 02, 2004 2:07 PM
To: ccielab@groupstudy.com
Subject: BGP Community-lists
Hi all,
I wanted to do a match (in a route-map) for routes with a well known
community attribute, say, for example, no-export. When I did a match
community ? I found that community-list numbers were the only option
availble. My question is, if possible, how would I do a match for a well
known community attribute?
Thanks in advance, PM
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