nanog mailing list archives
Re: BGP4 COMMUNITY attribute
From: "John W. Stewart III" <jstewart () isi edu>
Date: Thu, 27 Mar 1997 15:43:28 EST
the attribute is defined as transitive (i.e., once associated with a route it *stays* associated with the route). however, inUnless an intermediate provider deliberately changes the value, as opposed to appending to it.these values aren't an end-to-end thing .. it's simply a way for providers to more easily facilitate routing policies. your comment implies somebody being a bad guy...Actually, I hadn't necessarily meant to imply "being a bad guy". The comment was meant to show that the "intermediate" ISP has this kind of control over the attribute. In any case, if the decision about whether or not to pass on an attribute (or to modify it) was part of the intermediate ISP's policy, whether or not he/she is a bad guy would depend on varying points of view.
to date communities haven't been an end-to-end thing. they have mostly had significance only to adjacent ASs. i do know of a small number of exceptions where a subscriber sets the communities, they're carried through a mid-level provider to a top-level provider, at which point the top-leve. provider reacts in some way (e.g., setting local-pref to a certain value) to me the practical bottom line seems to be that communities are being used to ease the configuration work to achieve certain routing policies, and since an AS has complete autonomy over its routing policies, that AS should have the freedom to keep, add to, or stomp on communities that it hears from others. it's possible that in the future we might have an end-to-end application of communities, but i don't know of one yet, so i'm loathe to mandate anything about how far communities are carried and how much they're kept intact /jws - - - - - - - - - - - - - - - - -
Current thread:
- BGP4 COMMUNITY attribute Walter Towbin (Mar 27)
- Re: BGP4 COMMUNITY attribute John W. Stewart III (Mar 27)
- Re: BGP4 COMMUNITY attribute John Scudder (Mar 27)
- Re: BGP4 COMMUNITY attribute Dave Siegel (Mar 28)
- Re: BGP4 COMMUNITY attribute John Scudder (Mar 27)
- Re: BGP4 COMMUNITY attribute Paul Knight (Mar 27)
- Re: BGP4 COMMUNITY attribute Alexandre Leib Grojsgold (Mar 27)
- <Possible follow-ups>
- Re: BGP4 COMMUNITY attribute Paul G. Donner (Mar 27)
- Re: BGP4 COMMUNITY attribute John W. Stewart III (Mar 27)
- Re: BGP4 COMMUNITY attribute Randy Bush (Mar 27)
- Re: BGP4 COMMUNITY attribute John W. Stewart III (Mar 27)
- Re: BGP4 COMMUNITY attribute Paul G. Donner (Mar 27)
- Re: BGP4 COMMUNITY attribute John W. Stewart III (Mar 27)
- Re: BGP4 COMMUNITY attribute George Matey (Mar 30)
- Re: BGP4 COMMUNITY attribute John W. Stewart III (Mar 27)