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

[Tom Barron]

>>>>> On Fri, 26 Jul 2002 10:35:30 -0400, Jeffrey Haas <jhaas at nexthop.com> said:
  Jeff> I'm not Andrew, but this still sounds good.

  >> 
  >> - strip all communities on input except
  >> * communities you tell your customers they may use
  >> * well-known communities 
  >> 
  >> - act on well-known communities and communities you tell your
  >> customers they may use
  >> 
  >> - strip all communities on output except
  >> * well-known communities
  >> * communities you have deliberately added to signal
  >> to the next AS

But note that this variant strips communities not of my own
definition if they aren't WellKnown.  I like this policy, but it would
damage your multi-AS-hop signalling cases, as an AS in the path of such
signalling would strip off the communities in question.

I'm inclined to say that where there is a genuine need to use communities
to signal further than an immediate AS-AS boundary, one ought to follow
Geoff and seek to get that community recognized as a WKC.  Then the above
policy would do no damage.

I'd be inclined to back off, however, if it turns out that - contrary to my
experience - there is indeed already significant use of ad-hoc, locally
significant communities to signal information further than the immediate
AS-AS boundary.  Before asking, say, NANOG, I want to make sure that we
frame the issue well ....

Thanks,

- Tom