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Re: Global BGP community values?

  • From: Vadim Antonov
  • Date: Tue Oct 05 02:41:44 1999

I proposed real metrics for BGP long time ago.  Back then
the idea didn't find any support -- apparently few people
felt it was needed.

The mechanism described in the draft is stragightforward and significantly
more powerful than the community attribute usage proposed by Hank - and
also can do everything MED and LOCAL_PREF can do, so these can
be retired.

Here's the URL:  http://www.civd.com/~avg

--vadim

--------------------------------------------------
Hank Nussbacher <hank@ibm.net.il> wrote:

I think everyone at one point or another has tried to influence incoming
data flows via BGP. About the only tool available to influence the BGP
decisions in far away places is via AS-PATH length.  This turns out to be
a fairly never-ending iterative process - that at best achieves 80% of its
intention. It also doesn't allow for accurate decision making.  As an
alternative, neighboring ISPs and their customers usually design some BGP
community system which is then used to influence the BGP decision process.

Why can't this be extended globally [if this has already been done and
written up in some BCP RFC - just point it out to me]?  What if we all
agreed that if some community value of say 1000000-2000000 [example] is
seen, then those community values are to take precedence above all other
metrics.  1000001 could mean - "this is the best path for me - always send
pkts this way no matter what the other metrics might say".  We could build
up a table of these global community strings.  ISPs that don't use it - no
harm done.  But the more ISPs (tier 1 & 2) that do use it - the better the
end customer and ISPs have on influencing data flow.

Comments welcome.

Hank Nussbacher





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