nanog mailing list archives

Re: Open Source BGP Route Optimization?


From: Per Gregers Bilse <bilse () networksignature com>
Date: Fri, 28 May 2004 14:37:23 +0100


On May 28, 10:37am, "Sam Stickland" <sam_ml () spacething org> wrote:
Are there any BGP extensions that would cause a BGP speaker to foward all of
it's paths, not just it best? I believe quagga had made some recent attempts

It has been discussed and been on wish lists, but:

in this direction. IIRC the problem isn't to do with the route annoucements,
it's the route withdrawals. I believe BGP only specifies the prefix being
withdrawn and not the path, so if it's advertised multiple paths to a prefix
it's impossible to know which has been withdrawn.

That is 100% correct, yes.  Selective withdrawal is not supported.

Another issue is that there isn't much point, as far as regular BGP
and routing considerations go.  Whichever is the best path for a border
router is the best path; telling other routers about paths it will not
use serves no (or at best very little) point in this context.

Funny coincidence, just earlier today I was talking to somebody about
BGP and its general applicability, and while there can be no question
that BGP has stood the test of time and achieved all its objectives,
there are things one would do differently if one were to start over.
But that's always the case.

Best,

  -- Per


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