Open Source BGP Route Optimization?

Sam Stickland sam_ml at
Fri May 28 09:37:44 UTC 2004

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
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withdrawn and not the path, so if it's advertised multiple paths to a prefix
it's impossible to know which has been withdrawn.


Per Gregers Bilse <bilse at> wrote:
> At first I wasn't sure what a "route optimizer" was supposed to do --
> the term is rather generic and could have a lot of different
> interpretations.
> A multi-path traffic balancing solution in the style of Cisco's OER
> has to be tightly integrated with the routing infrastructure.
> Specifically, it needs first hand BGP peer data in order to work
> reliably.  There will be a number of cases where an add-on solution
> might be able to improve on certain things, but there is one major
> hurdle: a BGP speaker only forwards its own best paths, so an add-on
> analyzer might well never learn about alternative paths.  The only
> way for any implementation to reliably learn (all) alternative paths
> and otherwise maintain routing integrity is by receiving BGP data
> first hand, ie directly peer with transit providers and other peers.
> Best,
>   -- Per

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