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 I believe BGP only specifies the prefix being withdrawn and not the path, so if it's advertised multiple paths to a prefix it's impossible to know which has been withdrawn. Sam Per Gregers Bilse <bilse@networksignature.com> 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