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Re: Open Source BGP Route Optimization?
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Per Gregers Bilse wrote: | On May 28, 10:37am, "Sam Stickland" <email@example.com> 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: | And as I said in my other post, there were two drafts submitted that never went anywhere. | |>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withdrawn and not the path, so if it's advertised multiple paths to a prefix |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it's impossible to know which has been withdrawn. | | But the "optimizing" device is in need of receiving all potential paths from the border routers. Essentially, it needs a complete picture of all viable paths, not just the best that each border has. It would not be advertising multiple paths. | That is 100% correct, yes. Selective withdrawal is not supported. | But the "optimizing" device wouldn't be advertising multiple paths. It would be advertising its selected path from all viable paths based on the selection criteria/policy implemented by the user. The optimizing device can then keep track of what it has advertised and withdraw as appropriate/necessary. | 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. | The point is not to tell other borders about paths it will not use, but for the "optimizing" device to select the desired path from all available paths and cause that path to become "best path" for all border routers. And "best" in this case is a user influenced choice based on any number of factors including path performance, cost, load, or other policies that the device can use as a selection criteria. | 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. | Does a great job at what it was designed for as appropriate for the time it was conceived. As always, times change. - -- ========= bep -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.2 (MingW32) iD8DBQFAt5SKE1XcgMgrtyYRAt+MAKDNboo++qImRl1eAofO/ICi5BsKEgCfVdzW jrVxUmirv7Hc2ZhlJCuV+bw= =TUny -----END PGP SIGNATURE-----