in-line reply On Mon, Aug 30, 1999 at 07:53:36PM +0200, Alex Bligh said:

Bryan,

...

I keep hearing bitching about how broken the BGP path selection process as 1) defined in the protocol spec and 2) as implemented by vendors, is.

Well this is a yet-another-knob-request. I have for a while now thought it would be useful to have an attribute which is kept local to the AS, and is if you like an "exit-penalty". This could be added to your IGP distance at the decision stage process. It's difficult to combine internal IGP metrics (especially if you use next-hop-self style peerings internally so lose the distance on the interface itself) *and* add make intelligent use of different quality interconnects (especially if these are interfaces on the same router).

Consider the case where you are prepared to send traffic from SOME parts of the country "around the long way" to avoid a particularly crappy interconnect, point, but not from ALL parts of the country.

On your point (2) I reckon Cisco implements the standard pretty well (i.e. where it diverges it's for reasonable reasons), or at

Um, Cisco uses as length and igp metrics in the route selection process. This is hardly in compliance with the RFC.

least it does when you've switched on "bgp deterministic-med" which gives you a good indication of how MED decisions are taken without this knob switched on.

-- Alex Bligh GX Networks (formerly Xara Networks)

-- =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Russell Briggs TEL: 512-322-9200 Senior Network Engineer CEL: 512-633-5983 Onramp Access, Inc. FAX: 512-476-2878 russb@quadrunner.com http://www.onr.com/ ----- End forwarded message ----- -- =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Russell Briggs TEL: 512-322-9200 Senior Network Engineer CEL: 512-633-5983 Onramp Access, Inc. FAX: 512-476-2878 russb@quadrunner.com http://www.onr.com/