nanog mailing list archives
Re: BGP Confederation config problem...
From: Blake Willis <blakew () cais net>
Date: Fri, 6 Mar 1998 18:44:49 -0500 (EST)
Andy, I would say that you should switch to two confeds, one on either side of the ocean. That should take care of the problem. BTW, did Minyah ever get her NAT problem straightened out? -Blake --------------------------------------------------------------------------- Blake Willis 703-448-4470x483 Network Engineer, New Customers blakew () cais net CAIS Internet, a CGX Communications Company --------------------------------------------------------------------------- On Fri, 6 Mar 1998, Andy McConnell wrote:
At each member AS, either IGRP or OSPF. They do not interact. By design... two of the AS's are across the Pacific from the other two :-) -Andy -- Andy McConnell $B%"%s%G%#(B $B%^%C%3%M%k(B Network Architect, NTT Multimedia Communications Laboratories Slogan of 105.9, the classic rock radio station in Chicago: "Of all the radio stations in Chicago ... we're one of them." On Fri, 6 Mar 1998, Blake Willis wrote: blakew> Andy, blakew> blakew> What IGP are you running on this network? blakew> blakew> -Blake Willis blakew> CAIS Engineering blakew> blakew> --------------------------------------------------------------------------- blakew> Blake Willis 703-448-4470x483 blakew> Network Engineer, New Customers blakew () cais net blakew> CAIS Internet, a CGX Communications Company blakew> --------------------------------------------------------------------------- blakew> blakew> On Fri, 6 Mar 1998, Andy McConnell wrote: blakew> blakew> > I have a problem I cannot solve. If anyone is running confederations like blakew> > mine, I would appreciate some help :-) blakew> > blakew> > We have a 4-memberAS confederation, each with two IBGP peers. The blakew> > arrangement looks sort of like an octagon. the "r" is AS3 is an internal blakew> > hop, not a BGP peer. blakew> > blakew> > _______ ______ blakew> > | R-----R---r | blakew> > | / | | | | blakew> > |AS2 R | |AS3 R | blakew> > ----|-- ----|- blakew> > | | blakew> > ____|__ ____|_ blakew> > |AS4 R | |AS1 R | blakew> > | \ | | / | blakew> > | R-------R | blakew> > ------- ------ blakew> > blakew> > The problem is this: How do you get BGP to choose the shortest "AS PATH", blakew> > since internal AS paths are ignored in selecting BGP routes? Right now, blakew> > to top router in AS4 will always choose a route through (2 3 1) instead of blakew> > (1), because it prefers "external" routes (even external confederation blakew> > routes) over internal routes. blakew> > blakew> > So, when given a choice, the router on the distant side of the AS will blakew> > ALWAYS prefer the three-AS-hop path, because it is external. Is there a blakew> > way around this?!? blakew> > blakew> > Avi Freedman suggested using a +1 metric when leaving each member-AS. blakew> > (Thanks Avi!) But it doesn't seem to help - perhaps I didn't do it right. blakew> > In fact, it doesn't look like the metrics are adjusted more than 1. for blakew> > example, from AS2, the lower router sees every route outside of AS2 as blakew> > having only metric 1! The top router in AS3 does not add 1 to the metrics blakew> > it readvertises to AS2. blakew> > blakew> > I've been stewing over this problem for some time... I believe there is blakew> > some clue that I've missed. Any help would be greatly appreciated! blakew> > blakew> > -Andy blakew> > blakew> > blakew> > -- blakew> > Andy McConnell $B%"%s%G%#(B $B%^%C%3%M%k(B blakew> > Network Architect, NTT Multimedia Communications Laboratories blakew> > blakew> > Writing about music is like dancing about architecture. blakew> > blakew>
Current thread:
- BGP Confederation config problem... Andy McConnell (Mar 06)
- Re: BGP Confederation config problem... Andy McConnell (Mar 06)
- Re: BGP Confederation config problem... dorian (Mar 07)
- <Possible follow-ups>
- Re: BGP Confederation config problem... Andy McConnell (Mar 06)
- Re: BGP Confederation config problem... Rich Sena (Mar 07)
- Re: BGP Confederation config problem... Andy McConnell (Mar 09)
- Re: BGP Confederation config problem... MAEMURA Akinori (Mar 09)
- Re: BGP Confederation config problem... MAEMURA Akinori (Mar 09)
- Re: BGP Confederation config problem... Alan Barrett (Mar 09)
- Re: BGP Confederation config problem... Rich Sena (Mar 07)
- Re: BGP Confederation config problem... Blake Willis (Mar 09)
- RE: BGP Confederation config problem... Richard Parker (Mar 07)
- RE: BGP Confederation config problem... Andy McConnell (Mar 09)
- RE: BGP Confederation config problem... Dave Van Allen (Mar 07)
- RE: BGP Confederation config problem... Andy McConnell (Mar 09)
- Re: BGP Confederation config problem... Richard Parker (Mar 10)
- Re: BGP Confederation config problem... Andy McConnell (Mar 10)
- Re: BGP Confederation config problem... Richard Parker (Mar 10)
- Re: BGP Confederation config problem... Andy McConnell (Mar 11)