I just spoke with a couple of the people involved in the SBC transition and they are thinking about putting a presentation for a NANOG after they transition the former Ameritech ASes.
This is a truly massive undertaking merging around 100 ASes from coast to coast and re-aggregating all of the routing and, from my viewpoint, have done an amazing job. I hope they do the presentation. R. Kevin Oberman, Network Engineer Energy Sciences Network (ESnet) Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab) E-mail: [EMAIL PROTECTED] Phone: +1 510 486-8634 > Date: Fri, 30 May 2003 09:03:54 -0500 (CDT) > From: Daniel Golding <[EMAIL PROTECTED]> > Sender: [EMAIL PROTECTED] > > > SBC just did one of the largest AS merges ever accomplished. Maybe one of > their engineers will give a brief report? One item to always look out for, > if you have BGP-speaking customers is the particular implementation of > "local-as" on your favorite brand of router. There are some variations... > > - Some include the "imposter AS" in the AS path > - Some have a keyword for stripping out the "imposter AS" > > The vendor documentation on this feature has been historically weak, > necessitating some lab work. > > This can be an issue, as you could be accidentally prepending route > announcements learned from your downstreams by having both the new and old > AS in the path. > > Thanks, > Daniel Golding > > On Fri, 30 May 2003, David Luyer wrote: > > > > > > > > Does anyone know of case studies of companies collapsing > > > multiple ASes > > > into one on their network? I have the Allegiance Telecom > > > presentation from > > > NANOG 27 but I would like to hear how other people have done > > > it as well. > > > > We have to date collapsed 6 AS numbers into 1. > > > > Approach was relatively simple - but it's been at > > least a couple of years since the last merge so I'm > > a little light on exact memory/detail: > > > > 1. Duplicate RADB (or other) entries across to new > > AS. > > > > 2. Merge interior routing protocols across the ASen > > which are about to be merged. > > > > 3. Gradually grow the largest AS adding a router at > > a time (notify the BGP peers on the router, set a > > time, make the change). > > > > To me this is one of the things where you can go over the > > top in planning (I know an ISP who have been planning an > > AS merge for years) or you can 'just do it'. > > > > The second hardest thing, if you bother to do it, is > > "cleaning" the old AS (in terms of RADB, other registries, > > route filters in peers, etc) before returning it to the > > registry. > > > > The hardest thing is convincing the registry to take them > > back... (you'd think that'd be easy, but it took by far > > the longest of the whole job). > > > > David. > > > > >