One of the projects I'm considering for the future is migrating our existing networks into a more unified network architecture and collapsing them into one large AS. Right now the networks I'm responsible for are networks we've picked up through acquisitions and assumed the responsibility for network management/operations. Each of the networks were running their own separate architectures (BGP, OSPF, etc) at the time we acquired them. Of those, all but a handful are still running as separate ASes with their own transit connections to ${UPSTREAMS} and private circuits back to our network. There are two key questions to answer to determine if the project is feasible and I can sell my management on it: 1) Does it make technical sense to collapse these networks into one AS? 2) Does it make financial sense to do this? The answer to 1) is yes and that the best way to migrate seems to be to migrate from the existing multi-AS architecture to one AS using confederations. This opens up a whole slew of other questions and points to consider. Some of these have been covered recently on NANOG, or in other discussion groups. * What is the most effective way to manage/control IGP expansion, especially if each regional network is already running their own OSPF implementation and meshed IBGP where needed? * Once done, I could probably disconnect some of the upstreams that I don't really need. Will the standard local-pref communities provided by the existing upstreams be sufficient to keep the network sane without requiring a great deal of manual intervention? Put another way, if I have an OC3c to upstream A in one location and a fractional DS3 to upstream A in another location, what is the best practice to keep that fractional DS3 from getting destroyed if the OC3c goes down? * The process of converting to confederations is not trivial. * Customer and upstream-facing BGP configurations for the networks that would be changing their local AS would need to be considered. * Any other significant gotchas I haven't considered? Once I answer all of the technical questions, I can begin answering the financial/administrative piece in question 2). If anyone has been through a project something like this, I'd definitely be interested to hear your thoughts and experiences. If I can make it to NANOG 24, I'll cover your beer and sushi for the night ;-) jms