Curtis Villamizar (curtis@ans.net) on November 27:
[lots deleted] Another way of estimating what can be aggregated is by determining from how many places all of the components of an aggregate could be heard in all backup situations. In some cases it might be reasonable to drop some degree of alternate connectivity (fourth or fifth preferred paths) and allow a number of holes (specifically aggregated components). In principle this could be done algorithmically using the IRR. In practice, you need to check with some of the parties involved to make sure registered information (particialrly aut-num AS peerings) are accurate beforehand.
Using the IRR you (or we) can select candidates for aggregation and then make sure the aggregation can really be asfely done. This is a little different in than you estimate in that it the viewpoint is what can we aggregate, rather than what might we see better aggregated in the future. The bgp paths at major interconnects could form a useful sanity check, making sure that AS paths do not conflict with IRR AS peering information for any candidate for aggregation. [lots deleted]
Actually we are working on such a tool, that we call CIDR assistant. A pre-alpha release of this tool will be available before/during the IETF, and there will be a discussion of this tool in the RPS wg. This tool considers the topology and the policies registered in the IRR before suggesting potential aggregations. The amount of policy/topology that is considered is configurable. Cengiz -- Cengiz Alaettinoglu Information Sciences Institute (310) 822-1511 University of Southern California http://www.isi.edu/div7/people/cengiz