(There are very few valid reasons to multi-home, please consult with RFC x, BCP y, and an experienced network engineer.) Roger that.
Some of the reasons I have seen discussed have included: 1.) Reliability / Availability 2.) Geographically distributed client locations I would like to add: 3.) Performance / Throughput The old "we'll just add another subinterface to the hssi port, they can't tell the difference anyway" school of network design just ain't gonna cut it anymore. The Internet has now become the e-Internet. Upstream providers are not created equal. IAP's and other end-systems will be migrating to, or multi-homing with, those service providers that can handle the additional traffic load generated by xDSL, cable, or other high bandwidth technology. (...And your point is?) I would argue that lower tier multi-homing has contributed to the growth of the CIDR tables. Examining and resolving the issues surrounding the cause, multi-homing, would be more beneficial than promoting an upstream provider policy dealing with the effect, CIDR growth. -brad (Rural CNE) bwalters@inet-direct.com