If you convince the registries to allocate no longer prefix than an /18 or a mix of lengths up to say /19 or /20 (such that no more than 1000ish are allocated) to ISP's or multihomed companies, and then require that the announcement must match the allocated block, you can guarantee that the routing table will not exceed the 1024 per /8.

Then, some of you will ask how to enforce this. Once every so often, you dump the BGP routing tables from strategic routers. If you see any non-matching prefixes, you send an email to the network coordinator for the allocated block giving them a set amount of time to clean it up. Any routes which are not cleaned up by the deadline are added to a filter list which could be carried on routers.

This method would have (at least) the following advantages (or disadvantages, from your particular viewpoint):

1) You could reasonably assure that the number of prefixes in an /8 would match what was allocated.

2) Because of 1, if you get the registries to set their allocation policies such that no more than 1024 (or the target number) blocks are allocated per /8, you can guarantee that the number of routes in an /8 is not too far out of wack with the target.

3) You can give those people moving providers a grace period to renumber, say 30 days. Essentially, the time given to clean up the routing tables. This would be a side effect of the "you have 30 days to fix the routing tables or else".

4) You eliminate the wasted space of addresses with prefixes longer than /18 being allocated.

An excellent, well thought out proposal. I like it. Eric -- Eric Kozowski Structured Network Systems, Inc. kozowski@structured.net Better, Cheaper, Faster -- pick any two. (503)656-3530 Voice "Providing High Quality, Reliable Internet Service" (800)881-0962 Voice 56k to DS1