if, by active, you mean being used on the global internet today, a dump of a friendly router's bgp data and trivial script should answer that, n'est ce pas?

The CIDR report already does this. The only portion I believe it lacks in this area is number of "allocated" ASs... -danny [snip] To: nanog@merit.edu Cc: tbates@cisco.com, eof-list@ripe.net, apops@apnic.net, routing-wg@ripe.net Subject: The Cidr Report Date: Fri, 02 Oct 1998 12:00:01 -0700 From: Tony Bates <tbates@cisco.com> [...] AS Summary ---------- Number of ASes in routing system: 4081 Number of ASes announcing only one prefix: 1973 (1035 cidr, 938 classful) Largest number of cidr routes: 342 announced by AS3561 Largest number of classful routes: 953 announced by AS701