Thus spake <Michael.Dillon@btradianz.com>
E.g prevously announced address-blocks that has disappeared from the global routing-table for more than X months should go back to the RIR-pool (X<=6).
In RFC 2050 section 3 a) the organization has no intention of connecting to the Internet-either now or in the future-but it still requires a globally unique IP address. The organization should consider using reserved addresses from RFC1918. If it is determined this is not possible, they can be issued unique (if not Internet routable) IP addresses.
Seems to me that the Internet routing table contents past and present are irrelevant. Note also that the so-called Internet routing table contents vary depending on where you look at it.
Obviously if the RIRs contacted the folks responsible for a given block and were provided justification for its continued allocation, then it should not be reclaimed. On the other hand, folks sitting on several class Bs and not using them could have their blocks reclaimed trivially; ditto for companies that no longer exist. The last is certainly doable without much risk of controversy. However, one of the articles referred to recently in this thread (I forget which) showed that even if we reclaimed all of the address space that is currently unannounced (in use or not), we'd buy ourselves a trivially short extension of the IPv4 address space exhaustion date. Considering the cost of performing the task, doing so seems rather pointless; our time would be better spent getting IPv6 deployed and either reengineering the routing system or switching to geo addresses. S Stephen Sprunk "Stupid people surround themselves with smart CCIE #3723 people. Smart people surround themselves with K5SSS smart people who disagree with them." --Aaron Sorkin