> Can you show me real examples of an RIR repossessing address > space? If > so, what is stopping them from reclaiming some of those /8s? ARIN regularly repossesses address space according to their treasurer. http://lists.arin.net/pipermail/ppml/2007-March/006129.html This fact is well known to those who regularly attend ARIN meetings and hear the reports on ARIN activities. MIT does keep its ARIN whois records updated, for instance Jeffrey Schiller who is the technical contact for 18/8 as well as MIT, last updated his contact info in 2001. http://ws.arin.net/whois/?queryinput=!%20JIS-ARIN The organization record was last updated in 2003. http://ws.arin.net/whois/?queryinput=O%20!%20MIT-2 Apparently MIT is not hiding from ARIN. In any case, MIT does have a legitimate claim to 18/8 due to the fact that its Laboratory for Computer Science was one of the research organizations on the ARPANET that participated in the development of the new internetwork protocol. At that time, the LCS network was assigned network number 18. Over time, this internetwork protocol became IPv4 and the network numbers turned into /8 CIDR blocks. RFC 739 may be of interest if you don't believe me. In any case, none of the RIRs reclaim addresses from organizations who appear to be operating IP networks which appear to have a technical justification for their address allocation. Since IPv4 addresses are not yet in short supply, there is not yet any formal move to audit existing blocks, whether from RFC 739 or from more recent RIR allocations. There is a proposal making the rounds, but it's poorly written and highly unlikely to get any traction. So to answer your question about what is stopping the RIRs from reclaiming the very earliest /8 allocations, it isn't yet worth the bother. Some of them have been returned voluntarily as you can see if you compare http://www.iana.org/assignments/ipv4-address-space with RFC 739. --Michael Dillon _______________________________________________ Ietf@xxxxxxxx https://www1.ietf.org/mailman/listinfo/ietf