Michael Dillon wrote: | In fact I can't | remember ever ... | hearing of a case in which an ISP lost a significant amount of business | because of renumbering. Renumbering is a fact of life on the Internet. People should be prepared to renumber, and technologies that facilitate easy renumbering should continue to be developed. That said, even if it were possible to renumber gracefully at any time, reducing the frequency and scope of renumbering is not in itself a bad idea. Therefore, I have no problem at all supporting an allocation policy designed to allow growing networks to undergo fewer renumberings, and to allow networks with many levels of administrative authority (as in the case of an ISP with downstream customers, some of which may also have downstream customers) to undergo nearly none. What appears to be the correct approach now has been outlined by Karl and implemented by RIPE. The test for who should get a minimum portable allocation unit (/19 these days) should be the only thing argued about. It should be easy for any ISP to obtain an initial allocation, and somewhat less easy for entities which do not re-allocate address space to others. Sean.