John C Klensin wrote: > Similarly, various applications folks within the IETF have > pointed out repeatedly that any approach that assigns multiple > addresses, associated with different networks and different > policies and properties, either requires the applications to > understand those policies, properties, and associated routing > (and blows up all of the historical application-layer APIs in > the process) or requires request/response negotiation that TCP > doesn't allow for (and blows up most of the historical > application-layer APIs). One of the original promises about That is a very old problem of IPv4, except that DNS takes care of multiple addresses of name servers at IP level and SMTP (and some TELNET implementation, though it is not very useful) supports multiple addresses of mail servers at TCP level. Thus, API of IPv4 must change. > IPv6 was no need for changes to TCP and consequent transparency > to most applications. Ha! There is no need for IPv6 specific changes. Masataka Ohta