> > So I've been watching this debate about globally > > ~unique site locals and I don't understand how the > > end node knows whether a particular destination > > address is in scope (reachable) or not. The old > > way, it just matched it to its own scoped prefix > > and was done with it. What I've been hearing is > > some desire to be able to patch together other > > sites (extranets)... how would a node know which > > scope address to use in that case? > > in general the only way for node A to determine whether node B > is reachable is for A to send a packet to B. if A gets a reply > from B, B is reachable. if A gets an ICMP message back, B > is not reachable (for temporary or permanent reasons). if A > gets nothing back, either B is (temporarily) unreachable or > B doesn't want to answer A. > > but you'll never be able to determine this by looking at prefixes.
Actually, the "Default Address Selection for IPv6" draft includes language of that nature. It would have to be amended to take into account the GUPI proposal. Something about assuming reachability of GUPI if on the same site, but not if on a remote site. And then, we would have to add policy hooks to mention "connected sites." -- Christian Huitema -------------------------------------------------------------------- IETF IPng Working Group Mailing List IPng Home Page: http://playground.sun.com/ipng FTP archive: ftp://playground.sun.com/pub/ipng Direct all administrative requests to [EMAIL PROTECTED] --------------------------------------------------------------------
