> 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. Keith -------------------------------------------------------------------- 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] --------------------------------------------------------------------
