On Tue, 2002-11-26 at 13:17, Christian Huitema wrote: > > > 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.
Is there really such thing as a "remote _site_" in the GUPI model ? Under the GUPI model, I would think you reach a "remote site" or remote destination (ie not internally connected) via global addressing. As I understand it, the GUPI model pretty much gets rid of the site model completely - it really is just catagorising connectivity and destinations as internal verses external - internal connectivity using GUPI addressing, via internally administered network infrastructure (including a VPN), verses external connectivity via the public Internet, using global addressing. Mark. ps. the word "site" we are using in these threads is becoming very overloaded with slightly different meanings, and it's becoming very confusing to know what people are referring to when they use the word "site", even when used multiple times within the same email. Maybe we should start using terms such as internal destinations (via GUPI addresses) or external destinations (via global addresses). It's tempting to use remote verses local destinations, but that also has some geographical connotations. -------------------------------------------------------------------- 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] --------------------------------------------------------------------
