Thus spake "Daniel Senie" <dts@senie.com> > At 01:00 PM 4/20/2003, Richard Carlson wrote: > >The question is - how do we provide some feedback to apps that > >they are trying to cross a scope boundary that it's a permanent error > >condition (5xx in SMTP verbiage)? One proposed notification > >method is the site-local prefix. Other methods can be created, but > >something needs to be done and simply killing site-locals and > >ignoring the underlying scoping issue is a non-starter. > > You mean aside from applications understaning that an ICMP > Destination Unreachable / Administratively Prohibited response from > the site firewall? Many firewalls simply drop packets which are prohibited without sending ICMP responses, not to mention all the places that filter all ICMP indiscriminately. > For that matter, IPv6 machines arguably could try their Site Local > address and be given that same feedback from the border router or > firewall, and use the response as an indication to go use their assigned > global address. The vast majority of applications do not pick their source address, nor is there a compelling reason for them to do so. A large number of applications don't even handle multiple destination addresses properly, so expecting this additional intelligence for the source address is irrational. S Stephen Sprunk "God does not play dice." --Albert Einstein CCIE #3723 "God is an inveterate gambler, and He throws the K5SSS dice at every possible opportunity." --Stephen Hawking