Let's ask a different question. Would the following be acceptable: ----- The address space FEC0::/10 is reserved for non-global use. It is intended not to be globally routeable. All routers MUST by default blackhole any packet destined to FEC0::/10, and MAY return a 'destination unreachable' message.
'Sites' using FEC0::/10 addresses MUST implement a filter at the 'site border' that discards source or destination addresses in the FEC0::/10 space. Routing protocols MUST NOT exchange reachability information concerning FEC0::/10 across the border. Any router or node not explicitly configured to do otherwise MAY discard (silently or otherwise) any packet with a source or destination address in FEC0::/10 space. Applications MAY choose to treat FEC0::/10 addresses differently to other addresses, and MAY prefer or disprefer them. Applications MAY assume that FEC0::/10 addresses will be filtered before reaching the global internet. ----- This seems to cover the minimum requirements of the relevant parties. The only global requirement is that all routers by default black-hole FEC0::/10. If you choose to use site local addresses, then you come under the border router requirements given in the second paragraph. The only bugbear I can see is source address selection. One easy solution is to 'prefer closest match' to whatever destination address the application selected, which will mean SL matches SL and link-local matches link local. Ensuring non-SL matches non-SL may be slightly trickier, depending on prefixes, though the current policy of allocating from 0000::/12 will prefer global-global. And maybe something should be added to say "If you stick these things in a globally accessible DNS, don't be surprised when connections to your hosts fail." And maybe a policy to NXDOMAIN reverse lookups for [C-F].E.F.in6.arpa. In short, there is almost no extra effort for those who don't implement SL addresses - all the work is pushed to those who do. Notice that the above text says nothing about how FEC0::/10 addresses are to be allocated. All it does is reserve the space as 'not globally routeable' and put policies in place to stop this information getting where it shouldn't. -- Andrew White [EMAIL PROTECTED] -------------------------------------------------------------------- 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] --------------------------------------------------------------------
