On Sun, Mar 16, 2003 at 07:38:09PM +0100, Erik Nordmark wrote: > > A possible way to approach this problem would be to make > the choice between A and AAAA be a function of whether there > is one or more IPv6 route off-link (or at least one IPv6 router sending RAs).
Note this cuts both ways. I've been in dual-protocol networks where IPv4 has been down and IPv6 up, so we ought to consider the general case of availability of connectivity off-link for either protocol. (But I do appreciate the issues here is - I think - what to do when deploying an IPv6 enabled host which receives AAAA responses in an IPv4-only network) A not-uncommon enterprise deployment method for dual-protocol now is to have a parallel IPv6 infrastructure with a separate off-site IPv6 link, such that IPv6 is routed within the site using (for example) BSD routers with RA's for subnets injected into the v4 VLANs (if your BSD box can VLAN-tag on a single interface, very few cables may be needed :). Thus the router giving connectivity off each subnet is different (in one case, the "smart" L2/L3 VLAN switching equipment, in the other, PC-based routers) , and either could fail. Such a deployment method is a short-term one until Cisco, Alcatel, etc offer v6 L2/L3 functionality as exists for v4 now. Most dual-protocol networks will probably in the medium-term fate-share IPv4 and IPv6, so the distinction will then be somewhat moot. Tim -------------------------------------------------------------------- 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] --------------------------------------------------------------------
