On Wed, 21 Dec 2005, Kevin Day wrote:
9) Once we started publishing AAAA records for a few sites, we started getting complaints from some users that they couldn't reach the sites. Some investigating showed that they had inadvertently enabled IPv6 on their desktop without having any IPv6 connectivity.
I would hazard an educated guess that the majority of these users had actually enabled 6to4 via some OS-provided convenience, which *would* work if it weren't for (a) IPv4 NAT already widely used in "home router" appliances, resulting in bad 2002:0a00::/24 or 2002:c0a8::/32 addresses, and (b) many IPv6-capable providers not providing a 2002:: route, or at least not providing a *working* one, to the 6to4 islands. Fixing (b) would much allieviate the following when the 6to4 address in question would otherwise be reachable:
11) Almost without fail, the path an IPv6 user takes to reach us (and vice-versa) is less optimal than the IPv4 route.
(If a user is implementing 6to4, it usually means that the v4 route *is* better, so 6to4 becomes a routing policy suggestion as well.) -- -- Todd Vierling <tv@duh.org> <tv@pobox.com> <todd@vierling.name>