On the mirrors site there is a link to ftp6.uni-erlangen.de which does not resolve and has not resolved on any of the machines i have tried.
AFAIK this IPv6-ftp is only accesable from German IPv6-addresses (with IPv6 it's easier to distuingish from which country the caller is coming (or better, where he ordered his IPv6 address) and so there are services only for a specific country). That doesn't make no sense for a world-wide mirror.
that mirror is clearly labled as "IPv6 only" on the mirrors page. closing.