On Mon, Aug 01, 2011 at 02:16:30PM -0500, Kevin Stange wrote: > Karabir suggested we start getting together a list of steps that need > completion to deliver an IPv6-preferenced or IPv6-only list of mirrors > for IPv6-only clients using CentOS. FWIW, Fedora hasn't had a significant need to IPv6-preferenced of IPv6-only mirrors. We do manage preference by ASN, netblocks (IPv4 and IPv6), internet2 (and related networks) and country. Fedora does have nameservers advertised on AAAA records, as well as A records. The inbound web proxies are reachable via both AAAA and A records, so MirrorManager does see a client's IPv6 or IPv4 address. MirrorManager replies to client requests with DNS names. Mirrors may themselves advertise a given name with an AAAA or A record. > Here's what I've got so far. Feel > free to add to it: > > Steps are in order of priority: > > - Establish at least two authoritative name servers for centos.org with > v6 IPs. > - Determine if centos.org registrar supports v6 glue, transfer to a > registrar that supports it if needed, then add the glue. > - Augment the current mirror database with a field for IPv6 support and > IPv4 support, filling in IPv4 as enabled for all existing mirrors. > - Build a list of centos mirrors which have AAAA records and/or consult > with mirror admins to identify the mirrors which are prepared to provide > preferred IPv6 connectivity to IPv6 clients. > - Prepare a separate monitoring system for IPv6 content to confirm that > mirrors are serving the content correctly over both v4 and v6. Right now Fedora's MM crawler runs on machines that can only speak IPv4. I trust mirror admins that if they're advertising both AAAA and A records, that both methods are equivalent and if one works, the other works. I haven't had a significant problem with this in practice. > - Modify the mirror list on mirrorlist.centos.org to provide IPv6 > mirrors with a higher priority than IPv4 mirrors when the client > accesses it via its AAAA address rather than A. > - Add AAAA for mirrorlist.centos.org > > Thoughts? Are there a bunch of mirrors for whom IPv6 bandwidth is "free", compared to IPv4? That's the only reason I can see going to this effort. I understand that bandwidth via Internet2 would be cheaper than commercial links, which is why MM sends I2-capable clients to I2-capable servers first. Otherwise, seems like a lot of work for not necessarily any gain. Thanks, Matt -- Matt Domsch Technology Strategist Dell | Office of the CTO