[CentOS-mirror] IPv6 mirrorlist

Anssi Johansson

centos at miuku.net
Sun Jun 17 16:13:29 UTC 2012

Hi, as Karanbir announced on the centos-announce mailing list about a 
week ago ( 
), mirrorlist.centos.org is now available over IPv6.

The new IPv6-enabled mirrorlist servers will only hand out mirror URLs 
that can be accessed over IPv6. Previously IPv6-only CentOS servers had 
to have their yum configuration changed to point to some IPv6-enabled 
mirror to receive updates, but now those IPv6-only CentOS servers can 
get their updates with the default configuration.

A side effect of this change is that dual-stacked boxes will also 
retrieve the list of mirrors over IPv6, and consequentially, they will 
no longer try to download the updates from IPv4-only mirrors, as the 
mirrorlist served to them does not contain any IPv4-only mirrors.

This means that the IPv6-enabled mirrors will now receive slightly more 
traffic than the IPv4-only mirrors. If you're running an IPv6-enabled 
mirror, now would be a good time to check the stats of your mirror to 
see if there's any increase in traffic. If you notice anything 
particularly interesting in your traffic stats, feel free to share your 

Just like the IPv4 mirrorlist, the IPv6 mirrorlist also uses GeoIP 
information to give a list of nearby mirrors. The coverage will improve 
as we get more IPv6-enabled mirrors. Additional IPv6-enabled CentOS 
mirrors are always welcome. The mirror monitoring scripts will pick up 
any added IPv6 addresses automatically, so you don't need to notify us 
if you add an IPv6 address for your mirror.

I'm running the scripts which check that the IPv6-enabled mirrors are up 
to date. While running the tests I noticed that there are still quite a 
few mirrors that have a published IPv6 address but are nevertheless 
unreachable by IPv6. http://tursas.miuku.net/tmp/centos_ipv6_mirrors.txt 
lists the current status of the mirrors that have an IPv6 address. 
Please check the status of your mirror from that list. Especially if you 
think "our organization can't possibly be affected", please check the 
list. There are some distinguished organizations on the list with a nice 
fat FAIL label next to them.

Please note that due to the way the list is compiled, the rsync mirror 
URLs (which are actually not used for the mirrorlist) are at the bottom 
of the list. The HTTP and FTP URLs are checked hourly, while the rsync 
URLs are checked only daily.

The next services to be enabled for IPv6 are most probably 
mirror.centos.org and msync.centos.org. The former would be needed for 
the CR repo, and the latter can be accomplished quite easily once the 
mirror.c.o IPv6 servers are in place.

If you run into problems with the new IPv6 mirrorlist, we'd be happy to 
hear about the problems. We're also available for questions on 
#centos-devel at irc.freenode.net.

Thanks for your attention :)

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