Hi. I would agree. IPv6 has nothing to do with mirror manager. It is a protocol wich client uses or not. If you have AAAA records and are on dual stack you will prefer to go thru IPv6. Otherwise if there is also A/CNAME record you will go over IPv4. Regards, Marko On Tue, 2 Aug 2011, Matt Domsch wrote: > On Tue, Aug 02, 2011 at 11:42:47AM -0500, Kevin Stange wrote: >> On 08/02/2011 10:10 AM, Matt Domsch wrote: >>> On Mon, Aug 01, 2011 at 05:45:16PM -0500, Kevin Stange wrote: >>>> We'd be catering to v6-capable (dual stack) clients by offering >>>> mirror choices with v6 ahead of v4 if the client seems to prefer v6. >>> >>> Here's where I start to lose you. We don't presently have a way for a >>> client to indicate to anyone anywhere that it "prefers" v6 instead of >>> v4, or vice versa. From the server side, it sees a connection, either >>> on v6 or on v4, and sees an address. We would have to add a flag into >>> the yum mirrorlist request URL to give the client an opportunity to >>> note its preference. Not hard technically, but the obvious >>> implementation would require manual configuration by each end user, >>> and that's nearly never done. >>> >>> How would you envision a client recognizing that it should prefer v6 >>> over v4, automatically? Solving that cleanly, the rest is >>> straightforward. >> >> We can tell if a client prefers v6 because it will access >> mirrorlist.centos.org using its IPv6 address. The client doesn't need >> to tell us explicitly because its decision to access the v6 address >> means it's decided to try the AAAA first. > > With all due respect, I disagree. Apps on a dual-stack system will > use IPv6 if they can, then IPv4, at a system level, provided an IPv6 > address is provisioned to the system. It has nothing to do with > connectivity between the system and any other mirror server on the > internet, which is what mirrors are trying to solve. > >> I suppose we could compile a list of prefers_v6 mirrors, but my thoughts >> didn't extend past concluding that if the client prefers v6 by evidence >> we just offer it the v6 mirrors sorted first so it can use the preferred >> protocol. > > I understand, but I don't think that's a good indicator for > preference, and I think specifying one protocol is preferred over > another doesn't buy us much. > > >> Do you think it's likely that mirrors will prefer avoiding v6 if they >> have enabled it? > > No. If they advertise both, they'll accept both. There's no way to > specify a mirror's preference for one or the other, just as there is > no way to specify a client's preference. If they want to avoid v6, > they simply don't advertise an AAAA record. :-) > > MirrorManager (and the respected MirrorBrain) aim to solve for the > "best" mirror on the assumption that closer mirrors network-wise are > preferred over mirrors that are further away, irrespective of a > client's IPv4 or IPv6 address. Both offer ways to direct clients to > preferred servers based on network characteristics (BGP ASNs, network > blocks) between client and potential servers, and only then falling > back to GeoIP, all of which are protocol agnostic (both v4 and v6 are > supported). > > Thanks, > Matt > > -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean.