Google enables IPv6 for most services (but there is a catch!)

Google has enabled IPv6 for most services but ISPs have to contact them and verify that their IPv6 is working properly before their users can take advantage of this.

I'm writing about this to spread the word.  Many readers of this blog work at ISPs and hopefully many of them have IPv6 rolled out, or are in the process of doing so.

Technically here's what happens:  Currently DNS lookups of www.google.com return A records (IPv4), and no AAAA records (IPv6).  If you run an ISP that has rolled out IPv6, Google will add you (your DNS servers, actually) to a white-list used to control Google's DNS servers.  After that, DNS queries of www.google.com will return both an A and AAAA record(s).

What's the catch?  The catch is that they are enabling it on a per-ISP basis. So, you need to badger your ISP about this.

Why not just enable it for all ISPs?  There are some OSs that have default configurations that get confused if they see an AAAA record yet don't have full IPv6 connectivity.  In particular, if you have IPv6 enabled at your house, but your ISP doesn't support IPv6, there is a good chance that your computer isn't smart enough to know that having local IPv6 isn't the same as IPv6 connectivity all the way across the internet.  Thus, it will send out requests over IPv6 which will stall as the packets get dropped by the first non-IPv6 router (your ISP).

Thus, it is safer to just send AAAA records if you are on an ISP that really supports IPv6.  Eventually this kind of thing won't be needed, but for now it is a "better safe than sorry" measure.  Hopefully if a few big sites do this then the internet will become "safe" for IPv6 and everyone else won't need to take such measures.

If none of this makes sense to you, don't worry. It is really more important that your ISP understands.  Though, as a system administrator it is a good idea to get up to speed on the issues.  I can recommend 2 great books:
The Google announcement and FAQ is here: Google announces "Google over IPv6". Slashdot has an article too.

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Posted by Tom Limoncelli at January 8, 2009 2:05 PM | Comments (5) | TrackBack (1) |

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Comments

Oddly, TWC - or Earthlink - does work w/ IPv6. At least over a Mac Airport Extreme.

But going to http://ipv6.google.com/ works for me at home.

Posted by: Matthew Barr at January 8, 2009 6:04 PM

Well, still think that having to have your ISP to check with Google that they are IPv6 compliant is not the right approach... We discussed about that at the HEAnet conference following Niall's presentation. But i know Google is never wrong :))

Posted by: FRLinux at January 8, 2009 7:53 PM

Speakeasy hasn't even bothered to roll out IPv6 yet even though they've been promising it for years. :(

The unfortunate part is that because of the way the phone system is setup here, in order to switch from Speakeasy to someone who's got their shit together, I have to go 3 weeks without service (otherwise I'd jump ship tomorrow).

Posted by: Paul at January 9, 2009 1:05 AM

The OS doesn't get "confused".

The problem is either:
- AAAA records get dropped by intermediate caching resolvers, thus making connecting to sites very slow
- broken routing
- broken pMTU.

Posted by: Jeroen Massar at January 9, 2009 5:51 AM

Another useful book with a focus on the Windows implementation is Understanding IPv6, 2nd ed.
http://www.microsoft.com/learning/en/us/books/11607.aspx

Posted by: Chris Knight at January 11, 2009 6:23 PM
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