This seems like a good place to ask--I'm on Time Warner. I have an ipv6 address, and can get to ipv6.google.com, so it seems like everything is in place. But all my web browsing (chrome or ff, Windows 7) defaults to use ipv4 everywhere.
Is there something I need to change on my end? I've got pretty vanilla settings. Thanks!
1. What kind of IPv6 connectivity do you have? If it's not a native deployment, it could be 6rd or 6to4. I believe that some applications/OSes will prefer IPv4 over non-native IPv6 when they have the choice, since the latter will be running through a proxy (and therefore will probably be slower).
2. It could be an OS setting. I think that most recent OSes will prefer IPv6 by default, but I could be mistaken.
3. Application settings could also be in play.
I installed a Chrome extension named "IPvFoo" that adds an indicator in the address bar to tell me whether I'm connecting over IPv4 or IPv6. When I'm at home (Comcast residential, native dual-stack), it shows me connecting over IPv6 a lot of the time, especially when I'm connected to larger sites; in fact, the majority of sites connect over IPv6 at least partially, since many popular services (Google Analytics, Google Fonts, some common CDNs for Javascript libraries) are available over v6.
I spent some time checking into things, and here's what appears to be happening:
1. I do get an IPv6 address from Time-Warner... and it appears to be legit. (It's not the link-local address; it starts with 2605:e000, which is in the Time-Warner block)
2. But... it appears to be non-routable from the general internet. I think this is Time-Warner's fault. But maybe it's my router. I am not sure. Traceroute from http://4or6.com/traceroute?l=en gives me this. (I attempted to obfuscate my real address with XXXX)
#traceroute 2605:e000:xxxx
traceroute to 2605:e000:xxxx (2605:e000:xxxx), 30 hops max, 80 byte packets
1 2607:f2f8:1600::1 (2607:f2f8:1600::1) 1.653 ms 1.597 ms 1.583 ms
2 2001:504:13::1a (2001:504:13::1a) 11.753 ms 11.746 ms 11.732 ms
3 twcable-backbone-as7843.10gigabitethernet17.switch2.lax2.he.net (2001:470:0:2bf::2) 2.618 ms 2.610 ms 2.599 ms
4 2001:1998:0:4::11d (2001:1998:0:4::11d) 3.956 ms 2001:1998:0:4::11b (2001:1998:0:4::11b) 3.477 ms 2001:1998:0:4::11d (2001:1998:0:4::11d) 5.512 ms
5 2001:1998:0:8::83 (2001:1998:0:8::83) 4.090 ms 5.784 ms 2001:1998:0:8::87 (2001:1998:0:8::87) 6.542 ms
6 2605:e000:0:4::41 (2605:e000:0:4::41) 6.753 ms 5.032 ms 5.011 ms
7 2605:e000:0:4::5:7f (2605:e000:0:4::5:7f) 6.859 ms 7.042 ms 7.128 ms
8 * * *
3. Since a recent firmware upgrade, my router detects this problem, and sometimes (but not always) decides to set up a 6to4 tunnel. I am not sure how this works, exactly.
4a. If the router does set up the 6to4 tunnel, I do have IPv6, but as organsnyder says, since 6to4 tunnels suck, the OS prefers to use ipv4.
4b. If the router does not set up the 6to4 tunnel, I have a completely non-functional IPv6.
Is there something I need to change on my end? I've got pretty vanilla settings. Thanks!