As my research is currently in networks, I have taken it upon myself to learn about IPv6. Luckily, my computer is running the right operating system to do that. Mac OS X has really good support for IPv6. If your network is configured for IPv6, it will automatically work. However, that is probably about two networks in the world. But there is an alternative: If your computer has a real IPv4 address, you can have IPv6 connectivity via 6to4, a transition technology that packages up IPv6 data and sends it over the IPv4 Internet. This article will tell you how to enable this on your Mac. [Note: This only works if you have a real IPv4 address, which means no gateways or NAT. If you are behind a gateway, you need a technology called Teredo, which is supported on Mac OS X by Miredo.]
Amazingly, Mac OS X 10.3 includes a UI for enabling 6to4: How to configure 6to4 in MacOS X. Once you have this turned on, you should be connected. See this list of IPv6 enabled sites for some stuff to visit to see if it works.
Run ping6 www.kame.net:
eitnaa221:~ vulturex$ ping6 www.kame.net PING6(56=40+8+8 bytes) 2002:8161:78dd:1::1 --> 2001:200::8002:203:47ff:fea5:3085 16 bytes from 2001:200::8002:203:47ff:fea5:3085, icmp_seq=0 hlim=60 time=278.998 ms 16 bytes from 2001:200::8002:203:47ff:fea5:3085, icmp_seq=1 hlim=60 time=278.914 ms 16 bytes from 2001:200::8002:203:47ff:fea5:3085, icmp_seq=2 hlim=60 time=278.683 ms ^C --- orange.kame.net ping6 statistics --- 3 packets transmitted, 3 packets received, 0% packet loss round-trip min/avg/max = 278.683/278.865/278.998 ms
Find out how your packets are getting there by running traceroute6 www.kame.net:
eitnaa221:/Users/vulturex root# traceroute6 www.kame.net traceroute6 to orange.kame.net (2001:200::8002:203:47ff:fea5:3085) from 2002:8161:78dd:1::1, 30 hops max, 12 byte packets 1 2002:c058:6301::c058:6301 105.518 ms 104.686 ms 104.623 ms 2 swizh2-g2-6.switch.ch 104.755 ms 104.936 ms 104.839 ms 3 swice3-10ge-1-1.switch.ch 108.791 ms 108.848 ms 108.531 ms 4 swice2-v211.switch.ch 108.741 ms 108.727 ms 108.7 ms 5 switch.ch1.ch.geant.net 109.572 ms 109.171 ms 108.928 ms 6 ch.fr1.fr.geant.net 117.016 ms 118.283 ms 125.403 ms 7 fr.uk1.uk.geant.net 124.035 ms 124.418 ms 126.861 ms 8 uk.ny1.ny.geant.net 193.145 ms 193.295 ms 192.767 ms 9 2001:468:ff:15c3::1 129.557 ms 139.696 ms 129.673 ms 10 2001:468:ff:f15::1 119.009 ms 119.267 ms 119.269 ms 11 2001:468:ff:f12::2 134.192 ms 127.58 ms 118.997 ms 12 kscyng-iplsng.abilene.ucaid.edu 129.018 ms 127.92 ms 128.888 ms 13 dnvrng-kscyng.abilene.ucaid.edu 141.652 ms 138.968 ms 139.539 ms 14 snvang-dnvrng.abilene.ucaid.edu 163.479 ms 164.459 ms 164.316 ms 15 losang-snvang.abilene.ucaid.edu 173.325 ms 173.397 ms 173.232 ms 16 3ffe:8140:101:1::2 277.119 ms 277.191 ms 277.021 ms 17 hitachi1.otemachi.wide.ad.jp 277.408 ms 277.41 ms 277.516 ms 18 pc3.yagami.wide.ad.jp 277.86 ms 277.813 ms 277.86 ms 19 gr2000.k2c.wide.ad.jp 279.598 ms 279.156 ms 281.679 ms 20 orange.kame.net 313.25 ms 278.978 ms 278.787 ms
Due to the magic of 6to4, there are a bunch of hops missing here. Between my computer and the first hop, the packets are carried over the IPv4 Internet. To find out how the data is getting to that first hop, run traceroute 192.88.99.1. Unfortunately, my current connection blocks traceroute packets, so I can't show you what happens here. But by looking at the domain names, I can tell you that my packets are travelling from my computer in Waterloo, Ontario, Canada, through Switzerland (switch.ch), through France, the UK, then back to North America via New York, over the Abilene Internet2 network, and finally to Japan. You can see that this extra round trip to Europe is far from optimal. And for me, somewhere in between my computer and my server, I get duplicate packets.
Ideally, in the future, ISPs will provide 6to4 routers for their customers. Unfortunately, today, there are only a few worldwide. You might be able to improve your connectivity by directing your traffic to a specific router, instead of letting the network carry your traffic to a public router. To do that, find a public 6to4 router, then use the Network control panel to change the router. I'm using Microsoft's router, and it seems to work a bit better than letting my data go to Europe and back.
Unfortunately, the current version of Safari prefers IPv4 addresses, since IPv6 sites are frequently broken. However, you can force Safari to prefer IPv6 addresses for testing.
So far, I only have one complaint: That is that Mac OS X doesn't use any intelligent selection of which addresses to use. For example, my server has both a "real" IPv6 address via Hurricane Electric's Tunnel Broker, and a 6to4 address. This allows it to respond to requests from other 6to4 hosts without having to go through a yucky, suboptimal 6to4 router. Unfortunately, Mac OS X just blindly selects the "real" IPv6 address, since it is listed first in DNS. It should realize that my default route to the IPv6 Internet is via 6to4, and it should prefer 6to4 addresses. I think I read this in an IETF Internet Draft somewhere, so it is the "correct" way to do things.