I can't seem to get packets to cogentco.com via IPv6. It appears to be reachable according to http://www.berkom.blazing.de/tools/ping.cgi and http://www.ipv6-test.com/validate.php, and I can get to other IPv6 hosts via my tunnel, so this appears to be a localized routing problem.

Code:

$ traceroute6 cogentco.com
traceroute6 to cogentco.com (2001:550:1::cc01) from 2001:470:1f07:189:21c:b3ff:febc:c615, 64 hops max, 12 byte packets
 1  2001:470:1f07:189:9284:dff:fed3:15d4  2.044 ms  3.095 ms  0.677 ms
 2  annodomini-1.tunnel.tserv4.nyc4.ipv6.he.net  78.759 ms  78.918 ms  78.096 ms
 3  gige-g3-8.core1.nyc4.he.net  78.151 ms  77.643 ms  78.305 ms
 4  * * *
 5  * * *
 6  * * *
 7  * * *
 8  * * *
^C


$ ping6 cogentco.com
PING6(56=40+8+8 bytes) 2001:470:1f07:189:21c:b3ff:febc:c615 --> 2001:550:1::cc01
Request timeout for icmp_seq=0
Request timeout for icmp_seq=1
Request timeout for icmp_seq=2
Request timeout for icmp_seq=3
Request timeout for icmp_seq=4
Request timeout for icmp_seq=5
Request timeout for icmp_seq=6
^C
--- cogentco.com ping6 statistics ---
8 packets transmitted, 0 packets received, 100.0% packet loss

I have two questions. I am a Comcast customer, using an Airport Extreme wireless router; I've been using 6to4 for a few weeks with Comcast's relays, but since it's 6to4, my computer would always prefer IPv4 to v6 when connecting to dual stack hosts. So I set up a tunnelbroker.net account to try out a more complete IPv6 experience.

So far, I'm running into two problems. One may be based on my own confusion, I'm not sure. I wasn't quite sure how to map from the addresses given to me by the tunnel broker to the ones to use for my Airport configuration. The tunnel broker lists "Server IPv4 address", "Server IPv6 address", "Client IPv4 address", "Client IPv6 address", and "Routed /64" (as well as some DNS addresses that I'm not using at the moment, to reduce the number of variables). The Airport configuration utility has fields for "Remote IPv4 Address", "WAN IPv6 Address", "IPv6 Default Route", and "LAN IPv6 Address". After some experimentation and Googling, I wound up putting the "Server IPv4 address" in the "Remote IPv4 Address" field, the "Server IPv6 address" in the "WAN IPv6 Address" field, the "Client IPv6 address" in the "IPv6 Default Route" field, and the "Routed /64" in the "LAN IPv6 Address" field. This appears to work—I can connect to v6 only hosts, I can connect to dual stack hosts which report that I'm using my v6 address, and traceroute6 shows packets going over my tunnel. But for some reason, my router has a blinking amber light and when I use the configuration utility reports a problem with tunnel configuration. It is not any more specific than that; it just says that there is a problem. Is there any way to get more information about what the problem may be, or are there any tests I can run to determine what issues might come up? Was I correct in my mapping between the parameters provided by tunnelbroker.net and what my Airport configuration is looking for?

The second issue is that when I try to connect to occaid.org via IPv6 (which is used by default now when I'm browsing the web), the packets are lost. My browser will wait a while sending SYN packets into the void, before giving up and switching to v4. Here's what I get from a traceroute:

Code:

$ traceroute6 occaid.org
traceroute6 to occaid.org (2001:4830:100:20::6) from 2001:470:1f07:189:21c:b3ff:febc:c615, 64 hops max, 12 byte packets
 1  2001:470:1f07:189:9284:dff:fed3:15d4  0.973 ms  1.016 ms  0.639 ms
 2  annodomini-1.tunnel.tserv4.nyc4.ipv6.he.net  52.941 ms  53.028 ms  59.149 ms
 3  gige-g3-8.core1.nyc4.he.net  60.327 ms  54.854 ms  52.728 ms
 4  10gigabitethernet2-3.core1.ash1.he.net  57.723 ms  67.492 ms  57.755 ms
 5  ibr01-ve96.asbn01.occaid.net  57.927 ms  59.586 ms  57.502 ms
 6  bbr01-p2-1.whkn01.occaid.net  65.395 ms  64.813 ms  66.598 ms
 7  bbr01-t1-0.bstn01.occaid.net  72.465 ms  73.069 ms  74.634 ms
 8  towardex-ic-1135-bos.customer.occaid.net  73.393 ms  74.972 ms  74.832 ms
 9  23.te3-1.bb2.bos.twdx.net  73.825 ms  73.194 ms  73.470 ms
10  * * *

I don't have access to any other IPv6 hosts, so I can't test if this issue is unique to my setup or if this is their problem (though Googling for "IPv6 ping" brings me http://www.berkom.blazing.de/tools/ping.cgi which also seems to indicated that they aren't pingable). Any tips on debugging or reporting this problem? Also, until it's resolved, are there any good ways to blacklist IPv6 for particular hosts, so I don't have to wait for connection attempts to time out before reverting back to IPv4?