I'm seeing sporadic IPv6 connectivity issues to forums.comcast.com:
casey@rome$ curl -I6 forums.comcast.com
HTTP/1.1 200 OK
[snip...]
casey@rome$ curl -I6 forums.comcast.com
curl: (7) couldn't connect to host
casey@rome:~$ traceroute6 forums.comcast.com
traceroute to forums.comcast.com (2620:6a:8000:4::11) from
2001:470:21:31::adf5:492a, port 33434, from port 42309, 30 hops max, 60
byte packets
1 2001:470:21:31::1 (2001:470:21:31::1) 1.713 ms 1.922 ms 2.039 ms
2 2001:470:1f:b::1 (2001:470:1f:b::1) 10.575 ms 3.343 ms 3.147 ms
3 10gigabitethernet1-1.core1.sjc1.he.net (2001:470:1:7c::1) 6.855 ms
4.225 ms 4.252 ms
4 10gigabitethernet2-1.core1.sjc2.he.net (2001:470:0:55::2) 4.271 ms
14.442 ms 4.469 ms
5 sjo-eqx-s1-link.telia.net (2001:2000:3080:1b7::1) 5.385 ms 4.669 ms
4.434 ms
6 internap-ic-140172-sjo-bb1.c.telia.net (2001:2000:3080:17f::2) 4.702
ms 4.803 ms 4.848 ms
7 border1-bbnet2.sje.pnap.net (2600:c02:0:102::1:1) 5.175 ms 25.023 ms
4.808 ms
8 lithiumtechinc-2.border1.sje.pnap.net (2600:c02:1001:3::2) 9.445 ms
8.120 ms 7.804 ms
9 2620:6a:8000:4::11 (2620:6a:8000:4::11) 5.491 ms 5.712 ms 5.873 ms
casey@rome:~$ traceroute6 forums.comcast.com
traceroute to forums.comcast.com (2620:6a:8000:4::11) from
2001:470:21:31::adf5:492a, port 33434, from port 42311, 30 hops max, 60
byte packets
1 2001:470:21:31::1 (2001:470:21:31::1) 1.574 ms 1.514 ms 1.856 ms
2 2001:470:1f:b::1 (2001:470:1f:b::1) 2.882 ms 3.089 ms 14.462 ms
3 10gigabitethernet1-1.core1.sjc1.he.net (2001:470:1:7c::1) 4.573 ms
4.466 ms 6.683 ms
4 10gigabitethernet2-1.core1.sjc2.he.net (2001:470:0:55::2) 4.525 ms
10.401 ms 4.748 ms
5 sjo-eqx-s1-link.telia.net (2001:2000:3080:1b7::1) 4.794 ms 4.931 ms
4.406 ms
6 internap-ic-140172-sjo-bb1.c.telia.net (2001:2000:3080:17f::2) 4.837
ms 4.922 ms 4.527 ms
7 border1-bbnet1.sje.pnap.net (2600:c02:0:101::1:1) 5.884 ms 4.626 ms
5.037 ms
8 border3-bbnet2.sje.pnap.net (2600:c02:0:102::1:3) 3157.850 ms !H
3270.481 ms !H 3226.411 ms !H
Is this perhaps a routing issue?
Casey