As shown below, they have major issues with MTU size on their IPv6 network. This is a major inconvenience and affects IPv6 users regardless of whether the site they are visiting is IPv6 enabled or not. In addition, it affects other Automattic sites hosted on Edgewall such as Gravatar and Akismet.
Ping6 works ok:
jmccrohan@lambda:~$ ping6 s0.wp.com PING s0.wp.com(2606:2800:234:1922:15a7:17bf:bb7:f09) 56 data bytes 64 bytes from 2606:2800:234:1922:15a7:17bf:bb7:f09: icmp_seq=1 ttl=55 time=34.9 ms 64 bytes from 2606:2800:234:1922:15a7:17bf:bb7:f09: icmp_seq=2 ttl=55 time=21.6 ms 64 bytes from 2606:2800:234:1922:15a7:17bf:bb7:f09: icmp_seq=3 ttl=55 time=25.9 ms 64 bytes from 2606:2800:234:1922:15a7:17bf:bb7:f09: icmp_seq=4 ttl=55 time=21.7 ms ^C --- s0.wp.com ping statistics --- 4 packets transmitted, 4 received, 0% packet loss, time 3004ms rtt min/avg/max/mdev = 21.600/26.050/34.968/5.438 ms
Wget over IPv6 fails:
jmccrohan@lambda:~$ wget -6 http://s0.wp.com/wp-content/js/devicepx-jetpack.js --2012-11-12 01:05:08-- http://s0.wp.com/wp-content/js/devicepx-jetpack.js Resolving s0.wp.com (s0.wp.com)... 2606:2800:234:1922:15a7:17bf:bb7:f09 Connecting to s0.wp.com (s0.wp.com)|2606:2800:234:1922:15a7:17bf:bb7:f09|:80... connected. HTTP request sent, awaiting response...
There is, however, a httpd listening on tcp6/80:
jmccrohan@lambda:~$ telnet s0.wp.com 80 Trying 2606:2800:234:1922:15a7:17bf:bb7:f09... Connected to cs82.wac.edgecastcdn.net. Escape character is '^]'. GET /index.html HTTP/1.1 host: s0.wp.com ^]quit telnet> quit Connection closed.
This leads me to believe there is a MTU issue somewhere. Thankfully I'm not the only one who is experiencing this. It has been discussed here and here too. If you are having issues, please get in touch via the comments below. I'd like to compare traceroutes.
EDIT 2: Edgecast have followed up via email to confirm that they have fixed the issue. Thanks Edgecast.