Linuxipv6slow
From TWUUG
Slow Broadband Performance
Late 2005, early 2006:
There are still reports of Linux problems with certain networks that are in the process of switching to IPV6. Seems to be an issue for some DSL providers. Symptoms are what appears to be VERY slow DNS resolution, but otherwise fast data transfer.
Does not appear affect Cox Communications (a cable ISOP). Verified as affecting Adelphia, Earthlink, and I think Cavalier. Since I have posted this notice, even people in Canada have confirmed the same issue with DSL providers.
Nobody seems to know EXACTLY what the problem is. I doubt there is something "wrong" with Linux's IPV6, it is more likely some compatibility issues with implementation on the ISP's side. If IPv6 is enabled under Linux, then Linux will notice IPv6 support if the ISP seems to offer it. Each DNS query is then made in the IPv6 style, but the ISP doesn't respond, so Linux waits to timeout and then tries an IPv4 style DNS query, which succeeds immediately.
Solution/Workaround
The immediate solution is to simply turn off IPV6 in Linux until things are figured out (not like you need it right now anyway). With sysconfig-type Linux's (Mandriva, Fedora, Redhat, SuSue, etc):
Edit /etc/sysconfig/network
Add "NETWORKING_IPV6=no"
Edit /etc/sysconfig/network-scripts/ifcfg-eth0 (or whatever device)
Add "MII_NOT_SUPPORTED=yes", "IPV6INIT=no", and "IPV6TO4INIT=no"
Then you will have to either reboot, or manually stop the networking, remove the ipv6 modules, and restart networking.
