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Re: Network Connects Slowly In Kernel 2.6 Using IPv6



On Wed, 2004-04-21 at 15:00, Jeff Pitman wrote:
> Hi all:
> 
> The following is just a "word of warning" about IPv6 causing initial 
> connect slowness in Kernel 2.6. Target audience: packagers of kernel 
> 2.6 in Fedora Core 2 (maybe provide a work around or configurable shut 
> off mechanism) or any kernel hackers or someone with additional 
> familiarity. I'm writing this purely out of my personal experience and 
> hope that it might be helpful for those on this list.
> 
> Without disabling IPv6 in /etc/modprobe.conf with "alias net-pf-10 off", 
> in certain environments that evidently do not support "it"--"it" being 
> quite a nebulous definition since I am far from understanding any piece 
> of IPv6--initial network connections will be obnoxiously slow, both DNS 
> lookups and simple "telnet www.google.com 80" tests.

With ipv6 enabled, the libc resolver will afaik try to
resolve hostnames as ipv6 addresses first. For alot of reasons
that might take a long time..

(one example is me having a local dns server used for internal hosts on 
a network not always on the internet, and havinf "forward" hosts
in named.conf... ipv6 dns lookups takes a damn long time to timeout when
not connected to the internet.)
 
So perhaps there should be(and maybe there is..) a way to say
try ipv4 first in /etc/resolv.conf ?




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