FC2 and kernel 2.6.7 upgrade problems.

[Andreas M. Kirchwitz]

Steven Stern <subscribed-lists at sterndata.com> wrote:

 >>Kernel 2.6.7 uses different network parameters than kernel 2.6.6.
 >>For example, window scaling is turned on in 2.6.7 (but it was off
 >>on 2.6.6). This causes problems with most firewalls. Execute the
 >>following command with root privileges, that should "fix" the
 >>networking problem for all new connections:
 >>
 >>	sysctl -w net.ipv4.tcp_default_win_scale=0
 >
 > Does this apply to relatively dumb switches, too?
 
Usually not. ;-)

 > I'm seeing tremendous slowdowns with 2.6.7.

You might want to try the following changes as well
(as they were the default in kernel 2.6.6):

	sysctl -w net.ipv4.tcp_moderate_rcvbuf=0
	sysctl -w net.ipv4.tcp_bic=0

However, it looks like there were a lot more networking-related
changes from 2.6.6 to 2.6.7. After disabling window scaling, I got
back my full bandwidth, but interactive sessions (like remote
shell) are still a little bit bumpy.

While IPV4 basically now works for me, IPV6 is still catastrophic.
But I haven't found a work-around for that problem yet (kernel
options for IPV6 seem to be the same between 2.6.6 and 2.6.7, but the
ChangeLog lists a couple of IPV6-related changes). Disabling IPV6 is
not an option for me, so I'm still trying to find out what's
different with IPV6 in 2.6.6 and 2.6.7.

Sometimes I have the feeling that Fedore Core 2 doesn't use the
original kernel 2.6.7 but applied some very strange patches.

	Greetings, Andreas