Re: network problems with kernel-2.6.17-1.2139_FC5

I've just updated to the 2139 kernel and I'm encountering some network

problems.  Connections inside my department seem fine but connections

to anywhere outside (other departments on campus, the rest of the

world) lock up after some fairly small amount of traffic.  The

problems disappear if I reboot back into the 2133 kernel.

The symptoms are very similar to some that I recall from a couple of

years ago with the move to the 2.6.7 kernel where some of the

networking parameters changed.  At that time, there were problems with

various firewalls/routers and the solution was to do

   sysctl -w net.ipv4.tcp_default_win_scale=0

   sysctl -w net.ipv4.tcp_moderate_rcvbuf=0

(or the equivalent in /etc/sysctl.conf).

tcp_default_win_scale doesn't seem to exist anymore, but setting

tcp_window_scaling to 0 seems to work, at least as far as I've been

able to check quickly.  But I don't really understand what these

parameters represent and don't want to mess things up.  

Can the gurus tell me what, in words of one syllable, what changed in

this respect from the 2133 kernel to the 2139 and what the right fix

is?  What am I losing if I set tcp_window_scaling to 0?  I have some

influence on the settings of my department's network equipment, but

the connection to the campus backbone is controlled by the Office of

Information Technology, which generally doesn't respond well to

requests from Linux users in the science and math departments.  So if

it's a question of me changing things on my Fedora boxes or OIT

changing settings on its network equipment, I'll be the one making the

changes.

Thanks,

  George