Networking gets extremely laggy after a random amount of time.

Networking gets extremely laggy after a random amount of time.

[Maciej Sołtysiak]

Hi,

I have been writing about this problem several times, always without
receiving any pointers on how to approach this.

Networking gets extremely laggy after a random amount of time.
Sometimes it is 5 minutes, sometimes 30hours, sometimes 5 days.

By laggy, I mean that each connection that is established from or to
the linux box (even on the same LAN) is very slow and jitters.
SSH and telnet sessions jitter. When I press a key for a few seconds
it writes in batches, like:
eeee e ee ee eeeeeee e ee

Other streams like http, smtp are very slow.

The only thing that fixes this is to do a /etc/init.d/networking restart

It has been happening on Debian woody and sarge with kernels
from 2.4.16 (the earliest tested) to 2.4.23-rc4 and even on each
2.6 kernel I tried on that box.

The machine is not loaded, and connections I make that are
on localhost device are ok, when these conditions are on.

It propably is NIC related, but I do not know how to investigate
this. I have two 3com 3c905c-tx NICs. One of them is connected
to the LAN, and the other is connected to a hub and is sometimes
used to listen in promiscous mode to investigate traffic.

I would appreciate any pointers on where to look for problems.

Best regards,
Maciej

Re: Networking gets extremely laggy after a random amount of time.

[Alex Bennee]

On Wed, 2003-11-26 at 10:58, Maciej Sołtysiak wrote:
<snip>
> Networking gets extremely laggy after a random amount of time.
> Sometimes it is 5 minutes, sometimes 30hours, sometimes 5 days.
> 
> By laggy, I mean that each connection that is established from or to
> the linux box (even on the same LAN) is very slow and jitters.
<snip>
> It propably is NIC related, but I do not know how to investigate
> this. I have two 3com 3c905c-tx NICs. One of them is connected
> to the LAN, and the other is connected to a hub and is sometimes
> used to listen in promiscous mode to investigate traffic.
> 
> I would appreciate any pointers on where to look for problems.

Whenever I've come across problems with multiple NIC systems the first
thing I check is the routing is what I expect. Use "route -n" and check
that your WAN traffic really does go straight to the WAN and your LAN
traffic is as you expect.

Is your local LAN connections laggy as well? If not it could be your
problems are at the WAN end (BB connection?).

-- 
Alex, homepage: http://www.bennee.com/~alex/
Lazlo's Chinese Relativity Axiom:
	No matter how great your triumphs or how tragic your defeats --
	approximately one billion Chinese couldn't care less.