Re: Other computers HIGHLY degrading network performance (DoS?)

Martin Josefsson
2001-10-27T08:41:38Z

On Sat, 27 Oct 2001, Anuradha Ratnaweera wrote:

> > > Just found out that this is _not_ a problem of the "download accelerator", but
> > > something to do with queuing algorithm of the router. Even a normal wget
> > > process or a big mail has a big impart on the network. Hopefully an iptables
> > > firewall would solve the problem.
> >
> > I'd advice you to seriously look over your network, are you 100% sure you
> > don't have a duplex-issue anywhere?
>
> I will double check. I wonder if this is the cause, because the network is 100
> Mbps, but the router is switching only at 64kbps.

Our network almost died when someone changed the duplex in the switch
here...

> > I've been running linuxrouters for quite a while and right now I have a few
> > linuxrouters routing 100Mbit/s internetconnections. We have never had any
> > problems like the one you describe so my first guess would be that you have a
> > duplexproblem, probably between the linuxrouter and the switch it's connected
> > to on the inside, that's usually where it's located.
>
> We have a hub, and not a switch. Can this be the reason? BTW, how come that a
> duplex issue can result in such huge degradations?

If you are trying to run full-duplex against the hub it till completely
kill the performance of the entire hub, been there, done that. When I did
that one I could only push 5-50kB/s through the hub.

> > I seriously doubt that this a problem with the networking in linux.
>
> Not in linux, may be the way they have _used_ linux on the router ;-)

Hehe, I think you'll have to have quite weird QoS rules to manage to do
something like this :)

/Martin

Never argue with an idiot. They drag you down to their level, then beat you with experience.