[geeks] Network Slowness

[Mike Meredith]

On Thu, 24 May 2007 10:30:58 -0400, Sridhar Ayengar wrote:
> The speed LED for all three ports on the switch reads as gigabit, and 
> ifconfig (on UNIX) and Network Connections (on Windows) report that
> I'm connected at 1000Mbps.

Also check (if possible) if both ends are autonegotiating full duplex;
if you've got a mismatch there, you will get terrible performance.
Gigabit (I think) is supposed to be full duplex only, but it's still
worth checking.

> > * PA-FE-TX? Is that 100BaseFX ? Might be worth disconnecting that
> 
> No, that's 100BASE-TX.  And the indicator LED for that port on the 

I meant 100BaseTX; brain fart got in the way :)

Still worth trying without it connected just in case.

> > 890Mbps. It may just be the Procurve just isn't up to the job.
> 
> I had a little trouble parsing the next-to-last sentence there.  What 
> did you mean?

Well I can't see what's wrong with the sentence right now (brain is a
little frazzled from staring all day at php code), but it's obviously
bad English if you can't understand it!

I just meant that not all switches will do gigabit very well, and
perhaps your Procurve is one of the switches that choke when pushing
packets that fast.

Other things to try :-

* Switch to using nc (as others have said) to benchmark the network ...
  it may not be what you want to use, but it eliminates an unnecessary 
  variable. And you should  get some nice big numbers out of it once
  you have fixed this problem :)

* Check the stats that ifconfig gives you to see if you are getting
  any errors there.

* Do a tcpdump (or similar) on the network transfer to see if you're
  getting lots of tcp retransmits. You should probably see some, but
  not *too* many. 

* Swap out the cable(s) 

(some bastard spammer is joe-jobbing my redhairy1.demon.co.uk domain 
 at a rate of 50 backsplatters every 10 minutes :( )

-- 
Mike Meredith (http://zonky.org/)
  'I find film very seductive ... like a woman my parents would not
like me to date. She's expensive, inconvenient, and you really can't
know you'll get what you want. But you'll be certain you'll want a
cigarette before the night is out.