Using iperf on Mac Powerbook G4

[Laurence K. <la...@me...>]

Having used iperf on a Mac PowerBook G4 (800MHz, 1Gig RAM) running OS 
10.2.4 over the last few weeks, I would like to find out whether there 
are others successfully using iperf on the above mentioned platform.

I am running into problems using iperf to generate UDP traffic between 
a Linux desktop machine (Pentium II) and my Mac Powerbook connected 
using a crossover cable.  At bandwidth settings of over 1Mbps, I notice 
increasing packet loss  when the Mac is the server and the linux 
machine is the client.
Note that I was running the terminal program on the Mac in order to 
fire up iperf and to see the results of the iperf tests.

Here are the test results:

Client	Server	Time		Bandwidth        Pkt Loss
Linux	Mac		120		10M			1.9%
Mac		Linux	120		10M			0.045%
Linux	Mac 		120		50M			12%
Mac		Linux	120		50M			0.054%
Linux	Mac 		120		90M			19.23%
Mac		Linux	120		90M			0.123%

I then closed all programs running on the Macintosh, logged out and 
then ssh'ed back in from the linux box and got the following results:

Client	Server	Time		Bandwidth        Pkt Loss
Linux	Mac 		60		90M			0.078%
Linux	Mac 		60		50M			2.5%

NOTES. I have verified these results using different cables to ensure 
that the cable was not at fault

My questions/comments are these:
	* why is there any packet loss whatsoever?
		 - the network consists of a crossover cable
		- the Mac Powerbook G4 has a Gbit interface
	* iperf appears to perform better when there are very few other 
processes running on the Powerbook.
	* could the network stack on the Mac be badly tuned for iperf testing?
	* could iperf be running inefficiently on the Mac and reporting 
incorrect numbers?


Any  other testing/debugging ideas would be much appreciated.

Cheers

________________________________________
Laurence Kirchmeier
Senior Systems Research Programmer
Merit Network Inc.
Email: la...@me...
Phone: 734 936-9703
________________________________________