Using iperf on Mac Powerbook G4
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
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Laurence Kirchmeier
Senior Systems Research Programmer
Merit Network Inc.
Email: laurie --at-- merit.edu
Phone: 734 936-9703
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