iperf results

[Matthew Jakeman]

Hi,

Some colleagues and myself have performed some simple tests on various OS's 
using iperf to simply fire packets from one pc to another over ethernet to 
test a few characteristics such as packet loss, jitter etc between IPv4 and 
IPv6. The configuration for all three OS's were 'out of the box' installs. 
The results we got back from that are strange for FreeBSD with regards to the 
packet loss iperf reports and I was wondering if anyone has any ideas why 
they might be as they are. The image at the link below shows the packet loss 
results for windows, Linux and FreeBSD for comparison! As you can see the 
packet loss for v6 is substantially less than v4 on FreeBSD, however this is 
still substantially larger than for the other two OS's, does anyone have any 
idea why this might be?

http://www.mjakeman.co.uk/images/4v6tests.jpg

One other question is that I tried altering the Mbuf size in the kernel config 
to 1500 using "options MSIZE=1500" but when i try to recompile the kernel 
with this value i get a compilation error "/usr/src/sys/kern/kern_mbuf.c: 
error: size of array `__assert123' is negative", be aware I have not looked 
much into why this might be happening at present but if there is a hard upper 
limit or any other reason that this might be happening I would be grateful to 
be informed of it.

Thanks in advance for any replies
Matt