UDP on FreeBSD

[Michael Proto]

On Wed, Mar 30, 2011 at 3:43 PM, Kyungsoo Lee <ulsanrub at gmail.com> wrote:
> Hi All,
>
> I want to check UDP on FreeBSD.
>
> I am using IPERF on FreeBSD for wireless testing with Proxim 8470 FC PCMCIA
> card on IBM T42 and T61.
>
> When I'm transmitting data from FreeBSD to FreeBSD or CentOS using Iperf
> with -u -b 100M on iperf, they had lost lots of packets. Sniffer near the
> two nodes shows the sender could not send all packets. Iperf sender said
> that they try to send 85469 packets but they lost 68824 packets. I think
> that the UDP buffer on the sender could not handle all packets.
>
> But if I'm trying to send data from CentOS to FreeBSD using Iperf with -u -b
> 100M option on iperf, the sender tries 18636 packets so they lost few
> packets like 1 or 2 packets.As a result, they have similar bandwidth result
> on the report. I think that it happens from different implement between
> FreeBSD and Linux.
>
> But I want to double check that this is normal for FreeBSD or not. If I have
> some missing points, let me know please.
>
> Thank you!
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Just a guess, but have you tried adjusting the net.inet.udp.maxdgram
sysctl? I believe the default is somewhat low for UDP transmit. I
don't know what size packets iperf is using but increasing the
maxdgram value might help your testing.


-Proto