Re: Iperf - packet size

[Marc Herbert <marc.herbert --at-- free.fr>]

On Mon, 7 Nov 2005, Ron Senykoff wrote:

> > > -l for length
> >
> > This is for UDP.
> >
> > The user interface offered by TCP hides such details. The best (and
> > indirect) way to change the size of packets sent by TCP is IMHO to
> > change the MTU (maximum transmission unit) of your network interface.
> >
>
> Thanks for pointing that out. I've been using iperf exclusively for
> testing VoIP which is UDP...

Actually from what I remember the -l 'option' has also an effect on
TCP tests: I think it sets in perf the size of application buffer
passed to the "send" system call, just like for UDP. But for TCP this
may, or may not, translate into IP packets of the same size, depending
on some other conditions and settings.

The reliable and easiest way IMHO is to tweak the MTU.


-- 
So einfach wie möglich. Aber nicht einfacher -- Albert Einstein