[netperf-talk] testing two 10G networkcards on same host

[Andrew Gallatin]

Alan Woods wrote:
> Hi Rick
> I am testing two  10G network cards on the same machine, I want to run netserver so it only looks at one card and net perf so it transmits through the other card. When I run it it runs ok but the results show that it must be just looping through the kernel and not transmitting through physical interface. As I only have one fast machine to do the testing is it possible to force netperf to transmitt through one physical interface to the second card interface.
>  I have card 1 on 10.0.2.2 and card 2 on 10.0.2.3
> 
> netserver -L 10.0.2.2, AF_INET -4
> netperf -H 10.0.2.3 -L 10.0.2.3,AF_INET -4
> 
> 
> Is it possible to do the test this way or does the server have to be on a
> seperate machine

Most OSes enable software loopback when both sides of a connection
are on the same host.  If you're running Linux, then there's a
kernel patch to disable this, and allow the traffic to flow
across the NICs.  See:

http://www.ssi.bg/~ja/#loop

I've never tried it myself, but it was used successfully
by one of our customers to validate a dual-port 10G NIC.

Cheers,

Drew