I want to benchmark my DUT network performance.
At the system level with linux kernel, I am using iperf and nuttcp utilities(DUT connected to Linux Machine) to analyse the througput.
Getting very less througput. Apart from the TCP/Ip stack and other things in linux kernel, I doubt on my network card on the linux macine that it is not providing full wirespeed(1Gbps) data to my DUT.
Anyone knows any network analyzer that can be used to measure the network throughput at system level.
regards,
Anunay

iperf will run at gig wirespeed, I use it at work. You need a 1G processor or greater and you need PCI-64 or PCI-E network card as a standard PCI card won't cut it as PCI won't keep up.

Drivers can be an issue, as can other things using system processes. I normally run iperf as the highest priority process using nice.

You also need to be aware of the fact that TCP throughput is limited by the transmission window. A default windows of say 8K, will definitely not fill 1G even with low latencies, so you need to make sure you are using larger window settings and assign big enough buffers, iperf lets you play with these things and they will have an effect.

Thanks for the responce Pete!!

Yes, I later reailised the mistake of using standard 32bit PCI.
I updgraded tp PCI-E, on my windows machine and used iperf via cygwin. This also didnt improve.
I will try same with Linux machine and your suggestions of TCP window size and task priority.

Right now two big questions:
i) How to know if it is my PC which is the bottle neck, because of which I am not able to pump data at required rate on to my DUT to test its performance?
ii) Is there any network analyzer that can replace PC in such tests? e.g. I have been using IXIA N2X for performance measurements at L2 level. But here I think I need an analyzer that can work at application level.

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Anunay

you can get iperf natively on both windows and linux, you shouldn't need to use emulation. That might well cause a problem.

You can try running each PC to itself by pointing the client at localhost (127.0.0.1), which might highlite one machine as behaving oddly.Or if you have a third machine its likely that the problem is only with one of them so you can trade the three off against each other until you identify the odd one out.

There are hardware specific test devices available to buy but unless your going to be using it all the time its gonna be expensive.

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Trying iperf with local host.. I have an apprehension about this..
May be in this case the underlying network driver will not pass the packets from iperf through all layers and it might have an internal loopback may be at IP level.
I will give it a try...

Regarding the test devices, my company is ready to buy one.
Is there some test equipment that can act as an NIC and Iperf can route the data through it?
For test equipments I think we can be sure about their performance compared to linux/windows PC.

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Anunay