How to test real network throughput between two points?

I find iperf to be one of the more useful utilities to test point-to-point bandwidth. It has many options to test over tcp/udp, with udp it can tell you how much jitter there was. Ports of iperf are available for almost every OS.

I also like testing with NDT, but it is isn't quite as easy to work with as iperf since NDT basically has to be setup as a server somewhere, and the client must have java installed.

I would pipe something like /dev/urandom (or /dev/zero to test the devices' compression if any) across using two *nix machines.

Listen and pipe to /dev/null on one machine

nc –l –p 7000 | /dev/null

Connect and pipe 100MiB of random data on the other

dd if=/dev/urandom bs=1M count=100 | nc 192.168.1.120 7000 –q 10

For realtime stats use pipeviewer

dd if=/dev/urandom bs=1M count=100 | pv | nc 192.168.1.120 7000 -q 10

Here's a brute-force and ignorance approach...

Many command-line FTP clients report transfer statistics, so you could simply use FTP to GET or PUT a large enough file for the statistics to be meaningful.

IxChariot. Not free, but it can simulate all kinds of traffic. SmallNetBuilder.com uses it for their product tests.

What do you consider "real network throughput?" This depends entirely upon your network's function and your users' needs.

For example, bandwidth is not going to be a defining attribute of how your network performs if you have six users that are not permitted to stream video/audio or transfer files. In that case, once you have enough bandwidth for their standard traffic more is simply a waste.

Benchmarks are useful for determining weak spots in your network, but you shouldn't take them as a reflection of user experience unless they mimic your users' traffic patterns.

If you're just trying to figure out how much bandwidth you can push through wireless bridge before it falls over, you really can't beat iperf and FTP (though you may need a couple machines testing at the same time). Remember to test bidrectional traffic as well.

If you're interested in figuring out projected user experience, we'll need some more information.