Wednesday, January 6, 2010

How to Test Bandwidth Between Two Windows Computers

In this post we will be looking at a handy little tool called IPerf which can be downloaded from here:

This was recommended to me by the network engineers at work as being one of the fastest and efficient ways to measuring bandwidth on a link. IPerf does not have to be installed, it runs simply in a command prompt window. You need to setup IPerf on both ends to perform testing.

To use IPerf to test your network speed perform the following:

On one end run IPerf as the server:

iperf -s

On the other end run IPerf as the client including the name or ip address of the iperf server.

iperf -c

Here we can see we are getting 8.93mbps over the link to my other end.

Another handy trick is you can test bandiwidth both ways by using the -d switch for duel-test. This should be done if your network is full duplex only! If your running half-duplex this is not a good test to do!

iperf -c -d

This testing was done over an MPLS cloud!


  1. Thanks for this post... Great tool!

  2. How to Test Bandiwidth Between Two Windows Computers Really? You don't have spell check?

  3. Super little tool. Thank you.

  4. Once again your blog helps me out a ton! Just an FYI, the link you have up there is dead as of this post. Here's a direct link:

  5. Thanks for this post! I'm not a network guy, just a developer trying to track down some performance issues, so I have a question. You say "If your running half-duplex this is not a good test to do!". Does that mean merely that the results will be invalid or can it cause some situation (like a race condition) that is bad news for your servers?

  6. It has Xperf which easier & graphical