Tools to test latency

Hi Rene,
I need some clarification on testing latency. I connected 2 PCS with nics at 1GB speed each, same vlan, 1 switch 3560 Gigabit switch, use a program called LANBench and the test was for 10 seconds from laptop-1 connected on port 1 to laptop-2 on port 2 and I get 112 megabytes in 10 seconds. Is this normal for a gigabit connection or what should be a normal speed rate? is there any other tool you can recommend?


Hello Alfredo

With the setup you described, it seems very strange that you would get such a low throughput. This can be due to many things, however, to start off I would first attempt just a simple file transfer between the devices. Before using a benchmarking software, I suggest using a protocol such as FTP to transfer a large file and see what kinds of data rates you get. Don’t use Windows file sharing (SMB) as that will add a lot of overhead not giving you a proper result.

Additional things you can do include:

* Make sure that the cables are good
* Make sure none of the ports on the switch are configured to function at speeds of 100Mbps
* Take a look at the show interface output and make sure that the connections to the two PCs are indeed 1000 Mbps
* Check to see if there are any errors on the interfaces

Also, make sure you are using the right units for your tests. Some benchmarking software uses the MegaBytes per second rather than the more conventional Megabits. A 1 Gbps connection should provide you with speeds of at least 100 MegaBytes per second and should actually approach 120.

I hope this gives you a good start to continue your troubleshooting…


Like Laz recommends, using something like FTP is a quick way to test the speed between two computers.

I do like iperf, there is an example for this in this lesson:

Iperf does require some configuration though, like setting the window size for high bandwidth interfaces like Gigabit.


Thanks for your quick replies and suggestions. I will test this weekend.