Iperf is an traffic generator.
It is distributed under BSD License .
Iperf has a client and server functionality, and can measure the throughput between the two ends, either unidirectonally or bi-directionally. It is open source software and runs on various platforms including Linux, Unix and Windows. It is supported by the National Laboratory for Applied Network Research.
When used for testing UDP capacity, Iperf allows the user to specify the datagram size and provides results for the datagram throughput and the packet loss.
Iperf can be downloaded here: http://sourceforge.net/projects/iperf/
# export PKG_PATH=ftp://ftp.openbsd.org/pub/OpenBSD/4.8/packages/i386
# pkg_add -vi iperf
# USE=threads emerge iperf
# iperf -s
# iperf -c 172.16.202.1
Where: 172.16.202.1 is ip address of server
Another example of usage:
On client side execute:
# iperf -c 172.16.202.1 -d
Using UDP mode
# iperf -s -u
# iperf -c 172.16.202.1 -u
See man pages for more details
Iperf GUI interface can be found here: http://code.google.com/p/xjperf/downloads/list