Iperf is a tool to measure maximum TCP bandwidth, allowing the tuning of various parameters and UDP characteristics. Iperf reports bandwidth, delay jitter, datagram loss. http://sourceforge.net/projects/iperf/
A tool that performs TCP throughput tests and RTT measurements at the same time.
RUDE is a package of applications to generate and measure the UDP traffic between two points. The rude generates traffic to the network, which can be received and logged on the other side of the network with the crude. Traffic pattern can be defined by user. Tool is available under http://rude.sourceforge.net/
nepim stands for network pipemeter, a tool for measuring available bandwidth between hosts. nepim is also useful to generate network traffic for testing purposes.
nepim operates in client/server mode, is able to handle multiple parallel traffic streams, reports periodic partial statistics along the testing, and supports IPv6.
Tool is available under http://www.nongnu.org/nepim/