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.
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/