iperf is a network performance testing tool hosted here [2]
There ares patch for iperf here [3] which adds support for DCCP [4] and selecting the DCCP [5] congestion control method and running continuously.
There is now a combined patch set based on the sources developed by Ian McDonald, which has support for DCCP, long unattended test runs, and TCP plug-able congestion control. Sources and information can be found here [6].
A UDP-Lite enabled clone of the above can be found in the UDP-Lite tarball [7].