Stress Testing LAN/WAN

[Brian Feeny]

I have the need to stress test a LAN and WAN.  The primary concern is  
the WAN which is at most OC-3.  The LAN would be an additional bonus  
if I could do that as well.
I am familiar with tools such as those from Spirent and IXIA which are  
very expensive.  I was wondering if someone has had to do this and can  
recommend some open source
tools that would work well.  I need to test a few different types of  
traffic, specifically trying to push traffic into various switch/ 
router policies to make sure everything is performing as
expected.  If anyone knows of some software that works well for this I  
would appreciate letting me know.

Thanks,

Brian