[Full-Disclosure] Is there any open source project support virtual machines

[Jianqiang Xin]

hi, all:
In our research project, we need to generate background traffic. One of 
the problem is how to use one or two machines to simulate hundreds of 
machines? Is there any open source project for this? Thanks very much 
for your help. By the way, does anyone happen to know any good project 
for background traffic generation ( we are interested in user behavior 
ones)? Thanks.

Wishes,

xin