Qcheck
"Simply the easiest way to go if you want to dig in and do your own testing on networking equipment. It's basically a subset of Ixia's more powerful IxChariot network performance testing program with an easy-to-use interface, and best of all....it's free! You do have to fill out a form to request the download because Ixia hopes that you'll like what you see and want to buy the full-featured Chariot, but that's a small price to pay for such a handy tool". More on Qcheck / Download Form