Load simulation on the Big-IP LTM VE

I'd also say that it depends on what kind of traffic need to be simulated.

 

In addition to the tools above:

 

 

For load testing WSDL/SOAP SOAPUI http://www.soapui.org will be great choice (base version is free).

 

For WEB UI scenarios Web Performance Tester http://www.webperformanceinc.com/ has a base version for free, which is limited for 10 users. Or HP Load Runner is really high scale tool with plenty of protocols and scenarios supported, but it's also expensive (has 1 month limited trial).

 

For diameter you can use Diameter plugin for jmeter from Computaris http://www.computaris.com/ (requires a license) or Seagull http://gull.sourceforge.net/. Seagull also has great support for Radius and it's a free tool.