Lately I have been playing with virtual routers using GNS3 which has come along quite a bit from being a front end to dynamips when I was studying for my CCIE a few years ago.
In particular I have been using GNS3 to run a topology of Nokia (previously Alcatel-Lucent) service routers. These routers are simulated using QEMU and it has been quite entertaining.
Just recently I have been needing to generate traffic – GNS3 supports the use of Ostinato as test appliance and while it seems quite powerful and perhaps not quite the same level as what you get from Ixia or Spirent, the cost makes it very appealing to invest your time in working things out.
I think my first real blog here will be to describe how I have been using Ostinato to be both a multicast source and multicast recievers at the same time using a SROS router topology.