In looking for open source routing and open flow solutions, I came across Brian Linkletter's site called Open-Source Routing and Network Simulation. I never realised that there were so many network simulators out there. His site specializes in evaluating many of them.
Two reviews stand out. The first is DNS and BIND demonstration using the Cloonix network emulator which provides a mechanism for experimenting with the DNS protocol and the various open-source implementations of DNS including BIND.
The second interesting network emulator is the OFNet SDN network emulator. it comes prepackaged as an .ova file. The article indicates that it comes with the Floodlight and Beacon controllers. I wonder if Ryu could be used? Anyway, based upon the article, the emulator has visual tools for watching OpenFlow messages, evaluating topologies, and show traffic patterns. Further into the article, the author installs OpenDaylight, so it does look like other controllers can be trialled.