AntNet has been the first ACO algorithm for routing in packet-switched networks. My first work on AntNet, under the supervision of Prof. Marco Dorigo, dates back to 1997. As a matter of fact, AntNet is the reference for routing algorithms designed following ACO or Swarm Intelligence principles. According to GoogleScholar, my AntNet's papers have got overall more than 3000 citations.
Muddassar Farooq made an implementation of AntNet for OmNet++. The implementation is very close to the original algorithm, but I didn't fully checked and tested the code.
Richardson Lima has also released, more recently, a version of AntNet for NS-2. He also made an AntNet web page. Since I'm not an NS-2 user, I haven't checked these implementations, but I guess the Lima's implementation can be used as a good starting point. If you plan to use Lima's code, please feel free to contact me to check/improve the quality of the implementation.
At IDSIA, Frederick Ducatelle and Liliana Carrillo made an implementation of AntNet for QualNet (ver. 3.8), the commercial network simulator from Scalable Network Technologies. The implementation has not been fully tested and the code needs to be polished. However, it works and can be definitely used as a starting point (anybody willing to check, improve, or port this code to newer QualNet versions, is most welcomed!).
General principles and applications of ACO and Swarm Intelligence to routing in telecommunication networks