http://www.fokus.gmd.de/step/simulations/sim.html#TCPdescribes his work. Christopher Hylands created a tar file that combines the two tar files below, and makes a few minor changes.
Below is a lightly edited local copy
The current version of the simulator includes the 4.3BSD Tahoe TCP version and implements slow start, congestion avoidance, silly window handling, round trip time estimation, the sliding window mechanisms and the fast retransmission algorithm. With the 4.3BSD Reno TCP the simulator also implements fast recovery.
For our tests we also implemented a TCP version using binary congestion notification in addition to the usual loss indication.
These models were compiled with Ptolemy0.5.2, so they might need some work to compile under Ptolemy0.6.