The performances of TCP over satellite can be very poor due to long delay, high bandwidth and BER characteristics. To integrate satellites' link in the Internet several algorithms and options have been created. Among these are Fast Retransmit, which avoids waiting for a timeout before a retransmission; Fast Recovery, which avoids doing slow start after a retransmission; and the SACK option, which permits better retransmissions.

The overall project consisted in modeling these algorithms and options within TCP with Opnet in order to provide public models. These models were realized with Opnet because it is one of the most used network modeling and simulating software packages.

This report contains a discussion on the problems of TCP over satellite, a description of the models, the algorithms and options they implement, and the results they provide.