By understanding protocols in computer communication, different cognition levels are involved. After a mere observation phase of predefined scenarios, interactively modifying parameters and rules to test the resulting behavior are best suited to become acquainted with a protocol. Because of the complexity of protocols, only a few consequences of such modifications can be seen directly. Therefore, support is needed to be able to estimate changes in protocol behavior caused by such modifications. We describe "HISAP" (Highly Interactive Simulation of Algorithms and Protocols), whose features enable such a way of training in computer protocols.