Oscillations of the Sending Window in Compound TCP

One of the key ideas of Compound TCP is to quickly increase the sending window, until full link utilization is detected, and then to keep it constant for a certain period of time. The actual Compound TCP algorithm does not hold the window constant but, instead, it makes it oscillate around the desired value. Using an analytical model and ns-2 simulations we study these oscillations on a Linux implementation of Compound TCP, in the case of a single connection with no cross traffic. Even in this simple case we show how these oscillations can behave in different ways depending on the bandwidth delay product. We also show how it is important to take into account, in the analytical model, that some implementation subtleties may introduce non-negligible differences in the behavior of the protocol.