TCP Reno congestion window ** Recall that the congestion window length changes with time as follows during TCP Reno's congestion avoidance phase: If an ACK is received, then increase cwnd by 1/cwnd. If congestion is detected, then decrease cwnd by cwnd/2. Suppose the probability of failed transmission is p: the probability of a successful transmission is then 1 - p. The transmission rate x = cwnd/RTT. (a) Write down the equation for the expected change of cwnd per time step. (b) At equilibrium, the expected change is 0. Using (a) show that x_tau = 1/RTT squareroot 2(1 - p)/p