In the data link layer, the Sliding Window is used for flow control.
There are two link utilization formula that can be use. They are :
U = 1, for N > 2a + 1
U = N/(1+2a), for N < 2a + 1
In both formula, N denotes the window size and a = Propagation time / transmission time
I am not really understanding which formula to use in what situation although the condition is specified. What does 2a+1 actually mean? Can anyone help me to understand it in simple term. Thanks!