Consider a pointtopoint link between nodes A and B with the

Consider a point-to-point link between nodes A and B with the following measured values: Link length = 2000 kilometers Signal propagation speed = 5 meters/nanosecond Link speed = 1 Mbps ACK processing time at node A = 10 milliseconds Packet processing time at node B = 20 milliseconds Packet size = 1500 bytes ACK size = 64 bytes Assume the node A is sending to node B and permits (acks) are granted after each packet is received. Compute the network utilization for the following cases: Stop-and-Wait with no channel errors. Sliding Window with no channel errors and W=10 (W is the window size) Stop-and-Wait with Prob[bit in error] = 0.0001

Solution

a. t_data=1500*8/1*10⁶ = 12 ms

t_prop= 2000*10³*10^-9/5=400 micro second=0.4 ms

t_proces=20ms

t_ack= 64*8/1*10⁶=0.512 ms

n/w utilization= t_data/t_data+t_ack+t_proces+2*t_prop

n/w utilization= 12/12+0.512+20+2*0.4=12/33.312

n/w utilization= 0.3602

b)n/w utilization= Wt_data/t_data+t_ack+t_proces+2*t_prop

10*12/12+0.512+20+2*0.4 = 120/33.312

As we can see value is more than 1 so n/w utilization=1.

c)n/w utilization = (1-Prob)t_data/t_data+t_ack+t_proces+2*t_prop

(1-0.0001)*12/12+0.512+20+2*0.4

11.9988/33.312 =0.36019