Let us consider an asymmetric bidirectional communication system between two endpoints A and B (e.g., A is a server and B is a host). A TCP connection is set up between A and B. A sends data segments...

Let us consider an asymmetric bidirectional communication system between two endpoints A and B (e.g., A is a server and B is a host). A TCP connection is set up between A and B. A sends data segments of lengthL1to B. B sends ACK segments of length L₂
back to A, one ACK per data segment. The link from A to B has a capacity C₁, the other link has a capacity C₂. At any given time there are W data segments in flight, i.e., A has sent them and is still waiting for their ACKs.

(a) Define a closed queueing network model of the communication system and find the state probabilities at equilibrium.

(b) Calculate the utilization coefficients of link 1 (from A to B) and link 2(from B to A) as a function of the variables L₁,L₂,C₁,C₂, and W.(c) Find the value of C₂
such that the two utilization coefficients are equal by assuming L₁
= 1500 bytes,L₂
= 50 bytes and

C₁
= 30 Mbit/s. Then, calculate the utilization coefficient as a function of W and for

W = 7.