Consider a network message transfer among a source S and a destination D by 3 routers R1, R2 and R3 as given below:-

            S -------- R1 --------- R2 --------- R3 --------- D

 A message M requires to be transferred from S to D.  M will be divided into packets; thus M/Packet Size is the number of packets. For example, if M is 100 MB, and packet size is 10MB then there will be10 Packets. Write a simple program to simulate the arrival of a packet at R1, then R2, then R3, and then D, and at last the program should indicate how long it would take for the entire message M to arrive at D.In the program the user should be able to choose different packet sizes, bandwidths of the links, link speeds and lengths of the links. Ignore the queuing and processing delays.