(a) The OSI protocol stack includes Session and Presentation layers in addition to its Application layer. TCP/IP applications, such as Telnet and FTP, have no such separate layers defined. Do you think that such a separation should be made? Give some advantages and disadvantages of incorporating the OSI approach into TCP/IP. (4 marks)(b) Show the calculations for finding the estimated percentages of overhead for TCP/IP protocol for IPv4 and IPv6 versions. (4 marks)(c) Why is the length of a TCP segment limited to 65,536 bytes? (2 marks)