TEZPUR UNIVERSITY 
		     Computer Networks (CS 703) :: Class Test I
    Time 90 min		          (September 2001)		Full Marks 40

    1. (a) Consider the three-way handshake in TCP connection setup.  Suppose
       that an  old  SYN  segment  from  station  A  arrives  at  station  B,
       requesting a TCP connection.  Explain  how  the  three  way  handshake
       procedure ensures that the connection is rejected.		    3

       (b) Explain the significance of the following in TCP protocol:	    6
	(i) MSS	  (ii) advertised window   (iii) Congestion window   (iv) RTT

       (c) Explain the relationship between advertised  window,  RTT,  delay-
       bandwidth product, and the maximum achievable throughput in TCP.	    3

       (d) Explain the scheme for computation of time-out duration in TCP.  3

       (e) What are the different modes of generating segments in TCP ?	    3

       (f) What are Integrated Service and Differentiated Service ?	    2

    2. (a) Briefly justify the need for session layer despite  the  transport
       layer. How is it that many real networks do not have a session layer ?
									4 + 3
       (b) How is synchronisation provided by  the  session  layer  different
       from that provided by any lower layers ?				    4

       (c) Why is base64 encoding used ? If an image file is of size  18  KB,
       how large will it be when encoded using base64 ?			2 + 4

       (d) Briefly explain the concept of Virtual terminal.		    3