55103-mt----computer Communications

NR

Code No: 55103/MT M.Tech. – I Semester Supplementary Examinations, September, 2008 COMPUTER COMMUNICATIONS (Common to Computer Science & Engineering/ Computer Science/ Neural Networks) Time: 3hours

Max. Marks:60 Answer any FIVE questions All questions carry equal marks ---

1.a) Explain the details of ARPANET b) Write the differences between connectionless services.

connection

oriented

and

2.a) Explain in detail about HDLC data link protocol. b) A channel has a bit rate of 4 kbps and a propagation delay of 20m sec. For what range of frame sizes does stop and wait give an efficiency of at least 50 percent. 3.

Write in detail about IEEE 802.3 standard for LANs.

4.a)

Explain about hierarchical routing. For hierarchical routing with 4800 routers, what region and cluster sizes should be choosen to minimize the size of the routing table for a 3-layer hierarchy. What is the need of fragmentation in Internetworking?

b) 5.a) b)

Discuss the TCP header format. Briefly describe the elements of transport protocols.

6.

Explain in detail about the different DES modes of operation.

7.

Explain the following congestion control algorithms a) Choke packets b) Load shedding c) Jitter control

8.

Write short notes on: a) E-mail c) Firewalls.

b) Public key cryptography ****