Jawaharlal Nehru Technological University Hyderabad 2007 M.C.A Computer Aplications COMPUTER COMMUNICATIONS - Question Paper

1.a) discuss various kinds of transmission technologies used in computer networks.
b) discuss about the ATM model.
2.a) discuss the performance of sliding window protocol. A channel has a bit rate of 4Kbps and a propagation delay of 20msec. For what range of frame sizes does stop and wait provide a frequency of at lowest 50%.
b) Imagine a sliding window protocol using so many bits for sequence numbers that wrap around never occurs. What relations must hold among the 4 window edges and the window size?
3.a) Measurements of a slotted ALOHA channel with an infinite no. of users show that 10 percent of the slots are idle
i) What is the channel load G?
ii) What is the throughput?
iii) Is the channel underloaded or overloaded?
b) discuss the operation of transparent bridge.
4.a) For hierarchical routing with 4800 routers what region and cluster sizes should be chosen to minimize the size of the routing table for a 3-layer hierarchy.
b) provide an argument why the leaky bucket algorithm should allow just 1 packet per tick, independent of how large the packet is.
5.a) explain the various ATM service categories and their characteristics.
b) Briefly define about congestion control in VC subnets.
6.a) discuss in detail 4 protocol scenarios for releasing connection.
b) Datagram fragmentation and reassembly are handled by IP and are invisible to TCP. Does this mean that TCP does not have to worry about data arriving in the wrong order.
7.a) What is a Key distribution centre? What is a certificate authority?
b) discuss about proxy based firewalls.
8.a) discuss about SNMP protocol.
b) Write the format of Pretty Good privacy message and discuss every item in it.

Earning:   Approval pending.