Code No: RR Set No. 1

Transcription

1 Code No: RR Set No (a) Write any four reasons for using layered protocols. (b) List two ways in which the OSI reference model and the TCP/IP reference model are the same and list in which they differ. (c) Which is the principle difference between CO communication and CL communication. [6+4+6] 2. (a) Briefly, explain about the DLL design issues. (b) If the bit string is bit stuffed. What is the output of the string? [8+8] 3. (a) Explain in detail the operation of slotted ALOHA. (b) Consider the delay of pure ALOHA versus slotted ALOHA at low load. Which one is less? Explain your answer. [8+8] 4. Explain congestion. How do we control the same? Which packets are used practically for this purpose? At what layer this is done? What is the difference between flow control and congestion control? [16] 5. (a) Imagine a generalized n-army problem, in which the agreement of any two of the armies is sufficient for victory. Does a protocol exist that allows blue to win? (b) Suppose that the clock-driven scheme for generating initial sequence numbers is used with a 15-bit wide clock counter. The clock ticks once every 100msec, and the maximum packet lifetime is 60sec. How often need resynchronization take place i. in the worst case? ii. when the data consumes 240 sequence numbers/min? (c) Why does the maximum packet lifetime, T, have to be large enough to ensure that not only the packet, but also its acknowledgements, have vanished? [6+6+4] 6. (a) Briefly discuss about Concatenated Virtual Circuits. (b) Briefly discuss about connection less Internetworking. [8+8] 1 of 2

2 Code No: RR Set No (a) Give the format of UDP segment and TCP segment? Explain when UDP is preferred to TCP? (b) What are blocking calls, primitives and non-blocking primitives? [8+8] 8. (a) What is public key cryptography? With an example, Explain RSA Algorithm. (b) Explain Diffie-Hellman key exchange Authentication protocol. [8+8] 2 of 2

3 Code No: RR Set No (a) Briefly explain about the TCP/IP reference model. (b) Compare and contrast OSI and TCP/IP models. [8+8] 2. Explain in detail about elementary DLL protocols. [16] 3. (a) Explain static channel allocation in LANs and MANs. (b) Explain five key Assumptions in Dynamic channel allocation in LANs and MANs. [8+8] 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 three-layer hierarchy? (b) Compute a multicast spanning tree for router C in the subnet below for a group with member at routers A, B, C, D, E, F, I, and K. Shown in figure 4b Figure 4b (c) Give an argument why the leaky bucket algorithm should allow just one packet per tick, independent of how large the packet is. [6+4+6] 5. (a) Define the following terms. i. Option Negotiation ii. Transport quality iii. Transport service user iv. Transport service provider (b) Explain in detail Four protocol scenarios for releasing a connection. [8+8] 6. (a) Briefly discuss ICMP. 1 of 2

4 Code No: RR Set No. 2 (b) Discuss the two styles of internetworking. [8+8] 7. (a) To get around the problem of sequence numbers wrapping around while old packets still exist, one could use 64-bit sequence numbers. However, theoretically, an optical fiber can run at 75 Tbps. What maximum packet lifetime is required to make sure that future 75 Tbps networks do not have wraparound problems even with 64-bit sequence numbers? Assume that each byte has its own sequence number, as TCP does. (b) AAL 3/4 allows multiple sessions to be multiplexed onto a single virtual circuit. Give an example of a situation in which that has no value. Assume that one virtual circuit has sufficient bandwidth to carry all the traffic. (c) In a network that has a maximum TPDU size of 128 bytes, a maximum TPDU lifetime of 30 sec, and an 8-bit sequence number, what is the maximum data rate per connection? [6+6+4] 8. (a) Explain in detail methods of DES chaining. (b) Briefly discuss about IDEA. [8+8] 2 of 2

5 Code No: RR Set No (a) Write any four reasons for using layered protocols. (b) List two ways in which the OSI reference model and the TCP/IP reference model are the same and list in which they differ. (c) Which is the principle difference between CO communication and CL communication. [6+4+6] 2. (a) What is the reminder obtained by dividing x 7 +x 5 +1 by the generator x 3 +1? (b) Frames of 1000 bits are sent over a 1-Mbps-satellite channel. Acknowledgements are always piggybacked onto data frames. The headers are very short. Three-bit sequence numbers are used. What is the maximum achievable channel utilization for i. Stop-and-wait ii. Go-back n. iii. Selective repeat. [8+8] 3. (a) What is meant by contention systems. (b) Explain CSMA/CD protocol. (c) Explain any one Collision free protocol. [4+6+6] 4. In the link state Routing Algorithm explain how to (a) Learn about neighbours (b) Measure the line cost. (c) Build Link state Packets (d) Distributing Link state packets, and (e) Compute the New routes. [16] 5. (a) Briefly explain the concepts of Flow Control and Buffering. (b) What is multiplexing? Briefly explain upward and downward multiplexing. [8+8] 6. (a) What is tunneling? Can tunneling be used in datagram subnets? If so, how? (b) With an example, explain Address resolution protocol. [8+8] 1 of 2

6 Code No: RR Set No (a) Draw and explain the structure of the ATM Adaptation layer. (b) Briefly discuss about TCP timer management. [8+8] 8. (a) What is Cryptanalysis? Briefly discuss about substitution cipher, transposition ciphers and one-time pads. (b) Explain any one secrete key algorithm. [8+8] 2 of 2

7 Code No: RR Set No (a) Write any four reasons for using layered protocols. (b) List two ways in which the OSI reference model and the TCP/IP reference model are the same and list in which they differ. (c) Which is the principle difference between CO communication and CL communication. [6+4+6] 2. (a) Mentioning the advantages and disadvantages, explain sliding window protocol using Go back n and using selective repeat. (b) Draw, and explain about HDLC protocol. [8+8] 3. (a) A 4-Mbps token ring has a token-holding timer value of 10m sec. What is the longest frame that can be sent on this ring? (b) In a token ring the sender removes the frame. What modifications to the system would be needed to have the receiver remove the frame instead, and what would the consequences be? [8+8] 4. (a) What are the problem which caused demise of distance vector routing? Explain the algorithm that replaced it? (b) With an example, explain Distance Vector Routing algorithm? [8+8] 5. (a) Explain Berkeley socket primitives for TCP. (b) Briefly explain the concept of Addressing in TL. [8+8] 6. (a) What is tunneling? Can tunneling be used in datagram subnets? If so, how? (b) What is three bears problem? Write short notes on CIDR. [8+8] 7. (a) Give the format of UDP segment and TCP segment? Explain when UDP is preferred to TCP? (b) Briefly discuss about TCP timer management. [8+8] 8. (a) What is MOSPF? Discuss briefly about Multicast Backbone. (b) What is ADSL? Draw, Explain the ADSL as the local distribution network. [8+8] 1 of 1