CCN Module: II : Peer to Peer Protocols ( 20 Marks ) By Kamal Rochlani

N.B: Questions printed in different color were asked in Mumbai University exams.

Peer to Peer Protocols & Service Models

(Q: 1) What is SDU & PDU? Also Explain the function of Peer to Peer Protocol . 3

(Q:2) What is service Model? What are two different types of service models? Explain them in detail. 10

End to End requirements & Adaption function ,End to End Versus hop by hop

(Q: 3) Write short note on : End to End Versus Hop by Hop 10

Data Link Controls

(Q: 4) Explain the function of data link layer (DLL). 4

(Q:5) Write short note on: Flow control in data link layer. 6 OR State few means of flow control in short. 8 OR Write short note on Error & flow control. 4

(Q:6) Explain ‘character based-framing’ & ‘bit oriented framing’ with suitable example. 10 OR Explain in brief the different framing methods. 4 OR Explain bit oriented framing, with the problems encountered in it. Discuss how length of fields can help in framing? 8 OR Explain ‘Character stuffing’. 5 OR Explain ‘ Bit stuffing’. 5 OR What is data transparency? Explain bit stuffing & Destuffing. 5 OR What should be the optimum frame size? Also explain what happens to framing in the presence of errors? 8 ARQ Protocol

(Q:7) What is ARQ? What are types of ARQs? 4

Stop and Wait ARQ

(Q:8) Explain simplex stop & wait protocol with examples and suitable diagrams. 10

Sliding window Protocols : Go Back-N ARQ , selective Repeat ARQ

(Q:9) What is sliding window Protocol? 4

(Q:10) Explain n bit sliding window protocol with suitable example? 6 OR Explain with example the number of frames that can be sent without acknowledgement for a window of size N for ARQ Protocols. 8

BE EXTC SEM VII -2- CCN QB By Kamal Rochlani

(Q:11) Explain Go-Back N technique of sliding window ARQ Protocol. 5

(Q:12) Explain sliding window protocol. Draw the sender and receiver windos for a system using Go-Back-N sliding window system given that

i. Frame 0 is sent; Frame 0 is ACKii. Frames 1 and 2 are sent; Frames 1 and 2 are ACK.

iii. Frames 3,4,5 are sent. Frame 4 is ACK. Timer for frame 5 expires.iv. Frames 5,6,7 are sent, Frames 4 through 7 are ACK. 10

(Q:13) Explain Selective Reject technique of sliding window ARQ Protocol. 5 OR Explain working of selective Repeat ARQ. 5

Sliding Window Flow control

(Q:14) Explain sliding window flow control with the help of neat diagram. 10 OR Explain how sliding window protocol is used for flow control? 10 OR What is significance of ACK & SEQ numbers in flow control protocol? Why Pipelining is necessary with sliding window protocol? 10

(Q:15) In sliding window flow control method. Why the size of window is one less than the modulo range? 4

(Q:16) Explain the relation between sliding window & ARQ Protocols. 8

Transmission Efficiency of ARQ protocols

(Q:17) Explain the Performance issues in ARQ. 10

(Q:18) Define utilization or efficiency of the line & derive expression for Stop & wait flow control & sliding window flow Control. 10 (Q:19)Derive transmission efficiency of Go-Back N ARQ. State the efficiency of Bit error rate & delay BW product on the Transmission efficiency. 10

(Q:20) which protocol Go-Back-N or Selective Repeat makes more efficient use of network bandwidth ? why? 5

(Q:21) PROBLEMS:

(i) An error free 128 Kbps satellite channel with a propagation delay of 270ms is used to transport 256 bytes frames in one direction with very short ACK’s coming back the other way. Determine the maximum throughput ( frames per sec)for window sizes of 1,7,15 & 127. 6

(ii) Calculate the throughput for stop & wait flow control mechanism if the frame size 4800 bits. Bit rate is 9600 bps & distance between device is 2000km. speed of propagation over the transmission is 200000 km/s. 5 (iii)A channel has a bit rate 4 Kbps and propagation delay of 20ms. For what range of frame sizes does stop and Wait gives an efficiency of at least 50%. 5

(iV) A channel has a bit rate of 4.8 kbps & a propagation delay of 20 msec. for what range of a frame size does stop

& wait protocols given an efficiency of 50%. 5BE EXTC SEM VII -3- CCN QB By Kamal Rochlani

Timing Recovery for synchronous services, Reliable stream service

(Q:22) Write short note on : Timing recovery for synchronous services & Reliable Stream service. 10 OR Explain the need of synchronization in detail. 8 OR Framing helps in synchronization & error handling. Explain with suitable examples. 8

Statistical Multiplexing

(Q:23) Write short on: Statistical Multiplexing 5

HDLC Date Link Control

(Q:24) Write detailed note on : HDLC data link control. 10OR

Explain HDLC frame format. 10 OR Discuss the various modes of communication ( response modes) , configurations & frame formats in HDLC. 10

(Q:25) The HDLC frame below is sent from primary to secondary answer the following questions – 4

01111110 00001111 10001011 FCS 01111110

i. What is the address of the secondary?ii. What is the type of frame?

iii. What is the sender sequence number ( if Present)iv. What is the acknowledgement number ( if Present)v. Does the frame carry user data ? if yes what is the value of data?

vi. Does the frame carry management data? If yes what is the value of data?vii. What is the purpose of the frame?

Ponit to Point Protocol

(Q:26) write short note on PPP or Point to Point Protocol. 10