DataCom exam10 - STUDENT ID N 0 MULTIMEDIA umveresnv mm...

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Unformatted text preview: STUDENT ID N 0 MULTIMEDIA umveresnv mm MULTIMEDIA UNIVERSITY THIRD TRIMESTER EXAMINATION, SESSION 2006/07 SUPPLEMENTARY ECP2056 — DATA COMMUNICATIONS AND COMPUTER NETWORKING (EE, TE, CE, ME, MCE, OPE, NANO and BMM) 22 JUNE 2007 3:00 PM — 5:00 PM (2 HOURS) INSTRUCTION TO STUDENT 1. This Question paper consists of 5 pages including cover page with 2 Sections and 6 Questions only. 2. Attempt TWO out of THREE questions from EACH SECTION. All questions carry equal marks and the distribution of the marks for each question is given. 3. Please print all your answers in the an3wer Booklet provided. ECP2056 DATA COMMUNICATIONS AND COMPUTER NETWORKING ‘ JUNE 2007 SECTION A (Attempt any 2 out of 3 questiOns fiom this section) Question 1 (a) What is data communications? Name four forms of data which may be transferred over communication systems. [6 marks] (b) The 081 (Open Systems Interconnection) Reference Model is a layered, abstract description for communications and computer network protocol design. Briefly explain the main functions of each layer, starting from the top-most to the bottom- most layer. [8 marks] (0) Referring to the 081 Reference Model, how can communication be achieved between two communicating systems? Explain your answer using an illustration which includes the communication between a layer of a system and its peer layer at a remote system. [11 marks] film (a) With the aid of diagrams, explain the meaning of the following operatioual modes of a communication channel. 1. Simplex [2 mark] ii. Half-duplex [2 mark] iii. Full-duplex [2 mark] (b) With the aid of diagrams, explain how frame synchronization is achieved with an asynchronous transmission control scheme, assuming the data being transmitted is: i. printable characters. [4 marks] ii. binary bytes. [4 marks] (c) Given data M = 1001001002 {leftmost bit is the most significant) and generator polynomial G(x) = x4 + x3 + 1 for generating a 4-bit CRC. i. Determine the transmitted bit stream. [3 marks] ii. Show how error detection is performed at the receiver side. [3 marks] iii. Assuming that during transmission, the third bit (counting from the most significant bit) is in error. What is the received bit stream? Show how the detection algorithm detects the error. [3 marks] (d) A digital signaling system is required to operate at 12800bps. If a signal element encodes a 4-bit symbol, what is the minimum required bandwidth of the channel? [2 marks] Continued LSUNNA/GHAJ’ZMS/MHH/TWH 2 / 5 ECP2056 DATA COMMUNICATIONS AND COMPUTER NETWORKING _ JUNE 2007 Question 3 (a) Define the functionality of flow control and error control in data link layer. [6 marks] (b) i. A computer is using the following sequence number: 0,1, 2, 3, 4, 5, 6, 7, 0, 1,2, How many bits are used to show the sequence number? [2 marks] ii. What is the maximum size of sender and receiver window if Go-Back—N ARQ and Selective Repeat ARQ are used? [8 marks] (c) A multiplexer combines five 100kbps channels. Every slot of the output frame has 4 bits. What are the bit rate and the frame rate of the output? [5 marks] (d) List out the step in analog-to—digital signal conversion. [4 marks] Continued LSUNNA/GHA/ZMS/MHHII'WH 3 / 5 ECP2056 DATA COMMUNICATIONS AND COMPUTER NETWORKING JUNE 2007 SECTION B (Attempt any 2 out of 3 questions from this section) Question 4 (a) Name three different types of fiber and sketch how the light propagates through them. [6 marks] (b) Explain and sketch a diagram to differentiate between non—persistent and p-persistent strategy. [11 marks] (0) A token ring network has 12 equally spaced stations and the length of the ring is 50km. The network has 20 repeaters with I bit delay. The data rate is I Mbps. The token generation time is negligible. Assnme that the propagation speed on the medium is 2x108ms‘1. i. Find the value of a if the utilization of the ring is 90%. [4 marks] ii. Find the corresponding frame length in (i) [4 marks] The network utilization is given by 1 a S I U z 1 +13/N —— a > 1 a (1 + a) where a is the ratio of propagation delay to frame transmission time N is the number of stations on the network Continued LSL/NNA/GHA/ZMS/MHH/TWH 4 / 5 ECP2056- DATA COMMUNICATIONS AND COMPUTER NETWORKING TUNE-2007 Question 5 (a) Describe the fundamental difference between circuit switching and packet switching. [2 marks] (b) What is virtual circuit packet switching? What is datagram packet switching? What is the key advantage of each? [4 marks] (c) You are required to build a three-stage space-division switch with 100 inputs and outputs. To do this, you need to use 10 crossbar switches at the first and third stage and 6 at the middle stage. i. Draw the configuration diagram. [4 marks] ii. Calculate the total number crosspoints. Show your calculation clearly. [2 marks] iii. Find the possible number of simultaneous connections. Show your calculation clearly. [2 marks] iv. If you only use a single crossbar switch (100x100), what are the possible numbers of simultaneous connections and crosspoints? Show your calculation clearly. [4 marks] v. By comparing your results in (iii) and (iv), derive a logical conclusion. State your analysis clearly. [3 marks] ((11) A network engineer has configured for a frame relay network to only transmit frames with size up to 1600 octets (including the overhead). A uSer wants to send a file of size 6000 octets over this frame relay network. What is the protocol efficiency in transmitting this file? Show your calculation clearly. (Hint: Protocol efficiency is the ratio of data sent and the bandwidth required. Assume the address field is 2 bytes.) [4 marks] Question 6 (a) Describe what an IP address is and how it is composed. [4 marks] (b) IPv4 is the current version of Internet Protocol, and IPv6 is the proposed successor of IPv4 in the near future. Explain four enhancements of IPv6 as compared to IPv4. [8 marks] (c) Complete and reproduce the table below in your answer booklet (please also show your working where necessary). IP address mm Subnet address W 129.228.16.113 _ 255.255.1920 — 195.128.354 _ 255.255.2550 — 125.105.37.191 — 255.255.255.224 _ [9 marks] (d) ARP (Address Resolution Protocol) is a protocol at the data link layer. What is the function of ARP? [2 marks] (e) i. How can various client and server applications be identified [1 mark] ii. What made up a socket address? [1 mark] End of Paper LSUNNA/GHA/ZMSI’MHH/TWH 5 /5 ...
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This note was uploaded on 08/27/2009 for the course FET etm taught by Professor Hi during the Spring '09 term at Multimedia University, Cyberjaya.

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DataCom exam10 - STUDENT ID N 0 MULTIMEDIA umveresnv mm...

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