Computer Networks Exam for Software Development Students, Autumn 2006, Exams of Computer Networks

Download Computer Networks Exam for Software Development Students, Autumn 2006 and more Exams Computer Networks in PDF only on Docsity! Cork Institute of Technology Bachelor of Science (Honours) in Software Development – Stage 2 (NFQ Level 8) Autumn 2006 Computer Networks (Time: 3 Hours) Answer 4 questions. All questions carry equal marks. Examiners: Ms. D. Griffin Dr. J. Twomey Dr. M. O’Cinneide Mr. M. Donnelly Q1. (a) Compare and briefly describe the following types of multiplexing: TDM and Statistical Multiplexing. (4 marks) (b) A number of 1200bps terminals are connected to a data-line having a bit rate of 19200bps. Estimate the maximum number of terminals that may be connected reliably to the line assuming low utilization. (4 marks) (c) If the bit rate of a particular system is EIGHT times the baud rate discuss in detail the consequences with respect to bandwidth requirements. (5 marks) (d) A telephone line has a bandwidth of 3500Hz and a Signal-To-Noise ratio of 33dB. Determine the maximum bit rate for error free communications. (Note log 2 X = 3.32 *log10 X). (5 marks) (e) Explain Pulse-Code-Modulation (PCM)? A PCM is used on an analogue signal band whose maximum frequency is 3000 Hz. If the modulation employs 8 bits, determine the bit rate and the equivalent bandwidth required. (7 marks) Q2. (a) Describe the operation of an Ethernet Network in relation to collision based mechanisms. (5marks) (b) What are the essential components of an Ethernet Frame? (3 marks) (c) In a network the segment length is 5000m. and the velocity of propagation on the network is 2.0*108 m/s . The data transmission rate is 25Mbps. Does this configuration support Ethernet? Derive the necessary relation. (8 marks) (d) List the main advantages of using optical fibers for data transmission. (4 marks) (e) The total latency of an FDDI ring consisting of 100 stations is 200 microseconds. Additionally, the latency per station is one microsecond. Determine the total or composite latency both in microseconds and also in terms of bits of delay assuming a transfer rate of 300Mbps. (5 marks) Q3 (a) Explain briefly what error detection is and how it functions. (3 marks) (b) Compare LRC, VRC and CRC and what does each type not detect? (5 marks) (c) What is the binary representation for the following polynomial:- X10+X3+X+1 (3 marks) (d) Find the CRC for the data 10110100 using the polynomial X3+X+1. (6 marks) (e) Another bit stream 10101110110 has been detected at the receiving end of a network. Has it been received error free ? [Use the polynomial X3+X+1 ] (6 marks) (f) When data is not received correctly what is the next stage in the process? (2 marks)