BSc. (Hons.) Software Engineering Cohort: BSE/02/PT - BSE/03/FT - BSE/04/FT

Resit Examinations for 2005 - 2006 / Semester 1 Examinations for 2006 - 2007 / Semester 1

MODULE: COMMUNICATION AND NETWORKING – DESIGN AND MANAGEMENT MODULE CODE: BISE042 Duration: 2 Hours and 30 minutes

Instructions to Candidates: 1.

Answer all questions.

2.

Questions may be answered in any order but your answers must show the question number clearly.

3.

Always start a new question on a fresh page.

4.

All questions do not carry equal marks.

5.

Use of silent calculators is permitted in the Examination Room.

6.

Appendix is attached at the end of the question paper.

7.

Total marks 100.

This question paper contains 3 questions and 5 pages. Page 1 of 5 SB 101

ANSWER ALL QUESTIONS

QUESTION 1: (32 MARKS) a) Describe four issues that are usually addressed in the Needs Analysis phase in the building-block approach to network design. [4X1 marks]

b) Sketch a typical hybrid star ring topology paying attention how the clients and switching hubs are connected. [3 marks]

c) Two important failure parameters are: MTBF and MTTR. i) Explain the difference between those two parameters. ii) Calculate the reliability and the availability of a system given the MTBF is 2000 hours and the MTTR is 3 hours with a mission time of 30 days. [4+3 marks]

d) In terms of hardware redundancy, contrast the following: i) Full vs. Differential backup ii) RAID Level 1 vs. RAID Level 5 [2+4 marks]

e) Differentiate between each of the following: i) Packet-Level Firewall and Application-Level Firewall ii) Request and Trap SNMPv1 header fields iii) 802.11a and 802.11g in terms of rated speed and frequency range.

[4+4+4 marks]

Page 2 of 5 SB/101

QUESTION 2: (33 MARKS) a) Suppose a web client makes a request for a resource located on an internal web server using on a 10Mbps Ethernet LAN. The client and the server are connected via a store-N-forward switch as shown below. Assume that data travels over the media at around 2X108 m/s and a maximum Ethernet II frame size of 1518 bytes.

Calculate the total time that elapses from when the request is made and the resource is fully displayed on the web client. (Assume that request/response and TCP control messages are of negligible size; ignore application layer overhead; switching time is 50 µs; web server average processing delay is 100 ms; web client processing delay is about 100 ms per 1024 bytes of frame data; the resource is a small graphic file of 9182 bytes)

[10 marks]

b) Give the routing and forwarding table of the router and switch respectively and determine if host B can communicate directly with host C and if host A can communicate directly with host C? (show your work).

[6 marks] (Continued)… Page 3 of 5 SB/101

Question 2 : (continued) c) Give an example of a BER transmitted byte-stream by using the following module of data type declarations and its corresponding instances: nic ::= OCTET STRING sex ::= BOOLEAN (male=1, female=0) age ::= INTEGER {nic, “H1707751234567”} {sex, male} {age, 31}

[6 marks] d) i) Give the structure of an ATM NNI cell header and describe the role of each field in the header. [5 marks]

ii) Using a sketch, show how ATM cells are routed and explain the difference between virtual paths and virtual channels. [6 marks]

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QUESTION 3: (35 MARKS) a) Below is a capture of an Ethernet II frame which contains an IPv4 packet and a TCP segment. Give the source MAC address for the frame in hexadecimal; the source IP address, the total length in bytes and the header checksum for the packet in decimal; the destination port number in decimal for the segment and hence deduce the application layer protocol this segment is destined to. 0015 daf3 0050 0204

563a 4000 9347 05b4

4c79 8006 9790 0101

0013 024a 8897 0800 4500 0030 4673 c0a8 0142 480e cf68 08af 0000 0000 7002 4000 35e7 0000 0402 [2+2+1+1+2+2 marks]

b) Given a following information by your ISP about your newly acquired 256 kbps Frame

Relay Over IP connection: Public IP: 202.123.21.121 /28 •

You are required to design a network layout which constitutes of a LAN having 4 subnets (with Internet connectivity) for each department in your company.



3 of the 4 subnets are assumed to have each around 50 hosts, inclusive of a file server, an internal web server and a network printer.



One of the 4 subnets is to be connected using a wireless Access Point and all the hosts (around 19) on that subnet are assumed to be Wi-Fi ready.



Finally, all 4 subnets should make use of dynamic addressing.

Draw the network layout and giving maximum information about: •

IP, Subnet Mask & Gateway addresses of all devices, servers, printers, and 1 host from each subnet.



Type and hierarchy of hardware devices, transmission media and network topology you might adopt, with justifications, where necessary.

[25 marks]

***END OF QUESTION PAPER***

Page 5 of 5 SB/101