B227 Data Communications

Assignment 2 (External Students only)

DUE DATE: 5pm Friday 12^th May 2000.

This assignment is worth 10% of your final mark in this unit. As stated in the unit outline, YOU MUST SUBMIT this assignment to pass the unit.

Questions:

Each question is worth 4 marks, plus an extra 8 marks for presentation to make a total of 100 marks. Presentation will consist of conciseness and clarity in writing, and neatness of submitted document.

1. In using a sliding window protocol with selective repeat, I have a sequence numbers 1-7 and maximum window size of 4 for sender and receiver. Describe a situation when this would cause a problem. How do you rectify this problem?
2. In designing a new data link layer protocol, I decide that since the IP protocol in the network layer already has checksuming for its packet headers, I don't need to include checksuming in my protocol. Would this be a rational decision? Why?
3. Under what scenario will a new station fail to ever join the logical ring in a 802.4 Token Bus network?
4. In slotted ALOHA, why does the throughput per frame time decrease when the network averages over 1 attempt at transmission per packet time?
5. From the textbook Computer Networks (3^rd Ed) by Andrew Tanenbaum, answer the following questions at the end of chapters:
   • Chapter 3, Questions 3, 7, 30.
   • Chapter 4, Questions 2, 10, 17, 22, 23, 25, 27, 30, 31, 35, 36, 39.
   • Chapter 5, Questions 1, 3, 7, 14.

Document author: H.L. Hiew, Unit Coordinator
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