B227 Data Communications

Assignment 1

DUE DATE: 5pm Friday 24^th March 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:

(10 + 5 + 5 marks)
1. Describe the concept of layered software as it applies to data communications.
2. Using your description, explain the reasons for having layered software in data communications.
3. Explain how the following components of layered software relate to one another:
  - services
  - interfaces
  - protocols
  - network architectures
  - protocol stack
  - reference model
(7 + 5 + 3 marks)
1. Give a brief comparison between the OSI and the TCP/IP reference model.
2. Explain why the OSI model was not as widely eadopted as originally expected.
3. Explain the ratinale behind the reference model used in the textbook (as given in fig 1-21).
(3 + 7 marks)
1. For the following transmission media, state the approximate bandwidth and channel capacity achievable (where possible):
  - Twisted Pair Wires
  - Baseband and Broadband Coaxial Cables
  - Fiber Optic Cables
2. For each of the media in (a), describe the factors that affect the bandwidth and channel capacity.
(15 marks)

Explain the following, highlight the differences between them:
1. circuit switching
2. message switching
3. packet switching