Home - CNDS - Teachers


Teachers Notes


Module number:


Module name:

Computer Networks and Distributed Systems

Module leader:

Dr William Buchanan



Timetable (Lecture/Tutorial)

The usage of Tutorial sessions is flexible and may vary depending on whether the main material has been covered in the Lecture session.

The main objective of the CNDS subject is to use the OSI model to present the functions of each of the lower five layers in a general way, and present specific protocols and networks which are implemented in these layers.

Week 1


Lecture: The first unit contains a basic introduction to networking, and focuses on the OSI model. Students should read the material on the OSI model as it provides a good foundation on the rest of the material. Unit 2 (Network Types), Unit 3 (Ethernet) and Unit 4 (ATM) focus on Layer 1 and Layer 2; Unit 5 (IP) focuses on Layer 3; Unit 6 (TCP) focus on Layer 4; and Unit 7 (Security) and Unit 8 (Session/Presentation) mainly focus on Layer 5 and Layer 6. A key objective of the module is the complete understanding of how data travels from one application to another over the Internet. The OSI model provides a good foundation for this understanding. In the teaching pack, the presentation material contains an introductory chapter on the Internet, WWW, and so on. This can be used to provide a broad overview of the subject, and, if possible, the lecturer should discuss current trends (such as the move towards new addressing systems). An important concept in the introductory material is to show that the WWW is just one of the applications of the Internet. If possible outline how the WWW differs from the Internet, and try to formalize the usage of these terms. Along with this the difference between an internet and the Internet can also be presented. It is unlikely that students will completely understand the OSI model at this stage, as it is presented in an abstract way. Once the main protocols have been covered it should become more apparent for it usage.

Lecture 1 (Pre-Introduction)
Lecture 2 (Introduction)

Tutorial: There will be no tutorial session in the first week, as this could be used to present the OSI model. If the lecturer has time they should outline the basic structure of the module, especially on the aims of the module, and the timetable (as defined in the Module Organizer).

Worksheet: In the first week, the students should also be introduced to the local network, and be given login's, as well as being shown how to access the Internet. The first Practical Worksheet should be completed over a period of two weeks, and is intended to be a gentle introduction to the WWW, and its search facilities. An on-line version is also available from the cnds@napier WWW site.


Week 2


Lecture: The second unit covers some of the fundamentals of networking, and discusses networking topology, networking elements, and an introduction to network cabling. A key concept is the difference of network topologies, and their advantages and disadvantages. In addition, it is important to understand the principles of CSMA/CD, as this will be expanded in the Ethernet unit. Finally, the usage of repeaters, bridges and routers, and their functionality should be highlighted. [Unit]

Lecture 3 (Network Types)

Tutorial: The final exam in the coming years will focus more on multiple-choice questions, so it is important that students gain access in these. If possible, the lecturer should get students to complete the tutorial for Unit 1 in a tutorial session. The answers to these could be discussed in an interactive way. This tutorial can also be completed as an on-line exam at the cnds@napier WWW site.

Worksheets: This should involve the completion of the research. Hopefully network logins, the distribution of notes, and so on, should be sorted-out, and every student can get access to the network, and the Internet.


Week 3


Lecture: As the project and some of the practical work is based on TCP/IP communications, it is important to cover the network layer before the rest of the material. This unit presents the network layer in a general way, in respect to its two main functions: network addressing and path determination. It then discusses the most widely used network layer protocol, which is IP. The main points to emphasize are data encapsulation, the IP header, IP classes and IP allocation. If possible use examples of IP address allocation from your own institution, and how these are used to segment the network. Note that there is no need to go into detail in many of the areas, as these should be left to the student to read the material in their own time. [Unit]

Tutorial: The tutorial session can either be used to cover the rest of the material from the IP unit, or can be used to cover the tutorial test. If there is not enough time for the tutorial, the tutorial in the following week can be used to cover two of the tutorial sessions.

Worksheet: This worksheet gives a basic introduction to the concept of ping, which is one of the most widely used techniques for testing a network connection. Various WWW sites around the Internet have been chosen. These can be changed, depending on the situation. NOTE: This worksheet can be customized for the required setup, the main principle is to show how ping is used to sense if a host is operating, and to give a basic measure of the time that data packets take to reach a destination.


Week 4


Lecture: Unit 6 provides a foundation on TCP/UDP. As with the unit on IP, this unit presents the functionality of the corresponding layer: the transport layer. This is then expanded to show how TCP/UDP implements the functions of the transport layer. The main point to emphasize is the functions of the Transport Layer, such as flow control and windowing, and how these are implemented in the TCP protocol. Particular attention should be paid to the difference between TCP and UDP, and that UDP would be used where a higher level protocol provides error detection, and recovery. As with the previous lectures, the students should be encouraged to read the whole of the unit. There is no need for the lecturer to go into any great detail on the topic as this is part of the independent learning for the student. As much as possible students should be encouraged to ask questions to the lecturer or from the cnds@napier site. [Unit]

Tutorial: This class can either be used to cover the tutorial sheets on Unit 2 and Unit 5, or can be used to cover some of the material not covered in lecture.

Worksheet: This worksheet outlines some of the main concepts in determining the route to a remote note (using traceroute). As with ping, this is used extensively to test a network when there is a fault. NOTE: This worksheet can be customized for the required setup.

Client program [ZIP]
Server program [ZIP]

Week 5


Lecture: Security is becoming one of the major issues on the Internet, and within corporate networks, thus this is an important area to discuss the main methods of protecting a network from external sources. The usage of firewalls is key to the understanding network security, especially in terms of how the firewall filters at both the network and the transport layer. If possible try and relate up-to-date security breaches to the material, especially in relation to the spread of macro/worm viruses. Along with this the material covers some of the ways that users must guard against external parties from reading and/or modifying their data. An important concept is that Ethernet, IP and TCP are open technologies and provide very little protection against users viewing and editing any transmitted or received data. [Unit]

Tutorial: This class can either be used to catch up on previous material, or to cover previous material.

Worksheet: This worksheet gives a basic introduction to how a user can determine the basic setup of their host (using WINIPCFG or IPCONFIG). NOTE: This worksheet can be customized for the required setup.


Week 6


Lecture: The third unit covers Ethernet, and should provide a foundation in the methods that Ethernet uses to communicate, and the different types of Ethernet. In the tutorial, the students will be given the second multiple-choice tutorial, which is based on the material in Unit 2. [Unit]


Week 7


Lecture: This is a continuation of the Ethernet material and discusses ARP. [Unit]

Week 8


Lecture: vLANs are becoming a major issue, and are the answer to increasing bandwidth, and improving security. The usage of switches is fundamental to this. [Unit]


Week 9


The forth unit gives an introduction to ATM. The main points to emphasize are that ATM integrates different types of networking traffic, and the method that ATM uses to route cells around the network. If possible discuss a practical network which uses ATM (see EaStMAN and SuperJANET structure, for an example). A few of the MANs around the UK are:



Week 10

Session and presentation layer

The main emphasis on this unit is on the difference between client-side includes and server-side includes. If possible highlight how client-side includes and server-side includes are integrated into a WWW page. [Unit]


Week 11


To be completed.


Week 12


To be completed.

Week 13


To be completed.


Week No.
Lecture/Tut 1
Lecture/Tut 2
Introduction (Unit 1)
OSI Model (Unit 1)
Network Introduction and Introduction to WWW (1)
Network Types (Unit 2)
Intro Tut
IP (Unit 5)
Network Types Tut
Ping (2)
TCP (Unit 6)
IP Tut
Tracert (3)
Security (Unit 7)
NetStat/IPConfig (4)
Ethernet (Unit 3)
Security Tut
WinSock (5)
ARP (Unit 3)
Ethernet Tut
Client-server (6)
Switches/LANs (Unit 3)
ATM  (Unit 4)
Switches Tut
WWW Programming (Unit 8)
WWW Programming Tut

Note 1. Practicals and the Project require customization for the local network, and will change depending on each College/University. Drafts of the Practicals and the Project are enclosed, and final versions will depend on the local College/University.

Reference material

Buchanan WJ, Mastering Computing, Palgrave.

Buchanan WJ, "Distributed Systems and Networks", McGraw-Hill, 2000, ISBN 0-077-09583-9.

Buchanan WJ, "Mastering Networks", Macmillan, 1999. ISBN 0-333-748042.