1. Activity 1 5 minutes to discuss and feedback on the following:
What is a computer network?
Write down all the words / phrases / acronyms you already know about computer networking.

2. Computer Communications and Networking
Topic 6 Lesson 1: LANs
Computer Communications and Networking

3. (this can involve physical or wireless connections, or both)
Networking - LANs
Learning Objectives:
i) Understand what is meant by computer networking
ii) Explain the advantages of a Local Area Network (LAN)
iii) Describe the hardware needed to create a LAN
iv) Understand the different roles of computers in peer-to-peer and client-server networks
v) Describe (using diagrams) bus, ring & star network topologies
What is a Computer Network?
Two or more computers connected together to share information and resources.
(this can involve physical or wireless connections, or both)

4. Networking - LANs A school network An office network A home network
Learning Objectives:
i) Understand what is meant by computer networking
ii) Explain the advantages of a Local Area Network (LAN)
iii) Describe the hardware needed to create a LAN
iv) Understand the different roles of computers in peer-to-peer and client-server networks
v) Describe (using diagrams) bus, ring & star network topologies
A school network
An office network
A home network

5. Networking - LANs
Learning Objectives:
i) Understand what is meant by computer networking
ii) Explain the advantages of a Local Area Network (LAN)
iii) Describe the hardware needed to create a LAN
iv) Understand the different roles of computers in peer-to-peer and client-server networks
v) Describe (using diagrams) bus, ring & star network topologies
Learning Check? So What is a Computer Network? Two or more computers connected together to share information and resources.

6. Networking - LANs What is a LAN? A LAN is a Local Area Network.
Learning Objectives:
i) Understand what is meant by computer networking
ii) Explain the advantages of a Local Area Network (LAN)
iii) Describe the hardware needed to create a LAN
iv) Understand the different roles of computers in peer-to-peer and client-server networks
v) Describe (using diagrams) bus, ring & star network topologies
What is a LAN?
A LAN is a Local Area Network.
It is a connected set of computers and other devices.
Each device is called a node (e.g. computer, printer, etc.)
A LAN is installed on one site.
Relatively small
All network infrastructure is owned by the organisation

7. Local Area Network (LAN)
Advantages
It allows communications between workers / students
It allows data to be shared
It allows peripherals (e.g. printers) to be shared
It allows computers to be upgraded more easily
It allows distributed processing – the ability for a single program to be run simultaneously at various computers.

8. Local Area Network (LAN)
Disadvantages
Expertise required to set up and maintain a large network (costly)
Security issues from unauthorised access to data
Measures to secure a network include:
Passwords – strong passwords use a range of character types
Changing passwords frequently
Not allowing users to install software
With wireless access, use encryption

9. Networking - LANs What is needed to make a LAN? Networking Equipment
Learning Objectives:
i) Understand what is meant by computer networking
ii) Explain the advantages of a Local Area Network (LAN)
iii) Describe the hardware needed to create a LAN
iv) Understand the different roles of computers in peer-to-peer and client-server networks
v) Describe (using diagrams) bus, ring & star network topologies
What is needed to make a LAN?
Networking Equipment

10. + Hardware needed At least two computers (Nodes)
Each having a NIC – network interface card (either wired or wireless)
The NICs convert the data signals from the nodes into data signals that can be transferred across the network.

11. Hardware needed
Data Transfer Media
Wires
Wireless Technology

12. OR Switch Hub A device that connects nodes together.
An intelligent device that can create and connect to different segments of the network.
This reduces network traffic because data packets are sent to the nodes or segment where they are needed rather than being broadcast to the whole network.
Hub
A device that connects
nodes together.
Makes all connected nodes
act as a single segment.
Not intelligent – data
packets are transmitted
across the whole of the
network.
Cheap devices – USB hubs
useful in home computer
installations.

13. Hardware needed
If the LAN is to connect to the Internet, a Router is needed.
Routers work with data packets to send data between networks (e.g. over the internet)

14. Side Track….Wireless Home Networks
Wireless access point
Wireless technology has many advantages over wired networks:
No building work needed
Quick to add new workstations
Flexible deployment of nodes
Visitors can access network / internet
But there are drawbacks:
Slower performance
Security issues

15. Networking - LANs Two Types of Network in a LAN: Peer-to-Peer
Learning Objectives:
i) Understand what is meant by computer networking
ii) Explain the advantages of a Local Area Network (LAN)
iii) Describe the hardware needed to create a LAN
iv) Understand the different roles of computers in peer-to-peer and client-server networks
v) Describe (using diagrams) bus, ring & star network topologies
Two Types of Network in a LAN:
Peer-to-Peer
Client-Server

16. Network types: peer-to-peer
All computers have the same status.
May be very slow because of
data collisions
shared processor power
Only suitable for small, low traffic networks.
Very popular for home networks

17. Network types: client-server
At least one computer is designated as a server.
This must be a high specification machine.
It offers services to client machines, such as centrally held software, data, file storage and peripheral access.
The server:
controls the network traffic.
Logs usage of resources.
Provides security.
Clients have to log in – this identifies users and assigns rights.
Big networks may have hundreds of servers.

18. Networking - LANs Bus Ring Star
Learning Objectives:
i) Understand what is meant by computer networking
ii) Explain the advantages of a Local Area Network (LAN)
iii) Describe the hardware needed to create a LAN
iv) Understand the different roles of computers in peer-to-peer and client-server networks
v) Describe (using diagrams) bus, ring & star network topologies
Different ways that LANs can be set up: …these network setups are known as topologies
Bus
Ring
Star

19. Network Topology The topology is the physical layout of the network.
It affects:
cost,
performance,
ease of installation.

20. Bus topology One common linking cable Nodes connected off the cable
Cheap
But:
Slows down when heavily trafficked
Lots of data collisions
Any breakage to cable affects the whole network
Only practical over limited distances

21. Ring topology One common linking cable Data passes all nodes
One direction traffic
Fast performance
BUT:
any problems and the whole network goes down.

22. Star topology Now the most common topology
Shared link to server(s) via hub or switch
Few data collisions
Fast
Can set up independent segments
BUT – the most expensive topology as it requires the most cable

23. Activity 2
30 minutes:
What type of network (client-server OR peer-to-peer) is suitable for ten or more users? Explain your choice. (3 marks)
State three types of resources that are commonly shared on a network. (3 marks)
Name a type of computer that can provide services but also request services off other computers. (1 mark)
Describe and illustrate a star network topology. (2 marks)
A small company has a tight budget & four workers. Describe the type of network topology that is best suited for them. (3 marks)
Explain what is meant by a client computer. (3 marks)
List the hardware that is required to connect any device to a Local Area Network (LAN). (5 marks)
In your own words, describe what a network switch does. (3 marks)