1. 1.4 Wired and Wireless Networks
In this unit you will cover…

2. 1. Types of Networks This lesson you will know:
The purpose of networks
The definition and difference between a WAN/LAN
The definition of a Client-Server network
The definition of a Peer-to-Peer network

3. L/O
To be able to identify and describe basic characteristics of a computer network
To be able to describe the main types of network infrastructure
To identify the difference between the main types of network

4. Networks
Networks are all around us; some are more obvious than others. You’d be pretty hopeless without them though
Firstly; get it into your head that network isn’t exclusively a Computing term
Think of all of the non-computer networks that we rely on daily…
Friend/family groups
Transport (roads, trains, busses, air-travel, etc.!)
Electricity grid
Without talking about computers, how could you define network?

5. Computer Networks
We already have a nice idea of why Computer Networks are useful but that’s only scratching the surface of how much we use them
30 seconds – think of as many different different Computer Networks that you rely on from day-to- day

6. Networks
You now know that a network is a group of things or people that are connected somehow
A Computer Network is a set of devices (computers) connected together allowing them to communicate and share resources
This isn’t limited to Desktop Computers. There are literally thousands of different networkable devices..

7. This astute lady is using her brain
WAN/LAN
You need to know the difference between a WAN and a LAN. It’s dead easy…
WAN - Wide Area Network
LAN – Local Area Network
Switch-your-brain-on time; Look at both of them and take a wild stab in the dark as to what’s different about them – I’ve got all day
This astute lady is using her brain

8. LAN
Local Area Network
These are Computer Networks that are restricted to a single geographic location
Examples that you use all the time include your home wireless network and the school network

9. LAN - Characteristics Covers a small, local geographic area
Ownership – usually the individual or organization owns and is responsible for all the equipment:
Cables
Switches
Devices
This equipment is dedicated – it’s not for anyone else!
Administration – The owner is responsible for all administration of the network

10. WAN Wide Area Network These cover a large geographic area
Some examples include:
JANET (the academic network that links schools and universities)
National Rail Network (tickets and times)
Retail (stock management, statistics etc)
The most obvious WAN that you probably didn’t think of is….

11. THE INTERNET (a WAN)
The Internet is the biggest Computer Network in existence, and it is constantly growing
The Internet is a collection of millions of computer networks that are connected together all across the world
We’ll look at the Internet in a lot more depth in a later lesson

12. WAN - Characteristics
Whereas a LAN depends on all its own network hardware a WAN will usually rely on external infrastructure
For example; the school is connected to the JANET Academic WAN for internet however this network is carried over BT and Virgin’s cabling across the country
Some WANs may use satellite, telephone lines, the internet. These links are SHARED and therefore not dedicated links.

13. Why different types? Why the different types of network?
Some things we want to share with other networks, some we do not (internal/external)
A way of identifying responsibility for different parts of large networks
Do you want strangers half way across the world accessing your files or watching your network security camera?

14. Task Complete “activity 1” from the shared area
Print and stick in your books

15. Exam Questions

17. Geographic!

20. Client-Server
¿Que?
A server in a network provides a shared service or resource that is available to devices on that network
The client (individual devices on the network) requests services from the server
These could be; login; file; print; update; internet services (to name a few!)

21. Client-Server
As the name suggests, a client-server network relies on a central server on the network
Servers often need to be high-specification
This is so they can run reliably and meet capacity requirements (all devices on the network are able to use them)
They might have specialist networking hardware, additional processors, redundant hardware and backup power
As a result they are often expensive and require maintaining to ensure consistent reliability

22. Real Life
Let’s think about how school uses a Client-Server infrastructure
Server:
Login services
File server
Print server
Internet filtering
Software updates
Security management
Client Devices:
All able to access the same resources
Consistent whichever you logon to

23. Summary – Client Server
A network which has one or more servers connected to it
A server is a central point on the network which provides a function (e.g. log on, file storage)
The server has control over the network
This has significant advantages:
Central security
One point of back up
Control over who can use the network and what they can do
Central administration, distribution of software etc

24. Peer-to-Peer
You may have heard the term “p2p” when talking about torrents/shady downloading
Peer-to-Peer is when devices on the network ask other “equal” devices (“peers”) on the network for files or services
There is no need for a central, super expensive server
Each “peer” can act as a client and server; asking for and providing services

25. Peer-to-Peer Same with torrents
Rather than the files all being stored and shared from one single location, the files are distributed from clients the same as your own on the internet
This means the files may be available closer geographically
No waiting for files to upload to a central server
The demand for files can be distributed, avoiding congestion on individual servers or networks

26. Peer-to-Peer - Summary
No central server; no need to keep a single computer running all the time
No one machine is in control of the network
Decreases time for data to send, fewer networks to send the call data through, reduced latency
What does latency mean?
An example of software that uses peer-to-peer is Skype

27. Peer-to-Peer vs Client-Server
Complete the worksheet “Activity 2”
Print and stick in your books
When finished, expand on each type – give examples of where you would find them and explain why they are used in this situation – are there any negatives still?

28. Review You should know What a computer network is
Why computer networks are so important
The characteristics of the following common network infrastructures
LAN/WAN
Client-Server
Peer-to-Peer
Why some tasks require different types of network

29. Exam Questions
Sample Question Paper - 8(a)