1. Networks
Mr Arthur

2. Aims of Lesson 1
1. Introduce networks
2. LANs
3. WANS
4. Transmission Media
5. Client Server and Peer-to-peer networks

3. Stand Alone/Networked
 A Stand Alone computer system is a computer that
is not connected to any other
 A network is a linked set of computer systems that
are capable of sharing programs, data and
sending messages

4. Local Area Networks
 A LAN is a network of computers connected over a
small geographical area, usually inside the 1 building
 Examples
 School LAN
 Network in a library
 Uses
 Sharing resources
 Sharing peripherals
 Email
 Transmission Media
 Copper Wire, Fibre Optic and Wireless

5. Wide Area Networks
 A WAN is a network of computers over a large
geographical area, such as across a country or the world.
 Examples
 The Internet
 Companies like the BBC communicating across the world
 Uses
 video-conferencing, use of e-mail, live chat
 Sharing Information - access to databases,
 E-commerce and entertainment
 Transmission Media
 Fibre Optic, Microwave transmission and Satellite

6. Client Server Network
 A client-server network is where all resources are stored
centrally on the server and are assessed by the client
stations
 Advantages
 Increased security as each user needs to log in
 Different levels of access are available
 Users can work on the same document at the same time
 Flexible uses of station, you can log on to a number of clients
and access your files
 Backup copies are completed centrally
 Disadvantages
 If the file server is down there is no access to data
 More expensive as you need to buy a server and server
software

7. Peer to Peer Network
 A peer-to-peer network is where each station has its
own local storage device.
 Advantages
 Easier to setup operating systems on stations in a peer-
to-peer
 Cheaper as no server is required
Disadvantages
 No central file storage – users must log in to the same
station to access files
 Users must backup their own data
 Peer-to-peer is less secure as users may not be required
to log in

8. Aims of Lesson 2
Last Lesson
 Introduce networks
 LANs
 WANS
 Transmission Media
 Client Server and
Peer-to-peer networks
 Today’s Lesson
1. Network Topologies
2. Network Interface
Cards
3. Hotspots

9. Star Topology
 All peripheral nodes are
connected to a central node
 If a peripheral node fails it has no
effect on the network
 If the central node fails the whole
network is “down”
 Advantage = Easy to add new
stations
 Disadvantage = Central node may
get congested with network traffic

10. Ring Topology
 Signals are sent around the
network from node to node
 If a node is faulty, then
there must be a method of
bypassing the failed node
 If a communications
channel fails, the network
fails

11. Bus Topology
 The bus topology has each node
connected to a main communication
channel (The Bus)
 If one node is faulty this has no effect
on the rest of the network
 If the bus is faulty, the whole network is
“down”
 Advantage = Easy to add new stations
 Disadvantage = Each node may have to
compete with each other in order to
transmit and receive data

12. Mesh Topology
 A mesh topology has
multiple direct connections
between each node
 The internet is an example
of a Mesh network
 Advantage = A node failure
has no effect on the rest of
the network
 Disadvantage = Expensive to
set up with a lot of cabling

13. Network Quiz
1. Give 3 functions of a LAN
2. Give 3 transmission media you would
associate with a LAN
3. Describe a client server network (2)
4. Give 2 advantages of a client server over a
peer to peer network
5. Describe a peer to peer network

14. Aims of Lesson 3
Last Lesson
 Introduce networks
 LANs
 WANS
 Transmission Media
 Client Server and
Peer-to-peer networks
 Network Topologies
 Today’s Lesson
1. Network Interface
Cards
2. Hotspots
3. Router
4. Hubs

15. Network Interface Cards
 Network Interface Cards = a small
printed circuit board inside the
computer system allowing it to
communicate with the network.
 The NIC provides the computer
with a unique Media Access
Control (MAC) address made up
of 6 bytes

16. Hotspots
 An area where network
signals may be received
 Usually located in built up
areas
 May be deliberate
hotspots in a University or
may be accidentally
created
 Warchalking
 Wardriving

17. Router
 A router is a device
which links 2 or more
networks
 The router takes
packets of data and
decides which route
through the network the
packet should take

18. HUBs
 A hub is a device with
multiple ports which
allows more than 1
device to share the
same wire
 The hub will also boost
or amplify signals
 Multi-port repeater

19. Switch
 A switch operates like a
smart hub
 The switch separates
the network into
segments
 More than one machine
can speak at once and
only the intended
recipients receives the
signal

20. Aims of Lesson 4
Last Lesson
 Introduce networks
 LANs
 WANS
 Transmission Media
 Client Server and Peer-to-
peer networks
 Network Topologies
 Network Interface Cards
 Hotspots
 Router
 Hubs
 Today’s Lesson
1. Mainframes/Super
computers
2. Current network trends
3. Technical reasons for
increasing number of
networks

21. Mainframes and
Supercomputers
 Mainframes
 A large powerful computer
which can process a very
large amount of data at a
high speed
 May be connected to
hundreds of dumb terminals
 Multi-programming
 Multi-tasking
 Multi-processors
 Supercomputers
 More powerful than a
Mainframe
 Supercomputers are used
for intensive mathematical
calculations like weather
forecasting, aerospace
engineering

22. Current Network Trends
 Higher Bandwidth
 Increasing amount of data carried
along communications channel
 Virgin Media advertising 20Mbps!!!
 There will be a limit however,
depending on the distance from
subscriber and the telephone
exchange
 Wireless Functions
 WiFi, Bluetooth, Zigbee

23. Technical Reasons for Increasing
Number of Networks
 Advances in computer hardware
 Faster, Multiple processors
 Cheaper, higher capacity RAM chips
 Increasing Backing storage capacities
 Increasing data transfer rates
 Improved Network software
 Browsers = improved functionality using
plug-ins, allowing streamed video, animated
graphics to be displayed
 Operating Systems designed with
networking functions built in

24. Final Network Lesson
Last Lesson
 Introduce networks
 LANs
 WANS
 Transmission Media
 Client Server and Peer-to-peer
networks
 Network Topologies
 Network Interface Cards
 Hotspots
 Router
 Hubs
 Mainframes/Super computers
 Current network trends
 Technical reasons for
increasing number of networks
 Today’s Lesson
 File, Print and Web servers
 Legislation
 Computer Misuse Act
 Copyright Designs and
patents act
 Data Protection Act

25. File/Print/Web Servers
 File Server
 A file server provides central disk
storage for user’s programs and
data on the network
 The file server will run 24 hours a
day and must have a fast
processor, lots of RAM and much
larger hard disk capacity
 Controls security on the network
 Backed up using a Digital Audio
Tape (DAT)
 Print Server
 A print server will allow multiple
clients share the same printer
 The print server will use a
spooler program and the printer
will probably have a buffer as
well
 Web server
 A web server is a computer
that provides WWW
services to a network
 You have the benefit of
“always on” fast access to
pages
 Every computer that host a
website must have a web
server program

26. Misuse of Networks
 Copyright Designs and Patents Act
 This makes it illegal to copy music,
programs, movies etc without the
permission of the owner
 Computer Misuse
 Makes it illegal to hack or spread viruses
 Data Protection Act
 Controls the storage of personal
information