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