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Outcome 2: Networks
Communications
 When computers were first introduced, they were
standalone devices. As they became widely used,
manufacturers designed hardware & software so each
could communicate with each other.
 Originally only large computers had the ability to
communicate with another, however today, the
landscape has changed dramatically, with even the
smallest computers and devices being able to
communicate with each other.
Communications
 For successful communications between two devices,
you need:
 A sending device that initiates an instruction to transmit




data/information/instructions
A communications device that converts the
data/information/instructions into a usable signal
carried by the transmission media
Transmission media, on which the signal travels
A communications device that converts the
data/information/instructions into a usable signal that
the receiving device can use
A receiving device that accepts the data, instructions, or
information.
Communications
 Sending devices can usually also serve as receiving
devices
 Laptops, PC’s, mobile phones, GPS devices
 Primary function of a communications device (i.e.
broadband router) is to transmit data/information/
instructions between a sending & receiving device.
Communications
 Transmission media include CAT5/6, coaxial cabling,
WiFi.
 Data, information & instructions travel along
transmission media (aka a communications channel),
either in analog or digital form.
 Computers process data as digital signals so when
using a standard telephone line as the
communications channel, a modem (modulationdemodulation) to convert the digital signal into an
analog one & vice versa.
Communications
Modems convert the individual electrical pulses of a digital signal into analog signals
for data transmission over telephone lines. At the receiving computer, another
modem converts the signals back into digital signals that the computer can process.
What is a network?
A network is a collection of
computers and devices
connected together via
communication devices &
transmission media,
allowing computers to
share resources with one
another.
What is a network?
 Networks can be internal to an organisation or cover
the whole world by connecting to the Internet.
 Networks exist for sharing the information required
for an individual “to get the job done”. Sharing
resources, such as hardware & software, also makes a
network a valuable asset.
Advantages of using a network
 Facilitating communications

 Sharing hardware

Advantages of using a network
 Sharing software
 ______________________________
 Sharing data and information
 ______________________________
 Transferring funds
 ______________________________
Activity
 List the hardware that is shared over the MacKillop
network
 List (some of) the data & information that is shared
over the MacKillop network
Disadvantages of using a network
 User dependence
 ___________________________________
 Network Management
 ____________________________________
Types of networks
 The two basic types of networks are:
 Local Area Network (LAN)
 Wide Area Network (WAN)
Local Area Networks (LAN)
 A Local Area Network (LAN) connects computers &
devices in a small geographical area.
 Examples
 Home
 School
 Office building
 Each computer or device connected on the network is
known as a node. Often nodes are connected to the
LAN with cabling.
Wireless Local Area Networks (WLAN)
 A wireless LAN (aka WLAN) uses minimal physical
wiring, using wireless mediums (radio waves) instead.
 To do this, computers & devices must have wireless
capability, whether that be in-built or ad-hoc.
Wireless Local Area Networks (WLAN)
 Usually a WLAN will communicate with a traditional
(wired) LAN for access to resources, such as software,
hardware & the Internet.
Network Operating Systems (NOS)
 A Network Operating System (NOS) is the system software
that organises, controls & co-ordinates the
communications over a LAN.
 Tasks performed by the NOS include:
 Administration

Adding/deleting users & performing backup operations
 File/Printer management


Locating/transferring files
Prioritising print jobs
 Security

Monitoring & restricting access to network resources
Network Operating Systems (NOS)
 Three significant providers of NOS at present
 Microsoft (Windows Server 20xx)

Dominant market share
 Apple (Apple Workgroups Server)
 Novell(Netware)
Types of LAN
 Local Peer-to-Peer (P2P)
 A P2P network is a simple, inexpensive network in which
each node shares hardware & data with all of the other nodes
(computers) on the network.
 Each computer stores files on it’s own storage devices thus
each computer in the network contains both the NOS &
application software.
 Ideal for home users and very small businesses.
 Some operating systems like Microsoft Windows include P2P
utilities that allow you to set up a basic P2P network.
Types of LAN
 Client-Server
 A client-server network is a network in which one or more
computers act as a host (server) & the other computers (clients) on
the network can request services from the server.
 The major difference between the server and client computers is
that the server has more storage space & is more powerful. Some
servers have dedicated tasks (i.e. file/print servers). Generally, C-S
networks are used in organisations with more than 10 computers.
 Most client-server LANs have a Network Administrator due to their
larger sizes. The network admin is the person/people in charge of
the network.
 Costs associated with a server-based network are significantly
higher than those for a P2P network due to equipment costs
required at startup and ongoing tech support.
Activity
 Suggest reasons why a peer-to-peer network would not
be used in organisations in more than ten computers.
Wide Area Networks (WAN)
 WANs connect larger
areas, such as whole
states, or even the
world.
 Transoceanic cables
and satellites are used
to connect WANs
Types of WAN
 Internet P2P
 Internet P2P networks involve users with the same
networking software to connect to each other’s hard
disks with the intention of directly exchanging files.
 To maintain acceptable network speeds, most Internet
P2P networking applications limit the clients connected
to a particular client at the one time.
 Many businesses see an advantage to using P2P as it
allows their employees to exchange files, hence freeing
the company up from maintaining a network for this
purpose.
Types of WAN
 Internet P2P
 Two examples of networking software that enable
Internet P2P are Kazaa & LimeWire. These programs
were controversial (when they were the BIG thing) in
respect to copyright infringement of music.
 Using Internet P2P file sharing programs also expose
your computer to possible security threats such as
viruses & botnets.
Activity
 What type of network does MacKillop use? Justify your
answer.
Topology
 The physical topology of a network refers to
the configuration of cables, computers and
other peripherals.
 The main types of network topologies are:
 Bus
 Star
 Hybrid
Network Topologies: Bus
 A bus topology consists of a main run of cable
with a terminator at each end. All servers
workstations and peripherals are connected to the
linear cable
Network Topologies: Star
 A star network is
designed with each
node (file server,
workstation,
peripheral)
connected directly to
a central network hub
or server
Network Topologies: Hybrid
 A hybrid topology
combines
characteristics of bus
and/or star
topologies.
 It consists of groups
of star-configured
workstations
connected to a bus
backbone cable
Activity
 Read the section on Types of Network Topologies on
pages 54 & 55.
 List the advantages & disadvantages for each type of
network topology.
Intranets
An intranet is an internal network within an
organisation that uses internet & web technologies.
Intranets
 Common characteristics of Intranets
 Use a web server
 Support various types of multimedia
 Accessible via web browsers
Intranets
 Organisations employ the use of an intranet to publish
calendars, policies, manuals and to allow access to
documents required by the users.
 Intranets typically include connections to the Internet,
allowing employees access to relevant information
from the web.
Intranets
 Benefits of using an Intranet
 Allows restricted access to company information
 Facilitates communication
 Reduced paper usage
 Ease of use
Intranets
 Benefits of using an Intranet
 Global Access
 Ability to use multimedia
 Connection across different network platforms
 Dynamic information
Activity
 What are the benefits associated with an Intranet
being used in a school environment? Use MacKillop’s
Intranet as a reference point.