Computer Networks

Why Create Networks? Communication

Communication technologies such as e-mail, sms, video-conference can be used

Makes communication faster, more efficient and cheaper Data Sharing

Makes data easy to access and share Hardware Sharing

Expensive hardware resources can be shared instead of having to buy more (e.g. printers, copiers)

Internet Access and Internet Access Sharing Allow access to the wide variety of resources available on the Internet Allow an Internet connection to be shared among a group of computers instead

of 1 connection for each Data Security and Management

Centralizes the storage of information Controls can be placed on the storage and access and backup of information

Network Types

Local Area Networks (LAN’s) A group of computers connected in a small

geographical area An example is the St. Mary School network

Wide Area Networks Is a network that covers a wide geographical

area The most well known example is the Internet

Making the Connection The most common types of network

communication are: Twisted Pair Cable Fibre-Optic Cable Wireless (WiFi)

Twisted Pair Cable This is the most common type of

network cabling Within the cable are 4 pairs of

twisted wires carrying electronic signals

Maximum distance: 100m Max speed of 1000Mbps

Fibre-optic Cable

Data is transmitted along very thin fibres of glass using pulses of light

It can carry data over long distances (many km)

It is more expensive to purchase and install than twisted pair

Max speed of approx. 1000Mbps

Wireless (WiFi) Uses radio transmissions Indoor range is approx 30-70m Can be used in places wires may be

difficult or impossible to run More susceptible to signal loss than a

physical cable Max speed of 150Mbps (N) or 500-

1000Mbps (AC)

Directing Network Traffic In order for your network to function, it

needs to be able to pass information from node to node

Ideally, this would be done as efficiently as possible

The basic types of hardware that are used to do this are: Switches Routers

Switches

Send messages to the appropriate computer

Used to create LAN’s

Routers

Provide a boundary between networks

Used to create and access WAN’s

Wireless Router/Switch

Two main types available 802.11b (older 11 Mbps speed) 802.11g (older54Mbps speed)* 802.11n (current 150Mbps speed)* 802.11ac (newest 500-1000Mbps speed)

Capable of sending signal everywhere inside a house

* Speed can be doubled using some hardware combinations

A Typical Network

Internet

RouterISPSwitch

Local Network (LAN)

Wide Area Network (WAN)

Servers Servers provide services to devices on the

network Common types:

Mail File server Application Server DNS (Domain Name System) DHCP (Dynamic Host Configuration Protocol) Database server Web Server