Computer Networks
Why Create Networks?
Communication
Communication technologies such as e-mail, sms, video-conference can beused
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 insteadof 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 smallgeographical area
An example is the St. Mary School network
Wide Area Networks
Is a network that covers a wide geographicalarea
The most well known example is the Internet
Making the Connection
The most common types of networkcommunication are:
Twisted Pair Cable
Fibre-Optic Cable
Wireless (WiFi)
Twisted Pair Cable
This is the most common type ofnetwork cabling
Within the cable are 4 pairs oftwisted wires carrying electronicsignals
Maximum distance: 100m
Max speed of 1000Mbps
Fibre-optic Cable
Data is transmitted along very thinfibres of glass using pulses of light
It can carry data over longdistances (many km)
It is more expensive to purchaseand 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 bedifficult or impossible to run
More susceptible to signal loss thana physical cable
Max speed of 150Mbps (N) or 500-1000Mbps (AC)
Directing Network Traffic
In order for your network to function, itneeds to be able to pass information fromnode to node
Ideally, this would be done as efficientlyas possible
The basic types of hardware that are usedto do this are:
Switches
Routers
Switches
Send messages to the appropriatecomputer
Used to create LAN’s
Routers
Provide a boundary betweennetworks
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 everywhereinside a house
* Speed can be doubled using some hardwarecombinations
A Typical Network
Servers
Servers provide services to devices onthe network
Common types:
Mail
File server
Application Server
DNS (Domain Name System)
DHCP (Dynamic Host Configuration Protocol)
Database server
Web Server