Computer Science 1.3

Computer networks, connections and protocals

Advantages of networks

• you can share files

• you can share peripherals such as printers

• you can access files from other computers on the network

• servers can control backups, updates and files across all computers on the network

• people can communicate with each other (emails)

Disadvantages of networks

• there are increased security risks

• Malware can spread easily

• if a server fails, the network could fail

• computers may run slower if there is lots of traffic on the network

Features of a LAN

• small geographical area

• hardware is owned by organization

• they use copper, fibre optic and wireless connections

Features of a WAN

• large geographical area

• infrastructure is hired from telecommunication companies

• connects LANs

• uses fibre optic, telephone lines and satellite links

What is bandwidth?

The amount of data that can be sent and received in a given time. It is measured in bits per second

What factors affect network performance?

• Bandwidth

• Number of users

• Transmission media

• Error rate

• Latency

What is latency?

the delay from transmitting data to receiving it.

What is a client server model?

A network model where all the files on the network are stored in a server computer and client computers make requests to the server for access. The server is responsible for updating software and backing up files.

Advantages of a client server model:

• easier to manage the security of files

• easier to backup all stored data

• easier to provide network wide updates

Disadvantages of a client server model:

• it is expensive to set up and maintain

• an IT specialist is needed to maintain it

• the server is a single point of failure

What is a peer to peer model

A network model where there is not server and all computers make requests to each other for access to files.

Advantages of peer to peer models

• easy to maintain

• no IT specialist needed

• No single point of failure

• cheaper

• no expensive hardware

disadvantages of peer to peer models

• users must control backups

• less secure

• difficult to maintain well ordered file store

Characteristics of WAP

• wireless access (wifi)

• convenient

• less bandwidth

• security risks

• not as reliable as wired connections

Characteristics of a switch

• they direct network traffic

• they use mac addresses

Characteristics of a router

• use ip addresses

• allow lans to connect to the internet

• connect networks

Types of transmission media

• Copper wires

• Fibre optic cables

• satellite links

• telephone lines

Characteristics of copper wires:

• cheaper

• high bandwidth, reliability and security

Characteristics of fibre optic cables:

• faster

• higher bandwidth

• lower error rate

• longer distances