1.3 Networks

Two or more linked computers.

• Users can share files • Users can share peripherals • Users can access their files from other computers on the network • Servers can control security software updates and backup of data.

• Increased security risks to data. • Malware and viruses spread easily between computers. • Computer may run slowly if there is a lot of data travelling through the network.

Local Area Network

Wide Area Network

• Covers small geographical area. • All the hardware for a LAN is owned internally. • Wired with a UTP/fibre optic cable • Wireless using Wi-Fi.

• Covers large geographical area, linking LANs together. • Infrastructure between LANs is leased from the companies who own them. • WANs are connected with telephone lines, fibre optic cables or satellite links

• Cheap to set up • Easy to set up • Secure • Rapid communication between devices.

• Limited distance covered.

• Large distance covered. • Higher bandwidth.

• Less secure • Large installation cost

• Bandwidth • Contention rate • Latency • Error rate • Transmission media

The amount of data that can be sent and received at a given time. Measured in bits per second.

Too many users on the same network can cause it to slow down as bandwidth is limited.

The delay from transmitting to receiving data. Caused by bottlenecks in infrastructure of network or hardware not operating at the same speed.

The number of data collisions per second. The higher the error rate, the network slows down as data must be resent.

A server controls access and security to one shared file store, manages peripherals and backup of data. A client makes requests to the server for data and connections.

• Easier to manage security files. • Easier to backup all shared data. • Easier to install updates on all connected computers.

• Expensive to set up and maintain. • Needs IT specialists to maintain. • Single point of failure. • Users lose access if server fails.

All computers on the network are equal and are responsible for their own security and backups.

• Easy to maintain • No specialists required • No dependency on single computer • Cheaper to set up

• Less secure • Difficult to maintain file store • Users manage own backups

Wired - Ethernet Wireless - Wi-Fi, Bluetooth

Use physical wires to connect devices. Typically used in offices as cables limit their ability to move.