1.3 - Networks

A network in a small geographical area (same building or a small site)

Network owner The organisation using it

A network in a large geographical area (across a country or multiple e.g. The Internet)

Third parties

• Bandwidth -Interference (e.g. thick walls) -Transmission media -Amount of data being transmitted -Error rate -Latency

The maximum amount of data that can be sent across a network at once. Measured in bits per seconds

The delay from transmitting media to receiving it. Caused by bottlenecks (a junction where data gets held up) in the infrastructure of the network.

• Controlled centrally: easy to backup data and update software -Makes access to files more secure as sensitive data is stored on the server rather than on individual clients • Hardware, software and resources can be shared across the network • Easy to add new clients to the network

• Traffic congestion will cause network to slow down • Reliant on server: If the server fails, the whole network fails and users will lose access • IT technicians required to maintain the network • Malware can spread from the server to all computers on the network

• Simple setup: no server is required -Cheaper: No specialist staff or expensive hardware required • Not dependent on a server • Easy to share files between systems

• No central device to manage security or backups -Less secure as security software is individually managed • More devices = decrease in performance

Files broken down into smaller parts to be transferred across a network

• Source address • Destination address • Packet number • Protocol

The data itself

A checksum: a calculation to see if any errors or corruption has occurred during transmission

Layout of computer systems on a local network

Each computer system is connected to a central device (hub or switch)

• Improved security as data packets are sent directly to and from the hub / switch • Easy to add new systems • Fast transfer speeds as there are minimal network collisions

• Extra hardware required • If the central system fails, the whole network will fail

Each computer system is connected to every other computer system

• Not reliant on central node: If one cable or system fails, data packets can take an alternative route • Can withstand large amounts of data traffic • New systems can be added without disrupting the entire topology

• Large amount of cables mean it can be expensive to install and maintain • Redundant cabling

• Wireless Access Point (WAP) • Router • Network Interface Card (NIC) • Transmission medium • Switch

Links wireless and wired networks