A hub is a hardware device that connects multiples computers together in a network and allows them to share data packets. [Star network doesn't use hubs]
Each computer will be connected to a single 'port' on the hub (an 8 port hub will be able to connect up to 8 computers together).
- Data packet arrives at hub port.
- Transmits to all other ports.
Does not examine data packets like a switch does. Re-transmitting every packet to every port means data collisions are more frequent than a switch.
Data security is an issue as every computer encounters every data packet, even if they are not the intended recipient.
Cheap solution for a low-medium bandwidth network. A switch should be used if better performance and sophisticated handing of data packets is required.
A network cable can only have one data packet in it at any one time. 2+ computers place a data packet onto the network simultaneously = 'data collisions'.
Network protocol is set up to deal with this, declaring the collided data as unusuable, forcing the computers to re-send their data. Only causes a small delay on a small network. But is not suitable for hundreds of computers. The switch helps to solve this.
A switch has a number of ports and stores addresses of all devices that are connected to it on each port.
- Data packet comes into switch.
- Destination address examined.
- Direct connection made between two machines.
This means that virtual networks can be set up, which are useful for network managing.