Network devices:

HUB - This is cheaper than a switch. It does not learn where each device is so it sends a message to every device connected to it so it is slower since it takes up the network bandwidth. This is an example of a broadcast device.



Switch - This device is similar to a HUB however this device learns where each device is connected to it so after each message it stores where the device is. This means that it is quicker since there is less network traffic and only the device you want to send the message to receives it. This are examples of a uni and multi cast devices.



Router - This forwards data packets between computer networks. This creates an overlay inter network. It has 2 or more data lines connecting to different networks. Routers have different types of ports (RJ45, RJ11, Serial and Wi-Fi)




A broadcast is when data is sent to all devices on the network.
A multicast is when data is sent to some, specific devices on the network.
A unicast is when data is sent to one device on a network.

Physical connections

A cable or wire
Can be touched
Limited

Logical connections

Virtual connection
Can't be touched
Multiple connections for different things simultaneously using one physical connection

DTE/DCE:
DTE - Data transmitting equipment
- Usually an end device
- Receives clock signal
- Usually "our" stuff
DCE - Data communications equipment
- Usually a comms device
- Creates clock signal
- Usually "their" stuff

Networks

A network is 2 or more devices connected to each other by exchanging data.

LAN (Local Area Network) interconnects computers in a limited area such as a household/ building using network media. The characteristic of LAN is in contrast the WAN (Wide Area Network) LAN has a smaller geographic area and non-inclusion of leased telecommunication lines.

WAN (Wide Area Network) covers a broad area such as any telecommunications network that links across regional/ national boundaries etc. This is mostly used by businesses and governments to relay data among employee’s, clients etc. From various geographical locations, the internet can be considered a WAN as well. Essentially, it is the opposite of LAN (Local Area Network). It covers a wide area whereas LAN is limited to a local area.

PAN (Personal Area Network) is a personal area you set up with your own devices, with this you can set your own hot spot up and use your I Phone, Laptop etc.