Network
- Arrangement of 2 or more computers that are connected to share resources and data
A network allows users to
- Share data files with each other
- Share hardware devices such as printers
- Communicate with each other
- Share an internet connection and internet services
- Work together using web-based software
LAN
- Local area network
- Covers a small geographical area, one site or home
- Allows devices connected to share things with each other
- Privately owned by single organisation or household
WAN
- Wide area network
- Covers a larger geographical area
- Connects many LANs together
- Owned by external telecommunication companies
- The internet is the world largest WAN
Network speed: bandwidth
- The capacity of a network
- The maximum volume of data that can be transferred per second
Network speed: latency
- The time between the data being transmitted and the moment it reaches its destination
- Often referred to as ‘lag’
Data transfer rate
- The speed at which data is transmitted from one device and is measured in bits per second
Wired transmission media
- Copper wire - electric pulses
- Unshielded twisted pair - four thin copper wires covered in plastic insulation that are twisted together to help reduce interferrence
- Fibre optic - light pulses
Copper vs fibre optic: how it works
- Copper: electrical pulses
- Fibre: pulses of light
Copper vs fibre optic: range
- Copper: short, up to 100 metres
- Fibre: long distances with no loss of signal strength
Copper vs fibre optic: speed
- Copper: up to 10 Gbps
- Fibre: up to 100 Gbps
Copper vs fibre optic: latency
- Copper: High as copper is susceptible to interference + latency increases the further it travels
- Fibre: Low as data trasmission is less subject to interference
Copper vs fibre optic: uses
- Copper: Used to connect devices on a WAN
- Fibre: Used to connect LANs together to form wans and provide broadband services to private homes and businesses
Fibre to the cabinet (FTTC)
- Fibre optic calbes run from the nearest telephone exchange to a green cabinet in the street
- The final stretch from the cabinet to a customer’s home or business being connected by copper cable
Fibre to the premises (FTTP)
- Much faster broadband connection as the entire connection is fibre
Wireless transmission media
- Not a physical conductor, but radio waves, microwaves or infrared signals
- WiFi is a widely used type of wireless network technology
Bluetooth
- Works at distances up to 10 meters
- Between a wireless mous and a laptop
Zigbee
- Uses low-power radio waves
- Can connect thousands of IoT devices with radio transmitters/receivers embedded within them
Radio-frequency identification (RFID)
- Uses electromagnetic fields to identify and track tags attached to objects
- A radio transmitter/receiver is embedded in each tag
Near field communication (NFC)
- Uses electromagnetic fields to create a high-speed connection between two devices in very close proximity
- Most commonly useed in contactless payment systems
- Don’t need power supply
- Powered by electromagnetic field produced by the reader
Advantages and disadvantages: bus topology
Advantages:
* It is relatively cheap to install - little cabling needed
* If one node fails, the rest can still communicate
* Easy to add extra devices to the network
Disadvantages
* If the cable is cut or damaged, the whole netowrk stops functioning
* The more devices, the more collisions, therefore the slower it will run
* All nodes on the network ‘see’ traffic - this may be a security risk
Advantages and disadvantages: star topology
Advantages:
* If one node fails, the rest can still function
* A damaged cable doesn’t stop the network from working, just the device connected to it
* Data traffic only goes to recipient, therefore secure
* Easy to locate faults
* Nodes can be added or removed without having to take the whole network offline
Disadvantages
* If the central node fails, the whole netowrk stops functioning
* Network performance depends on the capacity of the central node
* A lot of cabling is required, making it difficult and expensive to set up
Advantages and disadvantages: mesh topology
Advantages:
* If one node fails, the rest can still function
* Very high performance - each node is connected to others
* Any number of nodes can be added easiy
* Nodes can be added or removed without having to take the whole network offline
Disadvantages
* Difficult and expensive to set up
IP address
- Internet protocol
- A set of rules governing data transfer on the internet
