Networks - Typologies and Networks continued continued (Types of protocols…
Networks - Typologies and Networks continued continued
Types of protocols:
Simple Mail Transfer Protocol, SMTP
– Used to send emails. Also used to transfer emails between servers.
Internet Message Access Protocol, IMAP
– used to retrieve emails from a server. The server holds the email until you delete it, you only download a copy. Used by most web-based email clients.
Post Office Protocol version 3, POP3
– used to retrieve emails from a server. The server holds the email until download it, then it is automatically deleted from the server.
File Transfer Protocol, FTP
– used to access, edit and move files between devices on a network.
HTTP Secure, HTTPS
– a more secure version of HTTP. Encrypts all information sent and received.
Hyper Text Transfer Protocol, HTTP
– used by web browsers to access websites and communicate with web servers.
Internet protocol, IP
- responsible for packet switching.
Transmission Control Protocol, TCP
– sets the rules for how devices connect to the network. It splits data in to packets and reassembling the packets back into the original data once they reach the receiving device.
Advantages of protocol layers:
Be changed without other layers being affected because layers are self-contained.
It breaks network communication into manageable pieces. Helps developers concentrate only one area of the network without worrying about the others.
Layer 1 – Link Layer
Passing data over the physical network. Responsible for how data is sent as electrical signals over cables, wireless and other hardware. Ethernet
Layer 2 - Network layer
Making connections between networks, directing data packets. Used by routers. IP
Layer 3 - Transport layer Controlling data flow
– e.g. splitting data into packets and checking packets are correctly sent and delivered. TCP
Layer 4 - Application layer
Turning data into websites and other applications. HTTP, FTP, SMTP
Each layer serves the layer above it – it does the hidden work needed for an action on the layer above.
Layers are self-contained-protocols in each layer do their job without needing to know what is happening in other layers.
A layer is a group of protocols which have similar functions.
Protocols: a set of instructions to follow.
Protocols cover how communication, between two devices should start and end, how the data should be organised, and what the devices should do if data goes missing.
Network protocols are a set of rules which control the communications between devices on a network.
Factors which can affect network performance:
Hardware and Choice of topology.
Wired Connections – faster and more reliable than wireless connections. Fibre optic cables can give a much better performance than copper cables. As wireless performance depends on signal quality and is affected by the range of the device.
Available bandwidth – bandwidth is shared between users of the network-too many users or heavy use may cause congestion and slow the network down. One can then limit bandwidth use of an individual.
Bandwidth – amount of data that can be transferred in a given time, the greater the bandwidth, the better the network can perform.