Protocols

Lesson 8 - Protocols

IMAP

Internet Message Access Protocol

Email protocols

Ethernet

Offers more functionality that POP

Messages remain on the server so they can be viewed by other devices

Set flags to show unread emails, replied, forwarded etc

Perform complex searches of the inbox

Handle multiple mail boxes

Ethernet is known as a family of protocols

Concerned with transmission via network cables - copper AND fibre

First introduced in 1980 and has been developed to operate on a range of speeds - hence FAMILY of protocols

SMTP

Simple Mail Transport Protocol

What is this called?

This protocol is used by email servers to exchange information with one another

Ethernet

The original ethernet standard used coaxial cable (which is what your home ariel uses) to transfer data at up to 2.94 Mbps

The latest standard uses twisted pair and fibre optic links to transfer at speeds up to 100 Gbps!

TCP/IP

A protocol used to communicate over the internet

Protocols

Consists of two protocols, TCP and IP

What does TCP stand for?

What does IP stand for?

POP - Post Office Protocol

Allows emails to be downloaded and deleted from a mail server

These emails can be viewed offline as they are downloaded onto the device being used

- POP can only handle one mail box

- Once downloaded from the server the email can't be accessed by other devices

- Complex searching of the inbox is not possible with POP

Transmission control Protocol

Prepares messages for transmission

When sending:

• Divides messages up into 'packets'
• Adds a sequence number so the message can be put back together
• Adds error checking information

A network protocol is an agreed set of rules governing how communication will take place between devices.

The ethernet protocol covers:

When receiving:

• Examines each packet for errors
• Fixes any errors if possible
• Uses sequence number to check for missing data - this is requested again
• Reassembles packets in the correct order

Internet Protocol

Hardware - This specifies the performance of the network cables and plugs used

Data Format - How the data is arranged for transmission and what does the receiving machine do with it?

How to deal with collisions - What happens if two nodes on the network communicate at exactly the same time?

The IP part of TCP/IP is responsible for adding the destination and source address to each packet

Why do you think that we would add a source address to each data packet?

Http(s)

• Hyper text transfer protocol

• The protocol that governs the World Wide Web

• Web pages are sent and received using HTTP

• Web pages are made up different elements such as images, text, video etc

• HTTP requests these file and assembles them into the web page

• HTTPS is a secure version that encrypts data before it is sent

A communication protocol will cover:

• How to set up a communication
• How to terminate communication
• How to start a message
• How to end a message
• How to format the data being sent
• How to deal with corrupt or missing data

FTP

File transfer protocol

This protocol governs the uploading and downloading of files to/from servers.

If you have ever uploaded an image online you have downloaded a song you have used FTP

Scrabble

• No more than four players

TASK

• First word must start at centre square

• All new words must join to an existing word, no diagonals

Learning objectives

• Highest score wins

To understand what is meant by the term protocol

To have an understanding of IP addressing, MAC addressing and protocols

To understand the concept of layers

Complete the exam style questions on this topic.

Starter

On your scrap paper, write a definition for the word protocol

Now write down how this applies to computers

The four layer model

We have talked about just a few protocols today but many more exist.

To help us keep track of these protocols and how they all link together the four layer model was developed

The four layer model

Each layer has a name an a number

Each layer serves a different function in network communication

Protocols on each later can only communicate with protocols that exist on the layers above and below them i.e layer 2 protocols can talk to layer 1 and layer 3 protocols

Why use a model?

• It helps us conceptualise a complex system of communication

• It is useful for manufacturers so that they know their new products will work with existing protocols

• We can understand roughly what a protocol would do just by knowing where it fits within the model