Data Packets (Cambridge (CIE) O Level Computer Science)

Data Packets

What are packets?

• Packets are small 'chunks' of data that make up a larger piece of data that has been broken down by the TCP protocol so that is can transmitted over the internet

• TCP stands for Transmission Control Protocol and is used for organising data transmission over networks

• Small 'chunks' of data are easier and quicker to route over the internet than big 'chunks' of data

  • Routing involves finding the most optimal path over a network

• Data can include anything from text, images, audio, video, animations, etc, or any combination of these

What do packets contain?

• A packet consists of:

• To transmit the message “This is a message :)”over the internet, TCP might break the message down into 4 packets

• Each packet contains a source IP address, destination IP address, payload (the data) and a packet number.

• Error checking and end of packet notifications have not been included in this example

• Error checks make sure that when a packet is received there is minimal or no corruption of the data

• Corruption is where packet data is changed or lost in some way, or data is gained that originally was not in the packet

• A parity bit checks that no bits have been flipped from 0 to 1 or vice versa

• A checksum performs a calculation and compares the result to the checksum value

• If the values are different then the data has been corrupted