What Is A Network Packet?

Date First Published: 15th February 2022

Topic: Computer Networking

Topic: Data Transmission Technologies

Article Type: Computer Terms & Definitions

Difficulty: Advanced

Difficulty Level: 8/10

CONTENTS

How Are Network Packets Made Up?

Learn more about what a network packet is in this article.

A network packet, also known as a datagram, is a segment of data that is sent over a network, such as a LAN. All methods of data transmission, such as emails and webpages use packets to send data and nearly everything that is done on the internet uses packets. For example, email messages use packets as the each email message is broken down into parts of specific sizes in bytes, containing all the necessary information that will help it to get to its final destination. This includes the IP address of the sender and the IP address of the recipient.

The TCP/IP protocol carries the network packets and the data. The main purpose of network packets is to ensure data reliability so that data does not have to be sent as a single large file. The term 'network packet' was invented in 1965 by Donald Davies, a computer scientist.

Network packets work by breaking down files into small chunks or bytes. Every HTML or URL request that is sent over the internet is broken down. The file is divided into bytes by the TCP/IP protocol for efficient routing and most packets contain 1000-1500 bytes of data.

Note:

Packets can also be referred to as a segment, cell, frame, or block, depending on the type of network.

How Are Network Packets Made Up?

Three different parts make up a network packet, which include:

Header - This contains instructions related to the data in the packet. The instructions could include a checksum, a destination address, a 16-bit identification number, an IP, the length of the packet, the size of the header and the payload, the packet number, and the protocol or the type of packet that is being transmitted.
Payload - This refers to the data within the packet and it is the basic information that the packet delivers to its final destination. The payload is usually filled with blank information in order for it to fit in with the requirements of a fixed-length packet.
Trailer - Also known as the footer, the trailer marks the end of the packet. It may contain the signature of the packet, 32 bits, and an error checking protocol. One of the most common types of error checking protocols is a CRC (cyclic redundancy check), which adds all of the 1s up in the payload before storing the result as a hexadecimal value. Matching values suggest a good packet and unmatching values suggest a bad packet. When values are unmatched, a request is sent from the receiving device to the originating packet to resend the packet. A common type of error is network packet loss, which is when a data packet fails to arrive at its destination. Network congestion and data transmission issues are the most common causes of this.