What Are Data Packets?

What are data packets?

In their simplest form, data packets are individual information organized into one packet sent through a network path. They break down data into separate bits to speed up the transmission from one system to another. An IP datagram contains the data and the IP header information, which forms an IP data packet to send over the specified network. Data packets use IP (internet protocol) and allow systems to communicate via the internet and other networks by sending and receiving data packets. 

When users send data, files, videos, images, audio, and text from one system to another, they break down into data packets, which assembles itself to the original data type upon arrival at the receiving system. 

Read more: What Is TCP/IP?

Why are data packets important?

Data network packets are essential because they simplify and speed up device communication. By breaking down data into packets, they make transmission more efficient by giving each network in TCP/IP to allow data to flow into different bandwidths, send data via multiple routes, and fix or resend paused or lost data. 

Without data packets, the internet's user experience would be slow. Packets allow faster speeds by breaking up information and even sending it through multiple networks before it reaches its destination. In turn, users enjoy more rapid access to their requested data. 

Read more: Information Technology (IT) Terms: A to Z Glossary

Network packet structure

Now that you know more about what a data packet is and how it works, let’s examine the structure of a data or network packet. A packet is a series of bits that has three sections:

• Headers

• Payload (the actual data sent)

• Trailer

Let’s take a closer look at each section of a packet. 

Read more: What Is Data Communication? Basics to Know

Header

The header of a data packet contains information that allows for the actual transmission of the data packet. It includes the IP address of the packet's sender and receiver, including the IP version (IPv4 or IPv6). The header tells the network which kind of data packet it is. It also tells the size of the data packet, including the header and payload in bytes. 

The header includes a 16-bit identification number so the destination computer can correctly identify and reassemble the payload from the data packet. A fragmentation offset is another value in the header that helps with this process. A flag in the data packet tells the network if it can fragment the packet by sending it through a separate network since some networks have a restricted maximum size of packets they can send. 

Lastly, the header consists of a checksum, a value that aids in checking for errors and verifying that the end user received the packet correctly. The checksum calculates all the bytes in the packet to ensure every byte is present; if not, the packet will be resent. In this way, the checksum reduces the margin of error. 

Read more: Understanding IPv4 vs. IPv6

Payload

The payload is the data, which could be a picture, video, text, or audio that the user sends. It makes up the bulk of the packet. However, network routers often do not read it. If the payload has a fixed length, such as the 32 bits of an IPv4 address, it inserts extra zeros to meet the length requirement. 

Trailer

The trailer is optional, and data packets don’t always include it. However, it often signals the end of a packet. The trailer may consist of additional error checking, most commonly cyclical redundancy checking (CRC). It works by adding up all of the ones in the payload, storing that value in the trailer for the receiving device to do the same process, and ensuring each byte is present. 

Read more: What Is a Data Link Layer?

Transmission elements

In addition to data packet structure, other transmission elements affect the sending and receiving of data packets. The following offers a look at some transmission elements:

• Bandwidth

• Network congestion

• Web browser

• Jitter

• Packet loss

Let’s examine each transmission element and how it affects the flow of a data packet. 

1. Bandwidth

Bandwidth is the speed available to an internet user in bits per second. This determines how much data you can send in any given second and, thus, how many packets your connection can send simultaneously. The more bandwidth you have, the faster you can transmit data. For example, if you have 100 megabits per second (Mbps), you can send 100 megabits of data in a second. 

2. Network congestion

Network congestion occurs when the number of packets sent overloads the network and slows data transmission. It can occur from a bandwidth that is too small compared to the number of packets sent through it or from an external issue with an internet service provider (ISP). 

3. Web browser

Web browsers receive packets and organize them into the webpage that the user requested. Webpages load based on how fast the bandwidth in the user’s internet connection is. 

4. Jitter

Jitter is a latency in which a signal is transmitted and received. It happens when network congestion, hardware performance, wireless network issues, and no pack prioritization cause data packet loss. The most common effect of jitter you may experience is choppy audio and video calls.

5. Packet loss

Packet loss occurs when a data packet in transmission disrupts the network it was traveling through. It leads to slow network processing and even network connectivity issues. Packet loss directly affects real-time network usage, such as when gaming or video streaming. Common causes include network congestion, software bugs, hardware issues, and cybersecurity threats. 

How to get started in data packets

Data packets contain information on where they came from, where they are going, and what data is within them. Understanding data packets is vital for IT professionals and network administrators who need to troubleshoot a network and cybersecurity analysts who may need to capture packets to examine network security threats. 

Network administrators typically require a bachelor’s degree in computer science or a related field. They are a higher level job for network technicians and those in networking with experience in the field. 

Learn more with Coursera.

Data packets are essential for data traveling between users on the internet. If you’re ready to learn more about networking, try the 4G Network Fundamentals course by Institut Mines-Télécom on Coursera. Or, if you want to build additional foundational knowledge, consider the University of California San Diego’s Advanced Data Structures in Java. This six-module course explores data structures and route planning applications. Upon completion of either program, gain a shareable Professional Certificate to include in your resume, CV, or LinkedIn profile.