What is UDP?

User Datagram Protocol (UDP) is a core communication protocol for transmitting data across the Internet. Unlike its counterpart, TCP (Transmission Control Protocol), UDP is a connectionless protocol that sends data without establishing a reliable connection between the sender and receiver. That makes UDP faster but also less reliable, as it does not check for errors or guarantee that data packets will arrive in order or at all. However, UDP is ideal for applications where speed is crucial, such as video streaming, online gaming, and voice-over-IP (VoIP). This article will explore how UDP works, its strengths and weaknesses, and when you might choose UDP over TCP.

This post includes:

• How UDP Works?
• UDP vs. TCP

How UDP Works

As a Transport Layer protocol, UDP’s primary function is to transmit data from one computer to another. It shares that purpose with TCP; however, their approaches to transmitting data are different, and each has its own benefits and drawbacks. Let us first explore how UDP actually works, and then compare it to TCP.

The biggest strength of UDP is speed. It can send data much more quickly than TCP because it does not wait for a connection to be established with the recipient. When using TCP, the protocol has to establish a firm connection between sender and receiver via what is known as a “handshake.”

UDP completely skips that step and sends data immediately without waiting to see if the receiving machine is available or ready. That is it. The moment the target computer is found, UDP begins streaming its datagrams (that is what UDP’s units of data are called) without any checks for errors.

Additionally, if any datagrams are lost along the way or corrupted, UDP does not have the functionality in place to resend them automatically. Finally, there is no guarantee that the datagrams will arrive in the order they were sent.

So, what is the point of UDP if it is so supposedly unreliable and skips what seem to be important steps? It is much faster and more efficient than TCP, and for many online applications, that matters immensely.

UDP vs. TCP

Since both UDP and TCP are transport protocols, it is normal to compare them, especially since they do their jobs so differently. This is especially true when UDP seems wholly unreliable when there is a perfectly good and stale solution in TCP.

Check out the table below for a complete comparison of the two, and you will see why UDP is absolutely necessary as a protocol.

As you can see, UDP does have some drawbacks, but they are for a reason. Where raw speed is required, TCP is too slow, and UDP shines. Here are a few of the many use cases for UDP.

• Voice over IP (VoIP);
• Video calls;
• Audio and video streaming;
• Online games;
• DNS lookup;
• Simple request-response communication via small amounts of data where error control is unimportant.

All of these UDP applications do not require the error checking and retransmission functionalities of TCP. In fact, they demand fast data transmission, and the occasional datagram loss is acceptable. Take online games, for example; the action on your screen should be quick, smooth, and uninterrupted rather than slow and delayed.

We know that this seems like a tiny thing, considering we connect to websites in the blink of an eye, and they run over TCP. However, remember that all of the use cases above send much more data back and forth between clients and the server.

Take the gaming example again: every button press that performs an action must be processed by the game’s server. Now, think about how many and quickly you hit buttons on an average gaming night. UDP is much better since it can send all that data to the server much more quickly, and the server can process them more easily.

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