PyNet Labs- Network Automation Specialists

Difference between TCP and UDP

Last Updated : July 1, 2022
udp vs tcp

Hi everyone, the topic for this blog is UDP vs TCP. We will dig deeper into the differences between TCP and UDP protocols. Both the protocols are part of the Transport Layer as data is transmitted using TCP and UDP and you can first learn about them in your CCNA Training. This article will take you through some differences in them. But before we start learning about the differences, let's first understand what TCP and UDP exactly are. 

What is TCP and UDP Protocol in Networking?

UDP stands for User Datagram Protocol, whereas TCP stands for Transmission Control Protocol. Both these protocols are part of the internet protocol suite. We will be discussing both one by one. 

What is TCP?

The transmission Control Protocol is a transport layer protocol that is required to transmit the data in two directions. It has the ability to check for errors and guarantees data delivery; that's why we call it a reliable protocol. TCP is connection-oriented, which means it will establish a connection with the other user before transmitting the data. These TCP features make it a perfect protocol for transmitting data like images, files, and web pages. 

At the same time is considered a heavy-weight protocol because of a larger overhead to fulfilling all of the mentioned responsibilities. Some examples of TCP connections include FTP, Telnet, SSH, SMTP, HTTP, HTTPS, etc. 

TCP exchanges some messages to build a reliable TCP connection between devices. Let's dive into how this works: 

udp vs tcp

Step 1: Handshake begins with an SYN segment (Synchronize Sequence Number). Clients send the SYN segment to the Server. SYN segment of data to Server, which tells it that client is ready to begin the communication. 

Step 2: Now, the Server responds to the client's request. This response includes SYN-ACK, where Acknowledgement (ACK) is the response to the client, and SYN contains the sequence number with which Server is likely to start the segment. 

Step 3: In the last step, the Client accepts the Server's response and creates a stable TCP connection through which they can share data. 

What is UDP?

User Datagram Protocol is a transport layer protocol used to transmit data. UDP, unlike TCP, has less overhead for establishing, maintaining, or terminating a connection; hence, it is faster than TCP. In UDP, the data is continuously sent to the recipient irrespective of whether it was received or not. 

UDP can be considered a lightweight protocol because of its lesser responsibilities while delivering data. It is unreliable because there is no acknowledgment after receiving the data successfully, which means the sender won't know if the data was lost during communication or received by the recipient.  

Some examples of UDP connections include DHCP, TFTP, Syslog, Media Streaming, etc. 


Now, let's understand some key differences between the TCP and UDP Protocols. 

Transmission Control Protocol 
User Datagram Protocol 
• Connection Oriented • Connection Less 
• TCP is reliable • UDP is unreliable
• TCP guaranteed ordering of message• UDP doesn't provide guaranteed ordering of messages
• TCP is a heavy-weight protocol• UDP is a light-weight protocol
• TCP is a slow protocol because of all these responsibilities• UDP is a fast protocol because of fewer responsibilities
• Flow-Control• No option for flow control

Let's understand the difference between TCP and UDP one by one: 

  1. TCP is called a connection-oriented protocol because it requires a logical connection to be established between the two devices to exchange the data. This connection is built by doing a three-way handshake. 

This process can be understood with the example of a telephone call where both the users have to get connected first over a session before they can exchange the messages or ideas. On the other hand, we have UDP, which is connection-less as it doesn't go through any process and can directly send the data to the recipient. 

  1. TCP is a reliable protocol as it provides the reliability of the delivery of packets to the receiver as a connection is built before data transmission. On the other hand, with UDP, we don't get any surety whether the data was delivered or not; hence, we call it unreliable. 
  1. TCP guarantees data delivery in the same sequence as the sender sent it. If the segments are received in the wrong order, TCP reorders them. In UDP, there is no such guarantee of the order of segments when they reach the destination. 
  1. TCP is considered a heavy-weight protocol because of all the responsibilities it performs. The connection establishment requires the exchange of 3 packets before any data can be exchanged. TCP also handles reliability and congestion and is a heavy-weight protocol with a header size of 20 bytes. 

UDP is lightweight as there are no such needs for connection establishment. UDP doesn't handle the ordering, reliability, etc., while data delivery; hence it ends up being a lightweight protocol with a header size of 8 bytes. 

  1. The speed of TCP is slower than the UDP as in UDP; there's no error recovery mechanism. It is a best-effort protocol which simply means that it will not guarantee the delivery of data. 
  1. TCP works with flow control, ensuring that many packets are not transmitted over the connection to the receiver, whereas the UDP doesn't follow a flow control mechanism. 

To summarize, we can conclude that both protocols have their features and are required in different types of data transmission. TCP is used mostly with web browsing protocols like HTTP and HTTPS for exchanging emails and file transfers. In these scenarios, features like controlling the segment size, data exchange rate, and network congestion would be beneficial.  

UDP is used extensively in the operation of Voice over IP, Trivial File Transfer protocol, Domain Name System, and online games. 

These are the main differences between TCP and UDP. If you liked this blog, UDP vs TCP, do let us know in the comment box below. You can subscribe to our free newsletter to receive updates on new blogs.

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If you still have some doubts about the topic TCP vs UDP then, here is the video you must consider watching to understand difference between TCP and UDP to its depth.

Frequently asked questions for UDP vs TCP:

Question – Which is better TCP or UDP?

Answer – Both these protocols are best in their way. TCP is a connection-oriented protocol, so it is better for the reliability of the data transmission. TCP ensures the data is received by the receiver, whereas UDP is a connection-less protocol that is better for faster and simpler data transmission. 

Question – What is the difference between TCP IP and UDP? 

Answer – Although both these protocols are transport layer protocols, the major difference between these is TCP is a connection-oriented protocol; it requires setting up a connection to send data. In comparison, UDP doesn't require any connection to send the data. 

Question – What is an advantage of UDP over TCP? 

Answer – UDP is a connection-less protocol known as a lightweight protocol. UDP is a much faster, simpler, and more efficient protocol than TCP. UDP is best for DNS, voice-over IP, and online games. 

Question – Why is TCP preferred to UDP? 

Answer – TCP is a reliable protocol that prioritizes the delivery of data to the receiver in the same sequence as it was sent. Other reasons why TCP is preferred to UDP: 

  • TCP used flow control to limit the number of packets sent 
  • TCP is a more reliable protocol 
  • Error recovery is possible with TCP 
  • TCP handles network congestion and exchange rates and controls the segment size. 

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