TCP vs UDP – What’s the Difference?

Introduction

In the world of networking and communication protocols, two fundamental players stand out: TCP (Transmission Control Protocol) and UDP (User Datagram Protocol). TCP vs UDP is a timeless comparison that holds significant importance in understanding how data travels across the internet. These two protocols form the backbone of internet communication, each with its own unique characteristics and applications.

Through this article, you will gain insights into their individual strengths and weaknesses. So, without further ado, let’s understand the difference between TCP and UDP.

TCP vs UDP

The main difference between TCP and UDP is that TCP is connection-oriented, ensuring reliable data delivery with error checking and retransmission, while UDP prioritizes speed over guaranteed delivery and is connectionless. Here are some other difference between these protocols –

In order to compare TCP vs UDP better, we will take a look at both protocols.

What is TCP?

TCP, short for Transmission Control Protocol, is a connection-oriented protocol that ensures reliable and ordered delivery of data packets between devices. It provides error detection, flow control, and congestion control mechanisms to guarantee the successful transmission of data.

TCP establishes a connection between a sender and a receiver before transferring data, ensuring that packets arrive in the correct order and without errors. It retransmits lost or corrupted packets and acknowledges the receipt of data, making it highly reliable.

How TCP Works?

TCP uses a 3-step process which is known as TCP Handshake:

1. SYN (Synchronize): Sender sends a SYN Request to start a connection.
2. SYN-ACK (Synchronize-Acknowledge): Receiver sends the SYN-ACK as acknowledgement.
3. ACK (Acknowledge): The sender confirms, and the connection is established.

Once the connection is active, TCP ensures that all data packets are delivered in order and without errors. If a packet is lost, TCP retransmits it.

Features of TCP

Here are some features of TCP –

• TCP establishes a reliable connection between the sender and receiver before data exchange.
• TCP detects and corrects errors in transmitted data using checksums and retransmission.
• TCP regulates the flow of data to prevent overwhelming the receiver or congesting the network.
• TCP assigns sequence numbers to packets for proper ordering.
• TCP uses acknowledgments to verify successful receipt of data.

Advantages of TCP

• Reliable data delivery
• Error detection and correction
• Ordered data delivery
• Flow control
• Congestion control
• Connection-oriented communication
• Compatibility
• Versatility
• Error recovery
• Widely adopted

Disadvantages of TCP

• More Overhead
• Limited scalability
• TCP is a more complex protocol compared to UDP
• Inefficient for low-bandwidth networks

Where TCP is used?

TCP (Transmission Control Protocol) is used in various applications and scenarios where reliable and ordered data transmission is essential. Here are some common use cases for TCP:

• Web browsing: TCP is used to establish a connection between web browsers and servers.
• File transfer: TCP is employed in protocols like FTP (File Transfer Protocol) and SFTP (Secure File Transfer Protocol).
• Remote access: TCP is utilized in protocols like SSH (Secure Shell) and Telnet to establish secure and reliable remote connections.
• VPN (Virtual Private Network): TCP is often used in VPN implementations to provide secure and reliable communication.
• IoT (Internet of Things) applications: TCP is used in various IoT applications where reliable communication and data delivery are crucial.

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.

How UDP Works?

Unlike TCP, UDP does not establish a connection before sending data. It just send packets known as Datagrams. It doesn’t ensure that the data arrives in order or without errors.

Features of UDP

Some of the features of UDP are –

• UDP is a connectionless protocol, meaning it does not establish a dedicated connection before transmitting data.
• UDP has minimal header overhead compared to TCP, making it more lightweight.
• UDP prioritizes speed over reliability, making it suitable for real-time applications that require quick data delivery.
• UDP supports broadcast and multicast communication, allowing efficient data distribution to multiple recipients.

Advantages of UDP

• Low overhead
• High-speed transmission
• UDP has a very simple design
• Reduced network congestion
• Suitable for loss-tolerant applications

Disadvantages of UDP

Here are a few disadvantages of using UDP (User Datagram Protocol):

• UDP does not provide built-in mechanisms for reliable data delivery, error correction, or retransmission.
• It does not ensure the ordered delivery of packets.
• UDP does not perform congestion control.
• Vulnerability to packet loss.
• Inefficient for large data transfers.
• Unsuitable for applications requiring guaranteed delivery.

Where UDP is used?

• UDP is widely used in real-time applications, such as video streaming, live broadcasting, online gaming, and voice over IP (VoIP).
• UDP is the primary protocol used for DNS resolution.
• UDP is often used in IoT applications for transmitting data from connected devices to servers or gateways.
• UDP is the underlying protocol for TFTP, a simple file transfer protocol used for bootstrapping network devices or transferring configuration files.
• UDP is used in DHCP for dynamic IP address assignment.

Difference between TCP and UDP

Now, let’s understand some key difference between TCP and UDP Protocols –

1. Connection

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.

2. Reliability

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.

3. Ordering of Messages

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.

4. Weight

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.

5. Speed

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.

6. Flow-control

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.

These are the main difference between TCP and UDP, explained in detail.

Similarities between TCP and UDP

TCP and UDP are different but share key features that make them vital for network communication. Here are their similarities:

• Transport Layer Protocols: Both TCP and UDP function at the transport layer of the OSI model. They handle communication between devices over a network, ensuring data is transferred from one device to another, either reliably (TCP) or quickly (UDP).
• Use IP for Packet Routing: Both protocols rely on the Internet Protocol (IP) to route packets across the network. When combined with IP, TCP forms TCP/IP and UDP forms UDP/IP, where IP handles packet delivery and TCP or UDP defines how data is sent.
• Support Multiplexing: TCP and UDP both support multiplexing, which lets multiple applications share a single network connection. They use port numbers to direct data to the right application.
• Send Data in Packets: Both protocols break data into smaller packets for transmission. These packets are reassembled at the destination. TCP uses sequencing to ensure correct order, while UDP does not.
• Operate on the Same Network: TCP and UDP can both function on the same physical network. The choice between them depends on the specific needs of the application (reliability for TCP, speed for UDP).
• Impact of Network Congestion: While TCP manages congestion through flow control, both protocols can face delays, packet loss, or retransmissions (for TCP) when the network is congested.

When to use TCP vs UDP?

• You should choose TCP, when you feel reliability, data accuracy, and order is crucial. It is mainly used for file transfers, web browsing, and emails because any missing or incorrect data can cause significant problems.
• Choose UDP when speed and low latency are more important than reliability. So, it is mainly used in video conferencing, live streaming, and online gaming because in these cases, data loss won’t have any major impact on the users.

Frequently Asked Questions

Q1. What is the difference between TCP and UDP?

TCP ensures reliable, ordered data delivery by establishing a connection, performing error correction, and retransmitting lost packets. UDP, on the other hand, is a connectionless protocol that prioritizes speed and low overhead but does not guarantee reliable delivery or perform error correction.

Q2. What is TCP IP and UDP protocol?

TCP/IP (Transmission Control Protocol/Internet Protocol) is a suite of communication protocols used for transmitting data over networks. TCP is a reliable, connection-oriented protocol that ensures ordered and error-free data delivery, while UDP is a connectionless protocol that offers faster, lightweight communication but does not provide reliability guarantees.

Q3. Why is TCP and UDP used?

TCP is used for applications that require reliable and ordered data delivery, such as web browsing and file transfer, while UDP is used for real-time applications that prioritize speed, such as video streaming and online gaming.

Q4. Is TCP or UDP used more?

TCP is generally used more than UDP due to its reliability and error correction mechanisms, making it suitable for a wide range of applications. However, UDP is favoured in real-time applications where speed is crucial and minor data loss is acceptable, such as video streaming and online gaming.

Conclusion

Now we have discussed the difference between TCP and UDP in detail. In conclusion, TCP and UDP are two essential protocols used for data transmission in computer networks. TCP ensures reliable and ordered delivery of data packets, making it suitable for applications that require data integrity.

UDP, on the other hand, provides faster and lightweight communication, prioritizing speed over reliability. Understanding the difference between TCP and UDP allows you to select the appropriate protocol for different use cases, optimizing performance and reliability based on your specific needs. TCP and UDP are a part of advanced network training, if you want to learn more about these protocols, you can learn it with CCNP ENCOR Training by PyNet Labs.