TCP vs UDP: Which Is Better Protocol?

The transmission protocol is the basis for maintaining normal data transmission. TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) are the most common protocols.

Whether browsing the web, watching streaming media, or using a VPN, the choice of transmission protocol will directly affect the speed, reliability, and security.

This article will explain the working principle, advantages and disadvantages, and application scenarios of TCP vs UDP, providing easy-to-read and comprehensive technical knowledge.

Difference Between TCP and UDP

TCP and UDP are both used to transfer data across networks, but they are designed for different purposes and are suitable for various scenarios.

1. TCP vs UDP: Connection Methods

• TCP: TCP is connection-oriented, which means that it establishes a reliable connection before data transmission begins.
• UDP: UDP is connectionless, meaning no formal connection is established when sending data.

2. Reliability

• TCP: TCP ensures data transmission by retransmitting lost packets, reordering out-of-order packets, and confirming data transmission with acknowledgments (ACKs).
• UDP: UDP does not check whether the packets have been delivered or delivered in the correct order.

3. TCP vs UDP: Speed ​​and Latency

• TCP: Slower due to connection setup, error checking, and retransmissions.
• UDP: Faster because it skips connection setup, acknowledgments, and retransmissions.

4. Data Transmission

• TCP: Data is transmitted in the form of a stream, which means that it is broken into packets, numbered, and reassembled in the correct order at the destination.
• UDP: Data is sent in separate packets (datagrams), each independent of the other packets.

5. Header size

• TCP: The header is large (20 bytes or more), including sequence number, acknowledgment, and error-checking fields.
• UDP: The header is small (8 bytes), making it lightweight and efficient.

6. Scope of use

• TCP: Web browsing (HTTP/HTTPS), file transfer (FTP), email (SMTP, IMAP, POP3), remote access (SSH, Telnet), database communication.
• UDP: Online games, video streaming, Voice over IP (VoIP), DNS lookups, live sports broadcasts.

7. TCP vs UDP: Multicast and broadcast support

• TCP: Does not support multicast or broadcast. It is designed for one-to-one communication.
• UDP: Supports multicast and broadcast, suitable for simultaneously sending data to multiple recipients.

8. Congestion control

• TCP: Implements congestion control to prevent network overload and adjusts data flow according to network conditions.
• UDP: Lack of congestion control can cause packet loss when network traffic is heavy.

TCP vs UDP: Summary Table

What is TCP?

TCP, short for Transmission Control Protocol, is the foundation of the Internet protocol suite. It ensures that your emails, web pages, and files arrive at their destination intact. Let’s take a detailed and comprehensive look at what TCP is.

TCP in a nutshell

Let’s say you are sending a data package and want it to arrive intact and correctly at the recipient. TCP does the following for your data on the Internet:

• It establishes a secure connection between devices before data transmission begins.
• It breaks the data into manageable chunks (called packets).
• It tracks and ensures the delivery of each packet, even retransmitting it if it is lost.

How does TCP work?

1. Connection establishment: TCP starts with a process called a three-way handshake:

• SYN: The sender signals its intent to start communicating.
• SYN-ACK: The receiver acknowledges and signals that it is ready.
• ACK: The sender confirms the acknowledgment, and the connection is established.

2. Data transmission: TCP breaks extensive data into packets, each numbered for easy reassembly. As packets travel across the network, TCP ensures that they arrive at their destination in the correct order. If a packet is lost, TCP retransmits it.

3. Error checking: TCP uses checksums to detect transmission errors. It returns an acknowledgment message (ACK) to the sender to confirm receipt.

4. Flow control: To avoid overwhelming the receiver, TCP uses a sliding window mechanism to adjust the rate at which data flows.

5. Connection termination: When the transmission is complete, TCP uses a four-step handshake to safely close the connection, ensuring that all data has been transmitted.

Why is TCP important?

• Reliability: TCP guarantees that your data arrives intact and in order.
• Widespread use: TCP powers most Internet applications, from browsing websites (HTTP/HTTPS) to sending email (SMTP) and downloading files (FTP).
• Error management: It detects and corrects errors, ensuring data integrity.

Applications of TCP

You interact with TCP every day without realizing it, for example:

• Web browsing: Accessing websites via HTTP/HTTPS.
• Email: Sending and receiving messages via protocols such as SMTP or IMAP.
• File transfer: Sharing files reliably via FTP.
• Streaming and Gaming: Enables stable connections for real-time interactions.

What is UDP?

UDP (User Datagram Protocol) is a core protocol in the Internet Protocol (IP) suite, primarily used to transfer data between devices over a network.

Main Features of UDP

• Connectionless Protocol: UDP does not establish a formal connection between the sender and receiver before transmitting data. Instead, it sends packets independently. This makes UDP faster because it eliminates the need for connection setup.
• No Acknowledgements or Retransmissions: UDP does not attempt to retransmit packets if they are lost or arrive out of order.
• Low Latency: Since there is no connection setup, acknowledgments, or retransmissions, UDP reduces latency in data transmission.
• Minimal Overhead: The UDP header is only 8 bytes long. This minimal overhead reduces processing and transmission time, making it a lightweight protocol.
• Supports Broadcast and Multicast: UDP supports sending data to multiple recipients at once.

How Does UDP Work?

1. Packet Structure: Each UDP packet or datagram consists of the following:

• Source Port: Identifies the sending application.
• Destination Port: Identifies the receiving application.
• Length: Specifies the size of the datagram.
  Checksum: Helps detect errors in the data.

2. Transmission process

• Data is divided into smaller units.
• Each datagram is sent independently to the destination, with no guarantee of delivery or correct order.
• The receiver processes the datagrams as they arrive, regardless of order or completeness.

When is it appropriate to use UDP?

UDP is best suited for applications where fast data transfer is more important than ensuring the packets reach their destination. Some common uses include:

• Live streaming: Services such as YouTube Live and online broadcasting use UDP to minimize buffering and provide smooth streaming.
• Video conferencing: Platforms like Zoom and Skype rely on UDP to reduce latency.
• Online gaming: UDP is used in multiplayer games to ensure fast data transfer, even if some packets are lost during gameplay.
• VoIP (Voice over IP): Applications such as WhatsApp and Skype use UDP to provide smooth, real-time voice calls.
• DNS queries: The Domain Name System (DNS) uses UDP for fast query-response transactions, which speeds up website lookups.

Disadvantages of UDP

• Unreliable: Since UDP does not guarantee delivery, packets may be lost and not in the correct order.
• No congestion control: UDP does not manage network congestion, which may lead to packet loss during periods of high traffic.
• No built-in security: UDP does not provide security features such as encryption, so applications must implement additional security measures.

Which Protocol is Better: TCP vs UDP?

There is no single answer to the question of whether TCP or UDP is a better protocol. Each protocol is designed for different purposes, and the best choice depends on the requirements of a specific application. You can make the choice based on your needs.

Choose TCP if:

• You need guaranteed delivery.
• Data order and integrity are critical.
• Your application requires reliable, session-based communications.

Choose UDP if:

• Speed ​​is more important than reliability.
• Occasional packet loss is acceptable.
• You are developing a real-time, low-latency application.

Which Protocol Does VPN Use?

When using a VPN, the protocol plays a crucial role in determining the speed, security, and reliability of the connection. Most VPNs use two transport protocols: TCP and UDP.

UDP is the default protocol for most VPNs, including LightningX VPN, because it prioritizes speed and low latency. However, UDP does not guarantee the delivery or order of packets. TCP focuses on data accuracy and reliability. It ensures that all packets are delivered and reassembled in the correct order.

LightningX VPN uses UDP by default to ensure users get a fast experience. However, it offers the flexibility to switch to TCP. You can experience smooth and clear videos when watching streaming media such as Netflix and TikTok, and get a stable network when transferring large files or browsing the web.

Conclusion

Whether it is TCP that requires data integrity or UDP that pursues high speed, both have their own advantages. You can choose the network protocol that best suits you based on the content.