TCP vs UDP: How to choose the right network transport protocol?

In network communications, TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) are two very important transport layer protocols. They have their own characteristics and are suitable for different types of application scenarios. This article will discuss in detail the structure, advantages and disadvantages, and applications of TCP and UDP protocols to help you understand how to choose the appropriate protocol in different situations.

1. What are TCP and UDP?

• TCP (Transmission Control Protocol)
  TCP is a connection-oriented protocol that establishes a reliable connection through a three-way handshake to ensure the accuracy of data transmission. It provides order guarantee, error detection and retransmission mechanism for data transmission, so it is considered a "reliable" transmission protocol.
• UDP (User Datagram Protocol)
  UDP is a connectionless protocol that does not have a connection establishment process. The data packets it transmits are called datagrams. The data sender does not wait for the receiver's confirmation information and directly sends the data out, so the transmission speed is fast, but it does not provide reliability guarantee.

2. The main differences between TCP and UDP

1. Connectivity
   • TCP : Connection-oriented. A connection needs to be established before sending data, and the connection needs to be disconnected after the transmission is completed. Reliable transmission is ensured through the "handshake" and "wave" processes.
   • UDP : Connectionless, data is sent directly without establishing and maintaining a connection. It is suitable for fast transmission without the need for reliability confirmation.
2. Transmission reliability
   • TCP : Ensures reliable data transmission, including confirmation mechanism, sequence control and packet loss retransmission mechanism, to ensure that data is transmitted to the receiver in sequence and without error.
   • UDP : Transmission reliability is not guaranteed. Datagrams may be lost or out of order in the network and will not be automatically retransmitted. It is suitable for scenarios with high real-time requirements and tolerance for certain data loss.
3. Data transmission order
   • TCP : Ensures that data is transmitted and received in order, suitable for scenarios where data must arrive in strict order.
   • UDP : Order of reception is not guaranteed, and datagrams may arrive out of order.
4. Transfer speed
   • TCP : Since it requires three-way handshake, confirmation, retransmission and other operations, it is relatively slow but more stable.
   • UDP : Since there is no connection establishment, confirmation, or retransmission operations, the transmission speed is faster and is suitable for scenarios with high real-time requirements.
5. Packet size
   • TCP : Transmitted in streaming mode, there is no limit on the size of data packets (but it will be transmitted in fragments).
   • UDP : The transmission unit is datagram. The maximum single datagram size is generally 64KB, which is suitable for fast transmission of smaller data.

3. Application scenarios of TCP and UDP

• TCP application scenarios
  1. HTTP/HTTPS : Scenarios such as web browsing have strict requirements on data integrity and order.
  2. Email (SMTP, POP3, IMAP) : Need to ensure the complete transmission of emails.
  3. File Transfer (FTP) : File integrity is very important and loss of data will result in file corruption.
• UDP application scenarios
  1. Live video streaming, online games, and voice calls (VoIP) : These services have high real-time requirements, and even if a small amount of data is lost, the experience will not be seriously affected.
  2. DNS : No connection is required when querying, and results can be obtained quickly without ensuring data reliability.
  3. Streaming media : The streaming of music and video requires the order and real-time nature of data arrival.

4. How to choose TCP and UDP?

1. Data reliability <br>If you have high requirements for data integrity, choose TCP; if you can tolerate a certain amount of data loss or have real-time requirements, choose UDP.
2. Network resources and transmission speed <br>In high-concurrency, high-traffic scenarios, UDP can generally provide faster speeds and less overhead.
3. Data order <br>If data must arrive in order (such as web pages, file transfers), TCP is preferred; if the order is not important, UDP is also a suitable choice.

V. Conclusion

TCP and UDP protocols have their own advantages and disadvantages. Choose the appropriate transmission protocol according to the application scenario and requirements. TCP provides high reliability and is suitable for scenarios with high data accuracy requirements; while UDP has advantages in real-time and speed. Understanding the characteristics of these protocols can help us make the best choice in development and application to better meet actual needs.