How to solve the packet loss problem in TCP transmission protocol

1. Before answering this question, we need to consider why the TCP protocol loses packets and under what circumstances packets are lost.

1. TCP protocol definition (Transmission Control Protocol) is a connection-oriented, reliable, byte stream-based transport layer communication protocol.

2. TCP is based on an unreliable network to achieve reliable transmission, so packet loss is bound to occur.

3. If you find that data is missing or packets are lost during the communication process, the most likely possibility is that there is a problem in the program sending or receiving process.

For example: I have 2 servers, A and B server.

When server A sends data to server B too frequently, server B cannot process it in time, resulting in data packet loss. (The reasons may be program logic problems, multi-thread synchronization problems, buffer overflow problems)

If server A does not control the sending frequency or resends the data, server B will receive less data, which will cause data loss.

2. How to solve the problem of packet loss after TCP protocol packet loss

In order to meet the TCP protocol and avoid packet loss, the TCP protocol has the following provisions:

1. Data fragmentation: The sender fragments the data, and the receiver reassembles the data. TCP determines the size of the fragment and controls fragmentation and reassembly.

2. Arrival confirmation: When the receiving end receives the fragmented data, it sends a confirmation to the sending end according to the fragmented data sequence number.

3. Timeout retransmission: The sender sets a timeout timer when sending a fragment. If no corresponding confirmation is received after the timer times out, the fragment data is resent.

4. Sliding Window: The receiving buffer space of each side of the TCP connection is fixed in size. The receiving end only allows the other end to send data that can be accommodated by the receiving end's buffer. TCP provides flow control based on the sliding window to prevent the faster host from causing the buffer of the slower host to overflow.

5. Out-of-order processing: TCP segments transmitted as IP datagrams may arrive out of order. TCP will reorder the received data and hand it over to the application layer in the correct order;

6. Duplicate processing: TCP segments transmitted as IP datagrams will be duplicated, and the TCP receiver must discard the duplicate data;

7. Data checksum: TCP will maintain the checksum of its header and data. This is an end-to-end checksum, the purpose of which is to detect any changes in the data during transmission. If the checksum of the received segment is wrong, TCP will discard the segment and will not confirm receipt of the segment, causing the other end to time out and resend.

TCP three-way handshake, four-way release diagram: