17.TCP congestion control
TCP congestion control means that in a TCP connection, the sender and receiver cooperate to control the flow of data packets in the network to avoid network congestion. TCP congestion control is an important part of the TCP protocol, which can ensure the stability and reliability of the TCP connection.
TCP’s congestion control mainly has the following purposes:
- Prevent network congestion: When the data packet traffic in the network is too large, it will cause network congestion, leading to problems such as packet loss and increased delay. TCP's congestion control can prevent network congestion by controlling the sending rate of data packets at the sender.
- Improve network throughput: TCP's congestion control can improve network throughput by avoiding network congestion.
- Ensure data transmission reliability: TCP's congestion control can ensure data transmission reliability by avoiding network congestion.
TCP’s congestion control mainly includes the following algorithms:
- Slow start algorithm : The slow start algorithm is a type of TCP congestion control algorithm. It is the initial stage of TCP congestion control. In the slow-start algorithm, the sender will start sending data packets at a very small rate, and then gradually increase the sending rate as time goes by.
- Congestion avoidance algorithm : The congestion avoidance algorithm is a type of TCP congestion control algorithm. It is a regular stage of TCP congestion control. In the congestion avoidance algorithm, the sender adjusts the sending rate based on the confirmation from the receiving end.
- Fast retransmission algorithm : The fast retransmission algorithm is a type of TCP congestion control algorithm, which is used to deal with packet loss situations. In the fast retransmission algorithm, the sender retransmits the lost packet when it receives three duplicate ACKs.
- Fast recovery algorithm : The fast recovery algorithm is a type of TCP congestion control algorithm, which is used to deal with packet loss situations. In the fast recovery algorithm, the sender will temporarily reduce the sending rate after retransmitting the lost data packets, and then gradually return to the original rate. <