End-to-End communication

1. End-to-end connection management

Generally, you can establish two points through the three-way handshake protocol. Computer A sends a single request to the connected tpdu with the serial number X. Computer B returns a PDU that confirms the request and its serial number, with the serial number y; computer A sends back a confirmation frame of computer B by the serial numbers x and y contained in the first data PDU.

If the request from computer A or confirmation from computer B is lost, computer A resends the request after the timer ends. If computer A is confirmed to be lost, computer B will terminate the connection after the timer ends.

After the communication between computer A and computer B is complete, the connection between the two ends must be terminated. To terminate a connection, perform the following operations: computer A requests to terminate the connection, and computer B confirms the request. If computer A receives the confirmation frame sent by computer B and then sends another confirmation frame, and terminate the connection. After receiving confirmation, computer B also terminates the connection.

2. End-to-End Error Control

In the communication process at the transmission layer, both connection-oriented and connection-free transmission require Error Control Coding and error detection box error handling for the transmitted content. The error control at the transport layer is implemented by the last error control measure on the basis of the Communication Subnet's error control, and the error rate is relatively low.Generally, the following three measures are taken: immediate error correction, notification sender retransmission, and loss.

3. End-to-End Traffic Control

In the same pair of transmission communication, the sending and receiving rates are independent, and the two transmission rates can be different. The general policy for controlling the speed of sending and receiving information data units on both computers is to set the cache, that is, to set the cache server for caching protocol data units on both computers.

Regarding the cache setting policy, the sender establishes a cache for low-speed burst data transmission. for high-speed and stable data transmission, in order not to increase the transmission load, the maximum transmission bandwidth is used, the cache is created on the recipient.

4. End-to-end congestion control

Congestion control is implemented through two methods: Open-loop control and closed-loop control.Open-loop control is designed to ensure that no congestion occurs during network work. However, this control method is too costly and difficult to implement for a changeable network. Therefore, the implementation of closed-loop control is as follows:

① Monitor where the network system is congested.

② Transmit congested information to a place where action can be taken.

③ Adjust the operation of the network system based on the congestion information to solve the congestion.

Next we will talk about the differences and connections between end-to-end and point-to-point communication:

The physical layer, data link layer, and network layer in the OSI Layer-7 model provide point-to-point communication services for hosts in the network environment.This type of communication is the communication between directly connected nodes and peer entities. It only provides the communication between one machine and another, and does not involve the concept of programs or processes. At the same time, point-to-point communication does not guarantee the reliability of data transmission, nor does it mean which two processes are communicating between the source host and the target host. End-to-End communication is based on point-to-point communication. It is a higher-level communication mode through point-to-point communication to complete the communication between applications (processes.The transport layer function in the OSI reference model is the final end-to-end reliable connection. "Terminal" refers to the "Port" of the user application. The port number identifies different processes in the application layer. Data Transmission of multiple processes is completed through different ports. Zookeeper