The Transport Layer (TransportLayer) is the fourth layer protocol of the ISOOSI protocol for end-to-end data transmission. This layer is the first end-to-end level of the two computers through the network for data communication, with buffering effect. When the network layer service quality cannot meet the requirements, it will improve the service to meet the requirements of the higher level; when the network layer service quality is good, it only uses very little work. The transport layer can also be multiplexed by creating multiple logical connections on a single network connection.
The transport layer provides transparent data transfer between end users and provides reliable data transfer services to the upper layers. The transport layer is controlled by traffic control, segmentation/reassembly and error on a given link. Some protocols are link oriented. This means that the transport layer can keep track of the segments and retransmit those failed segments.
(1) Segmentation and reorganization data
(2) Addressing by port number
(3) Connection management
(4) Error control and flow control, error correction function
The transport layer should provide the communication layer with the reliability of the communication service, avoiding errors such as packet errors, loss, delay time disorder, repetition, and out of order.
The transport layer is the highest layer responsible for data communication in the OSI layer model, and the middle layer between the lower three layers for network communication and the upper three layers for information processing. This layer compensates for the gap between the services required by the upper layers and the services provided by the network layer, and shields the high-level users from the details of the communication subnet so that the upper-level users see only one end-to-end between the two transport entities. A reliable data path that can be controlled and set by the user.
The services provided by the transport layer can be divided into transport connection services and data transmission services.
☆Transport connection service: Generally, for each transmission connection required by the session layer, the transport layer must establish a corresponding connection on the network layer.
☆ Data transmission service: Emphasis on providing reliable connection-oriented services (very early OSI began to develop standards for connectionless services), and provided flow control, error control and sequence control to achieve the transmission of messages between two terminal systems. Errors, no loss, no duplication, no disorder.
Simply put, the data link layer provides data transfer services for the network layer. Specifically:
1 link connection establishment, removal, separation.
2 frame delimitation and frame synchronization. The data transmission unit of the link layer is a frame, the protocol is different, the length of the frame and the interface are also different, but the frame must be delimited anyway.
3 sequence control refers to the control of the order of sending and receiving frames.
4 error detection and recovery. There are also link identification, flow control and more. The error detection uses square matrix code check and cyclic code check to detect the error of the data on the channel, and the frame loss is detected by the sequence number. The recovery of various errors is often done by feedback retransmission techniques.
Gear Sensor has been widely used in the automotive and industrial field, which is important to the measurement of velocity, angel, angular velocity, direction of rotation.
Gear Sensor,Custom Gear Sensor,Gear Sensor 3 Pins,Good Gear Sensor
Yuheng Optics Co., Ltd.(Changchun) , https://www.yhencoder.com