The encapsulation of data frames is not implemented in the network layer, but in the data link layer. The data link layer is between the physical layer and the network layer. The data link layer provides services to the network layer based on the services provided by the physical layer. Its most basic service is to reliably transmit data from the network layer to the target network layer of adjacent nodes.
The encapsulation of data frames is not implemented in the network layer, but in the data link layer.
The data link layer is the second layer in the OSI reference model, between the physical layer and the network layer. The data link layer provides services to the network layer based on the services provided by the physical layer. Its most basic service is to reliably transmit data from the network layer to the target network layer of adjacent nodes.
The data link layer defines how data is transmitted over a single link. These protocols are relevant to the various media in question.
Examples: ATM, FDDI, etc. The data link layer must have a series of corresponding functions, mainly including: how to combine data into data blocks. This data block is called a frame in the data link layer, and the frame is the transmission unit of the data link layer; How to control the transmission of frames on the physical channel, including how to handle transmission errors, how to adjust the sending rate to match the receiver; and provide management of the establishment, maintenance, and release of data link paths between two network entities.
Physical link (physical line): It is composed of transmission media and equipment. Original physical transmission lines refer to basic physical transmission media and equipment that do not use high-level error control.
Data link (logical line): On a physical line, the transmission of these data is controlled through some procedures or protocols to ensure the correctness of the transmitted data. The hardware and software that implement these procedures or protocols are added to the physical lines, thus forming a data link, a transmission path from the data sending point to the data receiving point. When multiplexing technology is used, there can be multiple data links on one physical link.
The network layer is located at the second layer in the three-layer structure of the Internet of Things. Its function is "transmission", that is, information transmission through the communication network.
The network layer serves as a link between the perception layer and the application layer. It is composed of various private networks, the Internet, wired and wireless communication networks, etc. It is equivalent to the human nervous center system and is responsible for transmitting the information obtained by the perception layer. , transmitted to the application layer safely and reliably, and then the information is processed according to different application requirements.
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