Teacher Ji Wang said: encapsulation and framing error detection flow control... Let's summarize in detail
What is the role of the data link layer above the physical layer and below the network layer?
1. Encapsulation and de-encapsulation (Encapsulation/De-encapsulation): The link layer is responsible for encapsulating the datagrams passed down from the network layer into frames (Frame), adding frame headers and frame trailers for transmission on physical media. At the same time, at the receiving end, the link layer is also responsible for decapsulating and restoring the received frame into a datagram.
2. Media Access Control (Media Access Control): The link layer protocol manages the access of multiple devices sharing the same physical media through the media access control mechanism. Through conflict detection, conflict avoidance and other technologies, coordinate access between devices, avoid conflicts, and achieve fair and orderly data transmission.
3. Error Detection and Correction : The link layer uses error detection techniques, such as cyclic redundancy check (CRC), to detect bit errors during data transmission to ensure data integrity. In some cases, the link layer can also perform simple error correction, such as repairing errors by retransmitting lost frames.
4. Flow Control: The link layer can limit the rate at which the sender sends data to the receiver through the flow control mechanism to prevent the receiver from being overloaded or losing data. Common flow control methods include Sliding Window Protocol and Token Bucket Algorithm. (This thing is going to be studied)
5. Link Management and Configuration: The link layer is responsible for managing and configuring devices connected to the same transmission medium. For example, the link layer protocol can support functions such as device discovery, address allocation, link status monitoring and reporting.