Data link layer



Data link layer is the second layer of OSI model. it handles data transfer between network and the physical layers. Data unit at the data link layer is called as frame. data link layer receives data from network layer. it adds header and trailer to the data and passes data to the physical layer. At the receive side, data link layer receives data from the physical layer. It detaches Header and Trailer rom the data and passes data to the network layer.  

RESPONSIBILITIES OF THE DATA LINK LAYER :-

  • Framing :- The physical layer delivers raw bits from the source to destination. during transmission, the value of the bits can change. It is also possible that the number of bits received by the receiver may be different from the number of bits send by the sender. To resolve the problem, The data link layer organizes the bit into manageable data unit called as frames.
  • physical addressing :- Data link layer adds header to the frame which contains the physical address of the sender of the sender or receiver. Headers are assigned when the frames are to be distributed various systems within the network.
  • Error Control :- Another function of the data link layer is error control. Error control detects and corrects errors. During transmission, If a frame,  If a frame is lost or corrupted, The data link layer retransmits  that frame. It also prevents duplicates of frame. It also prevents duplication of frame. Error control is accomplished using trailer at the end of the frame.