ABSTRACT
The data link layer offers an interface between the network layer and the lowest layer (physical) and provides a reliable connection for the transfer of data between two adjacent nodes (computers, IMPs, etc.) which are connected by a communication medium. Since communication media may experience noise in one way or another, the data link layer must provide a means to offer error-free data transmission to the network layer. This requires the data link layer to use techniques to detect and correct the errors introduced into communication media by atmospheric (or ground) conditions that will occur in the circuits of the physical layer. Further, it should support different types of communication media and accept the services offered by the physical layer protocols.
