The Data link layer is divided into two groups:-
1)MAC Layer:MAC may refer to the sublayer that determines who is allowed to access the media at any one time (usually CSMA/CD). Other times it refers to a frame structure with MAC addresses inside.
2)LLC Layer:The uppermost sublayer is LLC which multiplexes protocols running atop the data link layer, and optionally provides flow control, acknowledgment, and error notification. The LLC provides addressing and control of the data link.