Layer 2: Data link layer

The data link layer packages raw bits from the physical layer into frames (logical, structured packets for data). 

This layer is responsible for transferring frames from one host to another. 

It might perform error checking. This layer further consists of two sublayers : MAC and LLC.

Media access control

Media access control (MAC) data communication protocol is a sublayer of the data link layer (layer 2). 

The MAC sublayer provides addressing and channel access control mechanisms that make it possible for several terminals or network nodes to communicate within a multiple access network that incorporates a shared medium

 

e.g. Ethernet. The hardware that implements the MAC is referred to as a medium access controller.

Logical link control

The logical link control (LLC) data communication protocol layer is the upper sublayer of the data link layer, which is itself layer 2. 

The LLC sublayer provides multiplexing mechanisms that make it possible for several network protocols.

 

(IP, IPX, Decnet and Appletalk) to coexist within a multipoint network and to be transported over the same network medium.