Q. What is Data link layer?

Data link layer: data link layer is responsible for transmitting a group of bits between adjacent nodes. Group of bits is termed as frame. Network layer passes a data unit to data link layer and data link layer adds header information to this data unit. Data link layer performs below functions:

• Addressing: Headers and trailers are added containing physical addresses of adjacent nodes and removed on a successful delivery.

• Framing: Grouping of/bits received from network layer into manageable units termed as frame.

• Flow control: to regulate the amount of data which can be sent to the receiver.

• Media access control (MAC): who decide who can send data, when and how much.

• Synchronization: this layer also comprise bits to synchronize the timing to know the bit interval to recognize bit correctly.

• Error control: it incorporates CRC to ensure the correctness of the frame.

• Node to node delivery: it's also responsible for error-free delivery of entire packet/frame to the next adjacent node.