Data Link Layer — Layer 2

Open image in new window The Data Link Layer (sometimes abbreviated to Link Layer) provides transparent transfer of data link service data units between network entities. The Physical Layer described in the previous chapter provides transparent transmission of physical service data units between data link entities. Physical service data units consist of one bit in serial transmission or n bits in parallel transmission. In the Data Link Layer the service data unit is an arbitrary but variable number of bits, containing user data and protocol information from the layers above.