Data-link layer (DLL)

(1) Layer 2 of the OSI Reference Model. Provides reliable transit of data across a physical link. The datalink layer is concerned with physical addressing, network topology, line discipline, error notification, ordered delivery of frames, and flow control. The IEEE divided this layer into two sublayers: the MAC sublayer and the LLC sublayer. Sometimes simply called the link layer. Roughly corresponds to the datalink control layer of the SNA model. (2) A layer with the responsibility of transmitting data reliably across a physical link (cabling, for example) using a networking technology such as Ethernet. The DLL encapsulates data into frames (or cells) before it transmits it. It also enables multiple computer systems to share a single physical medium when used in conjunction with a media access control methodology such as CSMA/CD.