NETWORK CABLE

The physical layer is level one in the seven level OSI model of computer networking also as in the five layer TCP/IP reference model. It performs services required by the data link layer.

The physical layer is the most essential network layer, providing only the means of transmitting raw bits more often than packets over a physical data link connecting network nodes. Neither packet headers nor trailers are consequently added to the data by the physical layer. The bit stream possibly grouped into code words or symbols, and converted to a physical signal, which is transmitted over a physical transmission medium. The physical layer allows an electrical, mechanical, and procedural interface to the broadcast medium. The shapes of the electrical connectors, which frequencies to transition on, what modulation scheme to use and similar low-level things are specific here. An analogy of this layer in a physical mail network would be the roads along which the vans carrying the mail drive.