2.3.1. Physical Layer

The base layer, layer 1, is known as the physical layer. It characterizes the properties of the physical medium used to make a network association. The physical layer details result in a physical medium—a network link—that can transmit a flood of bits between hubs on the physical network. The physical association can be either point to point (between two points) or multipoint (between numerous points, for example, from one point to numerous others), and it can comprise of either half-duplex (one way at once) or full-duplex (both ways at the same time) transmissions. In addition, the bits can be transmitted either in series or in parallel. (Most networks utilize a serial stream of bits, however the OSI model takes into account both serial and parallel transmission). The detail for the physical layer likewise characterizes the cable utilized, the voltages carried on the link, the timing of the electrical signals, the distance that can be used, etc. A NIC, for instance, is a piece of the physical layer.