In the seven-layer OSI model of computer networking, the physical layer or layer 1 is the first (lowest) layer. The implementation of this layer is often termed PHY.
The physical layer consists of the basic networking hardware transmission technologies of a network. It is a fundamental layer underlying the logical data structures of the higher level functions in a network. Due to the plethora of available hardware technologies with widely varying characteristics, this is perhaps the most complex layer in the OSI architecture.
The physical layer defines the means of transmitting raw bits rather than logical data packets over a physical link connecting network nodes. The bit stream may be grouped into code words or symbols and converted to a physical signal that is transmitted over a hardware transmission medium. The physical layer provides an electrical, mechanical, and procedural interface to the transmission medium. The shapes and properties of the electrical connectors, the frequencies to broadcast on, the modulation scheme to use and similar low-level parameters, are specified here.
Within the semantics of the OSI network architecture, the physical layer translates logical communications requests from the data link layer into hardware-specific operations to affect transmission or reception of electronic signals.
Read more about Physical Layer: Physical Signaling Sublayer, List of Services, List of Protocols, Hardware Equipment (network Node) Examples, Relation To TCP/IP Model
Famous quotes containing the words physical and/or layer:
“Not too many years ago, a child’s experience was limited by how far he or she could ride a bicycle or by the physical boundaries that parents set. Today ... the real boundaries of a child’s life are set more by the number of available cable channels and videotapes, by the simulated reality of videogames, by the number of megabytes of memory in the home computer. Now kids can go anywhere, as long as they stay inside the electronic bubble.”
—Richard Louv (20th century)
“After a few months’ acquaintance with European “coffee,” one’s mind weakens, and his faith with it, and he begins to wonder if the rich beverage of home, with its clotted layer of yellow cream on top of it, is not a mere dream after all, and a thing which never existed.”
—Mark Twain [Samuel Langhorne Clemens] (1835–1910)