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In the seven-layer OSI model of computer networking, the physical layer or layer 1 is the first and lowest layer: the layer most closely associated with the physical connection between devices. The physical layer provides an electrical, mechanical, and procedural interface to the transmission medium.
This article lists protocols, categorized by the nearest layer in the Open Systems Interconnection model.This list is not exclusive to only the OSI protocol family.Many of these protocols are originally based on the Internet Protocol Suite (TCP/IP) and other models and they often do not fit neatly into OSI layers.
Physical layer specifications are included in the specifications for the ubiquitous Bluetooth, Ethernet, and USB standards. An example of a less well-known physical layer specification would be for the CAN standard. The physical layer also specifies how encoding occurs over a physical signal, such as electrical voltage or a light pulse.
The physical-layer specifications of the Ethernet family of computer network standards are published by the Institute of Electrical and Electronics Engineers (IEEE), which defines the electrical or optical properties and the transfer speed of the physical connection between a device and the network or between network devices.
The Layer 4: transport layer PDU is the segment or the datagram. The Layer 3: network layer PDU is the packet. The Layer 2: data link layer PDU is the frame. The Layer 1: physical layer PDU is the bit or, more generally, symbol. Given a context pertaining to a specific OSI layer, PDU is sometimes used as a synonym for its representation at that ...
IEEE 802.3 is a working group and a collection of standards defining the physical layer and data link layer's media access control (MAC) of wired Ethernet.The standards are produced by the working group of Institute of Electrical and Electronics Engineers (IEEE).
This layer deals with the physical plugs, sockets, electrical/optical specifications and the required line codes. The physical layer includes the medium over which the digital signals are transmitted. It can be twisted pair, coaxial cable, optical fiber, wireless, or other transmission media.
A network's physical topology is a particular concern of the physical layer of the OSI model. Examples of network topologies are found in local area networks , a common computer network installation. Any given node in the LAN has one or more physical links to other devices in the network; graphically mapping these links results in a geometric ...