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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.
The link layer corresponds to the OSI data link layer and may include similar functions as the physical layer, as well as some protocols of the OSI's network layer. These comparisons are based on the original seven-layer protocol model as defined in ISO 7498, rather than refinements in the internal organization of the network layer.
OSI model Layer Protocol data unit (PDU) Function [3] Host layers 7 Application: Data: High-level protocols such as for resource sharing or remote file access, e.g. HTTP. 6 Presentation: Translation of data between a networking service and an application; including character encoding, data compression and encryption/decryption: 5 Session
Protocol data units of the OSI model are: [1] 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.
Examples of data link protocols are Ethernet, the IEEE 802.11 WiFi protocols, ATM and Frame Relay. In the Internet Protocol Suite (TCP/IP), the data link layer functionality is contained within the link layer, the lowest layer of the descriptive model, which is assumed to be independent of physical infrastructure.
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 ...
The services and protocols specified in IEEE 802 map to the lower two layers (data link and physical) of the seven-layer Open Systems Interconnection (OSI) networking reference model. IEEE 802 divides the OSI data link layer into two sub-layers: logical link control (LLC) and medium access control (MAC), as follows: Data link layer. LLC sublayer