Search results
Results from the WOW.Com Content Network
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.
It is complemented by the MAC layer and the logical link layer. An implementation of a specific physical layer is commonly referred to as PHY. The Ethernet physical layer has evolved over its existence starting in 1980 and encompasses multiple physical media interfaces and several orders of magnitude of speed from 1 Mbit/s to 800 Gbit/s.
Distances between nodes, physical interconnections, transmission rates, or signal types may differ between two different networks, yet their logical topologies may be identical. A network's physical topology is a particular concern of the physical layer of the OSI model.
In the OSI model, the software to handle the media is defined at layers 1 and 2 — the physical layer and the data link layer. A widely adopted family that uses copper and fiber media in local area network (LAN) technology are collectively known as Ethernet.
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.
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.
The standard defines both the physical (Layer 1) and data-link (Layer 2) layers of the OSI model. The first edition of the 802.15.4 standard was released in May 2003. Several standardized and proprietary networks (or mesh) layer protocols run over 802.15.4-based networks, including IEEE 802.15.5, Zigbee, Thread, 6LoWPAN, WirelessHART, and ...
The internet layer has the responsibility of sending packets across potentially multiple networks. With this functionality, the internet layer makes possible internetworking, the interworking of different IP networks, and it essentially establishes the Internet. The internet layer does not distinguish between the various transport layer protocols.