1. See Open Systems Interconnection--Reference Model.
2. The layer (layer 1) that provides transparent transmission of a bit stream over a circuit built from some physical communications medium. [Tl.110-1987]

The branch of optics that treats light propagation as a wave phenomenon rather than a ray phenomenon, as in geometric optics.

The plane in the intelligent network conceptual model containing elements and their interfaces that implement functional entities. [T1.667-1999]

1. The measures used to provide physical protection of resources against deliberate and accidental threats [7498-2].
2. See communications security.

In a local area network (LAN) or a metropolitan area network (MAN) using open systems interconnection (OSI) architecture, the portion of the physical layer that (a) interfaces with the medium access control sublayer, (b) performs character encoding, transmission, reception, and decoding, and (c) performs optional isolation functions.

The physical configuration, i.e., interconnection, of network elements, e.g., cable paths, switches, concentrators.
Note: Physical topology is in contrast to logical topology. For example, a logical loop may consist of a physical star configuration, or a physical loop.

See yypW.

See noise weighting.

Protocol Implementation Conformance Statement

Synonym image.