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Physical Layer

The first and lowest layer of the OSI model, responsible for the physical connection between devices and the transmission of raw bitstreams.

Categorynetwork

Overview

The Physical Layer (Layer 1) deals with the hardware aspects of networking. It defines the electrical, mechanical, and functional specifications for activating, maintaining, and deactivating the physical link.

Key Responsibilities

  • Bit Transmission: Converting data into electrical, optical, or radio signals.
  • Physical Topology: Defining how devices are connected (bus, star, mesh).
  • Transmission Mode: Simplex, half-duplex, or full-duplex.
  • Hardware: Cables (Cat5e, Fiber), connectors (RJ45), and hubs.

Examples

  • Ethernet cables and connectors.
  • Fiber optic transceivers.
  • Radio frequencies used in Wi-Fi.

Related Terms

OSI ModelData Link LayerFiber Optics