OSI Layer Physical

In short: Layer 1 of the OSI model (physical layer) transmits raw bits as electrical, optical or radio signals.

In more detail: This is about the medium itself: cables, plugs, frequencies, voltage levels, bit rate.

In Depth

Devices and media

Network cables, fibre, coax, hubs, repeaters, radio (Wi-Fi).

Fault patterns

Cable break, poor connector contact, radio interference. With “no link” troubleshooting usually starts here. See OSI layers.

See also: OSI Layers, Cat Cable, Repeater, Hub