At which layer of the OSI/RM does a repeater operate?

A repeater operates at the Physical Layer of the OSI (Open Systems Interconnection) Reference Model. This layer is responsible for the physical transmission of data over network mediums. It deals with the actual electrical signals, light signals, or radio waves that carry the information. A repeater's primary function is to regenerate and amplify these signals to extend the distance over which they can travel without significant degradation.

Since a repeater operates at this fundamental level, it does not process or interpret any data; rather, it simply regenerates the electrical signals. This makes it distinct from devices that operate at higher layers, such as routers or switches that make decisions based on data packets and their protocols. Understanding that repeaters work solely with physical signals clarifies the nature of their operation within the OSI model, reinforcing the importance of the Physical Layer in network communications.