mediumdependent
Medium dependent, sometimes written as medium-dependent, is a term used in telecommunications and computer networking to describe the portion of the physical layer that is specific to a transmission medium. It designates interfaces, signaling methods, and electrical or optical characteristics that depend on the chosen medium (such as copper twisted pair, fiber optic, or wireless), as opposed to medium independent functions of the data link or higher layers. In practice, medium dependent interfaces define how a device connects to the physical medium and how signals are transmitted and received over that medium.
In Ethernet terminology, the physical layer interface between a device’s network interface card and the cable
The MDI encompasses electrical and optical specifications such as impedance, voltage levels, signaling polarity, and timing,