A PHY, an abbreviation for "physical layer", is an electronic
circuit, usually implemented as an integrated circuit, required
to implement physical layer functions of the OSI model in a network
interface controller.A PHY connects a link layer device (often called
MAC as an acronym for medium access control) to a physical medium
such as an optical fiber or copper cable. A PHY device typically
includes both physical coding sublayer (PCS) and physical medium
dependent (PMD) layer functionality.[16]-PHY may also be used as
a suffix to form a short name referencing a specific physical layer
protocol, for example M-PHY. .