Input Output Management

Management Data Input/Output, or MDIO, is a serial bus defined for the Ethernet IEEE 802.3 specification for Media Independent Interface, or MII. The MII connects Media Access Control (MAC) devices with physical bus interface, or PHY, circuits. The MII comprises:

• a data interface to the Ethernet link and
• a management interface, referred as MDIO or as Media Independent Interface Management (MIIM).

The MDIO bus provides access to the configuration & status registers of each PHY. These registers are used to initially configure each PHY and also to monitor status during operation.