Media Independent Interface

The term Media Independent Interface (MII ) was introduced at Fast Ethernet for network components. He tells Fast Ethernet chipsets into two components: the Media Dependent Interface (MDI ) and the MII. The interface between MII to MDI is a sub-component of the Ethernet chipset and with all manufacturers and all media (cable, fiber ) are identical. MDI is, however, the portion of the chip specific for the respective medium (cable, fiber) (transceiver) has to be designed. It also includes the physical ( electrical, optical ) and mechanical interface between the Physical Medium Attachment (PMA ) and the medium (cable). In classic 10 -Mbit Ethernet called the interface between MII and MDI and AUI interface, the transceiver corresponds to the MDI, the rest of the card starts with the MII and ends on the respective system bus ( PCI, EISA, etc.).

The purpose of this distinction was to be able to produce chips with MII in large quantities, which are then complemented by an MDI which is also produced across manufacturers in large quantities. Thus, the prices could be kept low. But there are also chipsets for network cards offered that do not have more MDI-/MII-Schnittstellen.

The 10 Mbps AUI predecessor, the Gigabit Ethernet version is GMII (Gigabit Media Independent Interface).