Confusion between MDI and MII

Question

1. Media Dependent Interface
2. Media Independent Interface

My understanding is 2. is an interface between PHY chip and MAC block on the board. PHY chip can be on the board, or detachable. It is rather PHY chip independent rather than being cable independent. 1. is a Medium dependent part of PHY chip.

My questions are

A. Is Media Independent Interface cable independent?

B. Between which two things are MDI and MII interfaces?

Answer 1

The MII (in its various incarnations RMII, GMII, SMII, ...) is the interface between the MAC and the PHY, ie. between data link layer and physical layer. The MII is entirely independent of the cable and the medium type (fiber, twisted pair, backplane, coax, twinax, ...).

The MDI is the part of the PHY that interfaces with the medium, usually a jack/receptacle/socket that accepts a plug - the ubiquitous 8P8C/"RJ45" jack, an LC optical socket or similar.