与100Mbps的Ethernet PHY chip沟通时所使用的接口。

信号脚位包含：

其中IC至PHY定义为输出、PHY至IC定义为输入

电气特性

使用8B/10B之编码，故其运作在125Mbps时，可以发送100Mbps之数据（包含档头），使用NRZ编码

数据源： 此接口由IEEE 802.3u所定义

The media-independent interface (MII) was originally defined as a standard interface used to connect a Fast Ethernet (i.e., 100 Mbit/s) media access control (MAC) block to a PHY chip. The MII design has been extended to support reduced signals and increased speeds. Current variants are reduced media-independent interface, gigabit media-independent interface, reduced gigabit media-independent interface, serial gigabit media-independent interface (SGMII), 10-gigabit media-independent interface, XAUI, GBIC, SFP, SFF, XFP, and XFI. The equivalent of MII for 10-megabit Ethernet is the attachment unit interface (AUI).