# Media Independent Interface (MII)

(at the network device).
(at the transciever).

40 PIN HI-DENSITY D-SUB FEMALE at the network device.
40 PIN HI-DENSITY D-SUB MALE at the transciever.

Pin | Name | Dir | Description
--- | --- | --- | ---
1 | V |  | +5 Vdc/ 3.3 Vdc
2 | MDIO |  | MII Data Input/Output
3 | MDC |  | MII Data Clock
4 | RxD |  | Rx Data
5 | RxD |  | Rx Data
6 | RxD |  | Rx Data
7 | RxD |  | Rx Data
8 | Rx_DV |  | Rx Data Valid
9 | Rx_CLK |  | Rx Clock
10 | Rx_ER |  | Rx Error
11 | Tx_ER |  | Tx Error
12 | Tx_CLK |  | Tx Clock
13 | Tx_EN |  | Tx Enable
14 | TxD |  | Tx Data
15 | TxD |  | Tx Data
16 | TxD |  | Tx Data
17 | TxD |  | Tx Data
18 | COL |  | Collision
19 | CRS |  | Carrier Sense
20 | V |  | +5 Vdc/ +3.3 Vdc
21 | V |  | +5 Vdc/ +3.3 Vdc
22 | GND |  | Ground
23 | GND |  | Ground
24 | GND |  | Ground
25 | GND |  | Ground
26 | GND |  | Ground
27 | GND |  | Ground
28 | GND |  | Ground
29 | GND |  | Ground
30 | GND |  | Ground
31 | GND |  | Ground
32 | GND |  | Ground
33 | GND |  | Ground
34 | GND |  | Ground
35 | GND |  | Ground
36 | GND |  | Ground
37 | GND |  | Ground
38 | GND |  | Ground
39 | GND |  | Ground
40 | V |  | +5 Vdc/ +3.3 Vdc

Note: Direction is DTE (Network device) relative DCE (Transciever).

Contributor: Joakim Ögren, Mark S Stephenson

Source:
Ethernet (IEEE802.3) page at Connectivity Knowledge Platform (Made IT)
A Tech Doc at Cisco Systems

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May be copied and redistributed, partially or in whole, as appropriate.
Document last modified: 2001-06-08