AUI

AUI = Attachment Unit Interface

15 PIN D-SUB FEMALE at the Ethernet card

15 PIN D-SUB MALE at the MAU (Medium Attachment Unit).

An Attachment Unit Interface (AUI) is a 15 pin connection that provides a path between a node’s Ethernet interface and the Medium Attachment Unit (MAU), sometimes known as a transceiver. It is the part of the IEEE Ethernet standard located between the MAC, and the MAU. 15 pin D-SUB female connector layout

An AUI connector is a 15-pin D-connector. It has a sliding clip in place of the thumbscrews normally found on a D-connector to hold two connectors together. This clip permits the MAU and MAC to be directly attached to one another even when their size and shape would preclude the use of thumbscrews.

AUI connectors became rarer from the early 1990s. This was because it became more common for computers and hubs to incorporate the MAU, particularly as the 10baseT standard became more common and use of 10BASE-5 (thicknet) and 10BASE-2 (thinnet) declined. The electrical AUI connection was still present inside the equipment. By the mid-1990s AUI had all but disappeared as fast ethernet, which has no direct equivalent of AUI, became more common. Gigabit and 10-gigabit Ethernet have roughly analogous transceiver interfaces — the pluggable GBIC module and the chip-to-chip XAUI interface (whose name derives from AUI) — though neither is electrically equivalent to the original AUI.

An AUI cable may be up to 50 metres long, although frequently the cable is omitted altogether and the MAU and MAC are directly attached to one another.

A modified form using a smaller connector called the AAUI was used on Apple Macintosh computers in the early 1990s.

References

• IEEE Std 802.3 — IEEE Standard for Ethernet (defines the AUI)

Category:Networking Connectors