EFM

Ethernet in the First Mile

EFM refers to the IEEE Std 802.3ah-2004 standard, an amendment to the Ethernet standard. The EFM standard was approved by the IEEE Standards Board in June 2004, and officially published on 7 September 2004.

The EFM amendment deals with a set of additional specifications, allowing users to run the Ethernet protocol over previously unsupported media, such as single pairs of telephone wiring and single strands of single-mode fiber.