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(EFM) Ethernet in the First Mile

What is “Ethernet in the First Mile”?

Ethernet in the First Mile (EFM) is the nickname of IEEE Std 802.3ah-2004, an amendment to the Ethernet standard, specifying “Media Access Control Parameters, Physical Layers, and Management Parameters for Subscriber Access Networks”. The EFM standard was approved by the IEEE Standards Board in June 2004, and officially published on 7 September 2004.

The “Last Mile” is the name traditionally given to the part of a public communication network that links the last provider-owned node (the central office, the street cabinet or pole) with the customer premsises equipment (CPE). The “First Mile” is the exact same thing, viewed from the customer's perspective.

EFM does not improve or replace the existing Ethernet. It is 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 (SMF). This makes the EFM port types suited for use in subscriber access networks, i.e. the networks that connect subscribers to their service provider.

What is the EFM standard about?

The EFM standard specifies the following new Ethernet transceivers (PHYs) that can be used for subscriber access networks. They can be used for high-speed Internet access in the same way ADSL and cable modems are being used today. Their low cost and high bandwidth make them extremely well suited for additional services such as voice-over-IP, TV-over-IP and video-on-demand.

2BASE-TL

supports bitrates of up to 5.696 Mb/s over voice-grade copper (telephone wires) at distances in the order of 2.7 km (based on SHDSL)

10PASS-TS

supports bitrates of up to 100 Mb/s over voice-grade copper (telephone wires) at distances in the order of 750 m (based on VDSL)

100BASE-LX10

offers 100 Mb/s over two strands of single-mode fiber at a distance of up to 10 km

100BASE-BX10

offers 100 Mb/s over one strand of single-mode fiber at a distance of up to 10 km

1000BASE-LX10

offers 1 Gb/s over two strands of single-mode fiber at a distance of up to 10 km

1000BASE-BX10

offers 1 Gb/s over one strand of single-mode fiber at a distance of up to 10 km

1000BASE-PX10

offers 1 Gb/s to be shared between up to 16 users of an Ethernet passive optical network (EPON) at a distance of up to 10 km

1000BASE-PX20

offers 1 Gb/s to be shared between up to 16 users of an Ethernet passive optical network (EPON) at a distance of up to 20 km

In addition, the EFM standard specifies an “Operations, Administration, and Maintenance” protocol for Ethernet, and management parameters for all the new PHYs and protocols.

What is the EFM Task Force?

The EFM Task Force is the group that developed the EFM standard. It was part of the IEEE 802.3 CSMA/CD Working Group, which operates under the IEEE 802 LAN/MAN Standards Committee (LMSC). Their website is at http://www.ieee802.org/3/efm.

What is the EFM Alliance?

The EFM Alliance is an industry consortium dedicated to promoting the EFM standard. They have published several white papers and tutorials on EFM-related topics. Their website is at http://www.efmalliance.org.

Where can I get a copy of the EFM standard?

IEEE 802 standards older than 6 months can be obtained free of charge through the Get IEEE 802® Program.

 

To whom can I turn if I still have questions about EFM or related standards?

An authorative answer to questions of interpretation can be obtained from the IEEE 802.3 CSMA/CD Working Group, parent of the EFM Task Force, through the interpretations process. This process should not be mistaken for a way to obtain free consultancy services.

For questions that go beyond mere interpretation, you should consult an expert. You may get an answer from the people in the Ethernet newsgroup. The email reflector of the EFM Task Force has recently been shut down.