Ethernet in the First Mile

Ethernet in the first mile (EFM) refers to using one of the Ethernet family of computer network protocols between a telecommunications company and a customer's premises. From the customer's point of view it is their "first" mile, although from the access network's point of view it is known as the "last mile". A working group of the Institute of Electrical and Electronics Engineers (IEEE) produced the standards known as IEEE 802.3ah-2004, which were later included in the overall standard IEEE 802.3-2008. Although it is often used for businesses, it can also be known as Ethernet to the Home (ETTH). One family of standards known as EPON uses a passive optical network.

With wide, metro, and local area networks using various forms of Ethernet, the goal was to eliminate non-native transport such as Ethernet over Asynchronous Transfer Mode (ATM) from access networks.

One early effort was the EtherLoop technology invented at Nortel Networks in 1996, and then spun off into the company Elastic Networks in 1998. Its principal inventor was Jack Terry. The hope was to combine the packet-based nature of Ethernet with the ability of Digital Subscriber Line (DSL) technology to work over existing telephone access wires. The name comes from local loop, which traditionally describes the wires from a telephone company office to a subscriber. The protocol was half-duplex with control from the provider side of the loop. It adapted to line conditions with a peak of 10 Mbit/s advertised, but 4-6 Mbit/s more typical, at a distance of about 12,000 feet (3,700 m). Symbol rates were 1 megabaud or 1.67 megabaud, with 2, 4, or 6 bits per symbol. The EtherLoop product name was registered as a trademark in the US and Canada. The EtherLoop technology was eventually purchased by Paradyne Networks in 2002, which was in turn purchased by Zhone Technologies in 2005.

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