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Note: Many topics at this site are reduced versions of the text in "The Encyclopedia of Networking and Telecommunications." Search results will not be as extensive as a search of the book's CD-ROM.
EtherLoop is a communication technology for the local loop that uses the Ethernet protocol. It provides high-speed data access for home users over the twisted-pair wire loop that stretches from homes to the telephone company CO (central office) or remote offices. EtherLoop uses the basic concepts of DSL technologies, such as HDSL and ADSL, but overcomes many of the limitation of these technologies by using the Ethernet packet-delivery algorithms.
According to Elastic Networks, which developed the technology, EtherLoop provides a solution that is simple to install, robust over distances up to 21,000 feet, and efficient in power consumption. Current data rates are as high as 4 Mbits/sec up to 6,000 feet, and as low as 400 Kbits/sec at 18,000 feet.
EtherLoop was designed as a competitor for cable modems in the area of high-speed data access. It uses features of both DSL and Ethernet. Data is transmitted in bursts to get around the interference problems that are inherent in DSL. The Ethernet packet data model reduces cost by providing compatibility with existing standards. At the same time, the collision problems usually associated with Ethernet are nonexistent because the local loop is a point-to-point link between two devices. A device at one end becomes a server and the other becomes a client. The client only speaks when the server allows, thus eliminating collisions.
This client/server point-to-point arrangement has some performance benefits. If a file is being transferred, it is going in one direction, and most of the time and bandwidth is spent transmitting in that direction. A small amount of bandwidth is used to transmit occasional acknowledgements in the other direction.
EtherLoop monitors the signal during silent periods and measures crosstalk and interference to determine line quality. Crosstalk may occur between any of the 50 wires in the cable bundle that connects to the telephone company central or remote office. If necessary, EtherLoop will change internal frequencies to reduce crosstalk and avoid interference. This rate adaptation allows the EtherLoop modem to immediately adapt to any noise.
The user connection consists of a PC connected to an EtherLoop modem that, in turn, is connected to the phone line. This connects to the telephone company office where an EtherLoop multiplexer receives the signal and forwards packets to an Ethernet switch that, in turn, delivers the packets to one of several destinations: the Internet, a private intranet, or an ATM/frame relay network. Home users are assigned static or dynamic IP addresses.
Copyright (c) 2001 Tom Sheldon and Big Sur Multimedia.