2BASE-TL

2BASE-TL

2BASE-TL is an IEEE 802.3-2005 Physical Layer (PHY) specification for a full-duplex long reach point-to-point Ethernet link over voice-grade copper wiring.

2BASE-TL PHYs deliver a minimum of 2 Mbit/s over distances of up to 2.7 km (9 kft), using ITU-T G.991.2 (G.SHDSL.bis) technology over a single copper pair. These PHYs may also support an optional aggregation or bonding of multiple copper pairs, called PME Aggregation Function (PAF).

Rates and Distances

Unlike 10BASE-T, 100BASE-T and 1000BASE-T PHYs, providing a single rate of 10, 100 or 1000 Mbit/s respectively, 2BASE-TL link rate can vary, depending on the copper media characteristics (such as length, wire diameter or gauge, number of pairs if the link is aggregated, amount of crosstalk between the pairs, etc.), desired link parameters (such as desired SNR margin, Power Back-Off, etc.), and regional spectral limitations.

For a single pair, the minimum possible link bitrate is 192 kbit/s (3 x 64 kbit/s) and the maximum bitrate is 5.7 Mbit/s (89 x 64 kbit/s). On a 0.5 mm wire with 3 dB noise margin and no spectral limitations, the max bitrate can be achieved over distances of up to 1 km. At 6 km the max achievable bitrate is about 850 kbit/s.

Note that the throughput of a 2BASE-TL link is lower than the link's bitrate by approximately 5%, used by the 64/65-octet encapsulation and PAF overhead.

History

See EFM History.

2BASE-TL Equipment Manufacturers

*Actelis Networks, Inc. (http://www.actelis.com)
*Nexcomm Systems, Inc. (http://www.nexcomm.co.kr)
*Hatteras Networks, Inc. (http://www.hatterasnetworks.com/)
*iTAS Technology, Inc. (http://www.itas.com.tw)

ee also

* Ethernet in the First Mile
* PME Aggregation Function
* 10PASS-TS
* G.SHDSL

External links

* [http://standards.ieee.org/getieee802/802.3.html Get IEEE 802.3] - "IEEE Standard for Information technology - Telecommunications and information exchange between systems - Local and metropolitan area networks - Specific requirements - Part 3: Carrier Sense Multiple Access with Collision Detection (CSMA/CD) Access Method and Physical Layer Specifications", IEEE Std 802.3-2005, December 2005.
* [http://www.ieee802.org/3/ah/ IEEE 802.3ah] - Ethernet in the First Mile Task Force archive


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