Ethernet in the First Mile

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Ethernet in the First Mile (EFM), also known as IEEE 802.3ah, is a collection of protocols specified in IEEE 802.3, defining the Ethernet in the access networks, i.e. first or last mile.

With Wide, Metro and Local Area Networks already standardized, the EFM allows continuous standard Ethernet network across the globe, eliminating non-native transport such as Ethernet over ATM from the access networks.

EFM defines how Ethernet can be transmitted over new media types:

• Voice-grade copper. These new EFM copper (EFMCu) interfaces allow optional multi-pair aggregation
• Long wavelength single fiber (as well as long wavelength dual-strand fiber)
• Point-To-Multipoint (P2MP) fiber. These new interfaces are known under collective name Ethernet over passive optical networks (EPON).

EFM also addresses other issues, required for mass deployment of Ethernet services, such as operations, administration & management (OA&M) and compatibility with existing technologies (e.g. spectral compatibility for copper).

History

The IEEE 802.3ah working group was established in 2001 in order to enable Ethernet penetration into the Access Networks. In parallel the EFM Alliance (EFMA) was formed by the participating vendors, to promote Ethernet subscriber access technology and support the IEEE standard effort.^[1]

The EFM standard was approved on 24 Jun 2004 and published on 07 Sep 2004 as IEEE 802.3ah-2004. In 2005 it was included into the base IEEE 802.3 standard. In 2005, the EFMA was absorbed by the Metro Ethernet Forum.^[2]

In early 2006, work began on a very high-speed 10 Gigabit/second EPON (XEPON or 10-GEPON) standard (http://www.ieee802.org/3/av/).

Details

The EFM defines the following new Ethernet physical layer (PHY) interfaces:

1. EFMC - EFM Copper
   • 2BASE-TL -- defined in clauses 61 and 63. Full-duplex long reach Point-to-Point link over voice-grade copper wiring. 2BASE-TL PHY can deliver a minimum of 2 Mbit/s and a maximum of 5.69 Mbit/s over distances of up to 2700 m (9,000 ft), using ITU-T G.991.2 (G.SHDSL.bis) technology over a single copper pair.
   • 10PASS-TS -- defined in clauses 61 and 62. Full-duplex short reach Point-to-Point link over voice-grade copper wiring. 10PASS-TS PHY can deliver a minimum of 10 Mbit/s over distances of up to 750 m (2460 ft), using ITU-T G.993.1 (VDSL) technology over a single copper pair.
2. EFMF - EFM Fiber
   • 100BASE-LX10 -- defined in clause 58, providing point-to-point 100 Mbit/s Ethernet links over a pair of single-mode fibers up to at least 10 km.
   • 100BASE-BX10 -- defined in clause 58, providing point-to-point 100 Mbit/s Ethernet links over an individual single-mode fiber up to at least 10 km.
   • 1000BASE-LX10 -- defined in clause 59, providing point-to-point 1000 Mbit/s Ethernet links over a pair of single-mode fibers up to at least 10 km.
   • 1000BASE-BX10 -- defined in clause 59, providing point-to-point 1000 Mbit/s Ethernet links over an individual single-mode fiber up to at least 10 km.
3. EFM PON - EFM Passive Optical Network
   • 1000BASE-PX10 -- defined in clause 60, providing P2MP 1000 Mbit/s Ethernet links over PONs up to at least 10 km.
   • 1000BASE-PX20 -- defined in clause 60, providing P2MP 1000 Mbit/s Ethernet links over PONs up to at least 20 km.

Additionally clause 57 defines link-level OAM, including discovery, link monitoring, remote fault indication, loopbacks and variable access.

See also

• IEEE 802.3

Further reading

• Beck, Michael (2005). Ethernet in the First Mile: The IEEE802.3ah EFM Standard. McGraw-Hill Professional. ISBN 978-0-07-145506-0. 
• Diab, Wael; Howard M. Frazier (2006). Ethernet in the First Mile: Access for Everyone. IEEE Standards Information Network. ISBN 978-0-7381-4838-0. http://shop.ieee.org/ieeestore/Product.aspx?product_no=SP1144. 

References

External links

• Download IEEE 802.3 - EFM is contained in section 5
• IEEE 802.3ah - Ethernet in the First Mile working group archives
• Ethernet in the First Mile FAQ
• "Ethernet OAM whitepaper" (pdf). http://www.rad.com/RADCnt/MediaServer/21878_EthOAM_WP.pdf. 
• EFM Knowledge Base at the UNH-IOL