EFM – Ethernet-First-Mile: ‘Symmetric DSL technologies’ For Enterprise

This is a standards-based solution providing extended Ethernet connectivity over copper voice-grade cabling using symmetrical DSL (Digital Subscriber Line) technologies.

EFM standard

The EFM standard (G.SHDSL.bis) is constantly being improved and can deliver symmetrical DSL line rates up to 15Mbps per wire pair on a ultra-short, low noise loops.

EFM ‘bonding

EFM ‘bonding; further enhances end-to-end DSL bandwidth and link reliability, up to eight wire pairs can be bonded, providing up to 100Mbps/100Mbps of symmetrical DSL bandwidth.

Typical applications

Zhone’s EFM products are extensively used to extend LAN’s (Local Area Network’s) beyond the 100 metre maximum reach of Ethernet systems when using structured cabling systems. EFM products can be used onsite using the structured cabling wires (Cat5, Cat5e, Cat6 etc.) or older voice-grade telephone cables (CW1308A) to interconnect the EFM devices often extending a LAN over a campus or large building environment over many kilometres of cabling.

EFM is also a very popular solution to extend Ethernet LAN’s over a WAN (Wide Area Network) for example to connect a remote office to the main office/data centre using wires provided by a telecommunications/service provider (e.g. British Telecommunications) often these are copper MPF (Metallic Path Facility) wires in a LLU (Local Loop Unbundled) environment or EPS8, EPS9 (Baseband Premier, Baseband Standard) copper wires in a smaller ‘budget-restricted’ environment.

Customer Premises Equipment

The EFM devices, known as CPE (Customer Premises Equipment) can be used in a Point-to-Point solution or in larger deployments in a Point-to-Multipoint solution, where numerous EFM CPE connect to a single EFM DSLAM (DSL Access Multiplexor) at the central hub.


The EFM CPE/Subscriber units have RJ45 connections to the LAN and a variety of cable options to connect to the WAN via NTE (Network Terminating Equipment, LJU361A standard phone sockets) or LTU’s (Line Terminating Units such as LTU38A, LTU39A) whereas EFM DSLAM’s have a 50pin RJ21 Telco connector to connect to the copper line plant and RJ45 connectors to the LAN.


Zhone are the world-leader in EFM technologies and Network Extender Technologies Ltd are proud to boast significant experience in this area, being the first UK provider of dual and quad bonding G.SHDSL technologies.


  • Point-to-Point Systems
  • CPE end devices
  • DSLAM Head-end Systems
  • Zhone Management Systems