The IEEE-802.3ah subcommittee is developing a standard for Ethernet over voice-grade copper. Dubbed as the Ethernet in the First Mile, the subcommittee has made great advances toward its goal of securing a standard for 10 Mbps services over at least 762 m of copper wire. The group expects to publish a final standard in 2004.
Long-reach Ethernet (LRE) extends Ethernet by utilising unconditioned, twisted-pair copper telephone wiring. LRE uses frequency-division duplexing to separate the downstream channel, the upstream channel and plain old telephone service (POTS), ISDN or PBX signalling services. This enables the overlay of LRE on existing POTS, ISDN or PBX signalling services without disruption. LRE and POTS/ISDN/PBX services may then be transmitted over the same line without interfering with each other. LRE provides full-duplex transmission at remarkable speeds and long distances:
* 15 Mbps symmetric rate (up to 975 m).
* 10 Mbps symmetric rate (up to 1219 m).
* 5 Mbps symmetric rate (up to 1524 m).
Because of these advances in speed and distance, a host of new value-added broadband services can be offered, including:
* Broadband Internet connectivity for business travellers, office workers and home users.
* Secure, high-speed network access through the addition of VPNs.
* IP telephony which allows remote users interact and collaborate in realtime.
* Converged video/voice/data applications, such as video-on-demand, videoconferencing and e-learning.
* For most implementations, three devices are required to effectively deliver LRE to users - an LRE switch, LRE customer premises equipment (CPE) and a POTS splitter.
LRE switches condition incoming and outgoing Ethernet packets so they can run over standard copper wiring. Otherwise, they act much as traditional Ethernet switches - directing, storing and forwarding packets, as well as matching destination and source addresses together into virtual channels. LRE switching units simply need to be installed in a building basement, along with the telephone equipment, using 10/100 Mpbs or 1000Base-T to uplink to the Internet router and/or local servers. 10/100 switch ports also can be used to daisy-chain multiple LRE switches.
Each LRE port is terminated in the room with a CPE device. The device splits LRE and POTS traffic, converting the LRE traffic into Ethernet traffic and vice versa. This provides Ethernet access to the LRE signals that are on the telephone wire, without interfering with the service already in place.
A POTS splitter lets LRE and POTS co-exist on the same telephone line. It is necessary for deployments in which the PBX system is on-site and POTS traffic must coexist over the same copper wiring as LRE traffic.
Together, these equipment provide a robust broadband solution that is:
* Low-cost - Building owners do not need to rewire their buildings to achieve remarkable increases in available bandwidth.
* High-speed - LRE delivers bandwidth of up to 15 Mbps.
* Extremely functional - LRE supports a range of broadband capabilities.
* LRE changes the economics of broadband provisioning by providing a cost-effective solution that preserves the existing communications infrastructure of multiunit buildings and enterprise campus customers.
For further information on TDK Semiconductor products, contact Electrocomp 011 458 9000 or see the new website: www.tdksemiconductor.com
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