s (750 m); on a long reach, it is 2Mbps up to 1.67 miles (2.7km). The EFM standards also address two modem options: Discrete Multitone (DMT), which is currently used in most DSL modems, and Quadrature Amplitude Modula- tion (QAM), which is used in HDSL and VDSL modems. Finally, the EFM committee is also concerned with inverse multiplexing, one application of which is the use of multiple transmission paths to create a high- bandwidth channel (referred to as bonding). ADSL2 defines an ATM-based inverse multiplexing scheme, but in general, the EFM committee favors an Ethernet- oriented approach. Resilient Packet Ring and Other New Standards Initiatives Several major standards initiatives are under way to address the resiliency and QoS issues of Ethernet. The IEEE 802.17 working group is defining the Resilient Packet Ring access protocol for use in LANs, MANs, and WANs, for transfer of data pack- ets at rates scalable to many gigabits per second. Resilient Packet Ring technology enables high-speed, survivable ring networks that are optimized for IP and other packet data. This new standard will use existing physical-layer specifications and will develop new interfaces, where appropriate. Major features of Resilient Packet Ring include a dual-counter-rotating ring format, automatic discovery for adding new stations, a fairness principle that The IP+Optical Control Plane replaces the contention-based Ethernet CSMA protocol with a priority-based access protocol, destination stripping or spatial reuse, and protection whereby Resilient Packet Ring can be restored in 50 milliseconds or less. In addition, Resil- ient Packet Ring can carry voice and data traffic, which means it is possible to define jitter-free services with low latency for voice and video. As mentioned earlier, Resilient Packet Ring aims to increase the efficiency of Ethernet and IP services, providing the resilience found in SDH/SONET networks as a function of their network restoration capabilities, and in this way optimizing the transport of data traffic o