gured to run either point-to-point links or over Resilient Packet Ring. WAN physical interfaces are designed for WANs and pack the Ethernet frames into an SDH/STM 64C payload (OC-192, or 10Gbps), provid- ing a usable capacity of 9.29Gbps. Table 11.1 compares the various physical inter- faces for 10GigE. Table 11.1 10GigE Optical Interfaces Characteristic LAN Physical Layer LAN Physical Layer WAN Physical Layer Interface Serial 4-Lane LAN/WWDM* Serial Usable data rate 10Gbps 10Gbps 9.29Gbps Physical media 1,550 nm/<40 km 1,275.2 nm, 1,300.2 nm, 1,550 nm/<40 km wavelength/range 1,324.7 nm, 1,349.2 nm 1,310 nm/<10 km 1,310 nm/<10 km For multimode fiber, range 850 nm/<65 m 850 nm/<65 m <300 m; for single-mode fiber, range <10 km Line rate 10.3Gbps 3.125Gbps 9.953Gbps WWDM (Wide WDM) refers to CWDM operating at 1,310 nm, compared to traditional CWDM, which operates at 850 nm. Chapter 11 Optical Networking EFM, standard 802.3ah, addresses Layer 1 enhancements for metro and wide area Ethernet services, such as providing for an extended range. EFM allows for opera- tion on copper wire and includes Layer 1 testing capabilities. Three main physical options for EFM are being developed: EFM fiber-As the name implies, this option is geared toward supporting Ethernet access over point-to-point fiber-optic facilities. Although there are currently a number of point-to-point fiber options available for Ethernet, they need enhancements in the areas of operations, administration, and maintenance. EFM PONs-In the context of the EFM standards, PONs provide for point- to-multipoint shared fiber access. (PONs in general are discussed in more detail earlier in this chapter and in Chapter 12.) EFM copper-This option supports point-to-point facilities over copper wire using DSL technology. This is an interesting option, given the huge amount of installed copper wire. This option mandates operation on telco unshielded twisted-pair, not LAN cable, and there are minimum perfor- mance goals. On a short reach, the goal is 10Mbps up to 0.5 mile