DSL Advances

7.5. Ethernet in the First Mile (EFM)

Figure 7.27 shows the basic concept of EFM [34]. One, two or four phone lines may be coordinated to deliver 10 or 100 Mbps symmetric VDSL service in EFM. Even though “Ethernet” physical-layer copper twisted-pair standards have long been established, they are restricted to a length of 100 meters for 10 Mbps (“10BT”), 100 Mbps (“100BT”) and 1000 Mbps (“1000BT”). Each uses a category-5, 5e, or 6 set of four twisted pairs in synchronous point-to-point transmission. Longer-length transmission fundamentally requires a different physical-layer modulation, while the upper layer “Ethernet/TCP/IP” functionality can be maintained so that the DSL line essentially looks like a “long-range Ethernet.” The current physical-layer ...