- The 100BASE-LX10 and 100BASE-BX10 PMD sublayers provide point-to-point 100 Mb/s Ethernet links over a pair of single-mode fibers or an individual single-mode fiber, respectively, up to at least 10 km. They complement 100BASE-TX (twisted-pair cable, see Clause 25) and 100BASE-FX (multimode fiber, see Clause 26). This clause specifies the 100BASE-LX10 PMD and the 100BASE-BX10 PMDs for operation over singlemode fiber. A PMD is connected to the 100BASE-X PMA of 66.1, and to the medium through the MDI. A PMD is optionally combined with the management functions that may be accessible through the management interface defined in Clause 22 or by other means.