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6.4. 100BaseTX

100BaseTX and 100BaseFX form the subgroup of 100BaseX, which is a part of the 100-Mbps Ethernet group of 100BaseT. Physical layers of both 100BaseTX, which uses two pairs of Category 5 unshielded twisted pair cables, and 100BaseFX, which uses two multimode fibers, are borrowed from existing FDDI standards to save the technology development time. Basics of physical layer 100BaseTX are defined in ANSI X3.263, FDDI Token Ring Twisted Pair Physical Layer, with modifications specified in Ethernet standards 100BaseX and 100BaseTX. The ANSI X3.263 standards define the MLT-3 line code, line voltages, and waveforms, as well as channel and crosstalk models. The 100BaseX standards specify the 4B5B encoding, while the 100BaseTX standards clarify ...