100BASE-T
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100BASE-T is any of several Fast Ethernet 100 Mbit/s (12.5 MB/s including overhead) CSMA/CD standards for twisted pair cables, including: 100BASE-TX (100 Mbit/s over two-pair Cat5 or better cable), 100BASE-T4 (100 Mbit/s over four-pair Cat3 or better cable, defunct), 100BASE-T2 (100 Mbit/s over two-pair Cat3 or better cable, also defunct). The segment length for a 100BASE-T cable is limited to 100 meters (as with 10BASE-T and 1000BASE-T). All are or were standards under IEEE 802.3 (approved 1995).
In the early days of Fast Ethernet, much vendor advertising centered on claims by competing standards that "ours will work better with existing cables than theirs." In practice, it was quickly discovered that few existing networks actually met the assumed standards, because 10-megabit Ethernet was very tolerant of minor deviations from specified electrical characteristics and few installers ever bothered to make exact measurements of cable and connection quality: if Ethernet worked over a cable, it was deemed acceptable. Thus most networks had to be rewired for 100-megabit speed whether or not they had supposedly been CAT3 or CAT5 cable plants. The vast majority of common implementations or installations of 100BASE-T are done with 100BASE-TX.
References
- This article was originally based on material from the Free On-line Dictionary of Computing, which is licensed under the GFDL.