100base-TX 100=100 Mbps base=baseband T=twisted pair....what the heck is the X for? So far I've heard transmit, ten, axial, but nobody can state their source.
Sorry if this is in the wrong forum, flame away. I'm studying for my network+ and can't find the answer to this anywhere.
I see you posted the same question in Yahoo Answers and got two rather useless responses.
I think 100BaseTX means "100BaseT extended".
IEEE 802.3 standard defines nomenclature, XBaseY, where:
? X = LAN Speed in Mb/s
? Base = Signaling method (baseband vs. broadband)
? Y= LAN segment length in 100M multiples (bus topology) or T for twisted pair wire, F for fiber (star topology)
I don't have any sources but I do know there is a sort of tradition in the IT industry of using the letter X to stand for "Extended". I mean this in the sense of stretching an already existing technology.
The first IBM PC in the 1980s was followed up by the PC-XT which stood for "extended technology". This was not a complete new generation of hardware. That came with the PC-AT ("advanced Technology") hardware standard which was the basis for what we still use today. Later on came the ATX ("AT eXtended").
Similarly with Ethernet. 100BaseT came first, using 2 twisted wires, then came 100BaseTX which used 2 higher quality twisted wires. Now you have 100BaseT4, with 4 wires and 100BaseFX with optical cable.
From Rich Seifert, one of the "designers of the commercial 10 Mb/s Ethernet, and author of the original DEC-Intel-Xerox Ethernet specifications."
It doesn't "stand for" anything. When we were developing the 100 Mb/s Ethernet standard, a proposal was initially presented for an encoding scheme that supported both twisted pair and fiber. To facilitate discussion, it was called "100BASE-X", where the "X" was a placeholder for whatever medium would ultimately be used. The symbolism stuck and we kept the "X" designation to indicate the use of 4B/5B block encoding; -TX meant that coding on twisted pair, and -FX meant that encoding used on fiber.
I think they used the X because there already was a 100BaseT2 and 100BaseT4, where the last number referred to the number of wire pairs -100BaseT2 used 2 pairs, 100BaseT4 used 4 pairs. Both of those were for Cat 3 cable. When they wrote the spec to require the use of Cat 5 cable, since there already was a 100BaseT2 and the new spec still used 2 pairs of wires, they substituted X to make it 100BaseTX.
