What does the X stand for in TX- FX

Question

Hello can anyone tell me what the X indicates in a TX or FX cable.Thanks,Justin.

Rich Seifert · Accepted Answer

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.

-- Rich Seifert Networks and Communications Consulting 21885 Bear Creek Way (408) 395-5700 Los Gatos, CA 95033 (408) 228-0803 FAX

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Rich Seifert · Answer

Total coincidence. Remember, ALL of the ANSI computer technology standards have an "X3" designation, from X3.1 (Synchronous Modem Signaling Rate standard) to X3.332 (SCSI-3) and everything in between.

-- Rich Seifert Networks and Communications Consulting 21885 Bear Creek Way (408) 395-5700 Los Gatos, CA 95033 (408) 228-0803 FAX

Send replies to: usenet at richseifert dot com

Justin Champion · Answer

Hello can anyone tell me what the X indicates in a TX or FX cable.Thanks,Justin.

Michael · Answer

So it's a coincidence then that the ANSI standards which these port types are based on, also have an X in their name? If I'm not mistaken, the PCS of

100BASE-X is based on the X3.263 standard (FDDI), and the PCS of 1000BASE-X is based on the X3.230 standard (Fibre Channel).

Michael (remove filter from email address)

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Michael · Answer

"Rich Seifert" worte:Maybe so, but not all the Ethernet port types reference ANSI X-seriesstandards! ;-) Anyway, thanks for clearing up this little mistery aboutEthernet.Note also that 10PASS-TS references American National Standard T1.424, butthe T's in both names have nothing to with each other either!Michael(remove filter from email address)

Justin Champion · Answer

Thank you this helpsJustin.

Andy Ball · Answer

Hello Rich,

RHS> Remember, ALL of the ANSI computer technology > standards have an "X3" designation, from X3.1 > (Synchronous Modem Signaling Rate standard) to X3.332 > (SCSI-3) and everything in between.

I would like a modem that runs as fast as SCSI ...over a domestic analogue telephone line. :-)

- Andy Ball

What does the X stand for in TX- FX

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