Ohms for 100Base-TX

Yes.

In theory, one could use 150 Ohm UTP, but I don't think any such cable is widely available. 150 Ohms is a common characteristic impedance of shielded (or screened) twisted pair.

-- 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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Thanks Rich for your reply and your time, it helps me.

Could I take the opportunity to have your opinion for 2 questions?

(1) I realized that the family 100Base-T has included 100Base-FX. So it is difficult to say that the T of 100Base-T is refering (in this case) to "twisted pair". Can we consider that it is just an enlargment ot the naming?

(2) For the 100 Mbit/s EFM, we have 100Base-LX10 and 100Base-BX10. I suppose they have been IEEE approved with 802.3ah in 2004.

Have you heard of G.985 that also described, in march 2003, an optical Ethernet 100 Mbit/s access? This is a specification for a bidirectional transmission on a fiber, downlink 1480 to 1580 nm, and uplink 1260 to 1360 nm.

It's curious for me that IEEE specifies, with 100Base-BX10, a similar technology to ITU-T G.985, just one year later? Have you pleased some information about that?

Thanks very much, best regards, Michelot

Yes; a triumph of marketing over engineering. (The widespread success of

10BASE-T at the time we were developing the 100 Mb/s version made the use of "100BASE-T" almost a foregone conclusion; the world instantly understood what it was--a faster version of what they already had.)

I have not been following the goings-on either in EFM or ITU G.985, so I can't comment.

-- 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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Bonsoir Rich,

Thanks for your reply. And between your words, it seems I'm hearing the sound of your voice...

Best regards, Michelot