[geeks] Whee! Lightning strikes, AGAIN!

[Sandwich Maker]

" From: gsm at mendelson.com
" 
" On Tue, Jul 28, 2009 at 12:25:14AM -0400, Lionel Peterson wrote:
" 
" >I'm not following you - are you saying that in Cat5e/Cat6 there are
" >four pairs communicating, or are you discussing Fiber?
" 
" Yes. 10Base-T and 100Base-T use 2 pairs, each at the rated speed, if you
" look at a plug with the tab up, wires 12345678, 1 and 2, 3 and 6. Up until 
" recently (2001 or so in high end stuff, 2005 or so in cheap stuff) direction
" mattered. Wires 4 and 5 were reserved for telephones so that if you accidently
" plugged a telephone line into an ethernet, it did not explode when the phone
" rang.

iirc this dates from at&t starlan, mid-'80s 1mb '1base-t'; they wanted
network and phone to the desktop on one cable.

100base-4 used all 4 pairs, dunno if bidirectional or 2 each way.
________________________________________________________________________
Andrew Hay                                  the genius nature
internet rambler                            is to see what all have seen
adh at an.bradford.ma.us                       and think what none thought