[geeks] Whee! Lightning strikes, AGAIN!

[Phil Stracchino]

Sandwich Maker wrote:
> " 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.

There were, what, *three* different competing 100Mbit-over-copper
implementations?  100baseTX, 100base4, and ...   my vague memory says
100baseVG?


-- 
  Phil Stracchino, CDK#2     DoD#299792458     ICBM: 43.5607, -71.355
  alaric at caerllewys.net   alaric at metrocast.net   phil at co.ordinate.org
         Renaissance Man, Unix ronin, Perl hacker, Free Stater
                 It's not the years, it's the mileage.