[geeks] Well, THAT was a setback

[Patrick Finnegan]

On Tuesday 19 January 2010, Jonathan Patschke wrote:
> On Tue, 19 Jan 2010, gsm at mendelson.com wrote:
> > BTW, just for the record 1000BaseT is not 1000 megabits per second
> > ethernet. It's four 250meg connections operating in parallel.
> 
> It's 1000 megabits/s, just not 1000MHz.

Right.  I guess it may increase the latency over having a 1000MHz 
connection in theory, but it's still ethernet, so I doubt you'd notice 
the difference. :)

> > I also have no idea of what happens when one of the connections
> > stops working, do you loose them all, or does it just slow down?
> 
> It's no-longer 1000baseT, then.  A reasonable controller will attempt
>  to renegotiate at 100baseTX.

Realistically, you'll lose link.  As long as the pairs 1/2 and 3/6 are 
connected, the gear will negotiate a 1Gb connection, which will then not 
work because of the missing pair.  If one of those two pairs is broken, 
it won't negotiate much of anything. :)  If you set it to force a speed 
instead of auto-negotiate (on both ends, or else you'll end up with a 
duplex mismatch), then you can get 100Mb to work over a broken cable as 
long as the pairs used for 100Base-T are connected.

Pat
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