Re: ethernet card

CJT wrote: 
P. Thompson wrote:

On Sun, 6 Nov 2005, CJT wrote:

CJT wrote:

Geoffrey S. Mendelson wrote:

In article <436CF621.70004@xxxxxxxxxxx>, CJT wrote:

You sure about that? My recollection is that Gigabit uses all 8. 





I'll check, I've don't think so, but occasionaly I'm wrong. :-)


I Google'd for it, and this is the first reference I found.  But I'm
fairly certain I've read it elsewhere, too, including in a textbook
on networking:

http://www.hardwaresecrets.com/article/231/2


FWIW, here's a cite with a little more impressive credentials:

http://www.cisco.com/en/US/tech/tk389/tk214/tech_digest09186a0080091a86.html


Figure 7 of the cisco site shows all four pairs in use.



I can say with certainty from experience that 10bt uses only two of the pairs, but 100bt and gigabit both use all four pairs. You have to make sure you use both wires from the same pair for each set of signals too, if you mix and match it doesn't work for 100 or gig, but 10 is slow enough that it doesn't seem to matter for short runs.
.

Relevant Pages

  • Re: ethernet card
    ... fairly certain I've read it elsewhere, too, including in a textbook ... Figure 7 of the cisco site shows all four pairs in use. ... but 100bt and gigabit both use all four pairs. ... My understanding is that all four pairs must be present anyway, in order for a cable to meet specs (I suspect that's to maintain distances within the bundle, which could affect crosstalk). ...
    (sci.electronics.repair)
  • Re: ethernet card
    ... P. Thompson wrote: ... fairly certain I've read it elsewhere, too, including in a textbook ... Figure 7 of the cisco site shows all four pairs in use. ... The e-mail address in our reply-to line is reversed in an attempt to minimize spam. ...
    (sci.electronics.repair)