[NCLUG] 100 Mbit cabling

[Mike Loseke]

Thus spake Michael Dwyer:
> 
> dherr at frii.com wrote:
> > I've heard two different answers to this question, and I'd like
> > to know the correct answer before I start pulling cable in my house.
> > For a 100 Mbit ethernet connection, are all 8 wires needed, or just
> > the same 4 wires that are used for 10-BaseT?  This will determine
> > how many 8-wire cables I need to bring to a given location.
> 
> For MOST 100MBit signals, (100TX?) you need the usual tx and rx pairs. 
> So, four wires.  But the question you /asked/ was about 100MBit 
> connections in general...  In which case, you DO need all eight wires. 
> I believe that the 100VG standard uses all eight wires.  ATM appears to 
> depend on four wires, but different pairs.  Ditto for Token Ring.
> 
> I suggest that you pull extra cable instead of trying to split them.  It 
> works, but it is a Bad Thing in the long run.
> 
> By the way, the wiring standards (ANSI/TIA/EIA-568) suggest:
> 
>    A minimum of two telecommunications outlets shall be provided to
>    each work area. The two outlets shall be configured as follows:
>      1. One connector shall be supported by a 4-pair 100d UTP
>         cable, Category 3 or higher
>      2. The other shall be supported by a minimum of one of
>         the following:
>         a. 4-pair 100 dUTP cable (Category 5 recommended)
>         b. 2-pair 150dSTP cable
>         c. 2-fiber, 62.5/125 um optical fiber cable
> 
> In other words, every work area should probably have a CAT3 phone line, 
> and the other should be a CAT5 wire.  You should only split the wires 
> when, two years down the road, you discovered that you didn't pull 
> enough cable. :)

 You can use cat-5 for phones too. I'd go cat-5 for both computer and
voice. At some point in the future you may want to use Gig-E and if you
swap some phone sets over to VoIP (or over a computer) you're not going to
want that useless cat-4 in the wall.

 The short answer to the original question is that 4-pair is more correct
for 100-Mbit.

-- 
   Mike Loseke    | kernel, n.: A part of an operating system
 mike at verinet.com | that preserves the medieval traditions of
                  | sorcery and black art.