[TriLUG] Phone/DSL wiring

[Brian Henning]

We'll see if anyone beats me to this:

First of all, a cat-5 crossover is NOT a pair-for-pair reversal.  A 
crossover only crosses the 1/2 and 3/6 pairs (as diagrammed below). 
Pairs 4/5 and 7/8 remain the same.

RJ45 cat5 pairing:

1 2 3 4 5 6 7 8
|-| | |-| | |-|
     |-----|

   1 2 3 4 5 6
   | | |-| | |
   | |-----| |
   |---------|

^^ RJ-11 (6-wire) pairing ^^

So, as you see, for the "middle two" pairs, plugging an RJ-11 wire into 
an RJ-45 jack will connect the correct wires (though some/many/most 
RJ-45 jacks can be damaged by plugging in an RJ-11 plug; the 
six-position RJ-11 plug overly compresses the #1 & #8 contacts of the 
RJ-45 jack).

Shameless plug:
If you're doing any wiring at all, spend the $100 on an Ideal VDV 
MultiMedia Cable Tester kit.  It will tell you every possible problem 
with any RJ-11, RJ-45, and coax cable.
/Shameless plug

Anyway, as you probably already know, typically 3/4 is the "first" line 
on a RJ-11 cable set, 2/5 is the second, and 1/6 is the third.  So your 
primary phone line would be on 3/4, and your fax/dsl line would be on 2/5.

www.cableorganizer.com is a site I tripped over that seems to be 
well-laid-out site, but I've done no business with them.  Your corner 
Lowes or Home Depot ought not be too terribly inflated price-wise, if 
you can find all the materials you need there.

Otherwise I don't see any practical reason not to try what you're 
suggesting.  Good luck.

~Brian



Rodent of Unusual Size wrote:
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> My DSL has been misbehaving lately, and a Covad tech came
> out to see what was going on.  It turns out that, not
> surprisingly, the problem lies in the mare's-nest of
> antique cables and connectors I'm using.  So I have to
> clean up my act.
> 
> I've got a single 2-pair RJ11 jack in the wall, behind a
> bookcase and inaccessible.  I've got a 2-pair flat
> phone cable coming out from there, which is obviously
> what I need to use as a base.  Line 1 (the first wire
> pair) is strictly house telephone; line 2 is work
> phone/DSL/fax machine.
> 
> Pretty much all Cat-5 stuff appears to be 4-pair and
> RJ45.  As long as I can mesh that with the 2-pair RJ11
> connector coming from the wall, it's just a matter of
> getting the right parts.  Unfortunately, I think it's
> still going to be messy:
> 
> wall ]=====[coupler]======[ Dual ]==[house phone]
>      ]=====[       ]======[ jack |
>                                  ]==x==//==> (xover cable)
> 
>> ==//==[coupler]==[ Dual ]==[DSL modem]
>                     jack ]
>                          ]==[filter]==[fax]==[work phone]
> 
> Does that look reasonable?  If so, I need to know whether
> a 4-pair crossover Cat-5 will work (I assume all the pairs
> are reversed individually?) and whether an RJ11 plug going
> into an RJ45 jack will Do The Right Thing.
> 
> I don't like two couplers and two dual-jacks, but I don't
> see how else to do it.  Maybe I'm stupid or just too
> tired.
> 
> If the crossover will work, and RJ11->RJ45 will work, and
> the above isn't so ghastly that you're all off hurling into
> the shrubbery, does anyone have an recommendations for where
> I should buy all this crap and what brands?  I'll still
> need RJ11 connectors on whatever I use between the dual-jack
> and the house phone, the filter and the fax, and the fax and the
> work phone.
> 
> Thanks..
> - --
> #ken	P-)}
> 
> Ken Coar, Sanagendamgagwedweinini  http://Ken.Coar.Org/
> Author, developer, opinionist      http://Apache-Server.Com/
> 
> "Millennium hand and shrimp!"
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-- 
----------------
Brian A. Henning
strutmasters.com
336.597.2397x238
----------------