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
----------------
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