Solved Need to free-up a spare pair between cable modem and router.

July 30, 2012 at 21:27:28
Specs: Windows Vista, Intel 1.4G / 1024MB RAM
Which pairs (colors) are NOT used in the CAT-5 cable between a cable modem and a Wi-Fi router? I'd like to split the cable so that I can go from the modem's RJ-45 to the router's WAN port, and then use spare conductors to bring a router LAN port back to the same location as the modem.

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#1
July 31, 2012 at 07:17:42
I'd like to split the cable so that I can go from the modem's RJ-45 to the router's WAN port, and then use spare conductors to bring a router LAN port back to the same location as the modem.

I don't think you'll be able to do this but I'm not 100% sure what it is you're attempting to achieve here. Please try to explain more clearly what it is you're doing and what you hope to accomplish by doing it.

If I'm reading this correctly, you would create what's called a "loop" in networking. A loop like this will down all network communication across the switch (router).

It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.

***William Henley***


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#2
July 31, 2012 at 08:01:00
No, not trying anything fancy; here's the deal. I have a CAT5 cable in an cable race that is sealed and that I cannot get to. It's the only cable from point A to point B. The TV-cable modem is at point A, the router is at point B.

Since a CAT5 cable has 4 pairs of wires (8 conductors), I figure that not all of these are used between the TV-cable modem and the WAN port of the router. So what I'd like to do is determine which pairs are needed to feed the router, then break the others out, splice them to another RJ45 plug, and bring a LAN port back to the TV-cable modem location so I can then splice in an RJ45 socket and plug a laptop into the network there. This would simply break the CAT5 cable into two, two-pair 'virtual cables.' This should work, providing that only 2 pairs (4 wires) are needed for either the WAN or the LAN hookup. I'm having trouble finding specs on which pairs are used for WAN and LAN connections.


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#3
July 31, 2012 at 08:18:02
✔ Best Answer
To answer your question, yes, a 100 Mbps connection only requires 2 pairs so you could break your cable as you suggest.

Here's how it's done:

http://www.intel.com/support/networ...

Pay attention to the following section:

100BASE-TX Adapters

Cable and Connector Pinouts

You'll need to punch wires #1, 2, 3, and 6 correctly into both RJ-45 ends. The listing for all 8 wires is just below.


I have an alternative suggestion for you. One I personnaly consider a better option if it's viable. Use the existing Cat5e cable to pull a couple more cables through the raceway.

It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.

***William Henley***


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#4
July 31, 2012 at 08:47:16
Perfect, William; thanks very much... just what I was looking for. Yeah, 'twould be nice to pull another couple as you suggested, but the existing cable is hopelessly tangled with all manner of things and sheetrocked-over. This is my only hope.

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