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Re: Doubling 100MBit ethernet by splitting the cable

At 1053556552s since epoch (05/21/03 11:35:52 -0400 UTC), Grzegorz B. Prokopski wrote:
> Long time ago I've read that 100mbit ethernet uses only 2 pairs
> which leaves half of wires unused and thus when there's such a
> need - these can be used to create second 100mbit connection
> on the same cable (and connect second computer w/o the need of
> another cable).

Ethernet does only use 4 of the 8 wires in the cable.  I think that
the original idea was to carry voice and data over the same cable.

To that end, the only time I've seen one cable used for two computers
was in a wall jack.  You take the cable from the conduit, use half
of the wires for one jack, and the other half for the second jack.  On
the other end, you'll have to spit the wire and punch down two
connectors for the wire.

I've seen solutions that come pre-made for this; they come as pairs of
plugs that use the same pinout on both ends.  One plug has two sockets
(female), and its complement has two male plugs that can be inserted
into a patch panel or hub.  Give Blackbox (www.blackbox.com) a call;
I'm sure they have the parts.

You can do this yourself, using plugs and jacks as necessary.  Be very
aware, however, that making custom cables (especially 100Mbs ones) can
be difficult.  The wires in ethernet cable are all twisted to prevent
interference, and untwisting them too much can result in a bad
connection.  So, when you strip the cable to connect the wires, make
sure you connect the terminators as close as you possibly can.

As for which cables to use, just look on google for a diagram of
making a crossover cable.  That will show you which of the 4 wires are
normally used, and you can duplicate that pinout twice for your

Best of luck!


Jason Healy

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