The connectors on the ends of the cable are clear plastic, in which you
can see 8 individual coloured wires.  If you unplug the cable and hold the
ends up next to each other, both facing the same way, so that you can see
the little wires, you should see that if it's a straight through cable, both
ends will have the colours in the same order.  If they're in a different
order, there's a 99% chance that it's a crossover (100% if it works...).

  A straight through cable connects pin X at one end to pin X on the other,
and is used to connect a device that sends on pin X to one that receives on
pin X, and vice versa on pin Y.  Alike devices both have their "send" on pin
X and the receive on pin Y, and so those pins need to be swapped to connect -
- that's what the crossover does.

  Between a computer an a router, GENERICALLY, you'd need a crossover; these
are "alike" devices.  But many home/office routers incorporate a small
network switch on the LAN side (these are any which include more than one
LAN port), and so these use straight through cables instead.  Many modern
small switches, and routers which include switches, have now added circuitry
which will sense whether a straight through cable or crossover is being
used, and internally cross/recross the port as necessary to make it work.
(This is a handy feature in small networks, and can be a deadly menace in
large ones....)

David Gillett


On 28 Oct 2005 at 11:10, D Duncan wrote:

> Is it possible to identify the purpose of a cable by the stuff that's
> stamped on the plastic cable covering?  The stuff that says
> "wonderful E1422890 CM 75(something)c LL43774 ETL verified E Patch cable"
>
> What I think I know is, _that_ would be a cable linking my computer
> to the router, or an Ethernet cable.  Therefore, it's patching my
> computer to the Internet using the Ethernet port/plug.
>
> Is there anything within that stamped info that tells me it's a
> straight through vs a cross-over patch?
> (now that I'm thinking about it, isn't a cross-over sort of just a
> one-way dialogue?  Am I making any sense?)
>
> Do I have any of that terminology correct?
>
> (I do have that particular cable linking my computer to my router,
> but I'm just curious about the stamped info and identifying cables)
>
> Thanks,
> Diane

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