[Gllug] Ethernet crossover wiring

[John Winters]

On Fri, 2006-02-24 at 16:10 +0000, Dan Stevens (IAmAI) wrote:
> > The result of making the standard lead in this form is that the
> > appliances at each end of the lead have to be wired differently to make
> > things work.  Thus NICs have a different interface from hubs and
> > switches and when you want to connect to devices which are the same
> > together you have to use a special lead.
> 
> Would I have to use a different cat5 cable to connect a computer to a
> router, and to connect a computer directly into another computer (peer
> to peer).

Yes.  Because of the mis-design of the CAT5 connections which I was
talking about, you have to have two different kinds of leads.

A so-called "straight" patch lead is used to connect a computer to a hub
or switch.

If you want to connect a computer to a computer or a hub/switch to
another hub/switch then you have to use a crossover lead.

Historically, quite a few hubs and switches have had a single socket
wired computer-style (either an extra socket or a switch on the box to
convert the wiring of one of the sockets) so that you can link two
hubs/switches with a "straight" lead.  Increasingly, switches are now
being built with auto-sensing capability.  They work out what kind of
lead you have used and re-configure their sockets to cope with whichever
it is.

HTH
John

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