[conspire] (forw) Re: [TAG] Wiring a house with ethernet

Rick Moen rick at linuxmafia.com
Thu Oct 20 16:27:34 PDT 2005

Quoting Dan Martinez (dfm at razorwind.org):

> (I'm a software type by day. No, really. I swear.)

Heh.  On the Linux Gazette "Answer Gang" mailing list where this
discussion originated, there was much amusement at the number of
nominally software-oriented participants who, when poked, turned out to 
have serious chops in data cabling.

Peter:  I note Dan's excellent point about the number of
connected-through wire pairs, which applies equally to straight-across
cables as to crossover ones.  In addition to that:  Decades of rubbing
shoulders with Great Murphy make me raise the subsidiary question of
whether _any_ ethernet cable works between that BCM5751 gigabit port and
your PowerConnect 2324 switch.  Unless you know that some _other_ cable
works in the same circumstances, you don't have enough to suspect a
problem _specifically_ with your suspect Cat5e cable.

Other causes of problems can include switch configuration (e.g., does
the switch port and the BCM5751 negotiate duplex mode correctly?), and,
well, the fact that Broadcom chips just suck.  ;->

To answer the question you posed:  Yes, that Cat5e cable, if of
reasonable lenght and connected through on all four pairs to _properly_
connected plugs, should work fine on gigabit.

And, yes, that http://www.finnie.org/network-tips/#gigabit-crossover
diagram could be a lifesaver:  A lot of us have been lazy for a long
time and haven't been bothering to construct crossover cables in a
future-proofed fashion.  The diagram shows how to get it right.

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