[clug] Assistance with networking

Michael James michael at james.st
Sun Jul 31 13:18:44 GMT 2005

On 31/07/2005, at 10:40 PM, Rob Bolin wrote:

> Greetings of mighty gurus of CLUG:
> I have a networking problem that is driving me up the wall, and  
> refuses to be
> solved by my miniscule amount of knowledge. It's not exactly a  
> Linux question
> - but I am running Debian etch on all relevant machines :-)
> I recently had my house wired with Cat5 cabling by a contractor.  
> For the kids
> bedrooms (x4), the contractor ran a single cable down the shared  
> wall and
> wired up two pair to one socket, and two pair to the other. He then  
> ran the
> other end to a "patch panel" mounted in the security system's  
> container. From
> this panel, I have run short cables into a 5 port hub. Because of  
> the way the
> contractor wired the cables, the northern 2 bedrooms run into one  
> hub socket,
> and the southern 2 bedrooms run into another hub socket. The hub is  
> then fed
> back to my main hub, via a cross-over cable (which research seemed  
> to suggest
> should be used to connect two hubs together). The main hub then  
> connects to
> everything else (a couple more computers and the firewall).
> My problem is that the connection between the "front" and "back"  
> sections is
> intermittent at best, with generally only one of the bedrooms being  
> able to
> connect to the "front" at any one time. The bedroom machines have  
> been tested
> to work properly and use DCHP for IP addresses on the network.
> I have a suspicion that I can't run Cat5 in the way that it has  
> been done and
> expect all four machines to run at the same time, but I have no  
> information
> to back it up. Does any one have an idea why it might be failing, or,
> alternatively does any one have a clue stick to beat me with?

What he has done is a kludge and totally out of any spec.

But it can be made to work.

But only at 10/100Meg.
Gigabit needs all 4 pairs.

100 Meg uses 2 pairs, one Rx one Tx.

I take it he has (I take it it was a he?) put 2 sockets on the  
outboard end
  but only 1 in the security cabinet.  This means you need to split  
them again
  before plugging them into the hub/switch which can only run 1  

Simplest is buy a pair splitter for connecting 2 ethernets through 1  
Jaycar, Dick Smith, computer fair. Don't pay more than $15.
Cheapest is to crimp 2 short patch leads into 1 RJ45. (Requires  
Most practical is to put sockets 3 and 4 onto the inboard end.
Best is to insist he run a cable per socket,
  (then you can split it again when you wan to run something else)

The strict wiring specifications insist on double sockets.
That's right, a single socket doesn't meet the regulations.
This is not bloody-mindedness on the regulators part, it's experience.

Basically depends how much you paid...


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