Newsgroups: comp.os.linux.networking
Subject: Re: using 10BaseT cards w/ phone lines (cheep home networking)?
References: 
[email protected] (Thas) writes:

> Greetings, 
> I have the need to use a linux box as a router (connect to the net via
> a 56K dial-up line for now) and share the connection to three other
> machines within the house (e.g. using the linuxrouter project) AND
> ofcourse I would like to experiment with some network game playing!
> 
> I was wondering if it would be possible to use the extra pair of wires
> in the domestic phone network to connect the PC's within a house? 

10Base-T needs two twisted pairs to operate. One pair is not enough.
If you have two free pairs for this and they are twisted, then you
have possibility to to run 10Base-T and telephone on the same cable.
The precessor of 10Base-T (1Mbps Starlan from AT&T) was planned
to share the same cable with both network and telephone. 
With 10Base-T you can also do this, although wiring standard
do not recommend this (for interference reasons), although it
often should work quite well.

> (In
> my case, my house is also prewired for intercom using similar twisted
> pair cables which I could exploit for carrying the network). 

If you have two free pairs then you could try this...
But don't be too dissapointed if it does not work well
(ti could work without problems or not).

> From the
> driver standpoint this should not require anything special (except
> perhaps to force some of the 10/100 cards to drop down to 10?).

You are right on this.

> I believe the 10BaseT cards were originally designed to do this.
> What sort of bandwidth can I expect?

You can expect very good network performance with propably
very temporary problems (possible on telephone ring, on/off-hook,
pulse dialling etc. if the cable is not very good).

In worst case you will not get any communication or the performance is
very poor.

Generally you get the full 10 MBps speed (or very close to it like
in any "better cable") or you will not get any usable results.

> If this is a viable option, why are there products on the market that
> are specifically ment for networking through the phone lines (HPNA?)?

HomePNA is a preduct deisgned to use telephone wiring for networking.
I have no personal experience on usin HomePNA products.

> My instict tells me that they share the SAME pair of cables as the
> voice lines but at different frequency band.

This is how HomePNA works.

> -Thas
> PS: I do not wish to consider running ethernet cables due the hassle
> and do not wish to consider wireless due to the cost. I'm just trying
> to be a typical linux minimalist :)

-- 
Tomi Engdahl (http://www.iki.fi/then/)
Take a look at my electronics web links and documents at 
http://www.epanorama.net/