Ethernet via existing phone wiring?

I want to connect several computers (in different rooms) with ethernet
in order to share a (potential) ADSL connection, and I hope I can avoid
rewiring. Near each computer there is a double phone socket, with the
first port wired to a standard BT phone line. The second phone ports
are all wired up ready for a second line, but have never actually been
used.

Can I use the redundant phone wiring for ethernet? I know the cabling
is not ideal (presumably not cat-5), and it has the wrong topology
(again, I assume), but will it work at all? Perhaps as 10Base-T only?

Peter

Peter Robinson wrote:

> I want to connect several computers (in different rooms) with ethernet
> in order to share a (potential) ADSL connection, and I hope I can avoid
> rewiring. Near each computer there is a double phone socket, with the
> first port wired to a standard BT phone line. The second phone ports
> are all wired up ready for a second line, but have never actually been
> used.
>
> Can I use the redundant phone wiring for ethernet? I know the cabling
> is not ideal (presumably not cat-5), and it has the wrong topology
> (again, I assume), but will it work at all? Perhaps as 10Base-T only?
>
> Peter


Yes it will work, remember that you need 4 wires though, 2 for the transmit
pair and 2 for the receive pair. Some telephone cabling has 6 wores some 8.
If you only have 6 wires, you may have to rewire or take the wire off
terminal 3, which will allow the extension to dial out but not ring.....
which may or not be a good idea. The rest of your phones should ring
provided they are wired back direct to the master socket and not via the
extn you are using for your ethernet.
My Efficient Networks 8561 router has a built in ADSL modem and 4 port
10Mbps LAN. My router is upstairs, the downstairs cable is about 12 metres
in total length. I notice no difference in using the ADSL connection, and
as a lan transferring data from my labtop to my desktop there is very
little difference. Possibly on a 100M LAN there would be a marked
difference or maybe if the wiring was a greater distance.
The difference between CAT 5 and twisted pair telephone cable is that CAT5
is copper, has lower ohmic resistance and less capacitance between pairs
which is why CAT5 will work well at high frequencies.

"Peter Robinson" <(E-Mail Removed)> wrote in message
news:1g51j61.119fbirostrx2N%(E-Mail Removed)...

> I want to connect several computers (in different rooms) with ethernet
> in order to share a (potential) ADSL connection, and I hope I can avoid
> rewiring. Near each computer there is a double phone socket, with the
> first port wired to a standard BT phone line. The second phone ports
> are all wired up ready for a second line, but have never actually been
> used.
>
> Can I use the redundant phone wiring for ethernet? I know the cabling
> is not ideal (presumably not cat-5), and it has the wrong topology
> (again, I assume), but will it work at all? Perhaps as 10Base-T only?

The critical thing is the number of pairs. 10Base-T and 100Base-TX Ethernet
use two pairs. Telephone wires often have only 2 pairs. (This will vary from
contry to country and with age of the building. You will need a 3 pair wire
or you need to give up telephone service.

I have been trying to convert whole appartement blocks in Helsinki to
Ethernet using existing telephone wires. All the installations and tests so
far have worked. The idea has been to to use 10Base-T MDU (Multi-Dwelling
Unit) switches.

The quality of telephone cable varies from manufacturer to manufacturer and
with age. It is how ever very difficult to compare as no rating for signals
above 1MHz is usually given to telephone cable. (All new US cable is I
belive rated at Cat-3.)

In my experiments I have been astonished to find that almost all
instalations work also at the higher speed of 100Mbps (without any errors on
the switch statistics). Top results on finnish telephone cable: 100base-TX
90 meters, 10Base-T 150 meters.

The category or Cat-rating of the wiring is not only dependent on the type
of cable, but equally on the splices and terminations. For best results you
should connect the telephone wire straight (end-to-end) to Cat-5 jacks
without any splices in between.

If you need to provide telephone and Ethernet-service on only two pairs
there is an alternative: http://www.etherSPLIT.com
This US product uses a band-pass filter similar to ADSL and HomePNA
splitters to run both Ethernet and telephone on only two pairs.

****

As more and more people are giving up telephone service it will soon be
possible to take over the old wiring for Ethernet. One reasion for this
trend is mobile phones; "voice goes mobile". The other is the arrival of
cheap (65$) VoIP-phones and services.

An other alternative is to one additional Cat-5 cable in to the existing
conducts (16 mm plastic PVC piping) and change the legacy faceplate to a
RJ-11/RJ-45 combination. The cost of renovating a whole building (50 - 150
appartments) starts at 100 euros (66£, 119$) at finnish market prices.

In this new infrastucture we will have an IP-phone in every appartment, a
stack of Ethernet-switches in the wiring closet in the basement and
100Base-TX or 1000Base-SX multimode fiber connections connecting
neighbouring buildings.

****

A few words about the MDU broadband business.

There are two ways of providing LAN-based Internet access to appartment
blocks and condos, Ethernet and HomePNA. (For HomePNA-based MDU switches
see: http://homepna.org/products/index.asp#mdu )

This technology is often viewed only as a way for large property owners to
increase their revenue. (The owner should use his monopolistic control of
access to the infrastucture to squeeze every last penny from the tennants.)
I see the thing differently; we should try to utilize the "economies of
co-operation" and bring LAN-based Internet to *every* home.

For LAN-based delivery of Internet service to work two things are important:
1) The LAN must be owner or controlled by the users
2) It must be independent of any commersial ISP, an "open access" network.

In Finland appartment buildings are usually wholly owned by the residents.
(The co-operative is in fact arranged as a limited stock company.) All that
is needed to make investment decisions for in-house networking is to call an
extra shareholders meeting. With the present rate of activity we will have
all of Helsinki wired in a few years.


--
Petri Krohn
petri. krohn <a@t> iki. FI(nland)
__________________________________________________ ___________
Fiber-optic Community Networking: http://www.HelsinkiOpen.net

"Petri Krohn" <(E-Mail Removed)> wrote in
news:bq8dbg$7po$(E-Mail Removed):

> "Peter Robinson" <(E-Mail Removed)> wrote in message
> news:1g51j61.119fbirostrx2N%(E-Mail Removed)...
>
>> I want to connect several computers (in different rooms) with
>> ethernet in order to share a (potential) ADSL connection, and I hope
>> I can avoid rewiring. Near each computer there is a double phone
>> socket, with the first port wired to a standard BT phone line. The
>> second phone ports are all wired up ready for a second line, but have
>> never actually been used.
>>
>> Can I use the redundant phone wiring for ethernet? I know the
>> cabling is not ideal (presumably not cat-5), and it has the wrong
>> topology (again, I assume), but will it work at all? Perhaps as
>> 10Base-T only?
>
> The critical thing is the number of pairs. 10Base-T and 100Base-TX
> Ethernet use two pairs. Telephone wires often have only 2 pairs. (This
> will vary from contry to country and with age of the building. You
> will need a 3 pair wire or you need to give up telephone service.

In North America each line only requires 1 pair. (Was 2 pairs a typo? - I
always mix up pairs and wires myself : b)

> I have been trying to convert whole appartement blocks in Helsinki to
> Ethernet using existing telephone wires. All the installations and
> tests so far have worked. The idea has been to to use 10Base-T MDU
> (Multi-Dwelling Unit) switches.

BTW, how reliable is HPNA when used in an apartment building? Was there a
reason you chose to go with 10Base-T instead of HPNA?



--
Lucas Tam ((E-Mail Removed))
Please delete "REMOVE" from the e-mail address when replying.
http://members.ebay.com/aboutme/coolspot18/

"anc" <(E-Mail Removed)> kirjoitti viestissä
news:3fc7a57a$0$12667$(E-Mail Removed).. .

> Yes it will work, remember that you need 4 wires though, 2 for the
transmit
> pair and 2 for the receive pair.

Four wires is not enough, at least if you want to run Ethernet for more than
a few meters or at the higher 100Mbps speed.
What you need is 2 twisted *pairs*.

> Some telephone cabling has 6 wores some 8. If you only have 6 wires,
> you may have to rewire or take the wire off terminal 3, which will
> allow the extension to dial out but not ring.....

I do not know how british telephones work. Most telephones around the world
carry the ring tone in the one and same pair as voice. (As an alterneting
current signal.) It is likely that this terminal 3 ring tone wire is not
part of any twisted pair. It will not work well for Ethernet (but could
carry voice for a few hundred meters).

Finnish 2-pair telephone cable has in fact 6 wires. Four wires form the blue
and the orange pairs. A red untwisted wire is supposedly for "signalling"
but I have not heard of it ever beeing used for anything. A 6th unshielded
wire is connected to the aluminium shield and should be used for grounding.
I theory you run POTS voice on the shield and the signaling wire and reserve
the two true twisted pairs for Ethernet.

> The difference between CAT 5 and twisted pair telephone cable is that CAT5
> is copper, has lower ohmic resistance and less capacitance between pairs
> which is why CAT5 will work well at high frequencies.

I have heard of lead wires being used for telephone in the thirties. All
newer finnish telephone wire is copper. This telephone cable (like most
european) has a larger cross area and a lower ohmic resistance than US Cat-5
or telphone cable.
The difference in networking and telephone cable is in the number of twists
per meter (or foot). Cat-3 cable has about 7 twists per meter (2 per foot),
telephone cable is about the same. Cat-5 or Cat-6 cable can have almost 100
twists per meter.

I do not think the capacitance between pairs differs in Cat-5 and telephone
cable. Also the impedance of the cable at 10MHz is the same, 100 ohms.
The difference is in the *cross-talk* or coupling between the pairs.

> ... 4 port10Mbps LAN.
> Possibly on a 100M LAN there would be a marked
> difference or maybe if the wiring was a greater distance.

When using poor quality cable for Ethernet you should manually configure all
your links to 10Mbps. Otherwise the the devices will autonegotiate a speed
of 100Mbps and the link may fail to work at all.

--
Petri Krohn
http://www.HelsinkiOpen.net

"Lucas Tam" <(E-Mail Removed)> kirjoitti viestissä
news:Xns9441A7EE5AD1Cnntprogerscom@140.99.99.130.. .

> BTW, how reliable is HPNA when used in an apartment building?

Finnish experiance shows it is about 100% reliable.
The sad thing is that HomePNA 2.0 at 10Mbps will not work in a shared
environment because of cross-talk. All HomePNA MDU switches are HomePNA 1.1.

> Was there a reason you chose to go with 10Base-T instead of HPNA?

1) You could buy 24-port managed (MDU) Etherent switches on eBay at $12.50 a
piece. New HomePNA switces could cost almost $100 a port (now down to $35).
I want to provide FREE services to my neighborhood so I personally can not
afford to by all this expencive hardware.

Also, there is an other volunteer group in Finland pushing hard for HomePNA.
With business going so well they do not need my help.
See: http://www.homepna.fi/

2) Some of the newer buildings in my neighborhood have telephone wiring with
3 pairs per appartment. If not, there is the option of adding new cable.

3) The ultimate aim is to build a high speed Ehternet-based fiber-optic
"community network" based on an "open access" business model* to connect all
the LAN wired buildings. The faster 10Mbps connetion will produce a need for
higher bandwith to the house and thus a need for the fiber-optic
connections. HomePNA at 1Mbps can be served, yet poorly, by one or two ADSL
lines at a max 4Mbps / 512kbps. Going for HomePNA prolongs the reign of the
telco monopolies.

4) Nothing beats a RJ-45 jack in the wall. The click of a RJ-45 plug being
inserted is music to the ears!


The difference between Ethernet, HomePNA or WLAN is marginal. All are
Ethernet-based Layer 2 technologies. All three can co-exist in the same
access network, even side by side in the same house. The key is to segment
the network virtually by VLANs and not physically by routers.

(* Open Access means that we do not provide the Internet service. These
services are provided by competing ISPs for real money. Each ISP is
allocated one or more 802.1Q VLANs on the Etherent network. Customesrs of
one ISP would be configured into this VLAN. The customers would typically be
whole houses with their own NAT-router, but individual users can also be
configured to a VLAN.)


--
Petri Krohn
petri. krohn <a@t> iki. FI(nland)
__________________________________________________ ___________
Fiber-optic Community Networking: http://www.HelsinkiOpen.net

In article <bq8gbc$b5c$(E-Mail Removed)>,
"Petri Krohn" <(E-Mail Removed)> writes:
> "anc" <(E-Mail Removed)> kirjoitti viestissä
> news:3fc7a57a$0$12667$(E-Mail Removed).. .
>
>> Yes it will work, remember that you need 4 wires though, 2 for the
> transmit
>> pair and 2 for the receive pair.
>
> Four wires is not enough, at least if you want to run Ethernet for more than
> a few meters or at the higher 100Mbps speed.
> What you need is 2 twisted *pairs*.

The chances of a domestic telephone installation of using twisted
pair cabling in the UK are close to the fine structure constant.
It simply will not work.

JAB.

--
Jonathan A. Buzzard Email: jonathan (at) buzzard.me.uk
Northumberland, United Kingdom. Tel: +44 1661-832195

"Petri Krohn" <(E-Mail Removed)> wrote in
news:bq8jur$drs$(E-Mail Removed):

>> Was there a reason you chose to go with 10Base-T instead of HPNA?
>
> 1) You could buy 24-port managed (MDU) Etherent switches on eBay at
> $12.50 a piece. New HomePNA switces could cost almost $100 a port (now
> down to $35). I want to provide FREE services to my neighborhood so I
> personally can not afford to by all this expencive hardware.

Ah IC - I didn't realize this was a free service!

I was just wondering why you were going through all the trouble rewiring if
HPNA was available. But considering the price difference and speed, I
understand you choice!

--
Lucas Tam ((E-Mail Removed))
Please delete "REMOVE" from the e-mail address when replying.
http://members.ebay.com/aboutme/coolspot18/

"Jonathan Buzzard" <(E-Mail Removed)@buzzard.me.uk> kirjoitti
viestissä news:i1n8qb.56m.ln@192.168.42.254...

> The chances of a domestic telephone installation of using twisted
> pair cabling in the UK are close to the fine structure constant.

Are you trying to say that domestic fixed telephone installations in the UK
use wire without *any* twists? I know that extension cords are made of flat
cable attached to RJ-11 plugs. I can not imagine anyone intalling this
inside walls as a permanent installation.

If you have more information, please post a link to some reference.

> It simply will not work.
What will not work? Ethernet over UK telephone cable? Or finding twists in
UK cable?


--
Petri Krohn
http://www.HelsinkiOpen.net

In article <bq90tj$3hg$(E-Mail Removed)>,
"Petri Krohn" <(E-Mail Removed)> writes:
> "Jonathan Buzzard" <(E-Mail Removed)@buzzard.me.uk> kirjoitti
> viestissä news:i1n8qb.56m.ln@192.168.42.254...
>
>> The chances of a domestic telephone installation of using twisted
>> pair cabling in the UK are close to the fine structure constant.
>
> Are you trying to say that domestic fixed telephone installations in the UK
> use wire without *any* twists? I know that extension cords are made of flat
> cable attached to RJ-11 plugs. I can not imagine anyone intalling this
> inside walls as a permanent installation.

I am indeed say that 99.999999% of all domestic extensions are wired
using untwised pair cable, with four cores. If there are twists they
must be about one twist per metre. They are certainly not visible
like you would find on Cat3 or Cat5.

This includes stuff that goes under the floor and behind walls. The
simple reason is that twisted pair cable is absolutely unnecessary
to carry a telephone signal. It does not do it any harm mind you.
If I where wiring a house now I personally would drop in Cat6 in
a structured form, but that is because I might want to do other
stuff in the future.


> If you have more information, please post a link to some reference.

A bit tricky that. You might try this site for infomation on
wiring UK telephone extensions

http://www.wppltd.demon.co.uk/WPP/Wi...telephone.html

The cable used is to British Telecom specification CW1308 and usually
has two pairs, though you can get it with more pairs if wanted. I
can't find a page saying what the specification of the cable is
however. It is not suitable for ethernet except over very short
distances.

>> It simply will not work.

> What will not work? Ethernet over UK telephone cable? Or finding twists in
> UK cable?

Both.


JAB.

--
Jonathan A. Buzzard Email: jonathan (at) buzzard.me.uk
Northumberland, United Kingdom. Tel: +44 1661-832195