Re: POTS and Ethernet over CAT-5 Cable

["Dan" <Dbambach@xxxxxxxxxx>]

Hi Issac:

I thought I was making a "responsible" answer. No where have I been able to
find a EIA/TIA, IEEE, etc. spec/standard that states that using CAT5 cable
for simultaneous applications that include ethernet is "approved". If I am
missing one, please send it to me as I would like to read it so I am better
informed when I answer questions. That said, I stand behind what I posted.
The general consensus is to make a informed decision, but most articles I
have read say do not do it. Some reasons given are: 1000mps use, PoE uses,
etc. Can it be done, yes. Would I do it, no. Two sites that talk about it:
http://www.swhowto.com/WhatWant.htm
http://www.zytrax.com/tech/layer_1/cables/mixed.html

Regards  Dan

"Isaac Wingfield" <isw@xxxxxxxxxxx> wrote in message
news:isw-BAA0E4.21140114082005@xxxxxxxxxxxxxxxxxxxxxxxxxxx
> In article <q-2dnZ2dnZ2LDsvFnZ2dndFbYt-dnZ2dRVn-yZ2dnZ0@xxxxxxx>,
> "Dan" <Dbambach@xxxxxxxxxx> wrote:
>
>> There is actually a lot of discussion about this in many engineering
>> circles. The general consensus is yes, Ethernet uses two pairs, which
>> leave
>> two pairs left for another Ethernet circuit, POTS, audio, etc. The
>> concern,
>> from what I have read in blogs is if you were to add something to the two
>> unused pairs that would create a high amount of energy (noise) that could
>> bleed over onto the Ethernet pairs causing packet errors and retries
>> slowing
>> the link down, or even crashing it. A POTS line works fine except I have
>> heard of the ringing cycle causing issues, but that was on a CAT5 and not
>> CAT5-E cable.
>
> You might take a look at the Ethernet spec, instead of just guessing; it
> specifically mentions using one (or both) of the spare pairs for POTS
> (or a second Ethernet). Why do you think they carefully avoided the 4-5
> pair for Ethernet, when you can plug an RJ-11 right in there and use it
> for a telephone?
>
> Isaac