T1 demarc extension

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A subcontract job I'm doing includes extending the T1 from the demarc
to the telco equipment wall in the tenent's office suite.  The
contractor has provided CAT5e UTP and jacks for this purpose.  From
what I gather, this is not the proper cable to use, and I should be
using either a cable with individually shielded pairs, or two separate
cables, each with an overall shield - one for transmit and one for
receive.  Is this correct?

Also, from what I gather, the pairs in use are 1&2 and 4&5 on an
8-position jack?  So, using the UTP provided, I wired the extension as
T568B at both ends.  Aside from any issues that arise related to my
first question, should this work?



Re: T1 demarc extension


Michael Quinlan wrote:
> A subcontract job I'm doing includes extending the T1 from the demarc
> to the telco equipment wall in the tenent's office suite.  The
> contractor has provided CAT5e UTP and jacks for this purpose.  From
> what I gather, this is not the proper cable to use, and I should be
> using either a cable with individually shielded pairs, or two separate
> cables, each with an overall shield - one for transmit and one for
> receive.  Is this correct?
>
> Also, from what I gather, the pairs in use are 1&2 and 4&5 on an
> 8-position jack?  So, using the UTP provided, I wired the extension as
> T568B at both ends.  Aside from any issues that arise related to my
> first question, should this work?
>
You can use the Cat 5e cable, though using the shielded cable is the
right cable to use.  The cat 5e cable will cause more bit errors than a
shielded cable, but, it will still work.  A lot of talk has been on here
before about it.  You may want to use Google and search for more info on
this cause I know there is a lot.


Re: T1 demarc extension


I did take a look.  But my searches yielded a lot of unrelated
messages, as the search term "T1" brought up almost all references to
ANY wiring scheme, because of pair 1 being T1 & R1, pair 2 being... you
get the idea.



Re: T1 demarc extension


Michael Quinlan wrote:

> I did take a look.  But my searches yielded a lot of unrelated
> messages, as the search term "T1" brought up almost all references to
> ANY wiring scheme, because of pair 1 being T1 & R1, pair 2 being... you
> get the idea.

Try DS1.



Re: T1 demarc extension


Michael Quinlan wrote:
> A subcontract job I'm doing includes extending the T1 from the demarc
> to the telco equipment wall in the tenent's office suite.  The
> contractor has provided CAT5e UTP and jacks for this purpose.  From
> what I gather, this is not the proper cable to use, and I should be
> using either a cable with individually shielded pairs, or two separate
> cables, each with an overall shield - one for transmit and one for
> receive.  Is this correct?

The absolute very best cable to use is what you describe, individually
shielded twisted pair cable. This is also referred to as T-1 screened cable.

Now back to the real world.

I install and extend special circuits for Verizon every day. We use
Cat-5 cable for nearly all demark extensions nowadays. There is nothing
wrong with using Cat-5 cable for T-1 extensions. Cat-5 cable works fine
for 100 Megabit ethernet signals, a 1.5 Megabit signal should be no
problem at all.

I've also installed and extended T-1's on regular 25pair cable with no
problems at all.

> Also, from what I gather, the pairs in use are 1&2 and 4&5 on an
> 8-position jack?  So, using the UTP provided, I wired the extension as
> T568B at both ends.  Aside from any issues that arise related to my
> first question, should this work?

Unless the environment is very EMI/RF hostile, or the extension is
*very, very* long, you should be just fine.

And yes, a T-1 circuit uses pind 1&2 and 4&5 the other pairs are unused.

John
--
John P. Dearing
A+, Network+, Server+
To reply: Just drop "YOURPANTS" in my address! 8-)


Re: T1 demarc extension


Verizon used a 50-pair cable to extend 10 POTS lines into the suite,
leaving 40 pair unused.  I offered to use 4 of those to extend the T1,
but the contractor wanted me to run a new CAT5e cable instead.

Thanks for the quick replies.  Now I feel more comfortable going back
on site tomorrow.



Re: T1 demarc extension


Michael Quinlan wrote:
> Verizon used a 50-pair cable to extend 10 POTS lines into the suite,
> leaving 40 pair unused.  I offered to use 4 of those to extend the T1,
> but the contractor wanted me to run a new CAT5e cable instead.
>
> Thanks for the quick replies.  Now I feel more comfortable going back
> on site tomorrow.

What I would do if *I* was presented with that situation would be to
split the T-1 between the two binder groups in the 50 pair cable. Put
one side of the the T-1 in the white/blue binder and the other side in
the white/orange binder. You only need two pairs for the T-1, not four.

Back in the old old days, T-1's were always put in separate binder
groups to reduce cross coupling between transmit and recieve. Just make
sure to clearly tag and protect the pairs you use for the T-1.

You really don't *need* a Cat-5 cable for T-1. It's only 1.5 Mb/s. Using
Cat-5 is nice, but overkill.

As I said before, I install and repair these circuits every day. I've
extended T-1's through over 1,000 feet of house cable and had the
circuit work absolutely fine with no errors whatsoever. House cable is
Category *nothing*. 8-)

John
--
John P. Dearing
A+, Network+, Server+
To reply: Just drop "YOURPANTS" in my address! 8-)


Re: T1 demarc extension



> Michael Quinlan wrote:
>> Verizon used a 50-pair cable to extend 10 POTS lines into the suite,
>> leaving 40 pair unused.  I offered to use 4 of those to extend the
>> T1, but the contractor wanted me to run a new CAT5e cable instead.
>>
>> Thanks for the quick replies.  Now I feel more comfortable going back
>> on site tomorrow.
>
> What I would do if *I* was presented with that situation would be to
> split the T-1 between the two binder groups in the 50 pair cable. Put
> one side of the the T-1 in the white/blue binder and the other side in
> the white/orange binder. You only need two pairs for the T-1, not
> four.
>
> Back in the old old days, T-1's were always put in separate binder
> groups to reduce cross coupling between transmit and recieve. Just
> make sure to clearly tag and protect the pairs you use for the T-1.
>
> You really don't *need* a Cat-5 cable for T-1. It's only 1.5 Mb/s.
> Using Cat-5 is nice, but overkill.
>
> As I said before, I install and repair these circuits every day. I've
> extended T-1's through over 1,000 feet of house cable and had the
> circuit work absolutely fine with no errors whatsoever. House cable is
> Category *nothing*. 8-)
>
> John


CAT 5 cable should not be a problem when extending a T1 from a DEMARC .
It is not the cable itself that determines the cable selection/design.
Rather it is DS1 signal loss that determines if TX/ & RX pairs must be
isolated from each other.

With a 0.0 to -7.5DBDSX T1 hand off level by the Telco at the DEMARC, A
T1 can be extended for a reasonably long distance as long as the
insertion losses of the cable @ 772KHz are not excessive enough as to
allow signal cross talk from one transmission pair (Strong signal) to
the other (Weaker signal) to occur.

Twisted 25 pair cable is OK for relatively short runs, however if used
on house riser, it is reccomended that different 25 pair binder group
pairs be used to isolate T1 RX/TX  pairs.

Bill


Extended Demark wiring


Michael,

take a look at the knowledge base article # 2374 on Kentrox's web

site.  it covers this issue very well.



www.kentrox.com

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