Multiple T1 transmissions on Cat5E

[Guest]

Archived from groups: comp.dcom.lans.ethernet (More info?)

My question is regarding the transmission of multiple T1 signals on
Category-5E cables bundled together. The reason I have this question is
one of my data center customers decided to extend (48) T1 lines from
the Telco room to IVR equipment over (48) Cat5E cables. Then terminate
on standard 48-port RJ-45 patch panel. The intent is to run each T1 on
an individual Cat5E cable (ie. Tx & Rx within each cable). My cusomter
claims that there would be no intereference between all these T1 lines
running together in the cable tray. The distance is over 100 feet.

Normally, the way I design T1 cable runs is to either use 56-pair ABAM
and terminate on a DSX panel; or substitute the ABAM with Category-3
and terminate each Cat-3 bundle one for Tx and one for Rx.

I was taught by an SBC engineer once that running more than 6-7 T1s in
individual Category-5E/6 cables next to each other will cause
interference or cross-talk. Is this true from your knowledge and
experience??

 

[Guest]

Archived from groups: comp.dcom.lans.ethernet (More info?)

Tech Geek wrote:

> My question is regarding the transmission of multiple T1 signals on
> Category-5E cables bundled together. The reason I have this question is
> one of my data center customers decided to extend (48) T1 lines from
> the Telco room to IVR equipment over (48) Cat5E cables. Then terminate
> on standard 48-port RJ-45 patch panel. The intent is to run each T1 on
> an individual Cat5E cable (ie. Tx & Rx within each cable). My cusomter
> claims that there would be no intereference between all these T1 lines
> running together in the cable tray. The distance is over 100 feet.

> Normally, the way I design T1 cable runs is to either use 56-pair ABAM
> and terminate on a DSX panel; or substitute the ABAM with Category-3
> and terminate each Cat-3 bundle one for Tx and one for Rx.

> I was taught by an SBC engineer once that running more than 6-7 T1s in
> individual Category-5E/6 cables next to each other will cause
> interference or cross-talk. Is this true from your knowledge and
> experience??

Since T1 can normally be run over pairs of a 25 pair cable where
the possible coupling should be much higher than adjacent Cat5
cables, I wouldn't expect much of a problem.

Both inductive and capacitive coupling between twisted pairs increase
with frequency, and T1 runs at much lower frequencies than ethernet.
That isn't a guarantee, but it is an indication that the problem
should be much less than for ethernet.

-- glen

 

[Guest]

Archived from groups: comp.dcom.lans.ethernet (More info?)

Tech Geek <oelissa@yahoo.com> wrote:
> each T1 on an individual Cat5E cable (ie. Tx & Rx within
> each cable). My cusomter claims that there would be no
> intereference between all these T1 lines running together
> in the cable tray. The distance is over 100 feet.

I don' t have direct experience with that many T1s, but I
wouldn't expect any problems over such a short distance in
such tightly twisted wire. There's a lot of power (current)
in a T1, but twist tames power.

> I was taught by an SBC engineer once that running more
> than 6-7 T1s in individual Category-5E/6 cables next to
> each other will cause interference or cross-talk. Is this
> true from your knowledge and experience??

What I've heard is there is a limit to the number of T1
that will run cleanly per cable binder-group (25pr). 1 is
fine. 2-3 usually work. 6+ is trouble. This depends on wire
guage, twist (Cat1 - 3) and cable feet.

-- Robert

 

[Guest]

Archived from groups: comp.dcom.lans.ethernet (More info?)

Tech Geek wrote:
> My question is regarding the transmission of multiple T1 signals on
> Category-5E cables bundled together. The reason I have this question is
> one of my data center customers decided to extend (48) T1 lines from
> the Telco room to IVR equipment over (48) Cat5E cables. Then terminate
> on standard 48-port RJ-45 patch panel. The intent is to run each T1 on
> an individual Cat5E cable (ie. Tx & Rx within each cable). My cusomter
> claims that there would be no intereference between all these T1 lines
> running together in the cable tray. The distance is over 100 feet.
>
> Normally, the way I design T1 cable runs is to either use 56-pair ABAM
> and terminate on a DSX panel; or substitute the ABAM with Category-3
> and terminate each Cat-3 bundle one for Tx and one for Rx.
>
> I was taught by an SBC engineer once that running more than 6-7 T1s in
> individual Category-5E/6 cables next to each other will cause
> interference or cross-talk. Is this true from your knowledge and
> experience??
>

I routinely get away with running two T1's on one 4 pair cat5 cable,
distance of about 75 feet. I got 11 T1's total, over six cat5e cables,
all in the same cable tray, all bundled together with tie wraps.

No issues. Works fine.

Your mileage may vary.


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[Guest]

Archived from groups: comp.dcom.lans.ethernet (More info?)

glen herrmannsfeldt wrote:

> Since T1 can normally be run over pairs of a 25 pair cable where
> the possible coupling should be much higher than adjacent Cat5
> cables, I wouldn't expect much of a problem.
>
> Both inductive and capacitive coupling between twisted pairs increase
> with frequency, and T1 runs at much lower frequencies than ethernet.
> That isn't a guarantee, but it is an indication that the problem
> should be much less than for ethernet.

The concern is near end cross talk, where the transmitter interferes with
the receiver. Using separate cables or individually shielded pairs fixes
that problem.