What E1 Cable should be used for a UC560?

[elias.ortiz]

This is a newbie question, I know, but I'm kind of newbie on this platform...

Should I use a CAB-E1-RJ45BNC= to connect a UC560 T1/E1 port to a digital E1 trunk that is wired on Coax? or is there another part number for UC560?

Thanks!

[David Trad]

Hi Elias,

This is dependant on the NTU that is being used, or if there is a direct termination from the MDF/IDF then you need to use the right wiring/pin-out configuration.

In most cases you can use a standard RJ-45 cable from the NTU to the E1 port, however some carriers depending on the NTU they are using (Adtrans of the like) may require a cross-over cable (Normally red in color), but this is not the case with the most modern NTU, they just use straight through cables.

If though the PRI/E1 is being delivered to a Fibre frame and then lead-in to an MDF/IDF you will need to make your own cable, and in this type of scenario I would refer you to this page HERE which will advise you as to how you should wire up your RJ-45 cable.

I hope this helps you out, If I did not quite get your question please let me know and I will re-do my answer.

Cheers,

David.

[paolo bevilacqua]

 In most cases you can use a standard RJ-45 cable from the NTU to the E1 port, however some carriers depending on the NTU they are using (Adtrans of the like) may require a cross-over cable (Normally red in color), but this is not the case with the most modern NTU, they just use straight through cables.

A standard Ethern patch cable is a poor choice for connecting E1/T1, even if it may work.

The reason is that pair twisting is different from Ethernet to E1/T1, so that the benefit of twisting are lost.

[David Trad]

A standard Ethern patch cable is a poor choice for connecting E1/T1, even if it may work.
The reason is that pair twisting is different from Ethernet to E1/T1, so that the benefit of twisting are lost.

That may be the case I guess, I have never looked at the cables that are provided with the NTU so I wouldn't know first hand. But I point out I have never seen a problem or had one even with a standard RJ-45... Is there any expected performance hit? Is the twist that much of an issue these days?

Cheers,

David.

[oni.somroy]

The twist is the whole 'balanced' part of it. It sends the same signal down both lines, but one's shifted 180 degrees out of phase. If one line picks up noise, the other line is used as a reference to cancel it out. Without this noise cancellation, the signal wouldn't travel as far.

[David Trad]

Thanks Oni..

You learn something new every day

I would not have looked at it that way given that they are only ever 30-50cm in length, I always figured loss of signal is not an issue.

Good conversation this thread

Cheers,

David.

[oni.somroy]

You're right! Loss isn't an issue for such a short length, so you'll be ok in that case.

The twisted pair concept also applies to 328ft ethernet cables, as well as 5 mile DSL lines which use UTP (Unshielded Twisted Pair), hence the name 100Base-T (T for twisted). Untwisting the wires in an ethernet or DSL cable would lower the signal to noise ratio and decrease the max distance.

[oni.somroy · Accepted solution]

Hi Elias,

It's not a noob question! Layer 1 info is difficult to find.

That looks like the right cable, but this one looks like it may be a better fit: CAB-ADPT-75-120

E1 (G.703) connections may either come in a 120-Ohm balanced signal on an RJ48 port OR as a 75-Ohm unbalanced signal on Dual BNCs. You need a 'balun' to convert the 120-Ohm balanced signal to the 75-Ohm unbalanced signal, and the CAB-ADPT-75-120 does just that.

Don't worry about the RJ45/RJ48 terminology. RJ48 is basically an RJ45, but instead of using pins 1,2,3,6 for Ethernet, it uses pins 1,2,4,5 for T1/E1.

Also, it's all about transmitting/receiving. Keep in mind that the Rx+ and Rx- from pins 1 and 2 of the RJ48 port will be connected to the inner and outer ring of BNC connector 1, and the Tx+ and Tx- from pins 4 and 5 of the RJ48 port will be connected to the inner/outer rings of BNC connector 2, so if for some reason you're not getting data, just try switching the BNCs around. The device you're connecting to must be transmitting on the same pins the UC560 is expecting to receive data on. If they're both transmitting on the same pins, no one's listening (i.e. receiving) .

-Oni

[paolo bevilacqua]

E1 (G.703) connections may either come in a 120-Ohm balanced signal on an RJ48 port OR as a 75-Ohm unbalanced signal on Dual BNCs. You need a 'balun' to convert the 120-Ohm balanced signal to the 75-Ohm unbalanced signal, and the CAB-ADPT-75-120 does just that. \

That is correct, but with the UCxx and VWIC cards, baluns are never necessary. The impedance can be changed via software with "line-termination 120" under controller E1.

So, one  have to check with telco first about the physicall connector they will use.

[oni.somroy]

Hi Paolo,

Thanks for the clarification.

I wasn't sure whether Elias was using CCA and whether CCA had options for configuring the impedance of the E1 port (or if it was automatic). Of course, this can be done with CLI as you stated, so he should be fine.

Just wanted you guys to keep in mind STAC will support CCA only or CLI only, but not both. So if a partner does not have their UC specialization, I reccomend sticking with CCA since it would be difficult getting support if they needed it.

Elias,

If you are UC specialized, this is of no concern to you since you can go CLI-only.

I also agree with Paolo--check with the telco about the physical pinouts/impedance of the connector they will use.

-Oni

[paolo bevilacqua · Accepted solution]

 
Should I use a CAB-E1-RJ45BNC= to connect a UC560 T1/E1 port to a digital E1 trunk that is wired on Coax? or is there another part number for UC560?

Correct, and configure line-termination 120 under controller E1.

[elias.ortiz]

Thanks!

Never imagined that such a newbie question would arise such a great flow of information!! Great answers guys!

I'll have a great trouble on deciding which answer to mark as the solution to my question, since all are correct and of great help.

Thanks Again to you all for the info!

By the way, I have posted another question related E1 and UC560 here: https://supportforums.cisco.com/thread/2096006

Would be spectacular if you guys could take a look at it.

Elias.