INTELLIGENT WORK FORUMS
FOR COMPUTER PROFESSIONALS

Log In

Come Join Us!

Are you a
Computer / IT professional?
Join Tek-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Tek-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Jobs

Extending a demarc to server room - need help

Extending a demarc to server room - need help

(OP)
My company is moving to a new building. I'm the onsite IT tech and I'm trying to work with our cabling company to get the 3 T1's extended from demarc to server room. Our corporate IT group said that I should have them mount a 12 port patch panel on board in demarc room and then use 25 pair cat5 cable to pulled over to server room, terminated on another 12 port patch panel. Ports 1-3 will be used for the 3 T1's we're installing. 4-12 will be for future growth. The problem I'm having is that the cabling company we are using typically does residential work (not my first choice) so they're not entirely familiar with the concept of "extending demarcs" and unfortunately, while I understand the concept, I've never actually been involved in doing it. I need to explain to these guys exactly how to punch it down and that's the part I don't know. I've punched down tons of regular 4 pair cat5 ethernet on patch panels and wall jacks.
I'm just not sure what to do with the 25 pair cable on a 12 port patch panel. If I understand it correctly, the T1's only use 2 pair, so are there 2 pair punched down for each port x 12 ports equals 24 pair with one pair left over? Or do I have that wrong? If I've got it right, which 4 termination points (of 1-8) are used to punch down on, on the back of the patch panel?
Hopefully I've explained my problem accurately and not caused any confusion?
Can anybody help me understand?
Thanks!

RE: Extending a demarc to server room - need help

I'd rather use seperate 5e runs for each T1, then do what you propose. Better isolation of the individual T1's.

Always look out for the next guy because it may be you!

RE: Extending a demarc to server room - need help

T1 uses 1&2 and 4&5 (White/Orange pair and White/Blue pair, using 568-B wiring scheme)

I would also use separate cables instead of 1 cable split up with 2 pairs per jack.

However, what is the distance of the run? Cat-5 isn't really what is spec'ed for T1's, and if you are going to run multiple T1's through one cable, you usually want to separate the transmits from the receives into different cables or at least different binders.

If it's just a short distance, run 12 Cat-5 cables, and punch them to a 12 port patch panel at each, use 568-A or B, just do it the same at each end.

RE: Extending a demarc to server room - need help

(OP)
Thanks for the replies. I think I pretty much get it. The problem is I'm just following direction from our corporate IT group.

Some answers to your questions...the distance is approximately 100-120 feet from demarc to server room.
I tried looking at what current tenants (and the previous in our suite) in the building have done and it's a mix of both. Some have done 1 cat5 per T1 and the previous tenants in our suite look like they ran a 25 pair punched down to a 110 block.

I'm not sure I understand this part - "Cat-5 isn't really what is spec'ed for T1's, and if you are going to run multiple T1's through one cable, you usually want to separate the transmits from the receives into different cables or at least different binders."

So if I'm understanding you guys correctly, I should be able to take the 25 pairs, punch down 2 pair on 1/2 and 4/5 (b standard) for each of the ports on the 12 port panel and be good. With one unused pair left.

I don't understand cabling well enough to know what the difference between running those 25 pairs through one big cable or separating them all out into 4 pairs per cable (a single cat5) x 12 cables, that would all still be within the same proximity of each other going through the conduit?

Thanks again for the replies. It really helps.

RE: Extending a demarc to server room - need help

As others have said, if possible I would also install one cat5e per T1 connection. I would also install a 25pair. The difference is that a cat5e cable is designed to transmit data without interference from other wires and without loss of data by using the twist ratio. so the signal is (mostly) contained within each cat5e cable. A cat3 25 pair does have some twist but each single pair is within the same cable and there will be some spill over of signal. Also when you break out the pairs you will have signal loss as well. Either way will most likely work and your T1 connection probably comes into the building (or at least starts out) as a cat3 25 pair.

RE: Extending a demarc to server room - need help

This is pretty basic work for any decent interconnect company, if the vendor you have isn't familiar with this type of work then I would highly recommend finding another one.

Jeremy J. Carter
Charm City Communications
Avaya/Nortel
Sales. Service. Installation
http://www.charmcitycommunications.com

RE: Extending a demarc to server room - need help

If you are in aunion area (city) use a union company.

Always look out for the next guy because it may be you!

RE: Extending a demarc to server room - need help

While CAT5e cable can be used to extend T1 circuits, it might be best to use cable and hardware that are specifically designed for the task.

I love2 "FEATURE 00"
http://mysite.verizon.net/vze7n25t/

RE: Extending a demarc to server room - need help

Absolutely, Dex. We have shielded T1 cables that we use sometimes. The manufacturer is:

Quabbin datamax 100 ohm

Search this and you should find them.

Always look out for the next guy because it may be you!

RE: Extending a demarc to server room - need help

In my day we used ABAM cable for T1. Transmit and Receive had to be in separate cables. The foil shield was grounded on one end only. Grounding both ends caused current flow and induced noise. Just a bit of trivia from long ago. ;)

Jim

RE: Extending a demarc to server room - need help

(OP)
Thanks to everyone for the responses.
I've been out of town and unable to check the forum.

Couple follow ups - the company we are using mainly does residential work, therefore they are not entirely familiar with doing commercial work, though they say they are. The guys they have doing clearly are not. This was not my choice and is out of my hands so I have to live with it and make the best of it.

I'm having it installed the way our corporate guys told me to and using the company that my local management said I had to use (cost reasons).

At this point, I just have to hope for the best. I'm pretty sure I've got a good enough understanding of it and have explained to them what we're looking for (they brought in another guy who seems to know more about it). Work to be finished today/tomorrow with circuits being turned up in 2 weeks. We'll see how it goes. Thanks for all your help/advice.

RE: Extending a demarc to server room - need help

If money is no object, I would run 3 shielded t-1 cables. The 2nd best, cheaper/easier/more available/just as good.... imo would be to run 2 - 4 pair cat-5 cables. Use 1 cable for transmit on patch panel ports 1-4 (blue pair on each port on the panel 568B). Use the 2nd cable for the receive on patch panel ports 1-4 (orange pair on each port on the panel 568B). 25 pair cables punched down for t-1s do not play nice with t1 crosstalk unless TX and RX are separated (i.e. - not wired on consecutive pairs). It's easy to split t1 TX and RX on 66 or 110 blocks but not so easy on a patch panel.

-CL

RE: Extending a demarc to server room - need help

The thing to remember is that your T1s probably arrive at the other side of the Demarc after having travelled over cable that may be decades old and originally intended purely for voice comms. My experience is that a 25 pair cable would be no detriment to the service!

RE: Extending a demarc to server room - need help

In the old days T1s TX and RX were in separate cables all the way from the CO to the customer premises.

Jim

RE: Extending a demarc to server room - need help

Ozzie is right on the money if you are gonna move the packages. However, if you are extending past the smart jack you might run into a little trouble.
I extended ckts over 300' a couple of months ago using non-shielded cat6 & have not heard any complaints yet. Knock on wood.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Tek-Tips Forums free from inappropriate posts.
The Tek-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Tek-Tips forums is a member-only feature.

Click Here to join Tek-Tips and talk with other members!

Resources

Close Box

Join Tek-Tips® Today!

Join your peers on the Internet's largest technical computer professional community.
It's easy to join and it's free.

Here's Why Members Love Tek-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close