Cabling jobs

Tiras25
Tiras25 used Ask the Experts™
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I will be bringing in 3-4 subcontractors later this week to bid the cabling portion of the job.  I need to select the best candidate.  I will have to decide on how many data-ports per cube.  I think 2 should be enough.  They have IP phones where the Ethernet plugs into the phone and from phone to the laptop.  So one port is always available.

So besides the price and the number of ports.  What else I should ask for?

Thanks.
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1. If possible I would rather avoid using the plug of the IP phone to connect a computer to it.
Reasons:
- The hub/switch inside those phones commonly supports only 100MBit/s
- If it comes to VOIP in a LAN, then it is very convenient if you can group those LAN connections that are used for VOIP traffic, e.g. into a VLAN, so that you separate VOIP traffic from other traffic. This, in combination with QOS helps you getting better voice quality results. But if you hang a VOIP telephone and a computer to the same line, such a separation is not possible.
- So, if you have the possibility to put 3 cables to each room, it would be better: one for VOIP and 2 for the computers. If by no means it is possible to put 3 cables, but only 2, then I would put it the other way arround: The laptop plugs into one port and the telephone into the other, and if an additional port is needed, use the one on the phone. But in this case you can not grop the telephone in a plain VOIP-VLAN, because then the computer plugged into the phone will have problems.

2. Other things to ask for:

What category of cables are you going to get, concerning their category and shielding..

1. category:
The category of TP cable determines the maximum speed. E.g.: You need as a minimum CAT5e for Gigabit speeds. http://en.wikipedia.org/wiki/Category_5_cable

2. The shielding of the cable.
UTP = Unshielded Twisted Pair
FTP = Foiled Twisted Pair (a plastic foil as a shield)
STP = Shielded Twisted Pair (a metal net as a shield)
SFTP = A metal net and a plastic foil as a shield

The higher the shield the less interferences you will have, the less problems you will have. Interferences could be e.g. power cables nearby the data cables, radio devices, mobile phones, etc. Problems could be e.g. reduced network speeds due to packet re-sends due to packet losses, interruptions, etc..

3. Where will all of those cables lead to? PATCH PANEL! All those cables should be joined at one place with a patch panel. This patch panel needs to be earthed properly, because all of those meters of cable act as a big antenna, on which little power differentials could occur that are high enough fry your hardware. Has the patch panel a connection for an earth? What shielding has it and what category is it, does it match the cables that you use?

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Commented:
Thank you!  
This is just a 10 users firm.  So they only have one switch.  Both phone and computers plugged into the same switch.  Do you think it would be better if they will be separated by ports but still go into the same switch?

Commented:
I just did the cabling plans for our new (LEED Certified Gold) office building last fall.  I put the following in the RFQ:
-Conduct a site/bid walk with all contractors.
-Share all the information on specs and questions pursuant to the specs with all bidding contractors.
-Cabling contractor to licensed and insured; cabling contractor to secure necessary permits.
-Cabling contractor to work through you (or your designee) and the general contractor (if appropriate) for construction/resource scheduling.
-2 CAT6 cables per location [terminated at RJ-45s jacks (one blue, one gray) at the cube side, terminated on patch panels at the head end.]  Provide a floor plan of the office space marking out locations (and number per location) for data ports
-Specify what type of rack/ladder/support equipment you'll want on the head end.
-If possible, put together a rack diagram so the contractor will know where and how you want the rack set up so they can put the patch panels in the right spots (i.e. all panels at the top, all panels at the bottom, panels every other 4U, etc.)
-All runs properly terminated, tested, and labeled.
-Specify that they bundle all runs with velcro strips and not zip-ties....I have seen too many contractors crank down on the zip-ties and cause problems with the bundle (cut conductors, stripped jackets, etc.).
-All runs certified upon completion of installation
-All runs warrantied for a suitable amount of time (my cabler was able to secure a 25-year warranty on the install he did for me).
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@tiras25:
Yes, it will still make sense, as far as you use a "manageable" switch, as opposed to dumb switches where you can't configure anything.
Look out that the manageable switch supports QoS (Quality of service) and VLAN (virtual LAN). You could then split the switch into 2 VLANs: 1 for the computers and 1 for the VOIP traffic. The result would be similar to using 2 separate switches.
You could place your telephone center solution inside the VOIP-VLAN. All traffic inbetween the center and the telephones would be separated from all the other network traffic. Then, when it comes to the center to be connected to the rest of the network so that it can communicate via the gateway with the outer world, QoS comes into play: You will then give this port a higher priority compared to the rest of the network..
Two ports per user (color coded to patch panels - all blues go to one panel, all whites to another, etc.)

One extra port per cube section.  So a quad cube will get 9 ports.  This leaves room for a printer/scanner, fax machine, or a small switch or WAP.

All cables _must_ be terminated.

All cables verified after termination.  Certification costs more money.  Verifier can be bought for $1,000-1,500...well within the budget of even a small installer.

VoIP phones with PoE take up all 4 pairs.  The extra port(s) on the phone are 10/100.  I use GigE on servers, desktops, and laptops.  Sharing a 10/100 port is a no-go.

All racks should be tied to a common ground.  Anti-stat mats with bonding wire attached to racks to surround racks.

Fire-resistant plywood on walls behind/around rack for anchoring.  Anchoring equipment to drywall is foolish.  Using drywall screw is also a no-no.  Use construction adhesive and bugle-head screws made for plywood (they don't have threads on the top portion of the screw).

Label.  Label.  Label.

Floorplans updated to as-built.  Then: label, label, label.

@alaghart:
True, PoE (Power over Ethernet) is another argument to NOT put phones & computers to the same cable!
Yes, I had one faulty PoE switch that didn't want to turn off the 48VDC that it was piping over the wire.  So, the port stayed hot even after we unplugged the phone.  Only a hard reset would clear the ports.

Luckily I found it during testing before we had any desktops on site.  Cycling through the ports making sure they could power up a phone...and noticed that some of the power indicators stayed on.  Could have been disastrous.

OK, so after  Label, label, label  ... add: Test, test, test.

Commented:
If you have a small firm with only 10 users then 2 jacks per cube is plenty.  Don't forget not to allocate for fax machines, printers, lunch room phone, etc.  People seem to want printers everywhere.  aleghart says label, label, label, ABSOLUTELY.  It will save you so much time in the years to come.  
I disagree with all the paranoid comments above about PoE and VoIP sharing the same cable.  I work for a VoIP company and I've never had an issue.  Especially when $ is a consideration, putting each on it's own seperate port chews up switch ports and can get expensive.  
While I agree with everything Tom says above, except the comment above by tom states "If it comes to VOIP in a LAN, then it is very convenient if you can group those LAN connections that are used for VOIP traffic, e.g. into a VLAN, so that you separate VOIP traffic from other traffic. This, in combination with QOS helps you getting better voice quality results. But if you hang a VOIP telephone and a computer to the same line, such a separation is not possible. "  This is just not true, QoS is quite possible with running the two on the same cable, it's called VLANs and 802.1p
Come on guys, this poor fellow has 10 users, so he'll fill a 24 port patch panel, you're giving him advice based on some big firm.  I'm sure money will be a big consideration for this small business.  Patch Panel, labelled, tested, and a floorplan marked up are all important.

I have <30 users in this office and have had no issues (or pushback due to costs) with segregating cables and using separate switches for PoE/VoIP and LAN.  I never considered myself too small to run a few extra cables, whether it was me doing it personally, or using a contractor.  Extra spool on the same pull is not hard, and should not incur a full retail price for a drop.

Also, if you do more than just LAN cables, it very normal to keep wiring separate and identifiable.  Things like controls, fire/safety, cameras, power, etc.  A couple of extra Cat5/6 won't break the bank compared to later retrofit or troubleshooting.

No matter how many cables you drop, you'll always have a spot where you'll say..."I wish I pulled one _right_here_."

By pulling the extra cable with each cubicle cluster I lowered the price by agreeing to best effort with verification testing, instead of 100% certified.  I was on-site monitoring construction and the tracing & verifying, so felt comfortable with that agreement.
I agree with aleghart!
Where I live, a 100m roll of Cat5e SFTP cable costs about 30-40€... a 24-port manageable 19" switch approx. 200€, a CAT5e 24x patch panel 40€. I do not think that these are high costs, not even for a small company, and - as aleghart said IMHO correctly - it's just peanuts compared to the amount of money, hassle and time spent if you have to enhance things afterwords because you pulled not enough cables right from the beginning.

We are living in a time where "everything is getting TCP/IP" and most of it runs via TP cables, or WLAN:
Printers, Scanners, MFP, video surveillance, wired telephones, DECT/WLAN telephone basis stations, door opening systems, NIS (network attached storage), etc. Do not think only about what's needed right now, but maybe also what will be needed or interesting in a scope of 2-5 years!

Further I would like to point out one IMHO important thing to think about:
It's not only the number of people working in the office, but also WHAT KIND of network traffic they are going to produce, what determines the needed specs! If e.g. they just surf and email a bit in the internet and make a couple of VOIP phone calls a day, well it might be ok if you put everything to one cable.
But if they produce some heavy traffic, then things might be much better if separated.

Example:
I have once set up a network for a company with <10 employees. Nevertheless I did not only separate their VOIP from their data, but even gave them 2 data cables per computer, teaming them to a 2x1Gigabit trunk. Why? They are working with very huge files (it's an imaging & media company working with very large photo, video, layout etc. files, commonly ranging from 150MB to 2GB each). These few people produce heavy network traffic all over the day since all the data flows between the clients and the file- and FTP-servers back and forth all over the time. Simultaneously they are talking almost all the time with 1-2 concurrent phone calls... Keeping those two things separated was crucial for no-compromise business grade phone call quality!

It all depends on what traffic is going to be on the network- but if in doubt, network cables would be the last thing that I would be miserly with.

Commented:
I'd use 4 ports per office, for extra devices and backups in case a port goes dead or is damaged.
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