Network cabling Tips

I'm looking for some useful information about how to design network cabling for a building.

I'm not so much interested in wiring standards such as 568A, but more interested in physically wiring the building.

For example:

Is it better to have all the cabling from all the data points in a building to go back to a central point (where line length permits), or is it better to have a number of local switches linked back to a core switch or router via fibre (or copper) links?

Any useful tips or URLs would be appreciated.

The short answer re: how much cable to run and where to run it is: It Depends^TM.

I like having as few wiring closets as possible, with either copper or fiber risers interconnecting the wiring closets (more runs than you think you'll ever need), and minimizing the number of overall Ethernet switches.. Unless you have some compelling need for more Ethernet switches you typically don't "save" a anything by running fewer long runs from a closet to an area and then "fanning out" from a "workgroup" switch with patch cables, etc. You end up with an unmaintainable mess (power cords kicked out, switches with junk stacked on them by users, etc).

I try to stay away from fiber unless I have a compelling reason (distance, electromagnetic noise, environmentals too harsh for copper, privacy concerns). Multiple copper runs aggregated together can deliver multiple Gb/sec more cheaply, today, than 10G on fiber (both because of the expense of the fiber versus copper cable, and because of the cost of the electronics on the end).

re: running and planning the physical cable plant, an almost verbatim theft from an earlier answer of mine applies:

If you're willing to spend a little money, you can get the "bible" for cabling installers: The "Information Transport Systems Installation Methods Manual" from BICSI. It's $129.00, but it's got an unbelievable amount of detailed information.

• Run more cable than you think you're going to need. The wire is cheap, the installation labor is not.
• Use well-labeled wall plates with some kind of documented labeling standard. It shouldn't be complicated, but it should be documented.
• If you can, create an as-built drawing. It will help you (or the next guy) when problems come up.
• No matter where you put wall plates, users will put bookcases, desks, 1000 pound safes, etc, in front of them. Try and get in touch with the office space-planning people to see where good wall-plate locations would be.
• If you're still using traditional non-IP telephones, coordinate with your voice vendor to run a single cable plant for everything if you are able. You can plug RJ-11 jacks into RJ-45 wall plates. Some people say that it's not a good thing to do, but I've seen it done for years w/ no ill effects.
• Run more cable than you think you're going to need. >smile< Having to put switches in offices because you add IP phones, network-printers, and an Ethernet-attached camera where you thought that only a PC was going to be located is no fun.

If you're worried about legal compliance, check with your local electrical or building inspector. Most states don't classify "low voltage data cable" under electrical inspection guidelines, but you may have fire inspection-releated concerns.

1. In the United States (not sure about UK, but knowing y'all's laws...), before tackling a cabling project, you should probably have your low voltage license unless the job cost is below $1000. There are exemptions in some areas, but be aware that you might be on the handle for fines for not complying with laws.
2. If you're not familiar with how to do a large scale infrastructure project like this, then you shouldn't be doing it.
3. The answer to your questions not only depends on what kind of building, but what kind of infrastructure you're dealing with that's already in place. For example: What kind of conduit is run between the floors? Where is the datacenter? How long will the runs be? How tight are the bends in any conduit? (Under the minimum fiber optic bend radius?) How close to electrical mains is your server room and/or the conduits that the data lines will be traversing? How many ports are we talking and how many hosts? What are their bandwidth needs? What's the intended topology of the network? Are you going to have voice (VOIP) lines run along with the data or will they be sharing a network?

In short: There's a reason that people who do this stuff get paid. Seek a professional.