Best efforts are spent in planning stages before the concrete is poured and the walls go up. There are three key areas that determine the network infrastructure and many gotchas that could undermine implementations today and in the future. As they say in real estate, "It's location, location, location" and so it rings true for the network.
The locations of the MDF (Main Distribution Frame) and any IDFs (Intermediate Distribution Frames) are critical for several reasons. First is access--not for people but for getting cabling to and from these locations to the endpoints. On the drawing below is a pink circle showing the initial proposed location of the MDF for a two-story building. By moving the location another 16 feet to the right (end of red line), a reduction in cabling distance was achieved and a space between floors was utilized for the riser cabling. This translates to less latency, fewer closets (only one) and less cost. The serviceability factor also improves since all gear--telephony, data, alarm, access control--is centrally located. This isn't possible in all situations but can be achieved in some.
Access Point (AP) locations are also critical in supporting the WLAN infrastructure, and using floor plans for electrical, ceiling and structural will give you a clearer picture of dimensions including height. Unfortunately, the timing of having solid plans submitted to architects for inclusion in the buildout doesn't lend itself to getting the best location of new access points. The workaround is to have a 10-20-foot service loop to allow for easy movement of AP locations.
Then after buildout is near completion, interior materials such as moveable walls may present new challenges for signal penetration. Again, it depends upon building materials used. Lastly, add a couple of drops in any areas of doubt.
Suitable electrical conduit is mandatory for underground cables and for building entrance cables for both public (utility) and private (campus or other) network wiring and fiber. Outside conduits entering a property vary from state to state as to requirements--sometimes between counties. The practice of using buried wire makes it difficult to repair and isolate problems or add new wiring when old wiring begins to fail.
Shown below are three new conduits for creating the new demarcation: three 4-inch conduits, two for Verizon (one active and one spare) and one for Comcast or other providers. Notice the bandits and black rubber seals over the conduits. When removing these covers you may get a blast of primer used to connect conduit elbows and pipes together, and the smell isn't pleasant, so you need to be careful in enclosed spaces.
Then electrical conduit for fiber between closets or Intermediate Distribution Frames (IDFs) will help future-proof for network growth. For our campus sites, I use 2-inch electrical conduit dedicated for fiber and backup underground Category 5E wire. I have the option to install 1/2-inch inner duct or even 3/4-inch if there are turns. The inner duct serves to isolate fiber from friction or "burning cable effect" when pulling new wires within the same conduit. The other option is to add armor shielding or a tougher outer jacket to the fiber cable.
In some new construction, key mistakes include not installing properly-sized pull boxes or not adding a plastic protective ring to both ends of the conduit to protect all cabling entering and exiting. The backup Cat5E serves as a copper link if the distance isn't an issue, and we also use the cable to provide alarm, elevator and security POTS services.
Locations of MDFs and IDFs, access points and conduit dictate your network infrastructure. Never leave it up to anyone to tell you the location; and definitely get in line early and submit your detailed requirements in writing to the architect for inclusion. Lastly, check the work to assure you get what you asked for. It's an imperfect process but you can negotiate for better locations.
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