Sunday, October 5, 2008

Planning a new exchange / La planification pour un nouveau commutateur

As I mentioned in my earlier posts, one of the key items in our village may be the design of the new telecommunications exchange they are building next year. I wrote to some Dutch friends (fiber experts) asking for their advice on a number of key questions.

Here is my attempt to paraphrase their answers:

  1. Question:
    Would it be better to build a separate exchange for fiber next to the copper exchange or to put the ODF in the same physical building?

    It is extremely important that the incumbent operator can't "hold anyone hostage" if fiber is going to terminate in the same building as copper. There are a number of points to consider in such a case:

    • There needs to be a room which is separate from the main DSL equipment and that is accessible from the outside for the ODF and fiber interconnection. This room needs to be large enough to accommodate operator's active equipment if necessary.

    • The municipality needs to have the key and control access rights to this room.

    • There needs to be a conduit from the room to the perimeter of the land owned by the incumbent and this needs to be large enough to accommodate all the fiber coming in (see size questions below).

    • There needs to be a separate power supply from France Telecom - essentially a second meter for the municipality to the room.

    • The room needs to be large enough to house a UPS and air conditioning if necessary.

    • There needs to be a hole in the wall between the fiber room and the ISP's equipment which is large enough to pass 3000+ fibers (1500 households x 2 + some spare)

  2. Question:
    How much space in the building/room is necessary to house an ODF?

    One ODF will support 800 fibers and it measures roughly 1 meter x 50 cm, including space for patch cords. You need to be able to access the ODF from the front and the back.

    One 19 inch rack will support the electronics for roughly 400 users, dissipating 3-5 watts per user. The rack needs to be accessible from the front side.

  3. Question:
    In planning for conduit access, how many fibers should we plan on for each home?

    There is no need for more than 2 fibers per residence. The trend is actually moving to one fiber per residence with three colors per fiber (data upload, data download and television). Putting in two fibers at the same time is a good way to hedge your bets though.

  4. Question:
    How much space will we need inside existing conduit to push out point-to-point fiber from the exchange point to the village?

    One of the projects in the Netherlands uses cables with 96 fibers inside. They can bunch 6 of these cables (6 x 96 = 576 fibers) into one 50 mm HDPE duct. It would take 6 of these 50 mm ducts to provide 2 point-to-point fiber connections to each of the 1500 households in the village, with a little to spare.

    Using these numbers, the space we'd need for the conduit leaving the exchange (before disaggregation) would be 100 mm x 300 mm.

As always, I'm grateful to my Dutch friends for their advice.

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