Large-scale wireless setups

Discussion in 'Networking Issues' started by Reivax, Aug 31, 2006.

  1. Reivax

    Reivax LI Guru Member

    So I am endeavouring on a project involving large-scale wireless networks. I need to cover a wide area in terms of square footage but with a relatively low userbase. Think farmland. I'm going to eventually work out complex grids of modified access points in this thread, but before I get into that, I want to make sure that I have wrapped my head around a very important issue.

    Consider if you will this topography:

    The text of the images is such:
    {Broadband connection} directly wired to {Router01} directly wired to {AP01} wirlessly linked to {AP02} wireleslly linked to {AP03} wirelessly linked to {Device01}


    SSID: MyNet01
    IP: static

    SSID: MyNet01
    IP: static

    SSID: MyNet01

    SSID: MyNet01
    IP: DHCP issued, probably

    The devices are in that order in the real world and AP01 may or may not be able to see AP03, but immediate neighbors can see eachother. I did in fact read the tutorial, but I just wanted to make sure I expanded it to a third access point properly with the gateway somewhere before the first access point.

    Basically all I ask, for now, is this: Is the layout proper? Can Device01 move from AP03 to AP02 to AP01 seamlessly? Are there any oversights? In order of AP02 to recieve from AP01, do I need to put a bridge to the uplink of AP02? I thought the firmware (or some variant of it) does not require it but I have been told otherwise.

    Attached Files:

  2. Toxic

    Toxic Administrator Staff Member

    to enable roaming make sure SSID is the same but use different channels on each AP.

    1, 6 and 11 the wireless cell (coverage of a WAP) should overlap the other AP so wireless roaming can take place.
  3. YeOldeStonecat

    YeOldeStonecat Network Guru Member

    I've done a few setups like that with MIMO products...worked well. The amount of "seamless" roaming on home grade products isn't as seamless as enterprise products. And it depends on the wireless NIC of the user, and what application they're running. It's not truely seamless..there's a little drop when it flips...but wether the user will know or not...varies.
  4. Reivax

    Reivax LI Guru Member

    Each ap needs a different channel? This may become a problem if there is a 5x5 grid of these, the interior units will each have 4 neighbors, one in each cardinal direction, and 4 others on each diagonal. If this network were to become huge, how should they be assigned? Keep in mind the antennas will probably be equiped with a some sort of reflector or totally rebuilt with some form of biquad assembly. (More on this later.)

    So next question, how far can these series of wireless repeaters work? Theoretically untill I run out of ip addresses/money. But at what point is there too much degredation?
  5. pablito

    pablito Network Guru Member

    While it is best to use different channels you can reuse channels if you must. I would reuse channels on units far enough apart that they don't see each other. In your case that should be no problem since you're talking of a large area.

    I've done this with a handful of APs and while walking a laptop around it was almost seamless. Some apps like certain VPN clients will drop during the transition but typical apps won't know the difference. Similar to a phone cell transition.

    You can get fancy with a mesh network to make redundant paths for the route back to the internet but that is another story....
  6. Reivax

    Reivax LI Guru Member

    Thats probably how it will end up, a WAN connection somewhere along a side, given a wired broadband link will typically mean electrial power nearby, the WAN connection in the middle if it is some sort of satelite link.

    Now to get tricky. What if I want multiple access points at the same location acting as a single access point? Allow me to explain. The location contains two WRT54Gs, for example. This gives me 4 antennas which can be reflected to 90 degree horizontal spreads each. Can I set one of the units to act as a repeater, and the other unit as simply an access point and wire it directly to the repeating unit? I know that its definately possible with at least two ways: 1. If they both act as indepenent repeaters that just so happen to be next to each other, unwired. 2. If both units were wired to eachother acting as access points, not repeaters, with a bridge, such as the WET54G, pluged into the uplink of one of the devices.
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