Multiple access points

Discussion in 'Wireless Networking' started by MLJ, Sep 22, 2004.

  1. MLJ

    MLJ Guest

    This is probably an easy one but here goes:

    I've set up a WAP in each of three wings of a school, with a fourth where
    the wings meet. These are USR turbo WAP/Router units, and all are connected
    to the school 100Mbit LAN
    These are basically configured with the same (hidden) SSID, 128bit WEP,
    channel 11 for the UK

    The clients are Dell Latitude d505 running XP Pro SP1 with Intel 2100bg
    wireless cards

    The problem I have is that the laptops don't seem to connect to the nearest
    WAP with the strongest signal - they seem to lock onto the other more
    distant units with the effect that the signal is poor and keeps dropping. I
    can check this via wireless stats on the laptop.
    Both WAP and Intel cards are at latest driver/firmware release, and the
    connection is being managed by the Intel software rather than windows

    Is this the best way to implement the network?
    Should the WAPs be configured to broadcast on different channels (ie to
    avoid interference) ?

    MLJ, Sep 22, 2004
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  2. MLJ

    Jeff Durham Guest

    Sounds like you are almost doing the right thing. :) First, you should
    choose different channels for the access points. Be sure to select
    non-overlapping channels though. For instance, 1, 6, and 11 do not overlap.
    If the wings are far enough apart, you could set them all to the same
    channel such as 1. Then set your one in the middle to either 6 or 11.
    Another possibility is to set the wings to 1, 4, and 8. Then set the one in
    the middle as 11 to minimize overlap.

    Second, because you are using XP, I would not hide the SSID. Many people
    say that this adds security, but it is security by obscurity. It is not
    difficult for a hacker to figure out an SSID. It is more difficult to
    figure out the WEP key. A casual user is not going to break your WEP key.
    A hacker may attempt and will have already quickly gotten by the hidden
    SSID. Also, Windows XP has reported problems with not working "as expected"
    with hidden SSIDs. I think this has to do with network detection when other
    wireless networks are in the area. I don't know if that would apply to your
    multiple access points or only if you have other wireless networks in the
    vicinity such as a building next store.

    Lastly, have you considered using WPA over WEP? It is more secure. Since
    you already have to setup a WEP key, you can use the WPA-PSK mode which
    requires a shared key. Most of the new products you buy off the shelf today
    support WPA. A better option is WPA-RADIUS, but that is more work and
    requires a radius server. One is provided in Win2k and Win2003 server. It
    is known as IAS.

    Jeff Durham, Sep 22, 2004
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  3. MLJ

    MLJ Guest

    Thanks for the reply
    The only problem I have with this is that the config software for the
    wireless client expects a channel (it doesn't seem to have a "dynamic"
    option), and at the moment all clients are set to channel 11
    If I adopt the setup below will the laptops still try to connect to a WAP
    broadcasting on 11 ?
    Would I be better off installing SP2 and changing wireless so that it is
    managed by Windows ?

    MLJ, Sep 22, 2004
  4. MLJ

    Jeff Durham Guest

    That is the first time I have seen a wireless config program where you
    specify the channel. Normally, the channel is set in the access point and
    the client figures out the channel dynamically. If Windows XP SP1 does not
    configure the card for you, I am not sure if SP2 will either.

    I have seen roaming work where all access points used the same channel
    number. In fact, that is what Linksys recommends. It is not a good idea
    because of the interference factor between access points. It will cut down
    on available bandwidth.

    You can try using the same channel provided the access points are far enough
    apart. You should also broadcast your SSID. Be sure to use WPA or WEP
    though. The only other solution seems to be to replace your wireless
    adapters to something more up-to-date.

    Jeff Durham, Sep 22, 2004
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