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  • Wireless Channel hopping gets interrupted

    Hi Folks,

    Here is the background.
    Simple wireless network with single SSID and about a dozen Aironet 1200 series WAPs.
    Clents configured to automatically connect to the network and it works fine throughout the Campus.
    It works fine when they roam as well as the client automatically connect to a different WAP with stronger signal through channel hopping
    Now the problem.
    The channel hopping and consequently access to the wireless network fails if there is an open network/internet session i.e a Browser or a .NET app we have here.
    Can anyone shed any light into this whether it can be resolved or it's just a technological limitation.

    Thanks in advance
    Last edited by L4ndy; 4th September 2009, 15:29.
    Caesar's cipher - 3

    ZKHQ BRX HYHQWXDOOB GHFLSKHU WKLV BRX ZLOO UHDOLVH LW ZDV D ZDVWH RI WLPH!

    SFX JNRS FC U6 MNGR

  • #2
    Re: Wireless Channel hopping gets interrupted

    What sort of security are you running on the wireless. We have the same devices running in schools here that requires a RADIUS for authentication and a certificate installed on each laptop. I can open IE and walk all round the school passing through all 14 APs and it does not drop off.

    What sort of signal strength and channel overlap you got?
    How did you do the site survey? Netstumbler or another "war driving" tool?
    Did you plot the APs on a map of the school?
    Are you using the omin directional antenna or have you used yagi antenna in some areas?
    Are you a single floor or multi story school?
    What are you using on the laptop. The Windows Wireless Configuration ot the utility that comes with the Wireless NIC on the laptop?
    What operating system is being used on the laptops? If Vista and XP, does the drop out happen on both systems? (If you have Macs, use the hammer method, preferable the 4lb model )
    Do the dop outs happen in the same location? Is there an intentional balck spot or s it caused by an external device. eg radio tower, mobile phone tower, power lines, metal fence/wall, microwave equipment etc etc.
    If you use Netstumbler, what happens with the signal when you walk through the drop out areas?
    I think that is enough question, do you? (Had to slip one more in)
    1 1 was a racehorse.
    2 2 was 1 2.
    1 1 1 1 race 1 day,
    2 2 1 1 2

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    • #3
      Re: Wireless Channel hopping gets interrupted

      Thanks mate, I think it's fair to say that you've pretty much covered all the troubleshooting steps for wireless issues

      I probably should've included some more info initially to answer some of Biggles' questions so here we are.

      The survey was done by an external company who charged a fortune for the priviledge (Our school has got more money than sense!)

      There are no Black spots in terms of coverage.
      Windows Zero configuration service is in charge of the configuration.
      Security - WPA2 Personal (AES+PSK).

      A little update though:
      I've since done some more testing and it looks like the problem exists only with some new 1242AG APs. User can roam freely with open sessions through the 1231g Aps. Should've probably mentioned last time that there are two models here 1231G and 1242AG .
      The only difference between the two is the IOS version. 13.8 and 14 respectively.

      Any more thoughts as to why it works fine with the old IOS??
      Can post the config file if needed.

      Thanks
      Caesar's cipher - 3

      ZKHQ BRX HYHQWXDOOB GHFLSKHU WKLV BRX ZLOO UHDOLVH LW ZDV D ZDVWH RI WLPH!

      SFX JNRS FC U6 MNGR

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      • #4
        Re: Wireless Channel hopping gets interrupted

        This has now ben resolved. It turns out that switch port security was enabled on the ports the AP was connected to.
        That was causing the connections to drop.
        No open sessions or any other factor, I initially thought of, had anything to do with it.

        Cheers
        Caesar's cipher - 3

        ZKHQ BRX HYHQWXDOOB GHFLSKHU WKLV BRX ZLOO UHDOLVH LW ZDV D ZDVWH RI WLPH!

        SFX JNRS FC U6 MNGR

        Comment


        • #5
          Re: Wireless Channel hopping gets interrupted

          This is where good complete and up to date documentation comes in handy.
          1 1 was a racehorse.
          2 2 was 1 2.
          1 1 1 1 race 1 day,
          2 2 1 1 2

          Comment

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