CRC

Discussion in 'Cisco' started by dt1649651@yahoo.com, Aug 15, 2005.

  1. Guest

    We have a warehouse with 3 AP1230 and around 20 wireless devices. We
    experience a lof of CRC errors.

    I checked some WLAN Analyzers and they are expensive.

    Any advice on picking an appropriate WLAN Analyzer or on this CRC
    problem is greatly appreciated.

    Thanks,

    DT
     
    , Aug 15, 2005
    #1
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  2. NetSteady Guest

    1) Can you explain a little bit more about the environment?

    2) Are all AP's on different channels?

    3) What version of code are you running?

    4) 20 devices is not an overload, so that shouldn't be the issue. What
    types of devices?

    5) Is there any external interference?
     
    NetSteady, Aug 16, 2005
    #2
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  3. Guest

    NetSteady wrote:

    Thanks for your reply.

    > 1) Can you explain a little bit more about the environment?

    This is a warehouse where we use our application to controler the
    inventory system. The warehouse structure is mostly built by steel and
    metal materials but those matertials are mostly at the roof level which
    is pretty much higher than where we install the APs. They have a
    special electric system that automatically control the light system
    inside the warehouse ( to turn the light off/on when needed ).

    > 2) Are all AP's on different channels?

    Yes, I have 3 APs running channels 1-4, 5-8 and 9-11 respectively.

    > 3) What version of code are you running?

    I am sorry, I do not fully understand this. I am using PPC 2003 as the
    OS of the devices. This is an in-house app running on PocketPc
    accessing the database server thru the wireless system.

    >
    > 4) 20 devices is not an overload, so that shouldn't be the issue. What
    > types of devices?

    Currently these devices includes 12 handhelds and 8 mobile printers.
    All these devices has built-in Cisco network cards.


    > 5) Is there any external interference?

    I wonder if the automatic electric system described above can cause any
    interference. They have a lot of trucks coming in and out also, but
    those trucks are only at the further side of the warehouse. Besides
    that, I do not know of any other causes that may cause the problem.
    Some documents say about the signal reflection, but I am not sure how
    much of this happens in this warehouse.

    I 've used some LAN analyzer but 've never touched to the WLAN analyzer
    and wonder which one is good in this case.

    Again thanks for your attention to this problem.

    DT
     
    , Aug 16, 2005
    #3
  4. NetSteady Guest

    DT,

    First, Make sure you're AP's are running on 1, 6, or 11 only.

    As far as an analyzer, I've used Commview for Wifi to do some
    troubleshooting, and it worked out pretty well. They have a demo
    available at

    http://www.tamos.com/products/commwifi/

    Finally, I believe that the electrical may be interfering with the
    wireless, and there's a quick and easy way to find out. If you're using
    Cisco cards, you should be using the Aironet Client Utility. Pull up
    the utility and look for the singal meter. When you place the card near
    your electrical equipment, you should see the noise level go through
    the roof. That's a quick-and-dirty way to find out if EMF is your
    culprit.
     
    NetSteady, Aug 16, 2005
    #4
  5. Guest

    NetSteady,

    Thanks for your advice.

    NetSteady wrote:
    > DT,
    >
    > First, Make sure you're AP's are running on 1, 6, or 11 only.


    Last night after posted my reply, I logged in to those 3 APs and set
    them up to 1, 6 and 11. It was about midnoght then and there was
    nobody working there, but I still see some Header CRC errors.

    >
    > As far as an analyzer, I've used Commview for Wifi to do some
    > troubleshooting, and it worked out pretty well. They have a demo
    > available at
    >
    > http://www.tamos.com/products/commwifi/


    I am going to have a look at this today.

    > Finally, I believe that the electrical may be interfering with the
    > wireless, and there's a quick and easy way to find out. If you're using
    > Cisco cards, you should be using the Aironet Client Utility. Pull up
    > the utility and look for the singal meter. When you place the card near
    > your electrical equipment, you should see the noise level go through
    > the roof. That's a quick-and-dirty way to find out if EMF is your
    > culprit.


    I have walked around the warehouse with my laptop/Cisco card/ACU and it
    shows the signal from excellent to good, but at the same time, the APs
    still shows many CRC errors.

    Thanks again for your advice,

    DT
     
    , Aug 16, 2005
    #5
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