Very high noise and excessive retries

Discussion in 'Networking Issues' started by FaQso, May 9, 2006.

  1. FaQso

    FaQso Network Guru Member


    I have a problem with my AP.
    It's a WRT54G v2. Tx power is set to 18dB. Bit rate is 11Mbit/s.
    And when I iwconfig eth1 I get this values:

    Link Noise level:-99 dBm
    Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
    Tx excessive retries:180 Invalid misc:0 Missed beacon:0

    I tried to reduce tx power to standard 28mW and I still get the same problem.
    On the other hand, my second router (WRT54G v2.2) with the same config gets noise level -24dBm and 1 excessive retry.

    Is it possible that there is something wrong with wireless chip driver on the v2 ?

  2. kg4mrv

    kg4mrv Network Guru Member

    Are these in different locations?

    Are you using them both at the same time?

    Are there any 2.4 GHz phones in the area?

    If you're using both in the same location, or actually even if not, try changing channels. Try 1, or 11.

    If possible eliminate, or at least move any cordless phones, including the base, from the routers vecinity.

    I have also seen microwave ovens couse loads of noise, but this would be intermittant.
  3. FaQso

    FaQso Network Guru Member

    These are different locations and I scanned the area for another AP's channels and set mine to unused one.
    They are used at the same time.
    I assume that with the "2.4 GHz phones" you refer to cellular phones? If so, than there are a lot of them around.
    But that is not a problem, because the WRT working normally has the same environmental conditions as the one that acts strange.

    The funny thing is that even if it has such high noise and excessive retries, it's still working fine.
    Could it be iwconfig malfunction?
    Another thing.
    root@OpenWrt:~# iwlist eth1 scan
    eth1      No scan results
    That can't be true, cuz I scanned with other WRT and Laptop, and they both find some other ap's.

    It all acts very strange. Have no idea what could it be.
  4. kg4mrv

    kg4mrv Network Guru Member

    Actually I meant 2.4 GHz cordless phones. Cell phones dont actually use 2.4 ghz range.

    Some other culpruts could be:

    Baby monitors
    wireless security cameras.
    wireless stereo speakers

    As a test swap the locations of the routers, this will determine wether its the router or the enviroment. I'm guessing the latter though.
  5. Toxic

    Toxic Administrator Staff Member

    I take it you tried this test with the unique channels 1, 6 and 11 ?

    if not please post you findings on them also.

    you could also try lowering Fragmentation Threshold and RTS Threshold to 2304 and setting Beacon Interval at 50.

    what mode are you running in? B mode G mode or mixed?
  6. FaQso

    FaQso Network Guru Member

    This router is placed in a room in campus dorm.
    So believe me, that there is minimum interference from other alectrical devices. :)
    There is no cordless phone or such things. And thank god, no baby monitors yet. I just placed another router elsewhere (100m away). It's working ok too.

    Here are scans with these three channels:
              Current Channel:1
    root@OpenWrt:~# iwlist eth1 scan
    eth1      No scan results
              Current Channel:6
    root@OpenWrt:~# iwlist eth1 scan
    eth1      No scan results
              Current Channel:11
    root@OpenWrt:~# iwlist eth1 scan
    eth1      No scan results
    Channel query is done by: iwlist eth1 channel

    Just set FT, RTS and beacon to those values and there is no effect.
    Or is the router required to reboot after these changes?

    I set the mode to B only.


    The rooms with AP's are from people that I barely know. I just asked them if I can place the router there. So I don't have direct access to the routers.
  7. Toxic

    Toxic Administrator Staff Member

    I guess then your wireless chipset on that router is done if you have no problem with another WRT54G

    have you tried to reset the router incase some incompataility issue with nvram settings?

    press reset for 30 seconds. you will loose settings but its the last resort before getting a replacement i guess

    you mention other APs what channel are they transmitting on?
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