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1410 - Data Retries/Latency/Packet Drops

Unanswered Question
Feb 22nd, 2012
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Hi All,


I have two 1410 bridges installed in a point to point link using external directional antennas.  The distance between the bridges is only 200M.  As you can see below from the output the RSSI and SNR are excellent with a good fade margin available.  These stats are almost identical to what my path profile calculated out to be.  During normal operation the latency on this link sub 2ms, during certain conditions the latency jumps to 40+ms and starts dropping packets.  I say certain conditions because we have not been able to pinpoint it.  Unfortunately at this time the customer does not have the ability to do any SNMP polling or collect any statistical information (working on getting this setup).  There are an excessive number of data retries and am not sure if that is normal.  During the issues I have observered the below command output and the numbers did not change, which leads to me believe that it is not a RF issue.  It almost looks like it's serialization delay, but I have no data to back that up.  During iperf performance testing of this wireless link I could push 54Mbps of UDP traffic no problem, no errors, no CRC's.  Really at a loss here.


Bridge Parameters

Encryption: WPA-PSK w/TKIP

Distance parameter: Configured to 1

Bridging two Vlan's

RF Power set to max

Auto channel assignment on startup



show dot11 associations all-client

Address           : 003a.9924.7bcf     Name             : BRIDGE1

IP Address        : 192.168.50.34      Interface        : Dot11Radio 0

Device            : br1410             Software Version : 12.3

CCX Version       : NONE


State             : Assoc              Parent           : Our Parent

SSID              : US-INFRA           VLAN             : 1

Hops to Infra     : 0                  Association Id   : 1

Tunnel Address    : 0.0.0.0

Key Mgmt type     : WPA PSK            Encryption       : TKIP

Current Rate      : 54.0               Capability       : WMM

Supported Rates   : 6.0 9.0 12.0 18.0 24.0 36.0 48.0 54.0

Voice Rates       : disabled

Signal Strength   : -54  dBm           Connected for    : 782214 seconds

Signal to Noise   : 37  dBm            Activity Timeout : 15 seconds

Power-save        : Off                Last Activity    : 0 seconds ago

Apsd DE AC(s)     : NONE


Packets Input     : 339401717          Packets Output   : 180783704

Bytes Input       : 197355750          Bytes Output     : 3876976162

Duplicates Rcvd   : 0                  Data Retries     : 25836710

Decrypt Failed    : 0                  RTS Retries      : 18

MIC Failed        : 0                  MIC Missing      : 0

Packets Redirected: 0                  Redirect Filtered: 0

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Justin Kurynny Wed, 02/22/2012 - 20:46
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Aaron,


Which version of code are you running on the bridges?



Justin

aaronlevy Thu, 02/23/2012 - 07:17
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Hey Justin,


Running the following;


Cisco IOS Software, C1410 Software (C1410-K9W7-M), Version 12.3(8)JEA3, RELEASE SOFTWARE (fc2)


Yes it's an old one, but I have not found any bugs or caveats for this IOS relating to my issue.  That being said I will  be upgrading to the latest. 

Justin Kurynny Thu, 02/23/2012 - 10:46
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Aaron,


I had trouble with (I think) this exact image several years ago. The bridges were close to each other (maybe 1/2 mile), RSSI was solid, everything looked good. The bridges would not maintain association and I saw an avalanche of TKIK/MIC errors in the logs on the root bridge. The weird thing was that the bridges were working fine for a few months and then one day they weren't. We fixed the issue with an upgrade to 12.4.


Please let us know if the upgrade helps.



Justin

aaronlevy Thu, 02/23/2012 - 11:08
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Thanks for the info!  I am not seeing any MIC errors at this time, but that's not to say it isn't happening.  I also noticed that the image I'm running is (LD) so I'm not too excited about running it.  Anyways, I will upgrade IOS and post the result.



Thanks!

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