DOT11-4-MAXRETRIES

adminedensa · ‎02-24-2010

I´ve a 877W router that disconnects wirelless clients one or two times per minute.

In syslog appears many times the following messages:

DOT11-4-MAXRETRIES: Packet to client XXXX.XXXX.XXXX reached max retries, removing the client.

I was looking in cisco web and find in http://www.cisco.com/en/US/products/hw/wireless/ps430/products_tech_note09186a008024aa4f.shtml where it say that such error messages can indicate a radio frequency (RF) problem.

I discard clients RF problems.

what else can i do.? If i should upgrade IOS what IOS slove this issued.

The router IOS is c870-advipservicesk9-mz.124-15.T4.bin.

Regards,

Juan Cruz

Javier Contreras · ‎02-26-2010

Hi Juan

aIOS AP radio has a default behaviour of retransmitting a frame for X number of times (normally 63 by default), and if it does not receive ACK from client, it will basically deauthenticate it, and set the client as it is not longer on the coverage area.

What you describe can be:
1. Bad RF coverage, so no matter what code version, it will remain happening. Get a "sh dot11 asssoc all" to see the signal level
2. Radio issue (bug), which may need troubleshooting. Easiest is to load latest code, and test from there.
3. Interference that is causing client to miss frames and/or AP not to hear correctly the ACK

You can change the retry feature, do this:
1. go to enable mode
2. go to config (conf t)
3. in do0
4. packet ret 64 drop

This will tell the AP not to remove station if it misses retry count, so it will stop your continuous associations, regardless of root cause.

if it is RF coverage (you see a low signal level in the dot11 assoc command, you may need to change router position, antennas, and/or add more APs to increase the needed coverage)

Regards

Kayle Miller · ‎02-26-2010

Juan,

Javier is correct on all counts, in most cases (I'd say 90%) the cause of the max-retries error is a result of RF coverage/interference. Something Javier didn't mention regarding the RF coverage is it may not necesssarily be the Access Point that is the issue, it could be the client; because wireless communication is a 2-way process there are a number of scenarios where the client device may hear the AP transmission but the AP never or only ocassionaly hears the client device. This is usually a result of the transmit powers and antenna on both devices.

So I would defintely check those things as well as the items indicated by Javier.

Hope this help.

Kayle

antoniofeijao · ‎06-26-2012

Hi Javier, your post have helped me a lot

I was having issues with MAC/iPhones Users

in my case was RF coverage/interference,

after aplying your recommendations and also added the line "...(config-if)# channel least-congested"

and fix my problem.

Thank you

AF

suresh natarajan · ‎07-20-2012

Thanks for the suggestion! it works good. By the by the default retries value is 63?

packet retries 64 drop >>>>> meaning try 64 retries and then start drop the packet but dont disassociate??? Meaning by default , 63 retries is doing ? just matter of 1 increase will help us to stabilize? Please clear my doubts... Thanks for your help.

Suresh