Summary:

How to troubleshoot smartphone or tablet that can't connect to Wi-Fi network due to legacy data rates (e.g., 802.11a, 802.11b and 802.11g).

Problem:

Staff member's personal smartphone won't connect to the guest Wi-Fi network.  All other devices connect to wireless network without issues.

Problem Device:

• Older Kyocera Android phone.  
• Problem device only connects with 2.4GHz radios.

Topology:

Multiple access point and wireless controller.  Single 2.4GHz SSID broadcast throughout the office.  Recent changes were made to roaming, data rates/ cell size, and power tuning (background).  Independent BSSIDs broadcast on separate radios: 802.11na and 802.11ng.    Legacy 802.11b data rates are disabled. The network continues support for 802.11G data rates (i.e., 54 Mbps):
set service-profile Guest_2.4 transmit-rate 11g mandatory 12,24.0,36.0,48.0,54.0 disabled 1.0,2.0,5.5,6.0,9.0,11.0,18.0 beacon-rate 24.0 multicast-rate AUTO

Solution:

1. Identify client session:
   

   
   *WLC# sh sessions network verbose
   
   Name:               last-resort-Guest 2.4GHz-570
   
   SSID:               Guest 2.4GHz
   
   MAC:                6c:xx:xx:xx:xx:xx
   
   AP/Radio:           1/1
   
   State:              DEASSOCIATED
   
   Device type:        android-generic (AAA)
   
   Radio type:         802.11ng
   
   Last packet rate:   6.0 Mb/s
   
   Last packet RSSI:   -49 dBm
   
   Last packet SNR:    46
   

   Session interpretation:
   
   • Session state is deassociated.  
   • Excessive of roaming attempts.  
   • Good signal strength and SNR.  
   • Last packet rate is only 6.0 Mb/s. 
   Data indicates the phone probably uses legacy wireless standards -it's old!


2. Enable log tracing to debug connection attempts:
   *WLC#set log trace enable severity debug
*WLC#set trace dot1x level 10 mac
*WLC#set trace sm level 10 mac
*WLC#sh log trace
SM Apr 14 13:45:08.197931 DEBUG SM-EVENT: Cannot set ipaddr for 6c:76:60:59:9e:6a
SM Apr 14 13:45:08.743477 DEBUG sm_do_flood_announce: 6c:76:60:59:9e:6a flood announce
SM Apr 14 13:45:16.176513 DEBUG SM-EVENT: (4601) rssi -69, rate code 0x0018, idle 48 secs
SM Apr 14 13:45:16.176661 DEBUG SM-EVENT: (4601) idle timer 132755 left, reset to 132000 ms
SM Apr 14 13:45:16.177599 DEBUG SM-EVENT: (4556) rssi -56, rate code 0x0018, idle 9 secs
SM Apr 14 13:45:16.177756 DEBUG SM-EVENT: (4556) idle timer 150259 left, reset to 171000 ms
SM Apr 14 13:45:16.179532 DEBUG SM-EVENT: (5415) rssi -76, rate code 0x0018, idle 20 secs
SM Apr 14 13:45:16.179653 DEBUG SM-EVENT: (5415) idle timer is tracking (160258 to go)
SM Apr 14 13:45:16.180066 DEBUG SM-EVENT: (4551) rssi -63, rate code 0x0018, idle 6 secs
SM Apr 14 11:12:44.674414 DEBUG SM-DOT11: sm_dot11_handle_deassociate: ev type 5 (good), token 0, mac 6c:76:60:59:9e:6a
SM Apr 14 11:12:44.674576 DEBUG SM-STATE: (2462) mac 6c:76:60:59:9e:6a, flags 1801800028834dh, to change state ACTIVE -> DEASSOCIATED, by sm_dot11_handle_deassociate
Log Interpretation:
   
   • SM=Session Management.
   • SM-DOT11=World Mode Multi-Domain Operation.  The DOT11D option makes access points advertise local settings, such as frequencies and power levels.
   • Rate code 0x0018 = 11Mb per Multi-band Atheros Wi-Fi (MADwifi) 5212.
   The deassociation was based on DOT11D.  In other words, due to AP frequency or power level restrictions.


3. Check the configuration for frequency or power restrictions:
   set service-profile Guest_2.4 transmit-rate 11g mandatory 12,24.0,36.0,48.0,54.0 disabled 1.0,2.0,5.5,6.0,9.0,11.0,18.0 beacon-rate 24.0 multicast-rate AUTO
Snap!  The service profile indicates that devices must connect at a minimum, 12Mbps -normally good policy.  However, we have a single client that can only connect at 6Mbps.

Available Options:

1. Remove 6Mbps from the list of disabled data rates.  N.B., Legacy devices on the BSSID has a negative impact for the entire wi-fi network. Is one person worth the trouble?  It certainly is if that person is your boss!
   
2. Create a dedicated legacy SSID -diplomatic solution.
3. Ask the employee to get rid of the stone-age device!   Suggest or provide a modern device that handles 802.11na!

 Thant's It!
http://www.cisco.com/web/techdoc/wireless/access_points/online_help/eag/123-02.JA/1400BR/h_ap_network-if_802-11_c.html
http://web.mit.edu/freebsd/head/sys/dev/ath/ath_hal/ar5212/ar5212_phy.c

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