Strange behavior with WLC 9800 and disabling broadcasting SSID on wlan

[czubachups]

Hello all,

we are running a WLC 9800-80 with 17.3.3 and have a strange issue with one of our networks. We have a wlan which has no authentication and should be hidden. It transmits on 5Ghz and 2.4 Ghz through the building. Now the WLAN stops transmitting on 2.4 Ghz as soon as we disable Broadcasting SSID. It still transmits on 5 Ghz when its hidden but completely stops on 2.4 Ghz. 

Is this a bug? we are only using C9130AXE-B as Aps. 

Any help or suggestion would be much appreciated. 

Thanks

Chris

[marce1000]

 - You may also have a sanity-check of the controller-configuration for that use the CLI-command : show tech wireless. Have the output analyzed with : https://cway.cisco.com/tools/WirelessAnalyzer/

 M.

[Arshad Safrulla]

Do you have FRA enabled on the AP's and 2.4 radio status on global RF configuration? Can you share the RF profile attached to these AP's? 

show ap fra 

show ap dot11 24ghz network

show wireless profile radio detailed <RF Profile name>

Also check whether you have manually disable 2.4 Radio in AP it self. For verification you can fire up WiFi Explorer in MAC or Winfi in Windows. 

[czubachups]

Here we go, let me know if you need anything else. The 2.4 Radio is not disabled on the APs since everything works when the network is not hidden. 

Sun Feb 20 2022 15:42:18 GMT-0500 (Eastern Standard Time)
===================================================================================
#show ap fra
FRA State : Disabled
FRA Sensitivity : medium (95%)
FRA Interval : 1 Hour(s)
Last Run : 2470 seconds ago
Last Run time : 0 seconds
Service Priority : Coverage
Client Aware FRA : Enabled
Client Select : 50%
Client Reset : 5%
AP Name MAC Address Slot ID Current-Band COF % Sensor % Suggested Mode
------------------------------------------------------------------------------------------------------
xxxxxxxxxxxxxxx xxxx.xxxx.xxxx 0 Monitor none none Monitor
xxxxxxxxxxxxxxx xxxx.xxxx.xxxx 0 2.4GHz none none 2.4GHz
xxxxxxxxxxxxxxx xxxx.xxxx.xxxx 0 2.4GHz none None (Static)
xxxxxxxxxxxxxxx xxxx.xxxx.xxxx 0 2.4GHz none None (Static)
xxxxxxxxxxxxxxx xxxx.xxxx.xxxx 0 2.4GHz none none 2.4GHz

#show ap dot11 24ghz network
802.11b Network : Enabled
11gSupport : Enabled
11nSupport : Enabled
802.11b/g Operational Rates
802.11b 1M : Unsupported
802.11b 2M : Unsupported
802.11b 5.5M : Unsupported
802.11b 11M : Unsupported
802.11g 6M : Unsupported
802.11g 9M : Unsupported
802.11g 12M : Mandatory
802.11g 18M : Supported
802.11g 24M : Supported
802.11g 36M : Supported
802.11g 48M : Supported
802.11g 54M : Supported
802.11n MCS Settings:
MCS 0 : Supported
MCS 1 : Supported
MCS 2 : Supported
MCS 3 : Supported
MCS 4 : Supported
MCS 5 : Supported
MCS 6 : Supported
MCS 7 : Supported
MCS 8 : Supported
MCS 9 : Supported
MCS 10 : Supported
MCS 11 : Supported
MCS 12 : Supported
MCS 13 : Supported
MCS 14 : Supported
MCS 15 : Supported
MCS 16 : Supported
MCS 17 : Supported
MCS 18 : Supported
MCS 19 : Supported
MCS 20 : Supported
MCS 21 : Supported
MCS 22 : Supported
MCS 23 : Supported
MCS 24 : Supported
MCS 25 : Supported
MCS 26 : Supported
MCS 27 : Supported
MCS 28 : Supported
MCS 29 : Supported
MCS 30 : Supported
MCS 31 : Supported
802.11n Status:
A-MPDU Tx:
Priority 0 : Enabled
Priority 1 : Enabled
Priority 2 : Enabled
Priority 3 : Enabled
Priority 4 : Enabled
Priority 5 : Enabled
Priority 6 : Disabled
Priority 7 : Disabled
Aggregation scheduler : Enabled
Realtime timeout : 10
A-MSDU Tx:
Priority 0 : Enable
Priority 1 : Enable
Priority 2 : Enable
Priority 3 : Enable
Priority 4 : Enable
Priority 5 : Enable
Priority 6 : Disable
Priority 7 : Disable
Guard Interval : Any
Rifs Rx : Enabled
802.11ax : Disabled
DynamicFrag : Enabled
MultiBssid : Enabled
Target Wakeup Time : Enabled
Target Wakeup Time Broadcast : Enabled
BSS Color : Enabled
Beacon Interval : 100
CF Pollable mandatory : Disabled
CF Poll Request Mandatory : Disabled
CFP Period : 4
CFP Maximum Duration : 60
Default Channel : 1
Default Tx Power Level : 1
DTPC Status : Enabled
Call Admission Limit :
G711 CU Quantum :
ED Threshold : -50
Fragmentation Threshold : 2346
RSSI Low Check : Disabled
RSSI Threshold : -127 dbm
PBCC Mandatory : unknown
Pico-Cell-V2 Status : unknown
RTS Threshold : 2347
Short Preamble Mandatory : Enabled
Short Retry Limit : 7
Legacy Tx Beamforming setting : Disabled
Traffic Stream Metrics Status : Disabled
Expedited BW Request Status : Disabled
EDCA profile type check : fastlane
Call Admision Control (CAC) configuration
Voice AC
Voice AC - Admission control (ACM) : Enabled
Voice Stream-Size : 84000
Voice Max-Streams : 2
Voice Max RF Bandwidth : 75
Voice Reserved Roaming Bandwidth : 6
Voice Load-Based CAC mode : Enabled
Voice tspec inactivity timeout : Enabled
CAC SIP-Voice configuration
SIP based CAC : Disabled
SIP call bandwidth : 64
SIP call bandwith sample-size : 20
Maximum Number of Clients per AP Radio : 200
WiFi to Cellular RSSI Threshold : -85 dbm

#show wireless profile policy detailed iCafe
Policy Profile Name : iCafe
Description : iCafe
Status : ENABLED
VLAN : xxxx-icafe
Multicast VLAN : 0
OSEN client VLAN :
Multicast Filter : DISABLED
QBSS Load : ENABLED
Passive Client : DISABLED
ET-Analytics : DISABLED
StaticIP Mobility : DISABLED
WLAN Switching Policy
Flex Central Switching : ENABLED
Flex Central Authentication : ENABLED
Flex Central DHCP : ENABLED
Flex NAT PAT : DISABLED
Flex Central Assoc : ENABLED
WLAN Flex Policy
VLAN based Central Switching : DISABLED
WLAN ACL
IPv4 ACL : Not Configured
IPv6 ACL : Not Configured
Layer2 ACL : Not Configured
Preauth urlfilter list : Not Configured
Postauth urlfilter list : Not Configured
WLAN Timeout
Session Timeout : 1800
Idle Timeout : 300
Idle Threshold : 0
Guest LAN Session Timeout : DISABLED
WLAN Local Profiling
Subscriber Policy Name : Not Configured
RADIUS Profiling : DISABLED
HTTP TLV caching : DISABLED
DHCP TLV caching : DISABLED
CTS Policy
Inline Tagging : DISABLED
SGACL Enforcement : DISABLED
Default SGT : 0
WLAN Mobility
Anchor : DISABLED
AVC VISIBILITY : Enabled
IPv4 Flow Monitors
Ingress
wireless-avc-basic
Egress
wireless-avc-basic
IPv6 Flow Monitors
Ingress
wireless-avc-basic-ipv6
Egress
wireless-avc-basic-ipv6
NBAR Protocol Discovery : Disabled
Reanchoring : Disabled
Classmap name for Reanchoring
Reanchoring Classmap Name : Not Configured
QOS per SSID
Ingress Service Name : AutoQos-4.0-wlan-ET-SSID-Input-AVC-Policy
Egress Service Name : AutoQos-4.0-wlan-ET-SSID-Output-Policy
QOS per Client
Ingress Service Name : Not Configured
Egress Service Name : Not Configured
Umbrella information
Cisco Umbrella Parameter Map : Not Configured
DHCP DNS Option : ENABLED
Mode : ignore
Autoqos Mode : Fastlane
Call Snooping : Disabled
Tunnel Profile
Profile Name : Not Configured
Calendar Profile
Fabric Profile
Profile Name : Not Configured
Accounting list
Accounting List : Not Configured
DHCP
required : DISABLED
server address : 0.0.0.0
Opt82
DhcpOpt82Enable : DISABLED
DhcpOpt82Ascii : DISABLED
DhcpOpt82Rid : DISABLED
APMAC : DISABLED
SSID : DISABLED
AP_ETHMAC : DISABLED
APNAME : DISABLED
POLICY TAG : DISABLED
AP_LOCATION : DISABLED
VLAN_ID : DISABLED
Exclusionlist Params
Exclusionlist : ENABLED
Exclusion Timeout : 60
AAA Policy Params
AAA Override : DISABLED
NAC : DISABLED
AAA Policy name : default-aaa-policy
WGB Policy Params
Broadcast Tagging : DISABLED
Client VLAN : DISABLED
Hotspot 2.0 Server name : Not Configured
Mobility Anchor List
IP Address Priority
-------------------------------------------------------
mDNS Gateway
mDNS Service Policy name : default-mdns-service-policy
User Defined (Private) Network : Disabled
User Defined (Private) Network Unicast Drop : Disabled
Policy Proxy Settings
ARP Proxy State : ENABLED
IPv6 Proxy State : None
Airtime-fairness Profile
2.4Ghz ATF Policy : default-atf-policy
5Ghz ATF Policy : default-atf-policy

[Arshad Safrulla]

Once of the AP's in monitor mode, So anyway this will not advertise the SSID's in 2.4GHz. 

As others mentioned reach out to TAC and let us know what was the fix. Also it is recommended that you upgrade the WLC to the latest Cisco TAC recommended IOS-XE code as some of the TAC engineers are now insisting to upgrade even before troubleshooting.

Recommended Cisco IOS XE Releases for Catalyst 9800 Wireless LAN Controllers - Cisco 

[Rich R]

https://bst.cloudapps.cisco.com/bugsearch/bug/CSCvz56650 looks like a possibility.

It is mentioned in the 17.3.4c release notes: https://www.cisco.com/c/en/us/td/docs/wireless/controller/9800/17-3/release-notes/rn-17-3-9800.html#Cisco_Reference.dita_36735745-0909-4e00-ac34-2c7d5f643277

I'd suggest upgrading to 17.3.4c as per TAC recommended https://www.cisco.com/c/en/us/support/docs/wireless/catalyst-9800-series-wireless-controllers/214749-tac-recommended-ios-xe-builds-for-wirele.html#anc9 and then test again.

If the problem is resolved that confirms you've hit a bug that's been fixed.  If not then next step is a TAC case.