Config Analyzer Voice - 40xxx related checks.

[Roger Nobel]

If you get error msg 40xxx and you wonder how to configure. Below I try to summarize cli command you 
need to fix the msg. Mostly focused on Cisco 792x Series deployments. 

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40001, Voice: 802.11a network has RRM Transmit Power Control set to automatic. 
Unless using WLC 4.1.185.0 (or later), using Radio Resource Management (RRM) can cause 
radio setting changes during the day, which trigger client disconnections. If this happens 
during a call, it will be disrupted, or end on one-way voice situation. How much affects this, 
depends a lot on RF conditions in the site, so it is not a black or white situation, and should be 
evaluated case by case. After 4.1.185.0 and above, using DCA is possible if correctly configured. 
REFERENCE: Radio Resource Management under Unified Wireless Networks 

>config 802.11a txPower global <power level>/auto 
OR 
>config 802.11a txPower ap <ap-name> <power level>

40002, Voice: 802.11b network has RRM Transmit Power Control set to automatic. 
Unless using WLC 4.1.185.0 (or later), using Radio Resource Management (RRM) can cause radio setting 
changes during the day, which trigger client disconnections. If this happens during a call, it will be 
disrupted, or end on one-way voice situation. How much affects this, depends a lot on RF conditions in 
the site, so it is not a black or white situation, and should be evaluated case by case. After 4.1.185.0 
and above, using DCA is possible if correctly configured. REFERENCE: Radio Resource Management 
under Unified Wireless Networks 

>config 802.11b txPower global <power level>/auto 
OR 
>config 802.11b txPower ap <ap-name> <power level>

40003, Voice: 802.11a network has RRM Dynamic Channel Assignment set to automatic. 
Unless using WLC 4.1.185.0 (or later), using Radio Resource Management (RRM) can cause radio setting 
changes during the day, which trigger client disconnections. If this happens during a call, it will be 
disrupted, or end on one-way voice situation. How much affects this, depends a lot on RF conditions in 
the site, so it is not a black or white situation, and should be evaluated case by case. After 4.1.185.0 
and above, using DCA is possible if correctly configured. REFERENCE: Radio Resource Management under 
Unified Wireless Networks 

>config 802.11a channel global auto 
OR 
>config 802.11a channel ap <ap-name> <channel#>

40004, Voice: 802.11b network has RRM Dynamic Channel Assignment set to automatic. 
Unless using WLC 4.1.185.0 (or later), using Radio Resource Management (RRM) can cause radio setting 
changes during the day, which trigger client disconnections. If this happens during a call, it will be 
disrupted, or end on one-way voice situation. How much affects this, depends a lot on RF conditions in 
the site, so it is not a black or white situation, and should be evaluated case by case. After 4.1.185.0 
and above, using DCA is possible if correctly configured. REFERENCE: Radio Resource Management under 
Unified Wireless Networks 

>config 802.11b channel global auto 
OR 
>config 802.11b channel ap <ap-name> <channel#>

40005, Voice: 802.11a Power Threshold %Controller Current Threshold% , is higher than recommended value of  
% App Configured Setting% Original value of -65 dBm is in general, too high. Recommended value is -70 dBm. 
If the version is before 4.1.185.0. REFERENCE: Radio Resource Management under Unified Wireless Networks 

>config advanced 802.11a tx-power-control-thresh -70

40006, Voice: 802.11b Power Threshold %Controller Current Threshold% , is higher than recommended value of  
% App Configured Setting% Original value of -65 dBm is in general, too high. Recommended value is -70 dBm. 
If the version is before 4.1.185.0. REFERENCE: Radio Resource Management under Unified Wireless Networks 

>config advanced 802.11a tx-power-control-thresh -70

40007, Voice: Aggressive load balancing is enabled. Check if providing voice services or low density of 
APs to disable it Do not enable aggressive load balancing unless the network has available a high density 
of access points in the area, and never if there is voice over wireless. If you enable this feature with 
access points spaced to far away from each other, it might confuse the roaming algorithm of some clients, 
and induce coverage holes in some cases. In the latest software versions, this feature is disabled by 
default. REFERENCE: Wireless LAN Controller (WLC) Configuration Best Practices 

>config load-balancing status disable 

40008, Voice: arpunicast is enabled, it must be disabled. 
arpunicast setting should not be enabled in normal circumstances. It may cause connectivity problems 
between devices on the same VLAN. Note that the original 7920 Deployment Guide incorrectly recommended 
that arpunicast should be enabled. 

>config network arpunicast disable


40009, Voice: DTIM value should be 2, currently it is  %DTIM value% , check in %band% Configuration for 
optimal battery life and performance, we recommend setting the DTIM period to “2”. REFERENCE: Cisco 
Unified Wireless IP Phone 7921G Deployment Guide 

>config 802.11b dtim 2
>config 802.11a dtim 2

40010, Voice: Beacon Interval should be 100, currently it is  %Controller Current Beacon interval% , 
check in %band% Configuration for optimal battery life and performance, we recommend setting the beacon 
period to 100 ms. REFERENCE: Cisco Unified Wireless IP Phone 7921G Deployment Guide 

>config 802.11b beaconperiod 100
>config 802.11a beaconperiod 100

40011, Voice: Short Preamble should be enabled, check in 802.11b Configuration 
Recommended value for the 792x. Use the short preamble setting in the radio configuration setting on the 
access point when no legacy clients that require a long preamble are present in the WLAN. By using the 
short preamble instead of the legacy long preamble, the wireless network performance is improved. 
REFERENCE: Cisco Unified Wireless IP Phone 7921G Deployment Guide 

>config 802.11b preamble short

40012, Voice: Low data rates (1 and 2 Mbps) should be disabled for voice, check in 802.11b Network 
Configuration REFERENCES: Cisco Unified Wireless IP Phone 7921G Deployment Guide, Cisco Unified Wireless 
IP Phone 7920 Design and Deployment Guide (Chapter 2) 

>config 802.11b rate disabled 1
>config 802.11b rate disabled 2

40013, Voice: 5.5 Mbps should be disabled for voice, check in 802.11b Network Configuration 
REFERENCES: Cisco Unified Wireless IP Phone 7921G Deployment Guide, Cisco Unified Wireless IP Phone 
7920 Design and Deployment Guide (Chapter 2) 

>config 802.11b rate disabled 5.5

40014, Voice: 802.11g speed set as mandatory, this will generate association problems with 7920. Check in 
802.11b Network Configuration Wrong configuration to support 7920 

>config 802.11b rate disabled 6
>config 802.11b rate disabled 9

40015, Voice: ACM is not enabled, check in 802.11b Voice Configuration 
Reported recommended value for the 792x 

>config 802.11b cac voice acm enable

40016, Voice: ACM is not enabled, check in 802.11a Voice Configuration 
Reported recommended value for the 792x 

>config 802.11a cac voice acm enable

40017, Voice: SSID WLAN has WMM disabled. It should be optional or enabled for voice. 
Recommended value for the 7921. REFERENCE: Cisco Unified Wireless IP Phone 7921G Deployment Guide 

>config wlan wmm require <wlan-id> OR >config wlan wmm allow <wlan-id>

40018, Voice: SSID WLAN has DHCP Required enabled. It must be disabled for voice 
This option might affect some client implementations which do not do a DHCP renew until the lease time 
expires. For example, Cisco 7920 or 7921 phones might have voice problems while they roam if this option 
is enabled, as the controller does not allow voice or signaling traffic to pass until the DHCP phase is
completed. Some third-party printer servers might also be affected. In general, it is a good idea not 
to use this option if the WLAN has non-Windows clients. This is because the more strict controls might 
induce connectivity issues, based on how the DHCP client side is implemented. REFERENCE: Wireless LAN 
Controller (WLC) Configuration Best Practices 

>config wlan dhcp_server <wlan-id> 0.0.0.0 

40019, Voice: SSID WLAN does not have AP CAC limit enabled 
Reported recommended value for the 792x 

>config 802.11b cac voice roam-bandwidth 6

40020, Voice: SSID WLAN has Client CAC limit enabled, must be disabled 
Reported recommended value for the 792x 

>config 802.11a cac voice roam-bandwidth 6

40021, Voice: SSID WLAN Client MFP as enabled, must be either optional or disabled 
Recommended value for the 792x. REFERENCE: Cisco Unified Wireless IP Phone 7921G Deployment Guide 

>config wlan mfp client disable <wlan-id> OR >config wlan mfp client enable <wlan-id> required

40022, Voice: SSID WLAN Platinum QoS settings are not set to 802.1p. 
On the 7920, to avoid issues on the time sensitive queue for APs, it is recommended to tag the frames this 
QoS profile. Check in Controller QoS Profiles. REFERENCE: Cisco Unified Wireless IP Phone 7921G Deployment
Guide 

>config qos dot1p-tag platinum 6

40023, Voice: No platinum level SSID found, possible incorrect configuration, or controller not intended 
for voice support No SSID found with platinum level QoS configured. This may be intentional (no voice 
support needed) or an incorrect configuration. REFERENCE: Cisco Unified Wireless IP Phone 7921G Deployment 
Guide 

>config wlan qos <wlan-id> platinum

40024, Voice: 802.11a Coverage Min Clients  %Controller Current Threshold%, is less than recommended value 
of %App settings Current Threshold% In some situations, while using RRM, it may be useful to change the 
current threshold. The effect is varies depending on the version used (RRM enhancements or not), so use 
with care. REFERENCE: Radio Resource Management under Unified Wireless Networks 

>config advanced 802.11a coverage level global 5 

40025, Voice: 802.11b Coverage Min Clients  %Controller Current Threshold%, is less than recommended value 
of %App settings Current Threshold% In some situations, while using RRM, it may be useful to change the 
current threshold. The effect is varies depending on the version used (RRM enhancements or not), so use 
with care. REFERENCE: Radio Resource Management under Unified Wireless Networks 

>config advanced 802.11b coverage level global 5 

40026, Voice: 802.11a Tx Power Threshold %Controller Current Threshold%, is higher than recommended value 
of %App settings Current Threshold% In some situations, while using RRM, it may be useful to change the 
current transmit power threshold. The effect is varies depending on the version used (RRM enhancements 
or not), so use with care. REFERENCE: Radio Resource Management under Unified Wireless Networks 

>config advanced 802.11a tx-power-control-thresh -70

40027, Voice: 802.11b Tx Power Threshold %Controller Current Threshold%, is higher than recommended value 
of %App settings Current Threshold% In some situations, while using RRM, it may be useful to change the 
current transmit power threshold. The effect is varies depending on the version used (RRM enhancements 
or not), so use with care. REFERENCE: Radio Resource Management under Unified Wireless Networks 

>config advanced 802.11b tx-power-control-thresh -70

40028, Voice: Low data rates (6 and 9 Mbps) should be disabled for voice, check in 802.11a Network 
Configuration (7921 recommendations) 
This is a "recommendation", with lots of variations depending on RF conditions, and desired coverage. 

>config 802.11a rate disabled 6
>config 802.11a rate disabled 9

40029, Voice: Session timeout should be high, to avoid voice disruptions during authentication 
Warns if the session timeout is less than 24 hours. Frequent reauthentications can disrupt active calls. 
Configure the session timeout as necessary. REFERENCE: Cisco Unified Wireless IP Phone 7921G Deployment 
Guide 

>config wlan session-timeout <wlan-id> 86400

40030, Voice: WLAN with EAP, without CCKM, call quality during roaming may be disrupted 
When using 802.1x type authentication, you should implement CCKM for authentication. 802.1x can 
introduce delay during roaming due to its requirement for full re-authentication. CCKM centralizes 
the key management and reduces the number of key exchanges. REFERENCE: Cisco Unified Wireless IP Phone 
7921G Deployment Guide 

>config wlan security wpa akm  cckm enable <wlan-id>

40031, Voice: Global Peer-to-Peer blocking is enabled, this is not recommended for Voice services 
REFERENCE: Cisco Unified Wireless IP Phone 7921G Deployment Guide 

>config wlan peer-blocking disable <wlan-id>

40032, Voice: WLAN Peer-to-Peer blocking is enabled, this is not recommended if using Voice services 
on this WLAN:XX REFERENCE: Cisco Unified Wireless IP Phone 7921G Deployment Guide 

>config wlan peer-blocking disable <wlan-id>

40033, Voice: WLAN has TKIP as L2 policy, and Hold Down timer is not disabled, this is not recommended, 
as it may cause voice problems in case of MIC errors introduced by other devices, 
TKIP countermeasure mode can occur if the Access Point receives two message integrity check (MIC) 
errors within a 60 second period. When this occurs, the Access Point will de-authenticate all TKIP 
clients associated to that 802.11 radio and holdoff any clients for the countermeasure holdoff time 
(default = 60 seconds). REFERENCE: Cisco Unified Wireless IP Phone 7921G Deployment Guide 

>config wlan security tkip hold-down 0 <wlan-id>

40034,Voice: WLAN has exclusion timer enabled, it is recommended to disable on voice WLANs to allow faster 
recovery Clients can be denied association to the network if they do not abide by the default 
Client Exclusion policies configured on the WLC. 

>config wlan exclusionlist <wlan-id> disabled 

40035,Voice: AP does not have antenna diverstity enabled. It is recommended to use diversity in all 
voice deployments, as much as possible in the given RF environment. This may not be possible depending 
on AP model REFERENCE: Cisco Unified Wireless IP Phone 7921G Deployment Guide 

>config 802.11b antenna diversity enable <ap-name>
>config 802.11a antenna diversity enable <ap-name>

40036,Voice: Max RF bandwidth is not matching the recommended: X% 

>config 802.11b cac voice max-bandwidth 75
>config 802.11a cac voice max-bandwidth 75

40037,Voice: Max reserved roaming bandwidth is not matching the recommended: X% 

>config 802.11b cac voice roam-bandwidth 6
>config 802.11a cac voice roam-bandwidth 6

40038,Voice: Traffic Stream Metrics collection is disabled. It is recommended, although not mandatory, 
to enable it" Traffic Stream Metrics (TSM) can be used to monitor voice-related metrics on the 
client-access point air interface. It reports both packet latency and packet loss. An administrator 
can isolate poor voice quality issues by studying these reports. REFERENCE: Voice over Wireless LAN 4.1 
Design Guide - Voice over WLAN Troubleshooting and Management Tools 

>config 802.11b tsm enable
>config 802.11a tsm enable

40039,Voice: Aironet Extensions are disabled, it is recommended to enable them, WLAN: 

>config wlan ccx aironetIeSupport enable <wlan-id>

40040,Voice: More than one WLAN with Platinum level found. Check if this is intentional (for example 
servicing 7920/7921). Not recommended otherwise 
Platinum QoS level provides a higher quality of service for voice over wireless. 

>config wlan qos <wlan-id> platinum

40041,Voice: Depending on your RF coverage, and desired call density, it may be recommended to disable high 
data rates for voice services (36, 48, 54 mbps) 
Having higher data rates enabled, without a very good RF signal coverage, may result in many dropped frames
resulting in reduced voice quality. Enable high data rates only when sufficient RF signal coverage is 
available. 

>config 802.11b rate disabled 36
>config 802.11b rate disabled 48
>config 802.11b rate disabled 54
>config 802.11a rate disabled 36
>config 802.11a rate disabled 48
>config 802.11a rate disabled 54

40042,Voice: Mac filtering in voice WLANs is not recommended due to potential delays on association 
process/roaming" or WLANs with voice services, MAC address filtering can introduce delays on roaming, as 
association/reassociation requests need to be validated against AAA before they are finally answered. 

>config wlan mac-filtering disable <wlan-id>

40043,Voice: DCA interval is recommended to be high, to prevent channel changes during working hours." 
It is good idea to have a long timer for DCA channel calculation, to minimize the possibility to have any 
disruptive channel change while a phone call is active 

>config advanced 802.11b channel dca interval 24
>config advanced 802.11b channel dca anchor-time 0
>config advanced 802.11a channel dca interval 24
>config advanced 802.11a channel dca anchor-time 0