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Cisco 5500 Series Wireless Controllers

Voice Over Wireless LAN (VoWLAN) Troubleshooting Checklist

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Voice Over Wireless LAN (VoWLAN) Troubleshooting Checklist

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Voice Over Wireless LAN (VoWLAN) Troubleshooting Checklist

Voice Over Wireless LAN (VoWLAN) Troubleshooting Checklist


Voice Over Wireless LAN (VoWLAN) Troubleshooting Checklist


Published: June 4, 2010
Revised: June 4, 2010

Voice Over Wireless LAN (VoWLAN) Troubleshooting Checklist

The following is a checklist that is recommended when troubleshooting a Voice Over Wireless LAN (VoWLAN). It also defines best practices and additional options that may need to be taken into consideration.

Table 1-1 VoWLAN checklist 

Recommendation
Best Practice
May Consider
Done

Verify an AP can be seen from the phone at -67 dBm or better in all areas to be covered. You also need to verify that the AP sees the phone at -67 dBm or better in all areas as well.

X

   

Ensure that the SNR is always 25 dB or higher in all areas to provide coverage.

X

   

Verify that channel utilization is under 50%.

X

   

Configure voice WLAN to use the 802.11a band.

 

X

 

If using EAP authentication, ensure that fast roaming is supported such as CCKM.

X

   

WMM should be allowed or required for the voice WLAN.

X

   

Voice WLAN should be marked with Platinum QoS.

X

   

Platinum QoS profile should have the 802.1p bits set to 6.

X

   

Verify the switch ports used to connect to the controller are set to trust CoS and ports to APs and uplinks are set to trust DSCP.

X

   

Verify that Call Admission Control is enabled globally for the radios.

X

   

Verify that Load-based CAC is enabled under Call Admission Control.

X

   

Ensure that Load Based CAC (7920 AP CAC) under the WLAN is enabled for the voice WLAN if the network has a mix of 7920 and 792xG Series wireless IP phones.

X

   

Ensure that Client Based CAC (7920 Client CAC) under the WLAN is disabled for the voice WLAN.

X

   

Verify that the EDCA profile on the controller is set to Voice Optimized.

X

   

Verify that Low Latency MAC is disabled.

X

   

Verify that the 12 Mbps data rate is enabled (default PHY rate of the phone).

X

   

If using 802.11b/g disable the 1, 2, 5.5, 6, and 9 Mbps data rates if possible.

X

   

If using 802.11a disable the 6 and 9 Mbps data rates if possible.

X

   

Verify coverage is designed for 24 Mbps to maximize throughput. Optionally disable 36-54 Mbps.

 

X

 

Optionally disable 36-54Mbps

     

Verify that Aggressive Load Balancing is disabled.

 

X

 

Disabled ARP unicast if running a pre-4.2 image on the controller.

X

   

Verify that DTPC is enabled so that the client and AP match tx power levels.

X

   

Verify the Beacon interval is set to 100 ms.

X

   

A DTIM of 2 is recommended.

X

   

Ensure DHCP required is not enabled for the voice WLAN.

 

X

 

Ensure that Aironet IE is enabled for the voice WLAN.

X

   

Verify that Client MFP is set to Optional or Disabled.

X

   

Session timeout for the WLAN should not be too short (300 seconds or more).

X

   

Verify that peer-to-peer blocking is disabled.

X

   

If using TKIP encryption, disable the hold down timer on the voice WLAN to prevent MIC errors from disrupting voice.

X

   

Verify that the radio of the AP has multiple antennas and that diversity is enabled.

X

   

Ensure controllers are configured for Symmetric Mobility if phones will be roaming between controllers.

 

X

 

Validate the virtual interface address is the same across all controllers in the same mobility group.

X

   

Validate that the mobility status shows as UP between all controllers in the same mobility group.

X

   

Enable Traffic Stream Metrics collection on the controller.

X

   

DCA Channel Sensitivity set to High to reduce chance of channel changes during business hours.

X