Cisco Cisco 2000 Series Wireless LAN Controller
8
Release Notes for Cisco Wireless LAN Controllers and Lightweight Access Points for Release 4.0.179.11
OL-11734-01
Important Notes
Operating Mesh Networks through Switches and Routers
In mesh networks that operate through switches and routers, network round-trip delays between access
points and the controller must be less than 100 milliseconds (ms); otherwise, timing problems may occur
during wireless client authentication. Also, network path outages of 7 seconds or longer between access
points and the controller may cause the access points to lose connectivity.
points and the controller must be less than 100 milliseconds (ms); otherwise, timing problems may occur
during wireless client authentication. Also, network path outages of 7 seconds or longer between access
points and the controller may cause the access points to lose connectivity.
Cisco 7920 Wireless IP Phone Support
When using Cisco 7920 Wireless IP Phones with controllers, make sure that the phones and controllers
are configured as follows:
are configured as follows:
•
Aggressive load balancing must be disabled for each controller. Otherwise, the initial roam attempt
by the phone may fail, causing a disruption in the audio path.
by the phone may fail, causing a disruption in the audio path.
•
The QoS Basis Service Set (QBSS) information element (IE) must be enabled. The QBSS IE enables
the access points to communicate their channel usage to wireless devices. Because access points
with high channel usage might not be able to handle real-time traffic effectively, the 7920 phone uses
the QBSS value to determine if they should associate with another access point. Use the following
commands to enable the QBSS IE:
the access points to communicate their channel usage to wireless devices. Because access points
with high channel usage might not be able to handle real-time traffic effectively, the 7920 phone uses
the QBSS value to determine if they should associate with another access point. Use the following
commands to enable the QBSS IE:
–
sh wlan summary
Note
Use this command to determine the WLAN ID number of the WLAN to which you want
to add QBSS support.
to add QBSS support.
–
config wlan disable wlan_id_number
–
config wlan 7920-support ap-cac-limit enable wlan_id_number
–
config wlan enable wlan_id_number
–
sh wlan wlan_id_number
Note
Use this command to verify that the WLAN is enabled and the Dot11-Phone Mode
(7920) field is configured for compat mode.
(7920) field is configured for compat mode.
–
save config
•
The Dynamic Transmit Power Control (DTPC) information element (IE) must be enabled using the
config 802.11b dtpc enable command. The DTPC IE is a beacon and probe information element
that allows the access point to broadcast information on its transmit power. The Cisco 7920 Wireless
IP Phone uses this information to automatically adjust its transmit power to the same level as the
access point to which it is associated. In this manner, both devices are transmitting at the same level.
config 802.11b dtpc enable command. The DTPC IE is a beacon and probe information element
that allows the access point to broadcast information on its transmit power. The Cisco 7920 Wireless
IP Phone uses this information to automatically adjust its transmit power to the same level as the
access point to which it is associated. In this manner, both devices are transmitting at the same level.
•
Both the 7920 phones and the controllers support Cisco Centralized Key Management (CCKM) fast
roaming.
roaming.
•
When configuring WEP, there is a difference in nomenclature for the controller and the 7920 phone.
Configure the controller for 104 bits when using 128-bit WEP for the 7920.
Configure the controller for 104 bits when using 128-bit WEP for the 7920.