Information Technology Reference
In-Depth Information
To p r e v i o u s l y s t o r e d W L C I P a d d r e s s e s
To I P a d d r e s s e s l e a r n e d b y D H C P o p t i o n 4 3
To I P a d d r e s s e s l e a r n e d b y D N S r e s o l u t i o n o f C I S C O - LWA P P - C O N T RO L L E R . l o c a l -
domain
The selected WLC is based on the following:
Previously configured primary, secondary, or tertiary WLCs
The WLC configured as the master controller
The WLC with the most capacity for AP associations
For controllers that have a CAPWAP image, the AP follows the follow ing proces s:
1. The CAPWAP AP starts the discovery process to find the controller by using a CAP-
WA P r e q u e s t . T h e W L C r e s p o n d s w i t h a C A P WA P r e s p o n s e .
2. If a CAPWAP response is not received after 60 seconds, the AP starts the discovery
process using LWAPP discovery.
3. If the AP cannot find a controller using LWA P P within 60 seconds, it returns to step 1.
WLC selection by a CAPWAP is a design decision. This is configurable in the WLC. The
AP selects the WLC to create a CAPWAP tunnel based on the information configured in
the WLC. The WLC responses contain controller sysName, controller type, controller AP
capacity and load, the master controller status, and the AP manager IP addresses. The AP
selects one or several WLCs to send a CAPWAP tunnel request based on Table 5-5. The
WLC validates the AP and sends a CAPWAP tunnel response, an encryption key is de-
rived, and future messages are encrypted. The AP then selects one WLC and sends a join
request.
Ta b l e 5 - 5
WLAN Controller Platforms
Order
WLC
First
Primary sysName (preconfigured)
Second
Second sysName (preconfigured)
Third
Te r t i a r y s y s N a m e ( p r e c o n f i g u r e d )
Four th
Master controller
Fifth
WLC with greatest capacity for AP associations
WLAN Authentication
Wireless clients first associate to an AP. Then wireless clients need to authenticate with an
authentication server before the AP allows access to services. As shown in Figure 5-6, the
 
 
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