Specifications

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Cisco IOS Software Configuration Guide for Cisco Aironet Access Points
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Chapter 11 Configuring WDS, Fast Secure Roaming, and Radio Management
Understanding Radio Management
Figure 11-2 Client Reassociation Using CCKM and a WDS Access Point
The WDS device maintains a cache of credentials for CCKM-capable client devices on your wireless
LAN. When a CCKM-capable client roams from one access point to another, the client sends a
reassociation request to the new access point, and the new access point relays the request to the WDS
device. The WDS device forwards the client’s credentials to the new access point, and the new access
point sends the reassociation response to the client. Only two packets pass between the client and the
new access point, greatly shortening the reassociation time. The client also uses the reassociation
response to generate the unicast key.
Understanding Radio Management
Access points participating in radio management scan the radio environment and send reports to the
WDS device on such radio information as potential rogue access points, associated clients, client signal
strengths, and the radio signals from other access points. The WDS device forwards the aggregated radio
data to the WLSE device on your network. Access points participating in radio management also assist
with the self-healing wireless LAN, automatically adjusting settings to provide coverage in case a nearby
access point fails. Refer to the “Configuring Radio Management” section on page 11-23 for instructions
on configuring radio management.
Understanding Layer 3 Mobility
When you use a WLSM as the WDS device on your network, you can install access points anywhere in
a large Layer 3 network without configuring one specific subnet or VLAN throughout the wired switch
infrastructure. Client devices use multipoint GRE (mGRE) tunnels to roam to access points that reside
on different Layer 3 subnets. The roaming clients stay connected to your network without changing IP
addresses.
The access point features that provide mobile clients with fast, secure Layer 3 mobility are IP-Based
Wireless Domain Services and Layer 3 Mobility Service Through Fast Secure Roaming Tunnels.
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Reassociation request
Reassociation response
Pre-registration request
Pre-registration reply
Roaming client
device
Access point Access point or switch
providing Wireless
Domain Services
Authentication server
Wired LAN
WDS