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Cisco IOS Software Configuration Guide for Cisco Aironet Access Points
OL-30644-01
Chapter12 Configuring WDS, Fast Secure Roaming, Radio Management, and Wi reless Intrusion Detection
Understanding WDS
Understanding WDS
When you configure Wireless Domain Services on your network, access points on your wireless LAN
use the WDS device (either an access point, an Integrated Services Router configured as the WDS
device) to provide fast, secure roaming for client devices in a given subnet and to participate in radio
management. An access point configured as the WDS device supports up to 60 participating access
points, an Integrated Services Router (ISR) configured as the WDS devices supports up to 100
participating access points.
Note A single access point supports up to 16 mobility groups.
Fast, secure roaming provides rapid reauthentication when a client device roams from one access point
to another in the same subnet, preventing delays in voice and other time-sensitive applications.
Access points participating in radio management forward information about the radio environment (such
as possible rogue access points and client associations and disassociations) to the WDS device.

Role of the WDS Device

The WDS device performs several tasks on your wireless LAN:
•Advertises its WDS capability and participates in electing the best WDS device for your wireless
LAN. When you configure your wireless LAN for WDS, you set up one device as the main WDS
candidate and one or more additional devices as backup WDS candidates. If the main WDS device
goes off line, one of the backup WDS devices takes its place.
•Authenticates all access points in the subnet and establishes a secure communication channel with
each of them, over the wired interface.
•Acts as a pass-through for all 802.1x-authenticated client devices associated to participating access
points.
•Registers all client devices in the subnet that use dynamic keying, establishes session keys for them,
and caches their security credentials. When a client roams to another access point registered to the
WDS device, the WDS device forwards the client’s security credentials to the new access point.
Table12-1 lists the number of participating access points supported by the platforms that can be
configured as a WDS device: an access point, an ISR.
Table12-1 Participating Access Points Supported by WDS Devices
Unit Configured as WDS Device Participating Access Points Supported
Access point that also serves client devices 30
Access point with radio interfaces disabled 60
Integrated Services Router (ISR) 100 (depending on ISR platform)