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Cisco Wireless LAN Controller Configuration Guide
OL-17037-01
Chapter 4 Configuring Controller SettingsWireless Device Access
Configuring Client Roaming
the session remains active. The tunnel is torn down, and the VoIP client must reauthenticate when the
VoIP telephone sends a DHCP Discover with a 0.0.0.0 VoIP telephone IP address or a 169.254.*.* VoIP
telephone auto-IP address or when the operator-set user timeout is exceeded.
CCX Layer 2 Client Roaming
The controller supports five CCX Layer 2 client roaming enhancements:
•
Access point assisted roaming
—This feature helps clients save scanning time. When a CCXv2
client associates to an access point, it sends an information packet to the new access point listing the
characteristics of its previous access point. Roaming time decreases when the client recognizes and
uses an access point list built by compiling all previous access points to which each client was
associated and sent (unicast) to the client immediately after association. The access point list
contains the channels, BSSIDs of neighbor access points that support the client’s current SSID(s),
and time elapsed since disassociation.
•
Enhanced neighbor list
—This feature focuses on improving a CCXv4 client’s roam experience and
network edge performance, especially when servicing voice applications. The access point provides
its associated client information about its neighbors using a neighbor-list update unicast message.
•
Enhanced neighbor list request (E2E)
—The End-2-End specification is a Cisco and Intel joint
program that defines new protocols and interfaces to improve the overall voice and roaming
experience. It applies only to Intel clients in a CCX environment. Specifically, it enables Intel clients
to request a neighbor list at will. When this occurs, the access point forwards the request to the
controller. The controller receives the request and replies with the current CCX roaming sublist of
neighbors for the access point to which the client is associated.
Note
To see whether a particular client supports E2E, click
Wireless
>
Clients
on the controller
GUI, click the
Detail
link for the desired client, and look at the E2E Version field under
Client Properties.
•
Roam reason report
—This feature enables CCXv4 clients to report the reason why they roamed to
a new access point. It also allows network administrators to build and monitor a roam history.
•
Directed roam request
—This feature enables the controller to send directed roam requests to the
client in situations when the controller can better service the client on an access point different from
the one to which it is associated. In this case, the controller sends the client a list of the best access
points that it can join. The client can either honor or ignore the directed roam request. Non-CCX
clients and clients running CCXv3 or below must not take any action. No configuration is required
for this feature.
Controller software release 4.2 or later supports CCX versions 1 through 5. CCX support is enabled
automatically for every WLAN on the controller and cannot be disabled. The controller stores the CCX
version of the client in its client database and uses it to generate and respond to CCX frames
appropriately. Clients must support CCXv4 or v5 (or CCXv2 for access point assisted roaming) in order
to utilize these roaming enhancements. See the
“Configuring Cisco Client Extensions” section on
for more information on CCX.
The roaming enhancements mentioned above are enabled automatically, with the appropriate CCX
support.
Note
Hybrid-REAP access points in standalone mode do not support CCX Layer 2 roaming.
