A new lightweight access point (LAP) has been installed in the Company WLAN. Which two
statements correctly describe the association process between this LAP and a WLAN
controller? (Choose 2)
A.
An access point will search for a controller using a broadcast address if using
LWAPP Layer 2 and a unicast address if using LWAPP Layer 3 mode.
B.
If multiple wireless controllers are detected by an access point, the controller with the
fewest associated access points is chosen to associate with.
C.
In order to associate in Layer 3 mode, the access point must have been
preconfigured with an IP address.
D.
Once an access point associates with a controller in LWAPP Layer 3 mode, it
receives an IP address from the controller.
E.
An access point first searches for a controller in LWAPP Layer 2 mode. If the search
is not successful, the access point then attempts to locate a controller in LWAPP Layer 3
mode.
F.
If multiple wireless controllers are detected by an access point, all of them will be
used and traffic will be load balanced.
Explanation:
This procedure for a LAP to register with a WLC is:
The LAP issues a DHCP request to a DHCP server in order to get an IP address, unless an
assignment was made previously with a static IP address.
If Layer 2 LWAPP mode is supported on the LAP, the LAP broadcasts an LWAPP discovery
message in a Layer 2 LWAPP frame. Any WLC that is connected to the network and that is
configured for Layer 2 LWAPP mode responds with a Layer 2 discovery response. If the LAP
does not support Layer 2 mode, or if the WLC or the LAP fails to receive an LWAPP
discovery response to the Layer 2 LWAPP discovery message broadcast, the LAP proceeds
to step 3.
If step 1 fails, or if the LAP or the WLC does not support Layer 2 LWAPP mode, the LAP
attempts a Layer 3 LWAPP WLC discovery.
If step 3 fails, the LAP resets and returns to step 1.
The LAP uses this information to make a controller selection, with use of these precedence
rules:
If the LAP has previously been configured with a primary, secondary, and/or tertiary
controller, the LAP examines the controller sysName field (from the LWAPP discovery
responses) in an attempt to find the WLC that is configured as “primary”. If the LAP finds a
matching sysName for the primary controller, the LAP sends an LWAPP join request to that
WLC. If the LAP cannot find its primary controller or if the LWAPP join fails, the LAP tries to
match the secondary controller sysName to the LWAPP discovery responses. If the LAP
finds a match, it then sends an LWAPP join to the secondary controller. If the secondary
WLC cannot be found or the LWAPP join fails, the LAP repeats the process for its tertiary
controller.
The LAP looks at the Master Controller flag field in the LWAPP discovery responses from
the candidate WLCs if one of these items is true:
No primary, secondary, and/or tertiary controllers have been configured for an AP.
These controllers cannot be found in the candidate list.
The LWAPP joins to those controllers have failed.
If a WLC is configured as a Master Controller, the LAP selects that WLC and send it an
LWAPP join request.
If the LAP cannot successfully join a WLC on the basis of the criteria in step 1 and step 2,
the LAP attempts to join the WLC that has the greatest excess capacity.
Reference:
http://www.cisco.com/en/US/tech/tk722/tk809/technologies_tech_note09186a00806c9e51.s
html