Which three Cisco Unified Wireless Network capabilities use information that is provided by Radio Resource Management neighbor messages? (Choose three.)
A. aggressive loadbalancing
B. dynamic channel assignment
C. hybrid remote edge access point
D. intercontroller mobility (that is, mobility groups)
E. over-the-air provisioning
F. rogue AP classification
Correct Answer: BEF
Explanation/Reference:
Explanation:
First, we should learn how the RRM works:
1) Controllers (whose APs need to have RF configuration computed as a single group) are provisioned with the same RF Group Name. An RF Group Name is an ASCII string each AP will use to determine if the other APs they hear are a part of the same system.(RF groups are groups of controllers that share the same RF group name and whose APs can hear the neighbor messages of each other)
2) APs periodically send out Neighbor Messages, sharing information about themselves, their controllers, and their RF Group Name. These neighbor messages can then be authenticated by other APs sharing the same RF Group Name.
3) APs that can hear these Neighbor Messages and authenticate them based on the shared RF Group Name, pass this information (consisting primarily of controller IP address and information on the AP transmitting the neighbor message) up to the controllers to which they are connected.
4) The controllers, now understanding which other controllers are to be a part of the RF Group, then form a logical group to share this RF information and subsequently elect a group leader.
5) Equipped with information detailing the RF environment for every AP in the RF Group, a series of RRM algorithms are used to optimize AP configurations. Information from Radio Resource Management (RRM) monitors the radio resources, performs dynamic channel assignments, provides detection and avoidance of interference, and provides the dynamic transmit power control (TPC).
The RRM neighbor message contains the following information:
* Radio Identifier: If the AP had multiple radios, this field identifies the radio used to transmit the message.
* Group ID: The 16-bit value and controller MAC address. This information is used to detect rogue access points. The access points will then check the beacon/probe-response frames in neighboring access point messages to see if they contain an authentication information element (IE) that matches that of the RF group. If the check is successful, the frames are authenticated. Otherwise, the authorized access point reports the neighboring access point as a rogue, records its BSSID in a rogue table, and sends the table to the controller.
* WLC IP Address: RF group leader’s management IP address. This address is discovered through Over-the-Air Provisioning (OTAP)
*AP Channel: The native channel that the AP uses to service clients.
* Neighbor Message Channel: The channel the message is sent on.
* Power: The power level at which the message is transmitted.
* Antenna Pattern: The antenna pattern currently in use
Note:
Dynamic channel assignment is used to dynamically allocate access point channel assignments to avoid conflict and to increase capacity and performance. For example, two overlapping channels in the 802.11g band, such as 1 and 2, cannot both simultaneously use 54 Mbps. By effectively reassigning channels, the controller keeps adjacent channels separated, thereby avoiding this problem.
Over-the-Air Provisioning (OTAP) is a method for APs to discover the management IP of a controller over the air.
A rogue AP isan AP that is unknown to the controller.
http://www.cisco.com/en/US/tech/tk722/tk809/technologies_tech_note09186a008072c759.shtml http://www.cisco.com/en/US/docs/wireless/
controller/5.2/configuration/guide/c52rrm.html
Explanation/Reference:
Explanation:
First, we should learn how the RRM works:
1) Controllers (whose APs need to have RF configuration computed as a single group) are provisioned with the same RF Group Name. An RF Group Name is an ASCII string each AP will use to determine if the other APs they hear are a part of the same system.(RF groups are groups of controllers that share the same RF group name and whose APs can hear the neighbor messages of each other)
2) APs periodically send out Neighbor Messages, sharing information about themselves, their controllers, and their RF Group Name. These neighbor messages can then be authenticated by other APs sharing the same RF Group Name.
3) APs that can hear these Neighbor Messages and authenticate them based on the shared RF Group Name, pass this information (consisting primarily of controller IP address and information on the AP transmitting the neighbor message) up to the controllers to which they are connected.
4) The controllers, now understanding which other controllers are to be a part of the RF Group, then form a logical group to share this RF information and subsequently elect a group leader.
5) Equipped with information detailing the RF environment for every AP in the RF Group, a series of RRM algorithms are used to optimize AP configurations. Information from Radio Resource Management (RRM) monitors the radio resources, performs dynamic channel assignments, provides detection and avoidance of interference, and provides the dynamic transmit power control (TPC).
The RRM neighbor message contains the following information:
* Radio Identifier: If the AP had multiple radios, this field identifies the radio used to transmit the message.
* Group ID: The 16-bit value and controller MAC address. This information is used to detect rogue access points. The access points will then check the beacon/probe-response frames in neighboring access point messages to see if they contain an authentication information element (IE) that matches that of the RF group. If the check is successful, the frames are authenticated. Otherwise, the authorized access point reports the neighboring access point as a rogue, records its BSSID in a rogue table, and sends the table to the controller.
* WLC IP Address: RF group leader’s management IP address. This address is discovered through Over-the-Air Provisioning (OTAP)
*AP Channel: The native channel that the AP uses to service clients.
* Neighbor Message Channel: The channel the message is sent on.
* Power: The power level at which the message is transmitted.
* Antenna Pattern: The antenna pattern currently in use
Note:
Dynamic channel assignment is used to dynamically allocate access point channel assignments to avoid conflict and to increase capacity and performance. For example, two overlapping channels in the 802.11g band, such as 1 and 2, cannot both simultaneously use 54 Mbps. By effectively reassigning channels, the controller keeps adjacent channels separated, thereby avoiding this problem.
Over-the-Air Provisioning (OTAP) is a method for APs to discover the management IP of a controller over the air.
A rogue AP isan AP that is unknown to the controller.
http://www.cisco.com/en/US/tech/tk722/tk809/technologies_tech_note09186a008072c759.shtml http://www.cisco.com/en/US/docs/wireless/
controller/5.2/configuration/guide/c52rrm.html