Cisco Cisco 5508 Wireless Controller 기술 참조

Max power and min data rate facilitate the maximum propagation of an NDP packet, that is, the RF 
Group will know the farthest reach that any AP in the group is capable of achieving.

An NDP message contains the following information:

When an AP receives an NDP message, it:

Validates that the message is from a member of its RF Group (hash); if not, it is dropped.

If valid, the AP forwards the message along with the received channel and RSSI to the controller.

The forwarded message is added to the neighbor database, which in turn is forwarded to the RF group 
leader periodically. For each AP, each radio can store up to 34 neighbors ordered by RSSI high to low.  

The following two distinct measurements are developed for each AP in the RF Group:

RX Neighbors–How the selected AP hears other APs.

TX Neighbors–How other APs hear the selected AP.

Neighbor entries on the controller are pruned every 60 minutes. If a new neighbor is discovered, the list 
is flushed and refreshed in its entirety to capture what the new neighbor can contribute.  

You must be mindful of the pruning interval. If an AP is disabled, it could be up to 60 minutes before it 
is flushed from the neighbor list.

You can observe neighbor messages over the air by using a packet capture tool and filtering on the 
multicast address 01:0B:85:00:00:00.