chapter 6; Topic 1

Measuring the RSSI of NDP messages from an AP

NDP message advertisement messages are transmitted using the band’s lowest data rate, regardless of whether or not the data rate has been enabled for use. The lowest data rate to send NDP messages allows it to be intelligent in noisy environments and further away from the AP. These advertisements are sent to multicast addresses recognized by other Cisco APs. The highest power is allowed to transmit the message in the channel and band so that the RMM can determine the signal strength effectively as it leaves the AP’s antennae. When sending AP, advertisements contain the following information; Radio ID, Group ID, and Encryption.

Measuring the RSSI of NDP messages from an AP; Internet source

https://www.cisco.com/c/en/us/td/docs/wireless/controller/technotes/8-3/b_RRM_White_Paper/rf-grouping.html

Every Radio or AP Channel sends the Neighbour Discovery Portal every 60 seconds or less. Neighbor messages are sent to a unique Multicast address of 01:0B:85:00:00:00. These messages are sent under two conditions; at the lowest data rate supported in the band and at the highest power allowed for the Channel/Band. Upon hearing an NDP message, the AP Validates that the message is from a member of its RF Group and forwards valid messages along with the RSSI and the received channel to the controller. Two distinct measurements are developed after the information has been transmitted successfully; the TX Neighbors and the RX Neighbors.