Technical Tip: How Mesh leaf FortiAP calculates the best Mesh root FortiAP

[mp2]

Description	This article describes how the Mesh leaf FortiAP calculates the best Mesh root FortiAP.
Scope	FortiAP-S and FortiAP-W2. Related Software Versions – FortiAP version 6.4 and later.
Solution	In a scenario where there are multiple Mesh root and a Mesh leaf FortiAP configured. The Mesh Leaf FortiAP calculates the best Mesh root FortiAP as below. Leaf AP will always choose the lowest s_tot’s bssid as the associate target: s_tot = s_hop + s_chan + s_rate + s_rssi +s_band             s_hop    = value_a X MESH_SCORE_HOP_WEIGHT             s_chan   = value_b X MESH_SCORE_CHAN_WEIGHT             s_rate   = value_c X MESH_SCORE_RATE_WEIGHT             s_rssi   = value_d X MESH_SCORE_RSSI_WEIGHT             s_band   = value_e X MESH_SCORE_BAND_WEIGHT The explanation for the above parameters is given below. Default Mesh SCORE _ Weight config: MESH_MAX_HOPS:          =4 MESH_SCORE_HOP_WEIGHT:  =50 MESH_SCORE_CHAN_WEIGHT: =1 MESH_SCORE_RATE_WEIGHT: =1 MESH_SCORE_BAND_WEIGHT: =100 MESH_SCORE_RSSI_WEIGHT: =100 s_hop calculation: s_hop   = value_a X MESH_SCORE_HOP_WEIGHT                  value_a = This bssid broadcast ap’s mesh hop count, if the parent ap direct connect to FGT value_a should be equal to zero s_chan calculation: s_chan  = value_b X MESH_SCORE_CHAN_WEIGHT               value_b = Command 'cw_diag –c mesh-ap' will print out a channel status table which will calculate and show each channel’s rssi_total.  value_b equal to the bssid’s channel rssi_total. s_rate calculation: s_rate = value_c X MESH_SCORE_RATE_WEIGHT               value_c = this bssid beacon frame’s data rate, after test following number show,                                            802.11n = -28                                            802.11bg = -10                                            802.11b = -2                                            802.11a = -10 s_rssi calculation:                 s_rssi = value_d X MESH_SCORE_RSSI_WEIGHT                value_d = this bssid’s rssi print out from command 'cw_diag –c mesh-ap'.                                            if rssi > 25, value_d = -1                                            if rssi <=25, value_d = 0 s_band calculation:               s_band = value_e X MESH_SCORE_BAND_WEIGHT               value_e = this bssid broadcast at 2.4 GHz or 5 GHz band                                            2.4GHz = 0                                            5   GHz = 1 This information can be found in the below output from the FortiAP CLI. Links: FortiAP CLI config and commands:  http://docs.fortinet.com/document/fortiap/6.2.0/fortiwifi-and-fortiap-configuration-guide/65088/fort... FortiAP mesh config: https://docs.fortinet.com/document/fortiap/7.2.0/fortiwifi-and-fortiap-configuration-guide/196651/wi...