Any way to adjust MESH roaming time?

[Andrew_Webster]

Hi,
Setup is RFS4000 + 4x AP6522 + 2x AP6522 setup as client bridges on vehicles.
I am noticing that roaming is taking about 4 seconds to complete when the vehicles move from one AP to the next (speed is slow, approx. 5 Km/h). The roaming duration is causing the client application to fail because the data stream is cut-off for 4 seconds while the roam is taking place. The applications is PLC traffic.
The wireless radios are using 5GHz non-DFS channels.
Signal levels are good, typically around -62 to -57dBm at the vehicle.

Is there any way to make the roaming process go quicker ?

I'm seeing this in the logs during roaming, it seems process is taking 3 seconds from start to finish according to the logs, but I'm seeing about 4 seconds of data loss in total.

Is the radio actually turning off and back on again during the roam?
2017-10-06 12:05:07 TV01 MESH MESHPOINT_ROOT_CHANGE Meshpoint 'BRIDGE' root changed from B4-C7-99-E7-B6-C2 to B4-C7-99-E9-17-42 via next hop B4-C7-99-E9-17-42
2017-10-06 12:05:04 TV01 DIAG NEW_LED_STATE LED state message RADIO_2_52G_LED_ON from module DOT11
2017-10-06 12:05:04 TV01 RADIO RADIO_STATE_CHANGE Radio 'TV01:R2' changing state from 'Initializing' to 'On'
2017-10-06 12:05:04 TV01 DIAG NEW_LED_STATE LED state message RADIO_2_52G_LED_ON from module DOT11
2017-10-06 12:05:04 TV01 RADIO RADIO_STATE_CHANGE Radio 'TV01:R2' changing state from 'On' to 'Initializing'
Relevant configs:
meshpoint BRIDGE
description Bridge mesh for vehicles
meshid BRIDGE
beacon-format mesh-point
control-vlan 61
allowed-vlans 1,60-61
security-mode psk
wpa2 psk 0 xxxxxxxxxxxxxxxxxxxxxxxxx
no root...
profile ap6522 AP-Bridge
...
interface radio2
meshpoint BRIDGE bss 3
...
meshpoint-device BRIDGE
root
monitor critical-resource action no-root
monitor primary-port-link action no-root
exclude wired-peer mint-level-1
acs channel-width 5GHz 20MHz
... profile ap6522 AP-TV
...
interface radio2
meshpoint BRIDGE bss 3
...
meshpoint-device BRIDGE
no root
path-method mobile-snr-leaf
acs channel-width 5GHz 20MHz
service meshpoint loop-prevention-port ge1 The only device overrides on the APs are "no ip igmp snooping".

Thanks!

[Alona]

Correction - since you are using AP 6522 - VMM on AP 6522 is not supported. SO what you have conifgured won't work at all.
The only think you can use if actual bridge functionality as I described. Meshpoint won't work for you at all as mobile-snr-leaf is not supported on AP 6522.

[Alona]

Did you configure channel-list under rf-domain? This is the channes ACS is going to use. If you know where you root Aps are - those are the channels that needed to be in that list and less channels - the better. Also you are trying to configure VMM here - not bridge. Some settings are missing like "rts-threshold 1" and rate selection needs to be opportunistic.

This AP also supports another feature - bridge without using MCX. Instead of configuring VMM - you configure just rf-mode bridge and define channels for bridge to search on. You won't need roots in this case as well. Roaming will be faster.