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How to configure RX-SOP on FortiAPs

By: Author Alex Lim

Posted on

Categories Networking

This article describes how to configure RX-SOP on FortiAPs.

Scope

FortiAPs

Solution

RX-SOP is an advanced feature called ‘Radio sensitivity’ on SSID advanced configurations.

RX-SOP determines the threshold where the FortiAP will start to demodulate and decode packets. The FortiAP would start ignoring 802.11 signals that exceed the threshold, without informing the STAs that the AP would not be listening to them, even when the FortiAP is sensed with good signal, modulation.

This is why it is necessary to proceed with caution and should not be enabled as a first solution. Instead, try to decrease the cell size by decreasing the Tx power of the radios individually, enabling ‘probe-resp-suppresion’, and/or enabling sticky-client-remove to avoid providing service to distant or weak clients.

This feature is especially useful in high-density environments where many clients are connected to one FortiAP or ambients where there is a very high rate of multipath signals.

It is possible to enable this configuration through CLI or GUI (must enable advanced wireless features first). To define the threshold, enter the commands manually on FortiGate’s CLI:

Warning

This feature is disabled by default and should not be enabled unless having already contacted a wireless expert or Fortinet Support. By enabling this feature, unwanted connectivity issues might occur. This feature should not be enabled as a first-step solution to decrease the cell size. Instead, try decreasing the TX power of the radios individually, enabling probe-resp-suppression, and/or enabling sticky-client-remove to avoid providing service to distant or weak clients Please proceed with caution.

Default configuration example

FortiGate:

config wireless-controller vap
edit "bridge"
set radio-sensitivity disable
next
end

FortiAP:

FAP-431-LAB # vcfg
-------------------------------VAP Configuration 1----------------------------
Radio Id 1 WLAN Id 0 fortinet-bridge ADMIN_UP(INTF_UP) init_done 0.0.0.0/0.0.0.0 unknown (-1)
...
rx sop=disabled

Enabling RX-SOP

FortiGate:

config wireless-controller vap
edit "bridge"
set radio-sensitivity enable
set radio-5g-threshold "-76" <--- Default value
set radio-2g-threshold "-79" <--- Default value
next
end

FortiAP:

FAP-431-LAB # vcfg
-------------------------------VAP Configuration 1----------------------------
Radio Id 1 WLAN Id 0 fortinet-bridge ADMIN_UP(INTF_UP) init_done 0.0.0.0/0.0.0.0 unknown (-1)
...
rx sop=enabled, rx_5g_threshold=-76dBm, rx_2g_threshold=-79dBm

Configured radio sensitivity example

FortiGate:

config wireless-controller vap
edit "bridge"
set radio-sensitivity enable
set radio-5g-threshold "-73"
set radio-2g-threshold "-73"
next
end

FortiAP:

FAP-431-LAB # vcfg
-------------------------------VAP Configuration 1----------------------------
Radio Id 1 WLAN Id 0 fortinet-bridge ADMIN_UP(INTF_UP) init_done 0.0.0.0/0.0.0.0 unknown (-1)
...
rx sop=enabled, rx_5g_threshold=-73dBm, rx_2g_threshold=-73dBm