Technical Note: FortiDDoS 'Invalid combination of global asymmetric mode' warning message

[cbenejean]

Description

This article addresses the following FortiDDoS message:

"Warning: Invalid combination of global asymmetric mode, SPP inbound operating mode and SPP TCP session feature control. Please check SPP : <SPP_NAME>"

This message may be seen when changes are made to the SPP settings.

Scope

FortiDDoS v4.1.6

Solution

This message means that the configuration is not optimized for your selection of SPP Detection Mode and/or Global Asymmetric Mode.

Whenever you change to Detection Mode or Asymmetric Mode, review the TCP Session Feature Control settings on the Protection Profiles > SPP Settings page to ensure the settings are compatible with the new mode.  In these modes, some anomalies cannot be tracked.

If you set a TCP session feature control parameter that is “Off” in the table in the current setting of the SPP; this message will be displayed. This is just to warn you that the parameter that is set to “Off” will not be taken into account in this mode because of the nature of the running mode.

You can accept the change anyway; this is only a notice message so you know what will be the consequence of such configuration.