MCLAG requirements

• There is a maximum of two FortiSwitch units per MCLAG. Both peer switches should be of the same hardware model and same software version. Mismatched configurations might work but are unsupported.
• The routing feature is not available within an MCLAG.
• When min_bundle or max_bundle is combined with MCLAG, the bundle limit properties are applied only to the local aggregate interface.
• On the global switch level, mclag-stp-aware must be enabled, and STP must be enabled on all ICL trunks. They are both enabled by default.

NOTE: If you are going to use IGMP snooping with an MCLAG topology:

• On the global switch level, mclag-igmpsnooping-aware must be enabled. By default, mclag-igmpsnooping-aware is enabled in the FortiSwitchOS CLI.
• The mcast-snooping-flood-traffic and igmp-snooping-flood-reports settings must be disabled on the ISL and FortiLink trunks; but the mcast-snooping-flood-traffic and igmp-snooping-flood-reports settings must be enabled on ICL trunks. These settings are enabled by default.
• IGMP proxy must be enabled.