Dell PowerEdge FN I/O Module Configuration Guide 9.10(0.0)

As soon as you enable the FCoE transit feature on a switch-bridge, existing VLAN-specific and FIP snooping configurations are applied. The FCoE database is populated when the switch connects to a converged network adapter (CNA) or FCF port and compatible DCB configurations are synchronized. By default, all FCoE and FIP frames are dropped unless specifically permitted by existing FIP snooping-generated ACLs. You can reconfigure any of the FIP snooping settings.

If you disable FCoE transit, FIP and FCoE traffic are handled as normal Ethernet frames and no FIP snooping ACLs are generated. The VLAN-specific and FIP snooping configuration is disabled and stored until you re-enable FCoE transit and the configurations are re-applied.