Product and Software: This article applies to all Aruba controllers and ArubaOS versions.
If the Prohibit IP Spoofing option is enabled, the controller denies all traffic from the client using an IP address that is used by another client that has an entry in the user table. Basically this option does not allow multiple MAC addresses to use the same IP address.
To check whether Prohibit IP Spoofing is enabled:
Configuration Tab > Advanced Services > Stateful Firewall > Global Settings.