Gateway Module
WARNING: This page is about a different car, the 2017 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.
The IPC and BCM are gateway modules. The BCM translates messages on the HS-CAN to the MS-CAN and vice versa. The IPC translates messages on the MS-CAN to the I-CAN and vice versa. This allows a message to be distributed throughout all 3 networks.
The IPC and the BCM are the only modules on this vehicle that have this ability.