WARNING: This page is about a different car, the 2013 Infiniti M56 and 2013 Infiniti M37. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: CAN Gateway CAN Communication Diagram
Courtesy of NISSAN NORTH AMERICA, INC.
The CAN gateway system communicates between two CAN communication circuits.
This system selects and transmits only necessary information.