This read-only object identifies, by controller index, which VSI controller instantiated a given cross-connect, pointing to the entry in vsiControllerTable for the protocol partner controlling the logical interfaces that support that cross-connect. An administrator uses this to trace a specific cross-connect back to the controller responsible for creating it, which is useful when a controller is being decommissioned or its cross-connects need to be inventoried. For example, before removing a controller, the admin would query for all cross-connects whose vsiXCControllerIndex matches that controller to understand the impact.