The physical port to which this interface is bound. If vRtrIfPortID is zero (0), then there is no binding between this virtual router interface and a physical port. Once an interface has been bound to a port, several steps are required to change the binding to some other TmnxPortID value. vRtrIfAdminState must be 'outOfService'; vRtrIfPortID must be set to zero (0) to disassociate the interface from the original port binding; finally, set vRtrIfPortID to the value for the new port binding. Setting vRtrIfPortID to 0x20000001 indicates that this interface is the system interface for the device.