1. A method comprising: at a Fibre Channel switch, storing data that assigns a relative domain field value to a run-time domain in one of a plurality of virtual storage area networks; determining the relative domain field value to use for a Fibre Channel identifier for each of a plurality of devices connected to the Fibre Channel switch based on the run-time domain of the respective device and the virtual storage area network in which the respective device is active; and storing in a memory of the Fibre Channel switch a Fibre Channel identifier for each of the plurality of devices, the Fibre Channel identifier comprising the relative domain field value determined for the device together with area and port values for the device.