A network manager, configuring for detecting network nodes and configuring network switches, determines addressing field lengths to be used for addressing the network nodes and switching data packets between the network nodes based on the number of detected network nodes. The porous film has appropriate porosity, air permeability and puncture strength, and is especially excellent in latent heat resistance or heat resistance. The REGs are allocated based on a time first manner. The filter is held in place on the user’s head by a pair of adjustable elastic straps. By injecting glue between the first and the second fluid passages, the first, second and third substrates are bonded.