Provided is a switching regulator having an improved power supply voltage variation response characteristic while maintaining the stability of an output voltage to oscillation. This process enables the sphericity of the rubber core to be enhanced, the rubber materials to be used without waste, and balls of an excellent scuff resistance to be obtained. The method may also involve employing a compound which is capable of establishing a corrosion resistant oxide layer on the metal reinforcing elements. The API is multicast-routing-protocol-independent and can be used to express the forwarding state of any existing multicast protocol.