To enable an effective use of a bandwidth in the network as a whole by sharing the bandwidth between an acture path and a standby path, or between a standby path and another standby path. 現用パスと予備パスとの間、あるいは予備パスと予備パスとの間で帯域を共用し、ネットワーク全体で帯域の有効利用を可能にすること。 - 特許庁