Abstract: This invention concerns a network comprising a master and slaves. In the network, each slave figures out its performance values as performance parameters and transmits the performance parameters to the master. The master performs a process of selecting a backup master as a candidate for the next master, on the basis of the performance parameters transmitted from the slaves. The master supplies BM information containing synchronization information and the address of the backup master selected, to the slaves. When the master is removed from the network, the slaves determine the next master in accordance with the backup-master information. Thus, the slaves can be immediately connected to the next master.