Optical transmission apparatus

An optical transmission method for transmitting an optical signal, comprising:

• storing, in a path information table, paths set in a network and wavelength channel information on the paths;
• and
• searching, by a controller, for an apparatus which performs route switching of paths using a plurality of grouped wavelength channels, based on fault information on the network detected by an optical transmission apparatus, fault information on the network detected by another optical transmission apparatus, and the paths and wavelength channel information on the paths stored in the path information table,
• wherein the controller performs the route switching of the paths upon determining that a number of operating paths is maximized by performing the route switching of the paths in the network and faults occur in one or more wavelength channels in a group;
• and wherein the controller stops performing the route switching of the paths upon determining that a number of operating paths is not maximized by performing the route switching of the paths in the network, even though faults occur in one or more wavelength channels in the group.