A communication method for a network where a plurality of communication devices (1, 2a - 7a) are interconnected in which two paths (WE, EW) having opposite directions are set between two adjacent communication devices and a plurality of channels (#1 - #48) are set in each of the two paths (WE, EW), said communication method comprising the steps of: providing working channels (#1 - #24) for all paths, and backup channels (#25 - #48) for the working channels for performing 1:1-protection communications, said working channels being set in one of the two paths, and said backup channels for said working channels being set in the other path, respectively, performing the 1:1-protection communications such that one of the communication devices switches channel for protection from said working channel to said backup channel when a failure is detected in said working channel; setting channel to be used for information traffic of a type where importance determined by the type of information to be transmitted is relatively high, to at least one of said working channels for said 1:1-protection communications when there is no failure, and to corresponding backup channel for the 1:1-protection communications when a failure is detected in said at least one of said working channels; setting channel to be used for data packet traffic of a type where said importance is relatively low, to at least one of channels other than said at least one of working channels set for said information traffic of a type where importance is relatively high, in said two paths, when there is no failure; characterized in that when a failure is detected in said at least one of working channels set for said information traffic of a type where said importance is relatively high, and when said backup channel set for said information traffic of a type where said importance is relatively high is same as said at least one of channels for said data packet traffic of a type where said importance is relatively low, rerouting said data packet traffic of a type where said importance is relatively low, based on each header of said data packet traffic of a type where said importance is relatively low, to at least one of said working channels. providing working channels (#1 - #24) for all paths, and backup channels (#25 - #48) for the working channels for performing 1:1-protection communications, said working channels being set in one of the two paths, and said backup channels for said working channels being set in the other path, respectively, performing the 1:1-protection communications such that one of the communication devices switches channel for protection from said working channel to said backup channel when a failure is detected in said working channel; setting channel to be used for information traffic of a type where importance determined by the type of information to be transmitted is relatively high, to at least one of said working channels for said 1:1-protection communications when there is no failure, and to corresponding backup channel for the 1:1-protection communications when a failure is detected in said at least one of said working channels; setting channel to be used for data packet traffic of a type where said importance is relatively low, to at least one of channels other than said at least one of working channels set for said information traffic of a type where importance is relatively high, in said two paths, when there is no failure; characterized in that when a failure is detected in said at least one of working channels set for said information traffic of a type where said importance is relatively high, and when said backup channel set for said information traffic of a type where said importance is relatively high is same as said at least one of channels for said data packet traffic of a type where said importance is relatively low, rerouting said data packet traffic of a type where said importance is relatively low, based on each header of said data packet traffic of a type where said importance is relatively low, to at least one of said working channels.