Patent ID: 8483052

Claim:
A communication network system comprising a plurality of communication devices, transmission links, and a route design device, each of the plurality of communication devices comprising a switching unit which switches traffic routes, the transmission links connecting the plurality of communication devices, and the route design device calculating routes of a plurality of detour paths such that the plurality of detour paths do not contend with each other when a failure occurs in calculation of the plurality of detour paths corresponding to different currently-used paths, wherein a start-point communication device of the plurality of communication devices comprising: a storage unit which previously stores information of a plurality of detour paths corresponding to but having routes different from a working path that is transferring traffic between the start-point communication device and an endpoint communication device; and a setting unit which receives a failure notification when a failure occurs in the working path, selects a detour path having the highest priority from among the plurality of detour paths stored in storage unit, the plurality of detour paths being switchable and for which a failure does not occur on adjusted links, and then reserves band for relevant communication devices among the plurality of communication devices along the selected route of the detour path, and performs cross-connection to recover from the failure, wherein the route design device comprises a detour path adjusting unit which assigns one of the plurality of detour paths a right to priority use for preferentially using the transmission links when a contention due to insufficient bands occurs in the transmission links between the plurality of detour paths corresponding to the different currently-used paths, and transmits, to the start-point communication device, information as an adjusted link, the information indicating each of the transmission links of the currently-used paths corresponding to a detour path acquiring the right to priority use, the information being associated with a detour path not acquiring the right to priority use, and the start-point communication device storing the information of the plurality of detour paths not acquiring the right to priority use.