Patent ID: 9716650
Date: 2017-07-25
CPC Classifications: H04L

Claim:
1. A communication system comprising: a work path and a protection path that are set between a first transfer apparatus including a first processor, and a second transfer apparatus including a second processor, one of the work path and the protection path being selected by the first transfer apparatus and the second transfer apparatus according to a control signal that includes first information indicating whether there is a failure in one of the work path and the protection path; and one or more third transfer apparatuses through which a third path passes, each of the one or more third transfer apparatuses including a third processor, wherein when a failure occurs in both the work path and the protection path, the first processor of the first transfer apparatus or the second processor of the second transfer apparatus transmits the control signal in which the first information has been changed to second information to the protection path and the one or more third transfer apparatuses, the second information including a specific signal indicating that a failure had occurred in both the work path and the protection path, the third processors of the one or more third transfer apparatuses, upon reception of the control signal that includes the second information, activate the third path, either the first processor of the first transfer apparatus or the second processor of the second transfer apparatus that has not transmitted the control signal, upon reception of the control signal that includes the second information, selects the third path, when at least one of the work path and the protection path is recovered from the failure, the first processor of the first transfer apparatus or the second processor of the second transfer apparatus transmits a second control signal in which the second information has been changed to the first information to the protection path and the one or more third transfer apparatuses, upon reception of the second control signal that includes the first information, the third processors of the one or more third transfer apparatuses disable the third path, and when either the first processor of the first transfer apparatus or the second processor of the second transfer apparatus that has not transmitted the second control signal receives the second control signal through the protection path or the third path, either the first processor of the first transfer apparatus or the second processor of the second transfer apparatus that receives the second control signal selects one of the work path and the protection path.