Patent ID: 6839480

Claim:
An optical transmission system comprising: an optical transmission apparatus having first and second optical switches; an optical receiving apparatus having third and fourth optical switches; and first and second transmission routes through which said first and second optical switches provided to said optical transmission apparatus are respectively connected to said third and fourth optical switches provided to said optical receiving apparatus, wherein said optical transmission apparatus has a branching portion for branching an input signal and outputting to any one of said first and second optical switches, and plural optical performance monitoring portions disposed of front and rear of said first and second optical switches to monitor optical signals, said optical receiving apparatus has a selecting portion for selecting and outputting any one of signals output from said third and fourth optical switches, and plural optical performance monitoring portions disposed of front and rear of said third and fourth optical switches to monitor optical signals, the switching of said branching portion and said selecting portion is carried out on the basis of monitoring results of said performance monitoring portions provided to said optical transmission apparatus or said optical receiving apparatus, thereby performing a switching operation of a redundant system of said optical transmission system, said optical transmission apparatus and said optical receiving apparatus transmits/receives control information so that alarms detected due to the route switching operation of an optical switch provided to each of said transmission apparatus and said receiving apparatus and the redundant system switching operation of said optical transmission system are at least concealed in both of said transmission apparatus and said receiving apparatus.