Patent ID: 7724653

Claim:
A transmission system comprising: a first transmission device; a second transmission device; a first layer 2 switch; and a second layer 2 switch, wherein the first transmission device includes: a first interface unit that is connected to the first layer 2 switch through a first transmission path functioning as an active path, a second interface unit that is connected to the first layer 2 switch through a second transmission path functioning as a stand-by path, and a first control unit that switches, when failure occurs in the first transmission path, the first transmission path from the active path to the stand-by path and the second transmission path from the stand-by path to the active path, and the second transmission device includes: a third interface unit that is connected to the second layer 2 switch through a third transmission path functioning as the active path, a fourth interface unit that is connected to the second layer 2 switch through a fourth transmission path functioning as the stand-by path, and a second control unit that maintains, even when the failure occurs in the first transmission path, the third transmission path as the active path and the fourth transmission path as the stand-by path.