Patent ID: 7307947

Claim:
A layer 2 function block for being installed in each node of a ring network having a plurality of nodes connected by a working channel and a protection channel, wherein: the layer 2 function block carries out the transmission of working traffic using both the working channel and the protection channel when no failure exists in the network, and the layer 2 function block carries out, the transmission of the working traffic using a path avoiding a point of failure that is established by means of layer 1 protection process when the failure occurred in the network, and said layer 2 function block includes: failure information means for receiving failure information indicating the state of failure occurring in the network and failure recovery information indicating the recovery of the network from the failure from the layer 1 and issuing port selection instructions based on the failure information and the failure recovery information; and layer 2 connection control means for controlling the connections between the layer 1 and upper layers by controlling its ports based on the port selection instruction supplied from the failure information means.