To obtain a layer 2 network having higher failure resistance which can sufficiently deal with multiple failures even if the failures are generated.

In the layer 2 network configuring a multi-ring type network in which a plurality of rings formed using a plurality of nodes are connected and preventing a network loop by port closure control, the plurality of nodes are each provided with a link state monitoring section for monitoring the state of a link between nodes, a failure state determining section 6 for determining the state of generated failures on the basis of the number of normal links between nodes obtained as a result of monitoring, and a port close control section 3 for executing closure control for ports to which a link between nodes is connected on the basis of a result of determination by the failure state determining section. When the failure state determining section 6 determines that a failure occurs, the port close control section 3 releases the closure of a closed port in order to ensure a detour path.

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