1. A communication apparatus forming a communication network applying a Layer 2 redundancy protocol, the communication apparatus comprising: a detection unit configured to detect a change in a port state of a physical path within the redundancy protocol; a first calculation unit configured to calculate a predicted amount of traffic to be allocated to the physical path for each of classes prioritized with predefined priorities within the traffic when the change in the port state is detected; a second calculation unit configured to calculate a bandwidth allocation ratio to a physical bandwidth of the physical path, for each of the classes to be allocated for the physical path according to the calculated predicted amount of traffic for each of the classes; a setting unit configured to set the bandwidth allocation ratio for each of the classes calculated by the second calculation unit; and a control unit configured to control a flow rate of the traffic for each of the classes to be flowed in the physical path according to the set bandwidth allocation ratio for each of the classes.