Abstract: Each of nodes along multiple routes in a communication network is provided with route information including information on the multiple routes each communicably coupling a transmission source and a transmission destination. A first route has power consumption least among the multiple routes, where the power consumption of a route is a total sum of power consumption of nodes along the route. Upon receiving realtime data, the each node transmits the realtime data using the first route when the first route has available bandwidth capacity enough for transmitting the realtime data, and sets a second route bypassing the first route when the first route does not have available bandwidth capacity enough for transmitting the realtime data. Upon receiving non-realtime data, the each node performs a predetermined processing without setting the second route, when the first route does not have available bandwidth capacity enough for transmitting the non-realtime data.