A communication carrier network is composed of a plurality of layers (network layers). For example, a network combining a packet layer enabling efficient use of a network resource by a statistical multiplexing effect, and an optical layer suitable for long-distance and high-capacity transmission, has been constructed. Known packet layer technologies include, for example, Multi-Protocol Label Switching (MPLS) and Multi-Protocol Label Switching-Transport Profile (MPLS-TP). Further, an optical layer is generally a circuit switched network, and an Optical Transport Network (OTN) is known as a typical technology. The OTN is further internally divided into layers such as time division multiplexing (TDM) and wavelength division multiplexing (WDM) layers, based on a difference in a path switching method. In general, independent control for each layer is performed on the networks.
Meanwhile, a technology of integrating control of a multilayer network is receiving attention. The reason is that an operational cost can be reduced by automated setting of a multilayer network, and also an equipment cost can be reduced by efficient utilization of a resource, based on information about a plurality of layers. As an example, PTL 1 discloses a multilayer path control technology by centralized topology design in a two-layered network based on a packet and WDM.
Further, PTL 2 describes a method of abstracting information about a path settable in a lower layer in a form of a node or a link, and advertising the information by a routing protocol in an upper layer, in order to enable optimum path setting.
Furthermore, in a technology described in PTL 3, a measurement result of an amount of traffic flowing over an upper path (a logical path in a packet network) is acquired in a multilayer network composed of the packet network and a circuit switched network. Then, routes in the circuit switched network and the packet network are calculated, and, when congestion occurs by traffic concentration in a part of lower layer links, a route avoiding the lower layer link is calculated. PTL 4 describes a technology for establishing a connection between a source node and a destination node in a short period of time, and PTL 5 describes a technology for generating a new route to a destination node.