Non-Patent Literatures 1 and 2 describes OpenFlow that achieves a centralized control network. OpenFlow treats communication as an end-to-end flow and performs path control, failure recovery, load balancing, and optimization for each flow. An OpenFlow switch (OFS), specified in Non-Patent Literature 2, comprises a secure channel for communicating with an OpenFlow controller (OFC), and operates according to a flow table, an addition to or rewriting of which is suitably instructed by the OFC. In the flow table, a set of matching rules (Match Fields) to be matched against a packet header, flow statistics (Counters), and instructions defining the processing content is defined for each flow (refer to “5.2 Flow Table” in Non-Patent Literature 2).
For instance, upon receiving a packet, the OFS searches for an entry having a matching rule (refer to “5.3 Matching” in Non-Patent Literature 2) that matches the header information of the received packet in the flow table. When an entry matching the received packet is found as a result of the search, the OFS updates the flow statistics (Counters) and performs the processing content (packet transmission from a designated port, flooding, discard, etc.) written in the instruction field of the entry on the received packet. On the other hand, when no entry matching the received packet is found as a result of the search, the OFS transmits a request (packet-in message) to the OFC via a secure channel to set an entry, requesting control information for processing the received packet. The OFS receives a flow entry defining the processing content and updates the flow table. As described, the OFS forwards a packet using an entry stored in the flow table as control information.
Further, as a related technology, Patent Literature 1 describes a data transfer method in a multi-domain network in which a plurality of domains are connected.    Patent Literature 1:    Japanese Patent Kokai Publication No. JP-P2010-199785A    Non-Patent Literature 1:    Nick McKeown, et al. “OpenFlow: Enabling Innovation in Campus Networks,” [online], [Searched on Feb. 14, 2014], the Internet <URL: http://www.openflow.org/documents/openflow-wp-latest.pdf>.    Non-Patent Literature 2:    “OpenFlow Switch Specification, Version 1.3.1 (Wire Protocol 0x04),” [online], [Searched on Feb. 14, 2014], the Internet <URL:https://www.opennetworking.org/images/stories/downloads/specification/openflow-spec-v1.3.1.pdf>.
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