Information system, control server, virtual network management method, and program

FIELD OF THE INVENTION

Reference to Related Application

0001The present invention is based upon and claims the benefit of the priority of Japanese patent application No. 2009-233895 filed on Oct. 7, 2009, the disclosure of which is incorporated herein in its entirety by reference thereto.

0002The present invention relates to an information system, control server, virtual network management method, and program, and particularly to an information system, control server, virtual network management method, and program providing a virtual network.

Background of the Invention

0003Patent Document 1 discloses a virtual network constructing device that realizes end-to-end security for each service, security between services at a client, and scalability for a large-scale system. According to this document, when a client selects an available service in launcher software transmitted from a path control server after the client's authentication request has been accepted, a corresponding path constructing request is transmitted to the path control server. The path control server issues the client an instruction for connecting to a base router, and also issues the base router an instruction for connecting to the client. The document recites that an in-base VLAN can be dynamically constructed between the client and the base router as a result.

0004Patent Document 2 discloses a system for managing customers in a hierarchical manner. Further, Patent Document 3 discloses a peer-to-peer network capable of providing a new network topology.

0005Non-Patent Document 1 proposes a technology called OpenFlow. 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 that functions as a forwarding node operates according to a flow table appended or updated by an OpenFlow controller according to OpenFlow protocol. In the flow table, pairs of a packet matching rule that specify a packet and an action such as outputting the packet to a specific port, discarding it or rewriting a header are registered as flow entries. When there is a corresponding entry, the OpenFlow switch processes a received packet according to an action written in the entry, and notifies the OpenFlow protocol of the reception of the packet when there is no corresponding entry.

PRIOR ART DOCUMENTS

0006Patent Documents

0007[Patent Document 1] Japanese Patent Kokai Publication No. JP-P2009-135805A

0008[Patent Document 2] Japanese Patent Kohyo Publication No. JP-P2007-525728A

0009[Patent Document 3] Japanese Patent Kokai Publication No. JP-P2008-306725A

0010[Non-Patent Document 1] McKeown, Nick et al., “OpenFlow: Enabling Innovation in Campus Networks,” [online], [searched on Jul. 17, 2009], Internet<URL:

0000http://www.openflowswitch.org//documents/openflow-wp-latest.pdf>

SUMMARY OF THE DISCLOSURE

Problems to be Solved by the Invention

0011The entire disclosures of Patent Documents 1 to 3 and Non-Patent Document 1 are incorporated herein in their entirety by once thereto.

0012The following analysis is given by the present invention.

0013The technologies of Patent Documents 1 to 3 logically divide a network, however, they do not perform detailed path control by determining a policy for each flow. Further, a method such as source routing can be used to perform path control, but the net data amount a packet can contain gets reduced in this case.

0014Regarding this point, Non-Patent Document 1 proposes a configuration in which path control is performed by the OpenFlow switch operating based on the flow table that defines an action for each flow, but the document only discusses network management, access control, and construction of a virtual network by virtualizing the OpenFlow switch as concrete examples of applications of this configuration.

0015The present invention has been made in considering the above circumstances, and it is an object thereof to provide a configuration capable of configuring a virtual network by virtualizing a physical network and achieving finely tuned path control in the virtual network.

Mean to Solve the Problems

0016According to a first aspect of the present invention, there is provided an information system, comprising: a plurality of physical nodes that hold control information defining an operation corresponding to the characteristics of an input/output packet(s) and that perform processing on an input/output packet(s) according to the control information; a first storage unit that stores configuration information of a virtual network including a virtual node configured using at least one of the physical nodes; a second storage unit that stores virtual network identifying information identifying the virtual network from characteristics of an input packet; and a control server that identifies a physical node configuring a virtual network that handles a packet having a characteristic common with a packet received by the physical node based on a request the physical node and that updates control information for each of the physical nodes.

0017According to a second aspect of the present invention, there is provided a control server, connected to a plurality of physical nodes that hold control information defining an operation corresponding to characteristics of an input/output packet(s) and that perform processing on an input/output packet(s) according to the control information, comprising: a first storage unit that stores configuration information of a virtual network including a virtual node configured using at least one of the physical nodes; a second storage unit that stores virtual network identifying information identifying the virtual network from characteristics of an input packet; and a control unit that identifies a physical node(s) configuring a virtual network that handles a packet having a characteristic in common with a packet received by the physical node based on a request from the physical node and that updates control information for each of the physical nodes.

0018According to a third aspect of the present invention, there is provided a virtual network management method executed by a control server connected to a plurality of physical nodes that hold control information defining an operation corresponding to characteristics of an input/output packet(s) and that perform processing on an input/output packet(s) according to the control information. The virtual network management method comprises a step of having the control server identify a physical node(s) configuring a virtual network that handles a packet having a characteristic in common with a packet received by the physical node(s) based on a request from the physical node(s) by referring to a first storage unit that stores configuration information of a virtual network including a virtual node configured using at least one of the physical nodes and to a second rage that stores virtual network identifying information identifying the virtual network from the characteristics of an input packet; and a step of updating control information for each of the identified physical nodes. This method is tied to the control server, a specific machine connected to the physical nodes and updating the control information thereof.

0019According to a fourth aspect of the present invention, there is provided a program, executed by a computer configuring a control server connected to a plurality of physical nodes that hold control information defining an operation corresponding to characteristics of an input/output packet(s) and that perform processing on an input/output packet(s) according to the control information, having the computer execute a process of having the control server identify a physical nodets) configuring a virtual network that handles a packet having a characteristic in common with a packet received by the physical node(s) based on a request from the physical node(s) by referring to a first storage unit that stores configuration information of a virtual network including a virtual node(s) configured using at least one of the physical nodes and to a second storage unit that stores virtual network identifying information identifying the virtual network from the characteristics of an input packet; and a process of updating control information for each of the identified physical nodes. Note that this program may be stored in a storage medium readable by a computer. In other words, the present invention can be embodied as a computer program product.

EFFECT OF THE INVENTION

0020According to the present invention, it becomes possible to perform path control according to the characteristics of a packet on a configured virtual network. Further, high-speed processing can be achieved since no inquiry to the control server is necessary after the control information has been updated and each physical node does not have to refer to a routing table.

BRIEF DESCRIPTION OF THE DRAWINGS

0021<figref idref="DRAWINGS">FIG. 1</figref> is a drawing for explaining an outline of the present invention.

0022<figref idref="DRAWINGS">FIG. 2</figref> is a drawing showing the configuration of a first exemplary embodiment of the present invention.

0023<figref idref="DRAWINGS">FIG. 3</figref> is a drawing showing a detailed configuration of a physical node of the first exemplary embodiment of the present invention.

0024<figref idref="DRAWINGS">FIG. 4</figref> is a drawing showing a detailed configuration of a control server of the first exemplary embodiment of the present invention.

0025<figref idref="DRAWINGS">FIG. 5</figref> is a drawing showing the configuration of a virtual network constructed by the control server of the first exemplary embodiment of the present invention.

0026<figref idref="DRAWINGS">FIG. 6</figref> is an example of a virtual node table held by the control server of the first exemplary embodiment of the present invention.

0027<figref idref="DRAWINGS">FIG. 7</figref> is an example of setting information of a virtual node held by the control server of the first exemplary embodiment of the present invention.

0028<figref idref="DRAWINGS">FIG. 8</figref> is an example of virtual network configuration information held by the control server of the first exemplary embodiment of the present invention.

0029<figref idref="DRAWINGS">FIG. 9</figref> is a schematic diagram of a virtual network corresponding to the virtual network configuration information in <figref idref="DRAWINGS">FIG. 8</figref>.

0030<figref idref="DRAWINGS">FIG. 10</figref> is an example of virtual network identifying information held by the control server of the first exemplary embodiment of the present invention.

0031<figref idref="DRAWINGS">FIG. 11</figref> is an example of management switch information held by the control server of the first exemplary embodiment of the present invention.

0032<figref idref="DRAWINGS">FIG. 12</figref> is an example of a flow entry held by the control server of the first exemplary embodiment of the present invention.

0033<figref idref="DRAWINGS">FIG. 13</figref> is a drawing showing a correspondence relation between the configuration in <figref idref="DRAWINGS">FIG. 2</figref> and the virtual network in <figref idref="DRAWINGS">FIG. 5</figref>.

0034<figref idref="DRAWINGS">FIG. 14</figref> is a sequence diagram for explaining the operation of the first exemplary embodiment of the present invention.

0035<figref idref="DRAWINGS">FIG. 15</figref> is a sequence diagram for explaining the operation of the first exemplary embodiment of the present invention.

0036<figref idref="DRAWINGS">FIG. 16</figref> is a sequence diagram for explaining the operation of the first exemplary embodiment of the present invention.

0037<figref idref="DRAWINGS">FIG. 17</figref> is a sequence diagram for explaining the operation of the first exemplary embodiment of the present invention.

MODES FOR CARRYING OUT THE INVENTION

0038First, an outline of the present invention will be given with reference to the drawings. As shown in <figref idref="DRAWINGS">FIG. 1</figref>, the present invention can he realized by a plurality of physical nodes <b>10</b> that hold control information defining actions according to characteristics of input/output packet(s) and that process the input/output packets according to the control information and a control server <b>20</b> that comprises a function of updating the control information of the physical nodes <b>10</b>.

0039The control sever <b>20</b> comprises a first storage unit (virtual network configuration information storage unit) <b>202</b> that stores configuration information of a virtual network comprised of virtual nodes which are virtualized versions of the physical nodes <b>10</b>; a second storage unit (virtual network identifying information storage unit) <b>203</b> that stores virtual network identifying information that identifies the virtual network from the characteristics of the input packet(s); and a control unit <b>210</b> that identifies a physical node(s) configuring a virtual network that handles a packet(s) having a characteristic in common with the packet(s) received by the physical node(s) and that updates control information for each of physical nodes <b>10</b> based on a request from the physical node <b>10</b> concerned.

0040The physical node <b>10</b> can be realized by a switch equivalent to the OpenFlow switch of Non-Patent Document 1 that operates according to the flow table or a router, and notifies the control server <b>20</b> that a packet not in the flow table is received upon reception of the packet (request for creating a flow entry; an arrow from the physical node <b>10</b> to the control unit <b>210</b> in <figref idref="DRAWINGS">FIG. 1</figref>).

0041Upon receiving the request for creating a flow entry, the control server <b>20</b> refers to the second storage unit <b>203</b> and identifies a virtual network to which the packet concerned should belong from the characteristics (port number, physical node ID, and header information) of the input packet. Next, the control server <b>20</b> refers to the first storage unit <b>202</b>, suitably performs forwarding processing on the received packet within the virtual network, identifies a physical node or nodes corresponding to the identified virtual network, and updates the control information of the identified physical node or nodes (arrows from the control unit <b>210</b> to the physical nodes <b>10</b> in <figref idref="DRAWINGS">FIG. 1</figref>). As described, subsequent packets are successively forwarded by the physical nodes according to the control information updated for each virtual network.

0042Further, the control server <b>20</b> can be realized by adding the functions relating to the virtual network described above to the OpenFlow controller of Non-Patent Document 1 as a base. Or it is also possible to realize the control server <b>20</b> by having another server that provides the functions relating to the virtual network described above work together with the OpenFlow controller of Non-Patent Document 1.

First Exemplary Embodiment

0043Next, a first exemplary embodiment of the present invention will be described in detail with reference to the drawings. <figref idref="DRAWINGS">FIG. 2</figref> is a drawing showing the configuration of the first exemplary embodiment of the present invention. With reference to <figref idref="DRAWINGS">FIG. 2</figref>, a plurality of physical nodes <b>10</b>, the control server <b>20</b>, and external nodes <b>30</b> are shown.

0044The physical nodes <b>10</b> are connected each other and it is configured by a switch or router that forwards a packet(s) sent/received to/from the external network <b>30</b>. In the present exemplary embodiment, the physical node <b>10</b> is assumed to be an OpenFlow switch.

0045The control server <b>20</b> is connected to the physical nodes <b>10</b> via secure channels and instructs the physical nodes <b>10</b> to update the control information. In the present exemplary embodiment, the control server <b>20</b> is assumed to be a server that comprises a function as the OpenFlow controller communicating with the physical nodes <b>10</b> using the OpenFlow protocol.

0046The external node(s) <b>30</b> is configured by a server(s) that provides various services to a user terminal accessing from the external network. In the present exemplary embodiment, the external node <b>30</b> is assumed to be an Http (Hyper-Text Transfer Protocol) server.

0047<figref idref="DRAWINGS">FIG. 3</figref> is a drawing showing a detailed configuration of the physical node of the first exemplary embodiment of the present invention. With reference to <figref idref="DRAWINGS">FIG. 3</figref>, the physical node comprises a server communication unit <b>11</b> that communicates with the control server <b>20</b>, a flow table <b>12</b>, and a control unit <b>13</b>. According to an instruction from the control server <b>20</b>, the control unit <b>13</b> adds a new entry to the flow table <b>12</b>, searches for an entry having a matching key that matches a received packet in the flow table <b>12</b>, and executes a corresponding action.

0048<figref idref="DRAWINGS">FIG. 4</figref> is a drawing showing a detailed configuration of the control server of the first exemplary embodiment of the present invention. With reference to <figref idref="DRAWINGS">FIG. 4</figref>, the control server <b>20</b> comprises a virtual node emulation unit <b>211</b>, a virtual network control unit <b>212</b>, a path control unit <b>213</b>, an OpenFlow protocol processing unit <b>214</b>, and a storage device that functions as a storage unit storing information discussed later.

0049In the example in <figref idref="DRAWINGS">FIG. 4</figref>, the control server <b>40</b> comprises a virtual node object storage unit <b>201</b>, the virtual network configuration information storage unit <b>202</b>, the virtual network identifying information storage unit <b>203</b>, a physical topology information storage unit <b>204</b>, a shortest path information storage unit <b>205</b>, a set flow forwarding path information storage unit <b>206</b>, a flow entry storage unit <b>207</b>, and a management switch information storage unit <b>208</b> configured by the aforementioned storage device.

0050In the explanation below, it is assumed that the control server <b>20</b> constructs a virtual network configured by a layer <b>3</b> switch (L<b>3</b>SW), a firewall (FW), a load balancer (LB), and a layer <b>2</b> switch (L<b>2</b>SW) shown in <figref idref="DRAWINGS">FIG. 5</figref>.

0051The virtual node emulation unit <b>211</b> performs processing as a virtual node using virtual objects having a class corresponding to the aforementioned L<b>3</b>SW, FW, LB, and L<b>2</b>SW stored in the virtual node object storage unit <b>201</b>. For instance, each virtual object is identified by a virtual node table shown in <figref idref="DRAWINGS">FIG. 6</figref> in which a virtual node ID on the virtual network is associated with an object ID.

0052<figref idref="DRAWINGS">FIG. 7</figref> shows an example of setting information of a virtual router object stored in the virtual node object storage unit <b>201</b>. The basic operation is the same as a normal physical router device. A destination is determined by referring to a routing table, and a MAC address is resolved by an ARP (Address Resolution Protocol) table and converted into a MAC address of a router of the source MAC address. What is different from a router device on a real network is that a virtual interface ID is stored in the routing table and the virtual interface ID is resolved as the destination. Therefore, upon receiving a packet specifying the virtual router as a virtual node ID from the virtual network control unit <b>212</b>, the virtual node emulation unit <b>211</b> performs processing as a router on the virtual network and outputs a converted packet of a virtual interface ID and destination MAC address.

0053The setting of the virtual node shown in <figref idref="DRAWINGS">FIG. 7</figref> can be changed by a user authorized to use the virtual network. Meanwhile, an association between the physical node and the virtual network discussed later is hidden from the user, and he can utilize the virtual node on the virtual network in the same way as a physical node.

0054The virtual network control unit <b>212</b> performs input/output of packet information from/to the virtual node emulation unit <b>211</b> according to an association between the configuration information of the virtual network stored in the virtual network configuration information storage unit <b>202</b> and the virtual network identifying information storage unit <b>203</b> and the real network thereof. Further, the virtual network control unit <b>212</b> temporarily stores the received packet in a packet cache <b>215</b> and creates conversion contents of a packet header to be instructed to a physical node to which the packet is ultimately outputted.

0055<figref idref="DRAWINGS">FIG. 8</figref> shows an example of the virtual network configuration information stored in the virtual network configuration information storage unit <b>202</b>. It is indicated that a virtual interface of a virtual node indicated in a KEY field is connected by a virtual interface of a virtual node in a Value field. In the example of <figref idref="DRAWINGS">FIG. 8</figref>, the virtual node of ID #<b>1</b> is connected to the virtual node of ID #<b>2</b> by a virtual interface of virtual interface ID #<b>10</b>, and the virtual node of ID #<b>2</b> is connected to an external node by a virtual interface of virtual interface ID #<b>30</b>. <figref idref="DRAWINGS">FIG. 9</figref> is a schematic diagram of a virtual network corresponding to the virtual network configuration information in <figref idref="DRAWINGS">FIG. 8</figref>. Based on the virtual network configuration information, the virtual network control unit <b>212</b> is able to specify a virtual node ID to the virtual node emulation unit <b>211</b>, receive a packet, and obtain the results thereof.

0056<figref idref="DRAWINGS">FIG. 10</figref> shows an example of the virtual network identifying information indicating an association between the virtual network and characteristics of a packet stored in the virtual network identifying information storage unit <b>203</b>. In the example of <figref idref="DRAWINGS">FIG. 10</figref>, there is an configuration in which for packet matching conditions indicated in a KEY field, a virtual network to which it should belong, the virtual node ID, and the virtual interface can be uniquely determined. Further, by performing a reverse lookup on the table shown in <figref idref="DRAWINGS">FIG. 10</figref>, a physical switch ID, physical port ID, vlan-tag on a real network to which a packet having a certain virtual network, virtual node ID, and virtual interface can be determined. The conversion operation between the virtual network and the real network described above is called “physical-virtual conversion” hereinafter in the present description. Further, physical node ID, physical port ID, and header information (source MAC address (mac(src)), destination MAC address (mac(dst)), VLAN number (vlan-tag), source IP address (ip(src)), destination IP address (ip(dst)), source layer <b>4</b> port number (<b>14</b>port(src)), and destination layer <b>4</b> port number (<b>14</b>port(dst)) are shown in the example of <figref idref="DRAWINGS">FIG. 10</figref>, but it is not necessary to use all these pieces of information and it may be configured so that other pieces of header information or packet information can be specified as necessary.

0057By providing as many the tables shown in <figref idref="DRAWINGS">FIG. 8</figref> as the number of virtual networks, a plurality of virtual networks can be constructed. Then, by defining packet characteristics for each user and a virtual network that the user is authorized to use using a table as the one shown in <figref idref="DRAWINGS">FIG. 9</figref> [sic. <figref idref="DRAWINGS">FIG. 10</figref>], a virtual network can be provided to a plurality of users in a form that the network is logically divided.

0058The virtual network control unit <b>212</b> supplies an input packet(s) to the virtual node emulation unit <b>211</b>, obtains the processing result thereof, and then supplies a physical node that has received this packet and the port number thereof, and a physical node after physical-virtual conversion performed on the packet on which network processing has been performed by the virtual node emulation unit <b>211</b>, and the output port number thereof, to the path control unit <b>213</b>.

0059The path control unit <b>213</b> calculates a forwarding path for outputting the packet supplied to the physical node based on physical network topology information stored in the physical topology information storage unit <b>204</b> from the physical node after the physical-virtual conversion. For this path calculation, for instance, Dijkstra's shortest path algorithm can be used.

0060Further, the path control unit <b>213</b> stores the result of the path calculation in the shortest path information storage unit <b>205</b> as a cache for a predetermined period of time. When performing subsequent path calculations, the path control unit <b>213</b> refers to the shortest path stored in the shortest path information storage unit <b>205</b> and is able to omit the path calculation processing if the cache remains.

0061Further, the path control unit <b>213</b> stores a pair of the flow and the shortest path information in the set flow forwarding path information storage unit <b>206</b> as well. When performing subsequent path calculations, the path control unit <b>213</b> is able to use the path information stored in the set flow forwarding path information storage unit <b>206</b>.

0062The shortest path information storage unit <b>205</b> and the set flow forwarding path information storage unit <b>206</b> can be omitted. Further, how much is stored in each path information can be suitably changed according to the purpose and the hardware specifications of this system.

0063The OpenFlow protocol processing unit <b>214</b> instructs each physical node <b>10</b> to update the flow table <b>12</b> according to the path information calculated by the path control unit <b>213</b> as described. <figref idref="DRAWINGS">FIG. 11</figref> shows an example of a management switch table that the OpenFlow protocol processing unit <b>214</b> refers to when performing this processing. <figref idref="DRAWINGS">FIG. 12</figref> shows an example of a flow entry.

0064<figref idref="DRAWINGS">FIG. 13</figref> is a drawing showing the correspondence relation between the virtual network shown in <figref idref="DRAWINGS">FIG. 5</figref> and the real network configuration shown in <figref idref="DRAWINGS">FIG. 2</figref>. For instance, when the physical node <b>10</b> #<b>1</b> in <figref idref="DRAWINGS">FIG. 13</figref> receives a packet from the port connected to the external network, the physical node <b>10</b> #<b>1</b> will issue an inquiry to the OpenFlow protocol processing unit <b>214</b> of the control server <b>20</b> if there is no entry matching this packet in the flow table <b>12</b>. The OpenFlow protocol processing unit <b>214</b> adds an ID of the physical node <b>10</b> #<b>1</b> and the port number to this inquiry and forwards it to the virtual network control unit <b>212</b>. The virtual network control unit <b>212</b> performs physical-virtual conversion on the received packet by referring to the virtual network configuration information storage unit <b>202</b> and the virtual network identifying information storage unit <b>203</b> and suitably performs network processing using the virtual node emulation unit <b>211</b> assuming that the packet is supplied to a virtual network indicated in the upper part of <figref idref="DRAWINGS">FIG. 11</figref>. Then, the virtual network control unit <b>212</b> performs physical-virtual conversion again on the processing result from the virtual node emulation unit <b>211</b>, and supplies the result to the path control unit <b>213</b>. Here, for instance, if a result that the packet should be outputted from a port of the physical node <b>10</b> #<b>2</b> connected to an HTTP server <b>1</b> is obtained from the result of virtual-physical conversion on the output of the virtual node emulation unit <b>211</b>, and the path control unit <b>213</b> calculates that a path from the physical node <b>10</b> #<b>1</b> to the physical node <b>10</b> #<b>2</b> is the shortest, the OpenFlow protocol processing unit <b>214</b> controls so that the packet is outputted from the physical port corresponding to the virtual interface of the physical node ID <b>10</b> #<b>2</b> and instructs the physical node <b>10</b> #<b>1</b> and the physical node <b>10</b> #<b>2</b> on the path to update the flow tables so that subsequent packets will be similarly processed.

0065As described, network processing equivalent to the virtual network in the upper part of <figref idref="DRAWINGS">FIG. 13</figref> is realized by the combination of the physical nodes <b>10</b> #<b>1</b> to <b>10</b> #<b>3</b> and the control server <b>20</b> shown in the lower part of <figref idref="DRAWINGS">FIG. 13</figref>, One of the benefits of this configuration is that, even if the configurations of the physical node and HTTP server are physically changed, this can be addressed by modifying the table used in physical-virtual conversion and illustrated in <figref idref="DRAWINGS">FIG. 10</figref>, and maintenance property will improve. For instance, when the physical node <b>10</b> #<b>1</b> shown in the lower part of <figref idref="DRAWINGS">FIG. 13</figref> is replaced, this can be addressed by modifying the table used in physical-virtual conversion and illustrated in <figref idref="DRAWINGS">FIG. 10</figref> and does not influence the configuration of the virtual network (refer to the upper part of <figref idref="DRAWINGS">FIG. 13</figref>) visible to a user.

0066Next, with reference to <figref idref="DRAWINGS">FIGS. 14 to 17</figref>, a sequence of the operation of the present exemplary embodiment is organized and described. In the explanation below, it is assumed that the physical node #<b>1</b> has received a new packet from a user terminal connected to the external network. Further, to simplify the description, it is assumed that one virtual router is provided as a virtual node in the virtual network.

0067As shown in <figref idref="DRAWINGS">FIG. 14</figref>, upon receiving a packet, the physical node #<b>1</b> searches for an entry having a matching key that matches this packet in the flow table <b>12</b> (step S<b>001</b>).

0068Here, it is assumed that this packet is the first packet and no entry corresponding to the received packet is registered in the flow table of the physical node #<b>1</b>. Therefore, the physical node #<b>1</b> issues an inquiry with the port number (input port number) that received the packet and the packet to the control server <b>20</b>, and requests the control server to generate and transmit a flow entry (step S<b>002</b>; packet receipt notification (Packet-In)).

0069Upon receiving the packet receipt notification (Packet-In the OpenFlow protocol processing unit <b>214</b> of the control server <b>20</b> adds the source physical node ID (input physical node) of the packet receipt notification (Packet-In) and forwards the packet to the virtual network control unit <b>212</b> (step S<b>003</b>). Note that the physical node ID can be derived from the management switch table shown in <figref idref="DRAWINGS">FIG. 11</figref> or a security channel identifier (SecChan identifier) that received this packet.

0070The virtual network control unit <b>212</b> stores the received packet in the packet cache <b>215</b> and performs virtual-physical conversion on the packet by referring to the virtual network identifying information illustrated in <figref idref="DRAWINGS">FIG. 10</figref> using the physical node ID (input physical node) of the packet source, the input port number, and header information (step S<b>004</b>). Note that the packet cache <b>215</b> may be omitted, and in this case the step in which the received packet is stored in the packet cache <b>215</b> is omitted.

0071Next, as shown in <figref idref="DRAWINGS">FIG. 15</figref>, when the virtual network control unit <b>212</b> supplies the packet after the virtual-physical conversion to the virtual router, the virtual router resolves the virtual interface ID of the packet source by referring to the routing table illustrated in <figref idref="DRAWINGS">FIG. 7A</figref> and transmits the packet whose MAC address has been rewritten (step S<b>005</b>).

0072The virtual network control unit <b>212</b> resolves the physical node ID that outputs the packet and the physical port ID thereof by performing a reverse lookup on the virtual network identifying information illustrated in <figref idref="DRAWINGS">FIG. 10</figref> using the virtual interface ID of the transmitted packet, and resolves the contents of header conversion instructed to this physical node by comparing the packet stored in the packet cache <b>215</b> at the time of the reception and the header information of the transmitted packet (step S<b>006</b>). Further, if the packet cache <b>215</b> is not provided in the virtual network control unit <b>212</b>, a solution such as a method for receiving a matching packet from the path control unit <b>213</b> may be suitably employed.

0073Next, the virtual network control unit <b>212</b> requests setting of a flow entry that includes the input physical node, the input port number, the header information, the resolved physical node ID and the physical port ID outputting the packet, and the header conversion contents.

0074Next, as shown in <figref idref="DRAWINGS">FIG. 16</figref>, the path control unit <b>213</b> that has received the request for setting the flow entry resolves the shortest path from the input physical node to the output physical node (step S<b>007</b>). The path control unit <b>213</b> transmits the received packet to the physical node #<b>2</b>, instructs the physical node #<b>2</b> to output the packet from a designated port, and requests the OpenFlow protocol processing unit <b>214</b> to add a flow entry that realizes the resolved shortest path.

0075The physical node #<b>2</b> outputs a received packet from the designated port according to the instruction from the path control unit <b>213</b> (step S<b>008</b>). Further, at this time, the OpenFlow protocol processing unit <b>214</b> may have the physical node #<b>2</b> execute an action of obtaining an IP DA (Internet Protocol Destination Address) from the header of the received packet, transmitting an ARP request to ports other than the port that received the received packet, and obtaining a corresponding MAC DA.

0076Further, the OpenFlow protocol processing unit <b>214</b> creates a flow entry to each physical node corresponding to the specified shortest path and transmits the flow entries to the physical nodes #<b>1</b> and #<b>2</b> (flow entry adding request; FlowMod (Add)). At this time, the OpenFlow protocol processing unit <b>214</b> sends a flow entry defining an action of converting the header to the physical node #<b>2</b> as well.

0077The physical nodes #<b>1</b> and #<b>2</b> add the flow entries to the flow tables <b>12</b> according to the instruction from the OpenFlow protocol processing unit <b>214</b> (step S<b>009</b>).

0078Then, as shown in <figref idref="DRAWINGS">FIG. 17</figref>, since the set flow entry is detected in a search in the flow table <b>12</b> (step S<b>101</b>), the physical node #<b>1</b> successively forwards subsequent packets to the physical node #<b>2</b> without issuing an inquiry to the control server <b>20</b> (step S<b>102</b>).

0079Similarly, since the set flow entry is detected in a search in the flow table <b>12</b> (step S<b>103</b>), the physical node #<b>2</b> successively outputs the packets received from the physical node #<b>1</b> from the designated port (step S<b>104</b>).

0080Although this is omitted in <figref idref="DRAWINGS">FIGS. 14 to 17</figref>, the same processing is performed in a flow in which the physical nodes #<b>1</b> and #<b>2</b> in <figref idref="DRAWINGS">FIGS. 14 to 17</figref> are switched when a response to the packet is transmitted from the packet output destination of the physical node #<b>2</b>.

0081In the exemplary embodiment described above, the explanation was given using an example in which a virtual router is provided as a virtual node, however, the firewall (FW) and the load balancer (LB) on the virtual network shown in <figref idref="DRAWINGS">FIG. 5</figref> can be similarly realized by defining the behavior of the physical node.

0082For instance, when the virtual node emulation unit <b>211</b> is operated as a firewall according to a firewall policy of performing filtering operation by referring to the header information of a particular layer, a function equivalent to the firewall on the virtual network can be realized by setting an action of having the physical node receive the packet outputted from the virtual router and drop a corresponding packet based on the result thereof.

0083Similarly, for instance, a function equivalent to the load balancer on the virtual network can be realized by setting an action of supplying an output from the firewall to the virtual node emulation unit <b>211</b> that operates according to a predetermined load balance policy and switching the destination of the packet based on the result thereof.

0084The exemplary embodiment of the present invention has been described above, however, the present invention is not limited to the above exemplary embodiment and further modifications, replacements, and adjustments can be added within the scope of the basic technological concept of the present invention. For instance, the OpenFlow switch is used as the physical node and the OpenFlow protocol is used in the communication between the physical node and the control server in the exemplary embodiment described above, however, the present invention is not limited to the example above and any switch or protocol having the same functions can be used. For instance, the physical node can be realized by a router on an IP network or an MPLS switch on an MPLS (Multi-Protocol Label Switching) network, in addition to the OpenFlow switch.

0085It should be noted that within the entire disclosure (including the claims) and based on the fundamental technical concept, modifications and/or adjustment of the disclosed exemplary embodiments or examples may be done. Also various combination and selection of the various disclosed elements may be done within the scope of the claims of the present invention. That is, variations or modifications that may be done by the person of ordinary skill in the art based on the entire disclosure and technical concept including the claims may be included.

EXPLANATIONS OF SYMBOLS

0086<b>10</b>, <b>10</b> #<b>1</b>, <b>10</b> #<b>2</b>, <b>10</b> #<b>3</b>: physical node

0087<b>11</b>: server communication unit

0088<b>12</b>: flow table

0089<b>13</b>: control unit

0090<b>20</b>: control server

0091<b>30</b>: external node

0092<b>201</b>: virtual node object storage unit

0093<b>202</b>: first storage unit (virtual network configuration information storage unit)

0094<b>203</b>: second storage unit (virtual network identifying information storage unit)

0095<b>204</b>: physical topology information storage unit

0096<b>205</b>: shortest path information storage unit

0097<b>206</b>: set flow forwarding path information storage unit

0098<b>207</b>: flow entry storage unit

0099<b>208</b>: management switch information storage unit

0100<b>210</b>: control unit

0101<b>211</b>: virtual node emulation unit

0102<b>212</b>: virtual network control unit

0103<b>213</b>: path control unit

0104<b>214</b>: OpenFlow protocol processing unit

0105<b>215</b>: packet cache