JP5495150B2 - Network system, network device, and path control method - Google Patents

Description

  The present invention relates to a network system, and more particularly to a controller that performs network communication path control.

  As one of the network system control methods, a CU (C: control plane / U: user plane) separated network system that controls a node device (user plane) from an external control device (control plane) has been proposed.

  As an example of the CU separation type network system, there is an open flow network system using an open flow technology that controls a switch from a controller to control a network path. The details of the open flow technique are described in Non-Patent Document 1. The OpenFlow network system is only an example.

[Explanation of OpenFlow network system]
In the OpenFlow network system, a controller such as OFC (OpenFlow Controller) controls the behavior of a switch by operating a flow table (Flow table) in the switch such as OFS (OpenFlow Switch).

  The switches in the OpenFlow network system are edge switches and core switches that form an OpenFlow network and are under the control of the controller. A series of packet flows from reception of a packet at the input side edge switch to transmission at the output side edge switch in the OpenFlow network is called a flow.

  The packet may be read as a frame. The difference between a packet and a frame is only a difference in data units (PDU: Protocol Data Unit) handled by the protocol. The packet is a PDU of “TCP / IP” (Transmission Control Protocol / Internet Protocol). On the other hand, the frame is a PDU of “Ethernet” (registered trademark).

  The flow table is a table in which a flow entry (Flow entry) that defines an operation (action) to be performed on a packet that meets a predetermined matching condition (rule) is registered.

  The rule of the flow entry is any one of a destination address (Destination Address), a source address (Source Address), a destination port (Destination Port), a source port (Source Port) included in the header area of each protocol layer of the packet, or Defined and distinguishable by various combinations using all. Note that the above addresses include a MAC address (Media Access Control Address) and an IP address (Internet Protocol Address). In addition to the above, information on an ingress port (Ingress Port) can also be used as a rule for a flow entry. In addition, as a rule of the flow entry, a part (or all) of the header area value of the packet indicating the flow can be set by a regular expression, a wild card “*”, or the like.

  The action of the flow entry indicates operations such as “output to a specific port”, “discard”, and “rewrite header”. For example, if the identification information (output port number, etc.) of the output port is indicated in the action of the flow entry, the switch outputs a packet to the corresponding port, and if the identification information of the output port is not indicated , Discard the packet. Alternatively, if the header information is indicated in the action of the flow entry, the switch rewrites the header of the packet based on the header information.

  The switch in the OpenFlow network system executes a flow entry action on a packet group (packet sequence) that conforms to the rules of the flow entry.

  In a network that separates the "packet transfer function" and the "route control function" into a network device and a controller, such as the OpenFlow network system, if a failure occurs in the controller that calculates and sets the packet path, A network device that performs packet transfer processing cannot transfer packets. Alternatively, the processing speed becomes very slow because it is necessary to request another controller for route calculation again.

  For this reason, considering the fault tolerance of the controller in charge of the control function, it is possible to multiplex the controllers.

  Also, from the viewpoint of fault tolerance and processing speed, it is conceivable that a plurality of controllers independently perform packet route calculation and setting to network devices without synchronization.

  However, from the viewpoints of availability and processing speed, when multiple controllers calculate routes independently without synchronization and set the network device, the setting instructions to the network device conflict because they do not synchronize. As a result, inconsistency may occur in the setting information of the network device. As a result, a closed circuit (loop) is formed on the network, and the packet may not reach the transmission destination.

  As a related technique, Japanese Patent Application Laid-Open No. 2006-020054 discloses a network connection device, a route information distribution program, and a route information distribution method. In this related technique, a route information update notification message is generated based on a prefix assigned to a child router, information on an assignment destination child router, and an assignment management table. This message conveys the possibility of updating (adding or deleting) route information. A route information update notification is transmitted to a router to which a prefix has already been assigned.

  Patent Document 2 (Japanese Patent Laid-Open No. 2007-096912) discloses a network repeater. In this related technology, a route information change packet is received from a network processor (NP) and the event is interpreted. The interpretation of the event is performed based on the header information of the route information change packet. When the event information is added, a route information addition process is executed. When the event information is changed, a route information change process is executed. When the event information is deleted, a route information deletion process is executed. When the processing is completed for all the route information change packets from the network processor (NP), a timer for starting the request transmission processing to the network processor (NP) is set.

Japanese Patent Laid-Open No. 2006-020054 JP 2007-096912 A

"OpenFlow Switch Specification, Version 1.0.0", [online], December 31, 2009, Internet (URL: http://www.openflowswitch.org/documents/openflow-spec.1).

  In order to solve the above problem, it is guaranteed that packets are transferred from the source to the destination when the route is calculated independently without synchronization between multiple controllers and set in the network device. There is a need for a technique to do this.

  As one of such methods, a method is conceivable in which a network device adds information to a packet, and a network device on the route reads the information to forward the packet to the correct route.

  However, when the network device changes the information of the packet, there may be a problem of processing overhead on the packet or transfer processing overhead due to information addition.

  Therefore, the present invention proposes a technique in which the network device does not change the packet itself while ensuring that the packet is transferred from the transmission source to the transmission destination.

  The network system according to the present invention includes a plurality of network devices, a plurality of controllers that set a flow entry in which rules and operations for uniformly controlling packets as flows are defined in a flow table of network devices on a route, including. The network device on the route adopts the route set by the controller that has completed the setting of the flow entry of all the network devices on the route earliest among the plurality of controllers, and sets the route set by the other controller. The packet is not adopted and the packet is transferred according to the flow entry of the adopted route.

  A network device according to the present invention includes a device that sets a flow entry in a flow table in which rules and operations for uniformly controlling a packet as a flow are defined in a flow table based on control from each of a plurality of controllers, Adopt the route set by the controller that completed the setting of the flow entry of all the network devices on the route the earliest among the controllers of the other, and reject the route set by the other controller, and the flow of the adopted route And a device for transferring a packet according to the entry.

  The route control method according to the present invention is a route control method implemented by a network device, and rules and operations for uniformly controlling packets as a flow are defined based on control from each of a plurality of controllers. Set the flow entry in the flow table, adopt the route set by the controller that completed the flow entry setting of all the network devices on the route earliest among the multiple controllers, and set other controllers Including transferring the packet in accordance with the flow entry of the adopted route.

  The program according to the present invention includes a step of setting, in the flow table, a flow entry in which rules and operations for uniformly controlling a packet as a flow are defined based on control from each of a plurality of controllers. Adopts the route set by the controller that has completed the setting of the flow entry of all the network devices on the route earliest among the controllers, disallows the route set by the other controller, and the flow entry of the adopted route The program for causing the network device to execute the step of transferring packets according to the above.

  That is, the program according to the present invention is a program for causing a network device to execute the processing in the above path control method. The program according to the present invention can be stored in a storage device or a storage medium.

  It is possible to delete a non-adopted route when the controller is multiplexed / redundant.

It is a figure which shows the structural example of the network system which concerns on this invention. It is a figure which shows the structural example of the controller in this network system. It is a figure which shows the structural example of the switch in this network system. It is a figure which shows the structural example of the flow entry in this network system. It is a figure which shows the structural example of the path | route deletion packet in this network system. It is a figure for demonstrating the operation | movement at the time of 1st packet reception. It is a figure for demonstrating the path | route which the some controller set. It is a figure for demonstrating the order of the employ | adopted path | route. It is a figure for demonstrating the condition where a path | route deletion packet flows into a non-adopted path | route. It is a figure for demonstrating the procedure of the whole deletion process of a non-adopting path | route. It is a figure for demonstrating the case where the deletion process of a non-adopting route is started before the setting of a non-adopting route. It is a figure for demonstrating the Example of this invention.

  The present invention is directed to a CU separation type network system. Here, an OpenFlow network system, which is one of CU separation type network systems, will be described as an example. However, actually, it is not limited to the open flow network system.

<First Embodiment>
Hereinafter, a first embodiment of the present invention will be described with reference to the accompanying drawings.

[System configuration]
A configuration example of a network system according to the present invention will be described with reference to FIG.

  The network system according to the present invention includes a controller 10 (10-i, i = 1 to x: x is the number), a switch 20 (20-j, j = 1 to y: y is the number), and a host 30 (30 -K, k = 1 to z: z is the number of units).

  Each of the controllers 10 (10-i, i = 1 to x) is a control device that controls a packet transfer path and the like in the network device.

  Each of the switches 20 (20-j, j = 1 to y) is a network device that transfers a packet.

  Each of the hosts 30 (30-k, k = 1 to z) is a terminal that transmits and receives packets.

[Hardware example]
Hereinafter, specific examples of hardware for realizing the network system according to the present invention will be described.

  As an example of the controller 10 (10-i, i = 1 to x), a computer such as a PC (personal computer), an appliance, a thin client server, a workstation, a mainframe, and a supercomputer is assumed.

  As an example of the switch 20 (20-j, j = 1 to y), a network switch is assumed. In addition, a router, a proxy, a gateway, a firewall, a load balancer, a bandwidth control device, a security monitoring control device, a base station, an access point, or a computer having a plurality of communication ports Conceivable.

  The above computer is assumed as an example of the host 30 (30-k, k = 1 to z). In addition, mobile phones, car navigation systems (car navigation systems), portable game consoles, home game consoles, portable music players, handy terminals, gadgets (electronic devices), interactive TVs, digital tuners, digital recorders, information appliances (Information home application), OA (Office Automation) equipment, etc. can be considered. The host 30 (30-k, k = 1 to z) may be mounted on a moving body such as a vehicle, a ship, or an aircraft.

  The host 30 (30-k, k = 1 to z) may be a relay device such as a switch in a network that does not support OpenFlow. That is, the network formed by the switches 20 (20-j, j = 1 to y) may be any network that supports OpenFlow (OpenFlow network system). Since the switch 20 (20-j, j = 1 to y) connected to any one of the hosts 30 (30-k, k = 1 to z) corresponds to an edge switch in the OpenFlow network system, the subordinate apparatus Can be processed in the same way by a terminal or an external network relay device.

  The controller 10 (10-i, i = 1 to x), the switch 20 (20-j, j = 1 to y), and the host 30 (30-k, k = 1 to z) are mounted on a computer or the like. It may be an expansion board or a virtual machine (Virtual Machine (VM)) built on a physical machine.

  Although not shown, the controller 10 (10-i, i = 1 to x), the switch 20 (20-j, j = 1 to y), and the host 30 (30-k, k = 1 to z) are programmed. This is realized by a processor that drives based on this and executes predetermined processing, a memory that stores the program and various data, and an interface used for communication with the network.

  Examples of the processor include a CPU (Central Processing Unit), a network processor (NP), a microprocessor, a microcontroller (microcontroller), or a semiconductor integrated circuit (LSI: Large Scale) having a dedicated function. Integration) or the like.

  Examples of the memory include semiconductor storage devices such as a RAM (Random Access Memory), a ROM (Read Only Memory), an EEPROM (Electrically Erasable and Programmable Read Only Memory), a flash memory, and an HDD (Hold SMD). An auxiliary storage device such as State Drive), a removable disk such as a DVD (Digital Versatile Disk), a storage medium such as an SD memory card (Secure Digital memory card), or the like is conceivable. A register may also be used.

  Note that the processor and the memory may be integrated. For example, in recent years, a single chip such as a microcomputer has been developed. Therefore, a case where a one-chip microcomputer mounted on the above-described computer or the like includes a processor and a memory can be considered.

  Examples of the interface include semiconductor integrated circuits such as substrates (motherboards and I / O boards) and chips that support network communication, network adapters such as NIC (Network Interface Card), and similar expansion cards and communication devices such as antennas. A communication port such as a connection port (connector) is conceivable.

  Examples of the network include the Internet, a LAN (Local Area Network), a wireless LAN (Wireless LAN), a WAN (Wide Area Network), a backbone (Backbone), a cable television (CATV) line, a fixed telephone network, a mobile phone network, WiMAX (IEEE 802.16a), 3G (3rd Generation), dedicated line (lease line), IrDA (Infrared Data Association), Bluetooth (registered trademark), serial communication line, data bus, and the like can be considered.

  However, actually, it is not limited to these examples.

[Controller details]
A configuration example of the controller 10 (10-i, i = 1 to x) will be described with reference to FIG.

  Each of the controllers 10 (10-i, i = 1 to x) includes a route calculation unit 11, a network management unit 12, and a packet processing unit 13.

  The route calculation unit 11 receives the topology information of the switch 20 (20-j, j = 1 to y) from the network management unit 12, calculates the route of the packet, and switches 20 (20-j, j = 1 to y). Set to.

  The network management unit 12 manages the topology information of the switch 20 (20-j, j = 1 to y) and the route calculated by the route calculation unit 11. Here, the network management unit 12 controls the behavior of the switch 20 (20-j, j = 1 to y) by a control message based on the OpenFlow protocol based on the topology information and the calculated route.

  The packet processing unit 13 receives a packet transferred from the switch 20 (20-j, j = 1 to y), analyzes the packet information, and transmits the analysis result to the route calculation unit 11.

  Note that the route calculation unit 11, the network management unit 12, and the packet processing unit 13 may be modules or components.

  The controller 10 (10-i, i = 1 to x) can manage the plurality of switches 20 (20-j, j = 1 to y) by the network management unit 12, and the switch 20 (20-j, j = 1 to y) and a dedicated line or a secure channel (Secure Channel) of a normal network.

[Switch details]
A configuration example of the switch 20 (20-j, j = 1 to y) will be described with reference to FIG.

  Each of the switches 20 (20-j, j = 1 to y) includes a flow table 21, a flow table management unit 22, and a packet processing unit 23.

  The flow table 21 manages a flow entry serving as route information. The flow table 21 can be stored in a storage device or a storage medium.

  The flow table management unit 22 adds / updates / deletes the flow entry of the flow table 21 according to the control message from the controller 10 (10-i, i = 1 to x). The flow table management unit 22 can also check the contents of the flow entry in the flow table 21.

  The packet processing unit 23 processes a packet. That is, the packet processing unit 23 performs overall processing related to packets in the switch 20 (20-j, j = 1 to y).

  The packet processing unit 23 includes a packet reception unit 231, a packet transfer unit 232, a packet discard unit 233, a route deletion packet generation unit 234, and a route deletion packet analysis unit 235.

  The packet receiving unit 231 receives and analyzes the packet. For packet analysis, the packet receiving unit 231 refers to the header information of the packet and checks whether there is a flow entry in the flow table 21 that matches the header information of the packet. If there is a matching flow entry, if the content of the flow entry is to be transferred to the next node on the route, the packet receiving unit 231 passes the packet to the packet transfer unit 232, and the next step on the route. Transfer to node. If the content of the flow entry is to discard (discard) the packet, the packet receiving unit 231 passes the packet to the packet discarding unit 233 and discards the packet. Further, if there is no matching flow entry, the packet receiving unit 231 passes the packet to the packet transfer unit 232 and inquires about the route of the packet to the controller 10 (10-i, i = 1 to x).

  The packet transfer unit 232 includes another switch 20 (20-j, j = 1 to y) adjacent to the switch, the controller 10 (10-i, i = 1 to x), and the host 30 (30-k, k = 1 to z) and the like are transferred. The packet transfer unit 232 is provided for each output port, and outputs the received packet from the output port.

  The packet discard unit 233 discards the received packet. Note that the packet discard unit 233 can discard not only the normal packet but also a route deletion packet described later.

  The route deletion packet generation unit 234 generates a route deletion packet for deleting the unaccepted route.

  The route deletion packet analysis unit 235 analyzes the received route deletion packet. As a packet analysis, the route deletion packet analysis unit 235 refers to the header information of the route deletion packet, and checks whether there is a flow entry of a rejected route that matches the header information of the route deletion packet in the flow table 21. If there is a matching flow entry, and if the content of the flow entry is to be transferred to the next node on the route, the packet receiving unit 231 passes the route deletion packet to the packet transfer unit 232, and the next on the route. Transfer to the node of the stage. If the content of the flow entry is to discard the route deletion packet, the packet reception unit 231 passes the route deletion packet to the packet discard unit 233 and discards the route deletion packet. Further, when there is no matching flow entry, the route deletion packet analysis unit 235 temporarily holds the route deletion packet, passes the route deletion packet to the packet discard unit 233 after a predetermined time elapses, and receives the route deletion packet. Discard. The route deletion packet analysis unit 235 may be integrated with the packet reception unit 231.

  The flow table management unit 22 and the packet processing unit 23 (the packet reception unit 231, the packet transfer unit 232, the packet discard unit 233, the route deletion packet generation unit 234, and the route deletion packet analysis unit 235) are modules. Alternatively, it may be a component.

[Flow table details]
The flow table 21 holds a flow entry 211. That is, the flow table 21 is a set of flow entries 211. The flow entry 211 is route information corresponding to each flow.

[Flow entry details]
A configuration example of the flow entry 211 will be described with reference to FIG.

  The flow entry 211 includes a flow header 2111, an action 2112, a route ID 2113, and a controller ID 2114.

  The flow header 2111 is an area (field) for describing basic flow information such as a transmission source IP address and a transmission destination IP address. That is, the flow header 2111 is an area for describing the rule of the flow entry 211.

  The action 2112 is an area for describing a flow processing method. That is, the action 2112 is an area for describing the action of the flow entry 211.

  The route ID 2113 is an area for describing a unique value (route identifier) for each route.

  The controller ID 2114 is an area for describing an identifier of the controller 10 (10-i, i = 1 to x) in which the flow entry 211 is set.

[Details of route deletion packet]
With reference to FIG. 5, the route deletion packet defined in the present invention will be described.

  The route deletion packet 50 is a control message packet for deleting the flow entry 211 for each flow constituting the flow table 21 of the switch 20 (20-j, j = 1 to y).

  The route deletion packet 50 includes a flow header 51, a route ID 52, and a controller ID 53.

  The flow header 51 is an area for describing basic information of a flow such as a transmission source IP address and a transmission destination IP address, like the flow header 2111 shown in FIG.

  The route ID 52 is an area for describing a unique value (route identifier) for each route, like the route ID 2113 shown in FIG.

  The controller ID 53 is an area for describing an identifier of the controller 10 (10-i, i = 1 to x) in which the flow entry 211 is set, similarly to the controller ID 2114 shown in FIG.

[Route Control Processing in the Present Invention]
With reference to FIG. 6, the operation at the time of receiving the first packet (First Packet) will be described in the following order (1) to (6) with the configuration shown in FIG.

(1) Step S1
When the switch 20 (20-j, j = 1 to y) receives a packet (1st packet) without information in the flow table 21, the first packet is sent to the plurality of controllers 10 (10-i, i = 1 to x). Forward. That is, when there is no flow entry 211 of the flow table 21 that matches the header information of the received packet, the switch 20 (20-j, j = 1 to y) determines that the packet is the 1st packet, and the plurality of controllers 10 The 1st packet is transferred to (10-i, i = 1 to x).

(2) Step S2
When receiving the 1st packet, the controller 10 (10-i, i = 1 to x) calculates a route and sets the switch 20 (20-j, j = 1 to y) on the route.

(3) Step S3
When the controller 10 (10-i, i = 1 to x) finishes setting of the switch 20 (20-j, j = 1 to y), the switch 20 (20-j, j) that is the transmission source of the 1st packet. = 1 to y).

(4) Step S4
The switch 20 (20-j, j = 1 to y) is not adopted for the controller 10 (10-i, i = 1 to x) which is not the controller 10 (10-i, i = 1 to x) which responded earliest. Send notifications.

(5) Step S5
The switch 20 (20-j, j = 1 to y) performs the deletion process of the flow entry 211 set by the controller 10 (10-i, i = 1 to x) which has been rejected.

(6) Step S6
The switch 20 (20-j, j = 1 to y) processes the packet according to the flow entry 211 of the adopted route.

[Details of Step S1]
When the switch 20 (20-j, j = 1 to y) receives a packet (1st packet) without information in the flow table 21, the first packet is sent to the plurality of controllers 10 (10-i, i = 1 to x). Forward.

  For example, when the switch 20-1 receives a packet from the host 30-1, the packet processing unit 23 determines whether the packet is a normal packet or a route deletion packet 50.

  When the packet is a normal packet, the packet processing unit 23 checks whether the header information of the packet matches the flow header 2111 of the flow entry 211 set in the flow table 21.

  If they match, the packet processing unit 23 processes the packet according to the action 2112 of the corresponding flow entry 211.

  If not matched, the packet processing unit 23 transfers the packet (1st packet) to the controller 10-1 and the controller 10-2 that manage the switch 20-1.

[Details of Step S2]
When receiving the 1st packet, the controller 10 (10-i, i = 1 to x) calculates a route and sets the switch 20 (20-j, j = 1 to y) on the route.

  In each of the controller 10-1 and the controller 10-2, when the packet processing unit 13 receives the 1st packet, the route calculation unit 11 is based on the topology information of the network management unit 12 and the analysis result of the packet processing unit 13. The route that the packet (1st packet) should take is calculated.

  Here, as shown in FIG. 7, a route calculated by the controller 10-1 is a route 100-1, and a route calculated by the controller 10-2 is a route 100-2.

  The path 100-1 is in the order of “switch 20-1” → “switch 20-4” → “switch 20-5” → “switch 20-6” → “switch 20-7” → “switch 20-8”. Become.

  The path 100-2 is “switch 20-1” → “switch 20-2” → “switch 20-4” → “switch 20-5” → “switch 20-7” → “switch 20-6” → “switch” 20-8 ".

  After completing the calculation of the route, in each of the controllers 10-1 and 10-2, the network management unit 12 assigns the flow entry 211 based on the calculated route to each switch 20 (20-j, j = 1 to y).

  The setting of the flow entry 211 to the switch 20 (20-j, j = 1 to y) is performed in order from the switch 20-1 closest to the transmission source host 30-1 on the route.

  For example, in the case of the path 100-1, the controller 10-1 sets the switch 20 (20-j, j = 1 to y) in the order of (1) to (6) in FIG. This order is different from the usual OpenFlow setting order.

  When setting is performed in order from the switch 20-1 close to the transmission source host 30-1 on the route, the switch 20-1 makes the flow entry 211 valid at the moment of setting, and receives the received packet according to the action 2112 of the flow entry 211. Will be processed. Therefore, for example, when the switch 20-4 receives a packet from the switch 20-1 before the setting of the switch 20-4 as the transfer destination on the path is completed, the switch 20-4 transmits the packet to the 1st packet. As a result, the data may be transferred to the controller 10 (10-i, i = 1 to x) again.

  Therefore, in the open flow, setting is performed in order from the switch 20 (20-j, j = 1 to y) close to the transmission destination host 30-2 on the route.

  In the present invention, by setting only the setting of the switch 20-1 closest to the transmission source host 30-1 on the route as the temporary setting (temporary registration), all the switches 20 (20-j, j = 1 to y) are set. The packet is prevented from being followed according to the flow entry 211 before the setting is completed.

  That is, unless the setting of all the switches 20 (20-j, j = 1 to y) on the route is completed, the packet is not transferred from the transmission source host 30-1 to the transmission destination host 30-2.

  In the case of the path 100-1, the controller 10-1 temporarily sets the flow entry 211 in the switch 20-1 closest to the transmission source host 30-1 on the path 100-1, and then the subsequent switch 20 (20-j , J = 1 to y) sets the flow entry 211 in the flow table 21 without temporarily setting.

  For example, in addition to the flow table 21 held by the switch 20 (20-j, j = 1 to y), by having a storage area that can hold the temporary flow entry 211, the flow entry temporarily set there. 211 may be held. Another method can be realized by having an area in which it is possible to determine whether the flow entry 211 is temporarily set or permanently registered.

[Details of Step S3]
When the controller 10 (10-i, i = 1 to x) finishes setting of the switch 20 (20-j, j = 1 to y), the switch 20 (20-j, j) that is the transmission source of the 1st packet. = 1 to y).

  When the setting of all the switches 20 (20-j, j = 1 to y) on the path is completed, the controller 10 (10-i, i = 1 to x) sends a setting completion notification to the switch 20-1 as a response. Send.

  At this time, the controller 10 (10-i, i = 1 to x) registers the flow entry 211 temporarily set in the switch 20-1 in the flow table 21.

  The switch 20-1 employs the route set by the controller 10 (10-i, i = 1 to x) that responded earliest as the route through which the packet passes.

  If the controller 10-1 and the controller 10-2 respond at the same time, the switch 20-1 selects either one so that the adopted route becomes one.

[Details of Step S4]
The switch 20 (20-j, j = 1 to y) is not adopted for the controller 10 (10-i, i = 1 to x) which is not the controller 10 (10-i, i = 1 to x) which responded earliest. Send notifications.

  It is assumed that the route adopted is the route 100-1 set by the controller 10-1.

  Since the controller 10-1 responded the earliest, the switch 20-1 notifies the controller 10-2 that has not been adopted that the route has not been adopted.

  This is performed in order to cause the controller 10-2 in the middle of setting to cancel the path setting when the non-adoption is determined.

  Therefore, when the controller 10-2 receives the non-adoption notification from the switch 20-1, the setting of all the switches 20 (20-j, j = 1 to y) on the route by the controller 10-2 is not completed. In both cases, the remaining settings are not performed.

[Details of Step S5]
The switch 20 (20-j, j = 1 to y) performs the deletion process of the flow entry 211 set by the controller 10 (10-i, i = 1 to x) which has been rejected.

  Here, the switch 20-1 deletes the flow entry 211 of the non-adopted route 100-2 set by the controller 10-2.

  The deletion route 100-2 is deleted by using the route deletion packet 50. The switch 20-1 transmits a route deletion packet 50 toward the switch on the non-accepted route 100-2.

  As shown in FIG. 9, the route deletion packet 50 flows through the non-adopted route 100-2.

[Rejected route deletion process]
With reference to FIG. 10, the overall procedure for deleting a non-employed route will be described.

(1) Step S501
In the switch 20-1, the packet processing unit 23 sets information on the rejected route 100-2 set by the controller 10-2 in the route deletion packet 50. Here, the packet processing unit 23 creates the route deletion packet 50 based on the flow header 2111 of the flow entry 211 of the non-adopted route 100-2, the route ID 2113, and the controller ID 2114 indicating the controller 10-2. That is, the flow header 51, the route ID 52, and the controller ID 53 of the route deletion packet 50 are equal to the flow header 2111, the route ID 2113, and the controller ID 2114 of the non-adopted route 100-2, respectively.

(2) Step S502
In the switch 20-1, the packet processing unit 23 checks whether the content of the action 2112 of the flow entry 211 of the non-accepted route 100-2 is the content to be transferred to the transmission destination host 30-2. That is, it is confirmed whether it is a switch at the end of the path.

(3) Step S503
In the switch 20-1, when the content of the action 2112 of the flow entry 211 is not the content to be transferred to the transmission destination host 30-2, the packet processing unit 23 processes the route deletion packet 50 according to the action 2112 of the flow entry 211. Here, in the switch 20-1, the packet processing unit 23 transfers the route deletion packet 50 to the next-stage switch 20-2 in accordance with the action 2112 of the flow entry 211.

(4) Step S504
In each switch 20 (20-j, j = 2 to y) on the rejected route, the flow table management unit 22 sends the route deletion packet 50 to the next switch 20 (20-j, j = 2 to y). , The flow entry 211 of the rejected route 100-2 that has been temporarily set or formally set is deleted.

(5) Step S505
In each switch 20 (20-j, j = 2 to y) on the rejected route, when the packet processing unit 23 receives the route deletion packet 50, the flow header 51, route ID 52, and Based on the controller ID 53, it is confirmed whether the flow entry 211 registered in the flow table 21 includes a flow entry 211 that matches the flow header 51, the route ID 52, and the controller ID 53 of the route deletion packet 50.

(6) Step S506
In each switch 20 (20-j, j = 2 to y) on the rejected route, the packet processing unit 23 has a flow entry 211 that matches the flow header 51, route ID 52, and controller ID 53 of the route deletion packet 50. In this case, it is confirmed whether the content of the action 2112 of the flow entry 211 is the content to be transferred to the transmission destination host 30-2. That is, it is confirmed whether it is a switch at the end of the path.

(7) Step S507
In each switch 20 (20-j, j = 2 to y) on the non-adopted route, the packet processing unit 23 does not transfer the content of the action 2112 of the flow entry 211 to the transmission destination host 30-2. The route deletion packet 50 is processed according to the action 2112 of the flow entry 211. Here, in each switch 20 (20-j, j = 2 to y), the packet processing unit 23 sends the route deletion packet 50 to the next-stage switch 20 (20-j, j) according to the action 2112 of the flow entry 211. = 2 to y).

(8) Step S508
In each switch 20 (20-j, j = 2 to y) on the rejected route, the flow table management unit 22 sends the route deletion packet 50 to the next switch 20 (20-j, j = 2 to y). , The flow entry 211 of the rejected route 100-2 that has been temporarily set or formally set is deleted.

(9) Step S509
In each switch 20 (20-j, j = 1 to y) on the non-adopted route, the packet processing unit 23, when the content of the action 2112 of the flow entry 211 is the content to be transferred to the destination host 30-2 That is, when the switch 20 (20-j, j = 1 to y) is the last switch 20-8 in the route, the transfer process is not performed and the flow header 51, the route ID 52, and the controller ID 53 of the route deletion packet 50 are matched. The flow entry 211 to be deleted is deleted, and the route deletion packet 50 is discarded. When the switch 20-1 that has received the 1st packet is the last switch in the route, the switch 20-1 may delete the flow entry 211 of the non-adopted route without generating the route deletion packet 50. . For example, when the non-adopted route is a communication route between hosts under the switch 20-1, or each of the hosts 30 (30-k, k = 1 to z) under the switch 20-1, A case where it is a relay device such as a router in a compatible network is conceivable.

(10) Step S510
Further, the switch 20 (20-j, j = 2 to y) on the rejected route includes the flow header 51, the route ID 52, the route deletion packet 50 in the flow entry 211 registered in the flow table 21. If there is no flow entry 211 that matches the controller ID 53, the received route deletion packet 50 is temporarily held.

(11) Step S511
The switch 20 (20-j, j = 2 to y) checks whether there is an additional setting of the flow entry 211 from the controller 10 (10-i, i = 1 to x).

(12) Step S512
When there is an additional setting of the flow entry 211 from the controller 10 (10-i, i = 1 to x), the switch 20 (20-j, j = 2 to y) has the flow header 2111 of the additionally set flow entry 211. Then, it is confirmed whether the route ID 2113 and the controller ID 2114 are compatible with the flow header 51, the route ID 52, and the controller ID 53 of the route deletion packet 50 temporarily held.

(13) Step S513
If the flow entry 211 matches the route deletion packet 50, the switch 20 (20-j, j = 2 to y) discards the registration of the flow entry 211.

(14) Step S514
The switch 20 (20-j, j = 2 to y) confirms whether a predetermined time has elapsed since the route deletion packet 50 is temporarily held.

(15) Step S515
The switch 20 (20-j, j = 2 to y) discards the stored route deletion packet 50 when a predetermined time has elapsed since the route deletion packet 50 has been temporarily stored.

[Details after Step S510]
For example, as shown in FIG. 11, in a state where the controller 10 (10-i, i = 1 to x) in which the path 100-2 is not adopted can only complete the setting up to the switch 20-5, A case where the route deletion process has started may be considered.

  In this case, the switch 20-7 cannot process the route deletion packet 50 because the flow entry 211 of the route 100-2 that has not been adopted is not set.

  At this time, the switch 20-7 temporarily holds the received route deletion packet 50.

  The reason why the route deletion packet 50 is temporarily held is that there is a possibility that the registration process of the flow entry 211 may be delayed.

  At the time when the deletion process of the rejected route starts, the controller 10-2 whose route has been rejected has received the rejected notification, so the remaining switches ( The flow entry 211 is not set for “switch 20-7” → “switch 20-6” → “switch 20-8”).

  However, since there is a possibility that the flow entry 211 is set after the deletion processing of the rejected route due to a network delay or the like, the switch 20-7 is delayed by the controller 10-2 whose route is not adopted. For the case where the flow entry 211 has been set, the route deletion packet 50 received from the switch 20-5 is held.

  When the flow entry 211 is set with a delay from the controller 10-2, the switch 20-7 discards the registration of the flow entry 211.

  When the flow entry 211 is set with a delay from the controller 10-2, the switch 20-7 transmits the route deletion packet 50 to the next-stage switch 20-6 according to the flow entry 211 just in case. You may do it. When the switch 20-6 receives the route deletion packet 50, the switch 20-6 performs the same processing as the switch 20-7.

  When the flow entry 211 that matches the information of the route deletion packet 50 to be held is not registered for a certain period of time, the switch 20-7 determines that there is no flow entry of an unaccepted route whose registration should be discarded, and the route deletion packet 50 is determined. Discard.

[Details of Step S6]
The switch 20 (20-j, j = 1 to y) processes the packet according to the flow entry 211 of the adopted route.

  Here, the switch 20-1 sets the flow entry 211 temporarily set by the controller 10-1 that responded earliest in the flow table 21.

  At this point, since the flow entry 211 that matches the information of the 1st packet is set, the switch 20-1 processes the 1st packet according to the action 2112 of the corresponding flow entry 211.

  The timing of setting the temporarily set flow entry 211 in the flow table 21 is almost the same as the “rejected route deletion process” in step S5.

  The switch 20-1 transfers the route deletion packet 50 to the switch 20-4 and then sets the temporarily set flow entry 211 in the flow table 21.

  After the temporarily set flow entry 211 is set in the flow table 21, the switch 20-1 transfers the received packet to the switch 20-4 on the adopted route according to the flow entry 211.

  Thereafter, each of the switches 20 (20-j, j = 1 to y) on the adopted route transfers the received packet to the next node on the adopted route according to the flow entry 211, and the packet Is transferred to the host 30-2.

  Here, there is a possibility that the switch 20 (20-j, j = 1 to y) that has not completed the process of deleting the unaccepted route receives the packet.

  In this case, since the switch 20 (20-j, j = 1 to y) cannot determine which flow entry 211 is the route 100-1, the switch 20 (20-j, j = 1 to y) waits for the completion of the deletion processing of the rejected route.

  Here, the switch 20 (20-j, j = 1 to y) determines that the deletion processing of the non-employed route is completed from the following two cases.

  (1) When there is only one flow entry 211 having a flow header 2111 that matches the flow header information of the packet, the switch 20 (20-j, j = 1 to y) indicates that the adopted controller 10 (10− It is determined that only the flow entry 211 set from i, i = 1 to x) is registered, and it is determined that the deletion process of the non-employed route has been completed.

  (2) If there are a plurality of flow entries 211 that match the information of the packet flow header, but the controller ID 2113 and route ID 2113 of these flow entries 211 are all the same, the switch 20 (20-j, j = 1 to y) determines that all of these flow entries 211 are registered from the adopted controller 10 (10-i, i = 1 to x), and the deletion processing of the non-adopted route is completed. Judge that you did.

  When the switch 20 (20-j, j = 1 to y) cannot determine the end of the deletion process of the unaccepted route for a certain period of time, that is, due to a cause such as a network delay, If it does not arrive and the non-accepted route is not deleted, the 1st packet is transferred to the controller 10 (10-i, i = 1 to x) at that time, and the route is reset.

[Example]
An embodiment of the present invention will be described with reference to FIG.

  Here, the controller 1 and the controller 2 are shown as examples of the controller 10 (10-i, i = 1 to x). Further, switches 1 to 4 are shown as examples of the switch 20 (20-j, j = 1 to y). Moreover, the host 1 and the host 2 are shown as an example of the host 30 (30-k, k = 1 to z). Host 1 is a transmission source host, and host 2 is a transmission destination host.

  (1) The switch 1 receives a packet from the host 1.

  (2) When the switch 1 is a packet that does not match the flow entry held by itself, the switch 1 transfers the packet as a 1st packet to a plurality of controllers that control the packet. Here, the switch 1 transfers the 1st packet to the controller 1 and the controller 2.

  (3) When the 1st packet is transferred from the switch, the controller 1 and the controller 2 calculate a route and set a flow entry for each of the switches on the route. At this time, the controller 1 and the controller 2 perform flow entry setting for each of the switches on the path in order from the switch 1 that has received the 1st packet. However, information (flag or the like) indicating provisional setting is assigned to the flow entry set in the switch 1 that has received the 1st packet. In other words, at this time, the flow entry set in the switch 1 that has received the 1st packet is not a formally set flow entry but a provisionally set flow entry. The information indicating the temporary setting is information indicating that the flow entry is still invalid. The switch 1 that has received the 1st packet does not transfer the packet in accordance with the temporarily set flow entry. Note that an area for storing information indicating temporary setting may be newly provided in the flow entry, or a part of an existing area in the flow entry may be used.

  (4) When all the settings of the switches on the path are completed, the controller 1 and the controller 2 transmit a notification that the setting is completed (setting completion notification), and the flow entry set in the switch 1 that has received the 1st packet The information indicating the temporary setting is removed from.

  (5) The switch 1 that has received the 1st packet adopts the route set by the controller 1 that has completed the setting of all the switches earliest (first) as the packet communication route, and other than the controller 1 that adopted the route. A notice of rejection is sent to the controller 2. When the controller 2 receives the non-employment notification, if the setting of the switch on the route is in the middle, the subsequent setting is stopped. Here, before setting the switch 4 on the route, the controller 2 receives a non-adoption notice and stops setting the switch 4 on the route.

  (6) The switch 1 that has received the 1st packet generates a route deletion packet in order to delete the route that has not been adopted, and sends the route deletion packet to the adjacent switch 3 in accordance with the flow entry of the route that has not been adopted. Transfer and delete the flow entry of the route that was not adopted. When a switch on the route that has not been adopted, including the switch 3, receives a route deletion packet, the switch is transferred to the adjacent switch 4 according to the flow entry that matches the header information of the route deletion packet, and then the flow entry is deleted. To do. Since the flow entry that matches the header information of the route deletion packet is not set, the switch 4 temporarily holds the route deletion packet and discards the route deletion packet after a predetermined time has elapsed. Note that when a flow entry that matches the header information of the route deletion packet is set, the switch 4 is identified as the last switch on the route that has not been adopted from the contents of the flow entry. The route deletion packet is not transmitted to the host 2, the flow entry that matches the header information of the route deletion packet is deleted, and the route deletion packet is discarded. Details of these processes are the same as the non-accepted route deletion process shown in FIG.

  (7) The switch 1 that has received the 1st packet transfers the packet after the 1st packet to the adjacent switch 2 in accordance with the flow entry of the adopted route.

  (8) The switch 2 transfers the first and subsequent packets to the adjacent switch 4 according to the flow entry.

  (9) The last switch 4 on the adopted route transfers the first and subsequent packets to the host 2 in accordance with the flow entry of the adopted route.

[Supplement]
In the embodiment of the present invention, the switch that receives the 1st packet is controlled by two controllers, but control by three or more controllers can also be realized. That is, the two controllers shown in the figure indicate “a controller adopting a route” and “a controller not adopting a route”, and the number of individual controllers is arbitrary.

Second Embodiment
The second embodiment of the present invention will be described below.

  In OpenFlow, the method of registering a flow entry in the flow table of a switch is roughly divided into two methods of “Proactive type” and “Reactive type”.

  In “Proactive type”, the controller calculates a route (path) of a predetermined packet group (flow) “in advance (before data communication starts)” and registers the flow entry in the flow table of the switch. In other words, the “Proactive type” here refers to “advanced flow entry registration” performed voluntarily by the controller.

  In the “Reactive type”, the controller calculates the route of the packet group (flow) when the switch receives an inquiry about the 1st packet (a new packet with no corresponding flow entry) from the switch, and flows to the flow table of the switch. Create an entry. That is, the “Reactive type” here refers to “real-time flow entry registration” performed by the controller in response to an inquiry from the switch during actual data communication.

  In the OpenFlow network system, basically, a “Reactive type” that registers a flow entry related to a received packet when the controller receives an inquiry about the 1st packet from the switch is the center.

  However, in actual hardware (HW), in order to reduce the processing frequency of the flow table and solve the performance problem, the “Proactive type” is considered suitable. For example, it is considered that the “Proactive type” is more suitable for processing even when a large number of first packets arrive at the controller. However, in reality, since it is considered that the number of flow entries becomes enormous if the complete “Proactive type” is used, it may be possible to escape from the restriction on the number of flow entries by making a part of the “Reactive type”.

  Further, if the “Proactive type” is used, a flow can be defined before the start of communication. Therefore, it is considered possible to avoid a problem of a large amount of flow due to a virus such as Nimda or an unauthorized access due to an unknown packet.

  In the above description of the first embodiment, “Reactive type” has been described. However, in practice, the present invention can also be implemented in a “Proactive type” OpenFlow network system.

  That is, each of a plurality of controllers calculates a route of a predetermined packet group that is expected to arrive without receiving a packet inquiry from the switch (before data communication starts), and switches on the route The flow entry may be registered in the flow table. The deletion process of the non-employed route in the switch is the same as that in the first embodiment.

<Summary>
As described above, according to the present invention, in a network composed of network devices in which a control function represented by OpenFlow is separated from an external controller, it is possible to delete unused paths when the controllers are multiplexed / redundant. To do.

  The present invention targets a network composed of network devices in which the functions of packet transfer and path control are separated.

  In the present invention, a plurality of controllers operate independently, and flow entries can be set for all network devices without communication between the controllers.

  In the present invention, the route is a route set by a controller that has completed setting earliest among a plurality of controllers.

  In the present invention, the network device generates a route deletion packet for deleting a flow entry of a route that is not used for communication.

  In the present invention, a network device transfers a route deletion packet to an adjacent network device on a route that is not used for communication.

  In the present invention, when the network device receives the route deletion packet, the network device analyzes the route deletion packet and, based on the analysis result, out of the flow entries set in itself, the flow entry that matches the header information of the route deletion packet Is deleted.

  In the present invention, when there is no flow entry that matches the route deletion packet, the network device temporarily holds the route deletion packet.

  In the present invention, when the flow entry registered by the controller matches the header information of the route deletion packet that is temporarily held, the network device discards the registration.

  According to the present invention, a communication path can be set without synchronization between a plurality of controllers. Further, by deleting the non-accepted route, a closed circuit is not created on the network, and a failure that the transfer is not correctly performed to the transmission destination does not occur. In addition, the network device does not perform processing such as addition or deletion of information on the packet.

<Appendix>
Part or all of the above-described embodiments can be described as in the following supplementary notes. However, actually, it is not limited to the following description examples.

(Appendix 1)
An apparatus for setting a flow entry in a flow table in which rules and operations for uniformly controlling a packet as a flow are defined based on control from each of a plurality of controllers;
Adopt the route set by the controller that completed the setting of the flow entry of all the network devices on the route the earliest among multiple controllers, and reject the route set by other controllers, and the flow of the adopted route A network device comprising a device for transferring a packet according to an entry.

(Appendix 2)
The network device according to attachment 1, wherein
An apparatus for receiving a setting completion notification indicating that the setting of all network devices on the route has been completed from each of the plurality of controllers;
In response to the setting completion notification, a device that creates a route deletion packet that matches the flow entry of the rejected route,
When a route deletion packet is received from the outside, a device that checks whether there is a flow entry that matches the route deletion packet,
A device that transfers a route deletion packet to an adjacent network device on the rejected route according to the flow entry of the rejected route;
A network device further comprising a device for deleting a flow entry of a rejected route.

(Appendix 3)
The network device according to attachment 2, wherein
A device that checks the contents of the flow entry that matches the route deletion packet;
A network device further comprising: a device that deletes the flow entry and discards the route deletion packet if the content is transferred to an adjacent destination host as a result of confirmation.

(Appendix 4)
The network device according to attachment 3, wherein
If there is no flow entry that matches the route deletion packet, when the flow entry is set from either a device that temporarily holds the route deletion packet or one of multiple controllers, the flow entry matches the route deletion packet. For example, a device that discards the setting of the flow entry;
A network device further comprising a device that discards a route deletion packet after a predetermined time has elapsed since the retention.

(Appendix 5)
A path control method implemented by a network device,
Based on control from each of a plurality of controllers, setting a flow entry in which rules and operations for uniformly controlling a packet as a flow are defined in the flow table;
Adopt the route set by the controller that completed the setting of the flow entry of all the network devices on the route the earliest among multiple controllers, and reject the route set by other controllers, and the flow of the adopted route A routing method comprising forwarding a packet according to an entry.

(Appendix 6)
The route control method according to attachment 5, wherein
Receiving a setting completion notification from each of the plurality of controllers indicating that the setting of all network devices on the route has been completed;
In response to the setting completion notification, creating a route deletion packet that matches the flow entry of the rejected route,
If a route deletion packet is received from outside, check whether there is a flow entry that matches the route deletion packet,
Forwarding the route deletion packet to the adjacent route control method on the rejected route according to the flow entry of the rejected route;
A route control method further comprising: deleting a flow entry of the rejected route.

(Appendix 7)
The route control method according to attachment 6, wherein
Check the contents of the flow entry that matches the route deletion packet,
As a result of confirmation, if the content is to be transferred to an adjacent destination host, the flow entry is deleted and the route deletion packet is discarded.

(Appendix 8)
The route control method according to appendix 7,
If there is no flow entry that matches the route deletion packet, the flow entry will be matched with the route deletion packet when temporarily holding the route deletion packet and setting the flow entry from one of multiple controllers. For example, discarding the setting of the flow entry,
A route control method further comprising: discarding a route deletion packet after a predetermined time has elapsed since holding.

(Appendix 9)
Based on control from each of the plurality of controllers, setting a flow entry in which a rule and operation for uniformly controlling a packet as a flow are defined in a flow table;
Adopt the route set by the controller that completed the setting of the flow entry of all the network devices on the route the earliest among multiple controllers, and reject the route set by other controllers, and the flow of the adopted route A program for causing a network device to execute a packet forwarding step according to an entry.

(Appendix 10)
The program according to appendix 9, wherein
Receiving a setting completion notification from each of the plurality of controllers indicating that the setting of all network devices on the route has been completed;
In response to the setting completion notification, creating a route deletion packet that matches the flow entry of the rejected route;
When a route deletion packet is received from the outside, a step of confirming whether there is a flow entry that matches the route deletion packet;
Transferring a route deletion packet to an adjacent program on the rejected route according to the flow entry of the rejected route;
A program for causing a network device to further execute a step of deleting a flow entry of a rejected route.

(Appendix 11)
The program according to attachment 10, wherein
Checking the contents of the flow entry that matches the route deletion packet;
A program for causing the network device to further execute a step of deleting the flow entry and discarding the route deletion packet if the content is transferred to an adjacent destination host as a result of the confirmation.

(Appendix 12)
The program according to attachment 11, wherein
If there is no flow entry that matches the route deletion packet, the flow entry is matched with the route deletion packet when the flow entry is set from one of multiple controllers and the step of temporarily holding the route deletion packet. For example, a step of discarding the setting of the flow entry;
A program for causing a network device to further execute a step of discarding a route deletion packet after a predetermined time has elapsed since the retention.

<Remarks>
As mentioned above, although embodiment of this invention was explained in full detail, actually, it is not restricted to said embodiment, Even if there is a change of the range which does not deviate from the summary of this invention, it is included in this invention.

  In addition, this application claims the priority based on the Japanese application number 2011-048143, and the content disclosed in the Japanese application number 2011-048143 is incorporated into the present application by reference.

Claims (10)

Multiple network devices,
A plurality of controllers for setting a flow entry in which rules and operations for uniformly controlling a packet as a flow are defined in a flow table of a network device on the route;
The network device on the route adopts the route set by the controller that has completed the setting of the flow entry of all the network devices on the route earliest among the plurality of controllers, and the route set by other controllers is not used. A network system that adopts and forwards packets according to the flow entry of the adopted route. The network system according to claim 1,
Each of the plurality of controllers, when completing the setting of all the network devices on the route, transmits a setting completion notification to the network device that inquired the packet,
In response to the setting completion notification, the network device that has inquired the packet creates a route deletion packet that matches the flow entry of the rejected route, and according to the flow entry of the rejected route, Transfer the route deletion packet to the adjacent network device on the rejected route, delete the flow entry of the rejected route,
When the network device on the route receives the route deletion packet, it checks whether there is a flow entry that matches the route deletion packet, and if there is a matching flow entry, the route deletion packet is sent according to the flow entry. A network system for transferring to an adjacent network device on the rejected route and deleting the flow entry. The network system according to claim 2,
The network device on the route confirms the content of the flow entry that matches the route deletion packet, and if the result of the confirmation is the content to be transferred to an adjacent destination host, deletes the flow entry and deletes the route. A network system that discards packets. The network system according to claim 3,
When there is no flow entry that matches the route deletion packet, the network device on the route temporarily holds the route deletion packet, and when the flow entry is set from any of the plurality of controllers, A network system in which if the flow entry matches the route deletion packet, the setting of the flow entry is discarded, and the route deletion packet is discarded after a predetermined time elapses after holding. Based on control from each of a plurality of controllers, means for setting a flow entry in which rules and operations for uniformly controlling packets as a flow are defined in a flow table;
Adopting the route set by the controller that has completed the setting of the flow entry of all network devices on the route earliest among the plurality of controllers, disabling the route set by the other controller, and adopting the route Means for transferring packets in accordance with the flow entry. The network device according to claim 5,
Means for receiving, from each of the plurality of controllers, a setting completion notification indicating that the setting of all network devices on the path has been completed;
Means for creating a route deletion packet that matches the flow entry of the rejected route in response to the setting completion notification;
Means for confirming the presence or absence of a flow entry that matches the route deletion packet when the route deletion packet is received from the outside;
Means for transferring the route deletion packet to an adjacent network device on the rejected route according to the flow entry of the rejected route;
Network equipment further comprising means for deleting the flow entry of the route that has not been adopted. The network device according to claim 6, wherein
Means for confirming the contents of a flow entry that matches the route deletion packet;
A network device further comprising means for deleting the flow entry and discarding the route deletion packet if the content is transferred to an adjacent destination host as a result of confirmation. The network device according to claim 7,
If there is no flow entry that matches the route deletion packet, the flow entry is deleted when the route entry is set by any one of the means for temporarily holding the route deletion packet and the plurality of controllers. A means for discarding the setting of the flow entry if it matches the packet;
Network equipment further comprising means for discarding the route deletion packet after elapse of a predetermined time from holding. A path control method implemented by a network device,
Based on control from each of a plurality of controllers, setting a flow entry in which rules and operations for uniformly controlling a packet as a flow are defined in the flow table;
Adopting the route set by the controller that has completed the setting of the flow entry of all network devices on the route earliest among the plurality of controllers, disabling the route set by the other controller, and adopting the route Routing method comprising: forwarding the packet according to a flow entry of: Based on control from each of the plurality of controllers, setting a flow entry in which a rule and operation for uniformly controlling a packet as a flow are defined in a flow table;
Adopting the route set by the controller that has completed the setting of the flow entry of all network devices on the route earliest among the plurality of controllers, disabling the route set by the other controller, and adopting the route A storage medium storing a program for causing a network device to execute a step of transferring a packet in accordance with the flow entry.

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