WO2014119602A1

WO2014119602A1 - Control apparatus, switch, communication system, switch control method and program

Info

Publication number: WO2014119602A1
Application number: PCT/JP2014/051913
Authority: WO
Inventors: 亮佑河合
Original assignee: 日本電気株式会社
Priority date: 2013-01-30
Filing date: 2014-01-29
Publication date: 2014-08-07

Abstract

The objective of the invention is to contribute to the improvement of resistance to troubles and of availability for a centralized control type of network using, as a control channel, a data transfer channel between switches. A control apparatus comprises: a topology storage unit that stores a connectional relationship between switches connected by a data transfer channel; a control channel management unit that manages the information of a control channel configured by use of the data transfer channel between the switches; a switch control unit that controls a group of switches via the control channel; and a control channel reconfiguration unit that changes paths of the control channel on the basis of information acquired from the switches.

Description

Control device, switch, communication system, switch control method and program

[Description of related applications]
The present invention is based on a Japanese patent application: Japanese Patent Application No. 2013-015091 (filed on January 30, 2013), and the entire contents of the application are incorporated herein by reference.
The present invention relates to a control device, a switch, a communication system, a switch control method, and a program, and more particularly, to a control device, a communication system, a switch control method, and a program for centralized control of switches.

In recent years, attention has been focused on a network in which a packet transfer function of a network device and a control function such as route control are separated. In such a network, the network device is responsible for the packet transfer function, and the controller separated outside the network device is responsible for the control function. In this way, it becomes possible to construct a network that is easy to control and rich in flexibility.

Patent Document 1 and Non-Patent Documents 1 and 2 propose a technique called OpenFlow that realizes the above-described centralized control type network. OpenFlow captures communication as an end-to-end flow and performs path control, failure recovery, load balancing, and optimization on a per-flow basis. The OpenFlow switch specified in Non-Patent Document 2 includes a secure channel for communication with the OpenFlow controller, and operates according to a flow table that is appropriately added or rewritten from the OpenFlow controller. For each flow, a set of match conditions (Match Fields), flow statistical information (Counters), and instructions (Instructions) that define processing contents are defined for each flow (non-patented). (Refer to “5.2 Flow Table” in Document 2).

For example, when the OpenFlow switch receives a packet, the OpenFlow switch searches the flow table for an entry having a matching condition (see “5.3 Matching” in Non-Patent Document 2) that matches the header information of the received packet. If an entry that matches the received packet is found as a result of the search, the OpenFlow switch updates the flow statistical information (counter) and processes the processing (designated) in the instruction field of the entry for the received packet. Perform packet transmission, flooding, discard, etc. from the port. On the other hand, if no entry matching the received packet is found as a result of the search, the OpenFlow switch sends an entry setting request to the OpenFlow controller via the secure channel, that is, a control for processing the received packet. An information transmission request (Packet-In message) is transmitted. The OpenFlow switch receives a flow entry whose processing content is defined and updates the flow table. As described above, the OpenFlow switch performs packet transfer using the entry stored in the flow table as control information.

JP 2011-170718 A

The following analysis is given by the present invention. As a control channel for communication between the control device of the network on the central control side and the switch, a control channel is prepared, and a control channel is provided in the data network between the switches without providing a control network. (Hereinafter referred to as “In-band control method”, for example, see Non-Patent Document 3). The in-band control method is a realistic method when the network becomes large, and it is considered that OpenFlow will spread in the future to be applied to large-scale networks and server virtualization environments.

However, the in-band control method has two major problems. The first problem is that even if a failure or the like of a switch on the path constituting the control channel has occurred, even if the switch and the switch connected thereto become uncontrollable, the control device immediately It is a point that cannot be detected.

The second problem is that even if the control device can detect that the switch has become uncontrollable, for example, by confirming the existence of the switch, the control channel is not reconfigured unless the control channel is reconstructed by some means. It is a point that the control of the switch which used the system cannot be resumed.

In Non-Patent Document 3, it is necessary to add a function for interpreting special frames to each switch, which may offset the advantage of the in-band control method that can be applied to a large-scale network.

An object of the present invention is to provide a control device, a switch, a communication system, a switch control method, and a program that can contribute to the improvement of fault tolerance and availability of a network that uses an in-band control method for a control channel.

According to the first aspect, a topology storage unit that stores a connection relationship between switches connected by a data transfer channel, and a control that manages information of a control channel configured using the data transfer channel between the switches A channel management unit, a switch control unit that controls the switch group via the control channel, and a control channel reconfiguration unit that changes a path of the control channel based on information obtained from the switch. A control device is provided.

According to a second aspect, there is provided a switch that includes a routing table for transferring control packets to a control device and rewrites the routing table in response to an instruction to change the control channel from the control device.

According to a third aspect, a topology storage unit that stores a connection relationship between switches connected by a data transfer channel, and a control that manages information of a control channel configured using the data transfer channel between the switches A channel management unit, a switch control unit that controls the switch group via the control channel, and a control channel reconfiguration unit that changes a path of the control channel based on information obtained from the switch. There is provided a communication system including a control device and a switch group for processing a received packet based on control information set by the control device via the control channel.

According to a fourth aspect, a topology storage unit that stores a connection relationship between switches connected by a data transfer channel, and a control that manages information on a control channel configured using the data transfer channel between the switches A control device comprising a channel management unit and a switch control unit that controls the switch group via the control channel receives information indicating a state of a data transfer channel used as the control channel from the switch. There is provided a method for controlling a switch, including a step of obtaining, and a step of changing a route of the control channel based on information obtained from the switch. This method is linked to a specific machine, which is a control device that controls the switch group through a control channel configured using a data transfer channel between switches.

According to a fifth aspect, a topology storage unit that stores a connection relationship between switches connected by a data transfer channel, and a control that manages information on a control channel configured using the data transfer channel between the switches A computer having a channel management unit and a switch control unit that controls the switch group via the control channel acquires information indicating the state of the data transfer channel used as the control channel from the switch. And a program for executing a process of changing the route of the control channel based on information obtained from the switch. This program can be recorded on a computer-readable (non-transient) storage medium. That is, the present invention can be embodied as a computer program product.

According to the present invention, it is possible to contribute to the improvement of fault tolerance and availability of a centralized control network that uses an in-band control method for a control channel.

It is a figure which shows the structure of one Embodiment of this invention. It is a figure for demonstrating operation | movement of one Embodiment of this invention. It is a figure for demonstrating operation | movement of one Embodiment of this invention. It is a figure which shows the structure of the communication system of the 1st Embodiment of this invention. It is a figure which shows an example of the control channel information hold | maintained at the control channel information storage part of the control apparatus of the 1st Embodiment of this invention. It is a figure which shows the detailed structure of the switch of the 1st Embodiment of this invention. It is a figure which shows the structure of the control information (flow entry) hold | maintained at the switch of the 1st Embodiment of this invention. It is a figure for demonstrating the operation | movement of the 1st Embodiment of this invention. It is a flowchart showing operation | movement (control channel establishment operation | movement) of the control apparatus of the 1st Embodiment of this invention. It is a figure for demonstrating the control channel establishment operation | movement by the control apparatus of the 1st Embodiment of this invention. It is a flowchart showing operation | movement (control channel switching operation) of the control apparatus of the 1st Embodiment of this invention. It is a figure for demonstrating the control channel switching operation | movement by the control apparatus of the 1st Embodiment of this invention.

First, an outline of an embodiment of the present invention will be described with reference to the drawings. Note that the reference numerals of the drawings attached to this summary are attached to the respective elements for convenience as an example for facilitating understanding, and are not intended to limit the present invention to the illustrated embodiment.

In one embodiment of the present invention, as shown in FIG. 1, a topology storage unit 315 that stores connection relationships between switches 33-1 to 33-4 connected by a data transfer channel, and a control channel management unit 313 And a control device 31A including a switch control unit 312 that controls the switch group via a control channel configured using a data transfer channel, and a control channel reconfiguration unit 314.

More specifically, the control channel management unit 313 manages information on the control channel configured using the data transfer channel between the switches 33-1 to 33-4. Then, the control channel reconfiguring unit 314 performs an operation of changing the route of the control channel based on information obtained from the switch.

For example, as shown in FIG. 2, in a situation where a control channel (shown by a double arrow line) is provided between the control device 31A and the switches 33-1 to 33-4, the switch 33-4 of the switch 33-3 is connected. Suppose that a failure occurs in the connection port. In this case, the control channel reconfiguration unit 314 refers to the topology storage unit 315 and determines that an alternative route passing through the switches 33-1 33-2, and 33-4 can be configured, and is shown in FIG. As described above, the route of the control channel of the switch 33-4 is changed. The trigger for the control channel reconfiguring unit 314 to change the control channel path is not limited to the failure of the switch port on the control channel. For example, the path of the control channel can be changed in response to the occurrence of congestion in the data transfer channel that accommodates the control channel or the new connection of the host to the switch controlled by the control channel.

As described above, since the control channel can be flexibly changed, it becomes possible to improve the fault tolerance and availability of the centralized control network.

[First Embodiment]
Next, a first embodiment of the present invention will be described in detail with reference to the drawings. FIG. 4 is a diagram illustrating the configuration of the communication system according to the first embodiment of this invention. Referring to FIG. 4, a switch 33 (hereinafter referred to as “switch 33” when the switches are not particularly distinguished) and a control device 31 that controls the switch 33 are shown. In FIG. 4, only one switch 33 is shown, but a plurality of switches 33 may be connected to the control device 31. Further, the control device 31 can control not only these directly connected switches but also other switches connected in a stack via the switch 33.

The control device 31 includes a path calculation unit 311, a switch control unit 312, a control channel management unit 313, a topology storage unit 315, and a control channel information storage unit 316.

The topology storage unit 315 stores topology information of a network configured by a switch to be controlled by the control device 31. The network topology information stored in the topology storage unit 315 may be set by a network administrator, or the control device 31 using information collected from the switch 33 using LLDP (Link Layer Discovery Protocol) or the like. May be automatically generated.

When the route calculation unit 311 receives a route calculation request from the switch control unit 312, the route calculation unit 311 refers to the topology information stored in the topology storage unit 315 and calculates a route between any switches. The Dijkstra method or the like can be used as a route calculation method. The routes calculated by the route calculation unit 311 include not only a route for transferring data packets but also a route (control channel) for transferring control packets between the control device 31 and an arbitrary switch. Therefore, the path calculation unit 311 has an alternative path calculation function of the control channel reconfiguration unit 314 described above.

Upon receiving a control information (flow entry) transmission request message (corresponding to “Packet-In message” in Non-Patent Document 2) from the switch 33, the switch control unit 312 requests the route calculation unit 311 to calculate a route. When the switch control unit 312 receives a route from the route calculation unit 311, the switch control unit 312 generates control information (flow entry) for transferring a packet along the route to the switch 33 on the route, and sends the control information to the switch 33 on the route. Set. Furthermore, when the generated control information (flow entry) is control information (flow entry) for constructing a control channel via the control channel management unit 313, the switch control unit 312 determines the control information (flow entry). ), Information on the switch in which the control information (flow entry) is set (described later flow entry owner information), and information on the switch controlled by the control channel (described later control channel owner information) The operation of saving in 316 is performed.

In response to a request from the switch control unit 312, the control channel management unit 313 receives control information (flow entry) as control channel configuration information and information on the switch in which the control information (flow entry) is set (described later). Flow entry owner information) and switch information (control channel owner information described later) controlled by the control channel are stored in the control channel information storage unit 316.

When the control channel management unit 313 receives a port failure status notification (for example, notified by “Port Status message” in Non-Patent Document 2) from the switch 33 via the switch control unit 312, the control channel management unit 313 receives the control channel. With reference to the information storage unit 316, the control channel affected by the failure of the port of the switch is searched, and when the affected control channel is found, the route calculation unit 311 is requested to calculate an alternative route. When the alternative route is calculated by the route calculation unit 311, the control channel management unit 313 replaces the control channel via the switch control unit 312 and is held in the control channel information storage unit 316. Update control information (flow entry).

FIG. 5 is a diagram illustrating an example of control channel information held in the control channel information storage unit 316. In the example of FIG. 5, the content of control information (flow entry) consisting of a combination of a match condition, a counter, and an instruction, information on the switch in which the control information (flow entry) is set (flow entry owner information), An entry associating information (switch channel owner information described later) of a switch controlled by the control channel is shown. The control channel information in FIG. 5 includes the control information (flow entry) set in the switch on the control channel of the switch 33-4 via the switches 33-1 and 33-2 in FIG. DPID) and the control target switch of the control channel are associated with each other.

FIG. 6 is a block diagram showing a detailed configuration of the switch 33. Referring to FIG. 6, the switch 33 includes a routing table 331 that defines next hop information of a control packet to be transmitted to the control device 31, and a control information storage unit 333 that stores control information (flow entry) received from the control device 31. A packet processing unit 332 that searches the control information (flow entry) stored in the control information storage unit 333 for control information (flow entry) having a matching condition that matches the received packet, and processes the packet; It has. As a result of the search, the packet processing unit 332 requests the control device 31 to send a control information (flow entry) transmission request when control information (flow entry) having matching conditions matching the received packet is not found. . When receiving the control information (flow entry) from the control device 31, the packet processing unit 332 stores the received control information (flow entry) in the control information storage unit 333. Further, when the packet to be transmitted is a control packet addressed to the control device 31, the packet processing unit 332 transmits the control packet from the port defined in the routing table 331.

Here, the control information (flow entry) held in the control information storage unit 333 of the switch 33 will be described. FIG. 7 is a diagram illustrating a configuration example of control information (flow entry) set in the control information storage unit 333 of the switch 33 by the control device 31. Referring to FIG. 7, the control information (flow entry) corresponds to a match condition, a counter that records statistical information of a packet that matches the match condition, and an instruction that indicates processing contents to be applied to the packet that matches the match condition. It is configured with. As shown in the lower part of FIG. 7, the match condition is configured by any combination of fields from layer 1 to layer 4. Each information can be set with a wild card. As instructions, it is possible to designate packet transfer (Output), discard (Drop), header rewriting (SET), and the like.

Note that the match condition in FIG. 7 is not limited to the illustrated example. For example, an IPv6 header or the like can be added to the match condition. The counter field may be omitted.

Each unit (processing means) of the control device 31 and the switch 33 shown in FIGS. 4 and 6 is executed by a computer program that causes a computer constituting these devices to execute the above-described processes using the hardware. It can also be realized.

Subsequently, the operation of the present embodiment will be described in detail with reference to the drawings. First, the operation of the control device 31 for establishing the control channel with the switches 33-1 to 33-4 in the configuration shown in FIG. 8 will be described.

In the configuration illustrated in FIG. 8, the switch 33-1 directly connected to the control device 31 transmits a control packet (for example, a Hello message of Non-Patent Document 2) to the control device 31 according to its own routing table 331. The control channel is established. Next, when the switch 33-2 (switch 33-3) tries to establish a control channel with the control device 31, the first control packet from the switch 33-2 (switch 33-3) The switch 33-3) is transferred to the switch 33-1 according to its own routing table 331. On the other hand, when the switch 33-1 receives the first control packet from the switch 33-2 (switch 33-3), the switch 33-1 matches the corresponding match from the control information (flow entry) set in the control information storage unit 333. Search for control information (flow entry) with conditions. However, at this time, the control information (flow entry) corresponding to the first control packet from the switch 33-2 (switch 33-3) is not set in the switch 33-1, so that the switch 33-1 does not control. The device 31 is requested to transmit control information (flow entry) by a Packet-In message.

FIG. 9 is a flowchart showing the operation (control channel establishment operation) of the control device 31 triggered by reception of the transmission request for the control information (flow entry). Hereinafter, the control channel establishment operation of the control device 31 will be described with reference to FIG. First, when the switch 33-1 receives a new packet (control packet of the switch 33-2 or 33-3) from an arbitrary switch (step S001), the route calculation unit 311 sends a transmission request for control information (flow entry). The header of the packet received (Packet-In message) is analyzed, and the transfer path is calculated. Further, the control device 31 uses the switch control unit 312 to generate control information (flow entry) to be set for the switch on the transfer path (step S003). At this time, the control device 31 controls not only control information (flow entry) for transferring a control packet from the switch to the control device 31, but also control information (flow entry) for transferring a control packet from the control device 31 to the switch. ) May be generated.

Next, in the control channel management unit 313, the control device 31 determines whether or not the calculated route is a control channel (step S004). Whether or not the calculated route is a control channel is determined whether or not the destination IP address of the target packet matches the IP address of the control device 31, and the reception port of the packet in the switch 33-1 is the switch 33-2. Alternatively, the determination can be made based on whether the connection port is 33-3.

If it is determined that the calculated path is a control channel, the control channel management unit 313 stores control information (flow entry) set in the control channel information storage unit 316 in the switch on the path shown in FIG. ) And two pieces of owner information are stored (step S005).

Thereafter, the control device 31 sets the flow entry generated by the switch control unit 312 to the switch on the route calculated in step S003 (step S006).

Finally, the control device 31 sends a control information (flow entry) transmission request (Packet-In message) to the switch 33-1 that is the transmission source of the control information (flow entry) transmission request (Packet-In message). Is instructed to transfer the packet that triggered the request according to the calculated route (step S007; using the Packet-Out message of Non-Patent Document 2).

As described above, the control packet that triggered the transmission request (Packet-In message) of the control information (flow entry) and the subsequent control packet are the control information (flow entry) set in the switch on the path constituting the control channel. ) And transferred.

Through the above processing, the switch 33-2 or 33-3 is added to the control target of the control device 31. Similarly, when the switch 33-4 transmits a control packet to the switch 33-2 or 33-3 determined in its own routing table 331, the switch 33-2 or 33-3 transmits to the control device 31. On the other hand, a packet-in message requests transmission of control information (flow entry) for processing the control packet from the switch 33-4. Then, the control device 31 calculates a necessary route and sets control information (flow entry), so that the switch 33-4 is added to the control target of the control device 31. Finally, as shown in FIG. 10, establishment of a control channel between the control device 31 and the switches 33-1 to 33-4 is realized.

FIG. 11 is a flowchart showing the operation (control channel switching operation) of the control device 31 according to the first embodiment of the present invention. Hereinafter, the control channel switching operation of the control device 31 will be described with reference to FIG. First, when each of the switches 33-1 to 33-4 detects a link down of a connection port with another switch, the switch 33-1 to 33-4 transmits a failure notification (port down) to the control device 31.

When the control device 31 receives a failure notification (port down) (step S101), the control channel management unit 313 searches the control channel information storage unit 316 for a control channel affected by the failure of the port of the switch. (Step S102). The presence of a control channel that is affected by a failure of a port of a switch is searched for an entry in which the flow entry owner information (switch information) of the entry illustrated in FIG. 5 matches the output port defined in the instruction field. Can be found at

As a result of the search, when a control channel affected by the port down is found, that is, when it is determined that the control channel needs to be replaced (Yes in step S103), the control device 31 uses the path calculation unit 311. , Calculate alternative routes. Further, in the control device 31, the switch control unit 312 generates control information (flow entry) to be set for the switch on this alternative route (step S104).

As a result of the calculation of the alternative route, when the alternative route can be calculated and control information (flow entry) can also be generated (Yes in step S105), the control device 31 switches the switch on the alternative route calculated in step S104 to the switch. The flow entry generated by the control unit 312 is set (step S106). Further, the control device 31 instructs the switch on the previous control channel to delete the control information (flow entry) for the control channel that is no longer needed, if necessary.

Finally, the control device 31 instructs the switch of the alternative path owner calculated in step S104 to switch the control channel (step S107). Specifically, processing for instructing rewriting of the routing table 331 is performed so as to change the port that outputs the packet addressed to the control device 31.

If it is determined in step S103 that control channel replacement is not required (No in step S103) and if an alternative route cannot be calculated in step S105 (No in step S105), the topology information in the topology storage unit 315 is used. A process of removing the corresponding switch and excluding it from the control target is performed.

Here, a specific example will be described to explain the control channel replacement. For example, it is assumed that the control channel of the In-band control method as shown by the double arrow in FIG. 10 has been established by repeating the series of processing shown in FIG.

From the state of FIG. 10, for example, assume that a failure has occurred in the link between the switch 33-1 and the switch 33-2. At this time, the switch 33-1 notifies the control device 31 that the port connected to the switch 33-2 is down.

The control device 31 that has received the notification refers to the control channel information held in the control channel information storage unit 316, and the control channel affected by the failure of the link is the control channel of the switch 33-2 and the switch It is determined that the control channel is 33-4. And the control apparatus 31 calculates an alternative path | route as shown, for example in FIG.

Then, the control device 31 deletes the control information (flow entry) set in the switch on the previous control channel, and causes the switch on the new control channel to transfer the control packet along the alternative route. Send control information (flow entry).

Finally, the control device 31 instructs the switch 33-2 and the switch 33-4 in which the control channel is changed to change the control channel (rewrite the routing table 331). Thus, the control channel replacement is completed.

Note that the following two methods are conceivable as a method of instructing the switch to rewrite the routing table 331.
(1) The first method is a method using UDP (User Datagram Protocol). A port for switching the control channel is prepared in advance in the switch 33 and is set in the Listen state. When receiving the control channel switching instruction from the control device 31, the switch 33 rewrites the routing table 331 and reconnects the control channel. The rewriting contents of the routing table 331 may be included in the control channel switching instruction.

(2) The second method is a method in which control information (flow entry) for rewriting the routing table is set in advance in the control information storage unit 333 of the switch 33. For example, control information (flow entry) in which predetermined matching conditions and instructions (processing contents) for decoding a packet by the network processor and rewriting the routing table 331 are set. Then, by causing the switch 33 to transmit a packet from the nearest switch, the routing table can be rewritten and the control channel can be reconnected. The rewriting contents of the routing table 331 can be controlled by setting a plurality of control information (flow entries) having different match conditions and rewriting contents of the routing table 331 and changing a packet transmitted to the switch.

Finally, the reason why the above control channel replacement is not realized by a general TCP (Transmission Control Protocol) will be described. That is, when the control device 31 and the switch 33 negotiate to establish TCP communication, the packet from the switch 33 is transmitted to the path in which the failure has occurred according to the routing table 331 before rewriting, and may fail. It is because there is sex.

For example, when the routing table 331 of the switch 33-4 in FIG. 12 is to be rewritten, a packet from the switch 33-4 to the control device 31 is transmitted to the switch 33-2 on the route before re-transition and is transmitted to the control device 31. Will not reach. In this regard, according to the above-described rewriting instruction method for the two routing tables 331, the routing table 331 can be reliably rewritten.

Also, when using the above-described two routing table 331 rewrite instruction methods, it is preferable to consider security. For example, there is a possibility that a malicious third party impersonates the control device 31 and instructs the rewriting of the routing table 331 to take over the switch.

It is conceivable to use a mechanism such as an electronic signature as a method for solving this problem. That is, when the control channel is established, the control device 31 and the switch 33 exchange their public keys with each other. When a failure occurs, the control device 31 issues a control channel switching instruction to the corresponding switch 33. The hash value is encrypted with the private key of the control device 31 itself to create an electronic signature. Then, the control device 31 encrypts the control channel switching instruction with the public key of the switch 33, adds an electronic signature, and transmits it to the switch 33. When the switch 33 receives the encrypted control channel switching instruction, the switch 33 decrypts the control channel switching instruction using the private key of the switch 33 itself. Next, the hash value of the control channel redirection instruction is obtained with the public key of the control device 31 exchanged in advance, and compared with the hash value sent from the control device 31 to confirm that it has not been tampered with.

As described above, according to the present embodiment, it is possible to improve fault tolerance and availability when a switch is controlled by an in-band control method in a centralized control type network represented by OpenFlow. Specifically, it is possible to determine whether or not there is an influence on the control channel from a change in the state of the port, and to deal with the problem with a minimum of downtime.

Then, if necessary, it is possible to calculate an alternative route for the control channel and replace the control channel to continue control of the switch.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and further modifications, substitutions, and adjustments are possible without departing from the basic technical idea of the present invention. Can be added. For example, the network configuration and the configuration of elements shown in the drawings are examples for helping understanding of the present invention, and are not limited to the configurations shown in these drawings.

In addition, for example, in the above-described embodiment, the control channel is replaced when triggered by the reception of the port down notification from the switch. However, the occurrence of congestion in the data transfer channel that accommodates the control channel, the control channel The control channel can be re-established when a host is newly connected to the switch controlled by the control. The occurrence of congestion in the data transfer channel can be confirmed by the controller 31 inquiring from the switch 33 the value of the counter that records the statistical information of the packet that matches the matching condition in the control information (flow entry). Further, a new connection of the host to the switch 33 can be detected by receiving from the switch 33 a Packet-In message for a packet transmitted from the host.

Finally, a preferred form of the invention is summarized.
[First embodiment]
(Refer to the control device according to the first viewpoint)
[Second form]
In the control device of the first form,
The control device that changes the path of the control channel when the failure occurs in a switch on the path of the control channel.
[Third embodiment]
In the control device of the first or second form,
A control device that changes a path of the control channel when congestion occurs in a data transfer channel on the path of the control channel.
[Fourth form]
In the control device according to any one of the first to third aspects,
The control channel reconfiguration unit transmits a control channel change instruction to the switch using UDP (User Datagram Protocol),
A control device that causes the switch to rewrite a routing table for transferring control packets to the control device.
[Fifth embodiment]
In the control device according to any one of the first to third aspects,
Control information for rewriting the routing table for transferring the control packet to the control device is set in the switch,
A control device that causes the switch to rewrite a routing table for transferring control packets to the control device by transmitting a control channel change instruction packet that matches the control information to the switch.
[Sixth embodiment]
In the control device of the fourth or fifth aspect,
A control device that adds a predetermined electronic signature to the control channel change instruction to the switch.
[Seventh form]
(Refer to the switch from the second viewpoint above.)
[Eighth form]
(Refer to the communication system according to the third viewpoint)
[Ninth Embodiment]
(Refer to the switch control method from the fourth point of view)
[Tenth embodiment]
(Refer to the program from the fifth viewpoint above)
Note that the seventh to tenth embodiments can be developed into the second to sixth embodiments as in the first embodiment.

It should be noted that the disclosures of the above patent documents and non-patent documents are incorporated herein by reference. Within the scope of the entire disclosure (including claims) of the present invention, the embodiments and examples can be changed and adjusted based on the basic technical concept. Further, various combinations or selections of various disclosed elements (including each element of each claim, each element of each embodiment or example, each element of each drawing, etc.) within the scope of the claims of the present invention. Is possible. That is, the present invention of course includes various variations and modifications that could be made by those skilled in the art according to the entire disclosure including the claims and the technical idea. In particular, with respect to the numerical ranges described in this document, any numerical value or small range included in the range should be construed as being specifically described even if there is no specific description.

31, 31A Control device 33, 33-1 to 33-4 Switch 311 Path calculation unit 312 Switch control unit 313 Control channel management unit 314 Control channel reconfiguration unit 315 Topology storage unit 316 Control channel information storage unit 331 Routing table 332 Packet processing 333 Control information storage unit

Claims

A topology storage unit for storing connection relationships between switches connected by a data transfer channel;
A control channel management unit that manages information of a control channel configured using the data transfer channel between the switches;
A switch control unit for controlling the switch group via the control channel;
A control channel reconfiguration unit configured to change a path of the control channel based on information obtained from the switch;
The control device according to claim 1, wherein the control channel reconfiguration unit changes the path of the control channel when a failure occurs in a switch on the path of the control channel.
The control device according to claim 1 or 2, wherein the control channel reconfiguration unit changes a path of the control channel when congestion occurs in a data transfer channel on the path of the control channel.
The control channel reconfiguration unit transmits a control channel change instruction to the switch using UDP (User Datagram Protocol),
4. The control device according to claim 1, wherein the switch rewrites a routing table for transferring a control packet to the control device. 5.
Control information for rewriting the routing table for transferring the control packet to the control device is set in the switch,
4. The control switch change instruction packet matching the control information is transmitted to the switch so that the switch rewrites a routing table for transferring the control packet to the control device. One of the control devices.
The control device according to claim 4 or 5, wherein a predetermined electronic signature is added to the control channel change instruction to the switch.
A routing table for transferring control packets to the control device according to claim 4;
A switch for rewriting the routing table in response to an instruction to change the control channel from the control device.
A topology storage unit for storing connection relationships between switches connected by a data transfer channel;
A control channel management unit that manages information of a control channel configured using the data transfer channel between the switches;
A switch control unit for controlling the switch group via the control channel;
A control device comprising a control channel reconfiguration unit that changes the path of the control channel based on information obtained from the switch;
A switch group that processes received packets based on control information set by a control device via the control channel.
A topology storage unit for storing connection relationships between switches connected by a data transfer channel;
A control channel management unit that manages information of a control channel configured using the data transfer channel between the switches;
A control device comprising: a switch control unit that controls the switch group via the control channel;
Obtaining information indicating a state of a data transfer channel used as the control channel from the switch;
Changing the path of the control channel based on information obtained from the switch.
A topology storage unit for storing connection relationships between switches connected by a data transfer channel;
A control channel management unit that manages information of a control channel configured using the data transfer channel between the switches;
A computer comprising a switch control unit that controls the switch group via the control channel,
A process of acquiring information indicating a state of a data transfer channel used as the control channel from the switch;
A program for executing a process of changing a route of the control channel based on information obtained from the switch.