WO2012101692A1

WO2012101692A1 - Communication system, control information relay device, control device, and control information transmission method and program

Info

Publication number: WO2012101692A1
Application number: PCT/JP2011/005555
Authority: WO
Inventors: Toshio Koide
Original assignee: Nec Corporation
Priority date: 2011-01-28
Filing date: 2011-09-30
Publication date: 2012-08-02
Also published as: JP2014507820A; JP5854049B2

Abstract

A communication system comprises a control device controlling a plurality of forwarding nodes, and forwarding nodes processing a received packet in accordance with control information received from the control device the system further comprising: a channel establishing unit establishing a control channel used in transmission of the control information between the control device and respective forwarding nodes, by using a network comprising the control device and the respective forwarding nodes; and an address conversion unit arranged between the forwarding nodes and the control device, the address conversion unit executing a first conversion process of performing conversion such that control information transmitted via the control channel from the control device can be recognized as being control information received from a prescribed control device by the respective forwarding node(s), and a second conversion process of performing conversion such that control information transmitted via the control channel from any one of the forwarding nodes can be recognized as being control information received from a prescribed forwarding node by the control device.

Description

COMMUNICATION SYSTEM, CONTROL INFORMATION RELAY DEVICE, CONTROL DEVICE, AND CONTROL INFORMATION TRANSMISSION METHOD AND PROGRAM

(Reference to Related Application)
The present invention is based upon and claims the benefit of the priority of Japanese patent application No. 2011-016324, filed on January 28, 2011, the disclosure of which is incorporated herein in its entirety by reference thereto.
The present invention relates to a communication system, a control information relay device, a control device, and a control information transmission method and program, and in particular, relates to a communication system, a control information relay device, a control device, and a control information transmission method and program, in which the control device uses control information to perform central control of forwarding nodes disposed in a network.

Technology referred to as OpenFlow is known as a communication system in which a control device performs central control of forwarding nodes (refer to Patent Literature 1, and Non Patent Literatures 1 and 2). In OpenFlow, communication is taken as end-to-end flow, and routing control, recovery from failure, load balancing, and optimization are performed in flow units. An OpenFlow switch specified in Non Patent Literature 2 is provided with a secure channel for communication with an OpenFlow controller that is positioned as a control device, and operates according to a flow table in which appropriate addition or rewriting is instructed by the OpenFlow controller. In the flow table are definitions of sets of matching rules (header fields) that refer to packet headers, flow statistical information (Counters), and actions (Actions) defining processing content, for each flow (refer to Fig. 14).

For example, when an OpenFlow switch receives a packet, an entry is searched for, which has a matching rule (refer to header field in Fig. 14) conforming to header information of the received packet, from the flow table. As a result of the search, in a case where an entry conforming to the received packet is found, the OpenFlow switch updates the flow statistical information (Counters) and also implements processing content (packet transmission from a specified port, flooding, dropping, and the like) described in an action field of the entry in question, with respect to the received packet. On the other hand, as a result of the search, in a case where an entry conforming to the received packet is not found, the OpenFlow switch forwards the received packet to the OpenFlow controller via a secure channel, requests determination of a route of the packet based on source and destination of the received packet, receives a flow entry for realizing this, and updates the flow table. In this way, the OpenFlow switch performs packet forwarding using an entry stored in the flow table as a processing rule.

Non Patent Literature 3 proposes building a secure channel with regard to the OpenFlow network as described above, in a real network using special frames and source routing (a control channel built in this real network is referred to below as an "in-band secure channel").

International Publication No. WO 2008/095010 Japanese Patent Kohyo Publication No. JP-P2009-510566A

Nick McKeown, and 7 others, "OpenFlow: Enabling Innovation in Campus Networks", [online], [search conducted December 22, 2010] Internet URL:http://www.openflowswitch.org//documents/openflow-wp-latest.pdf "OpenFlow: Switch Specification" Version 1.0.0. (Wire Protocol 0x01), [search conducted December 22, 2010] Internet URL:http://www.openflowswitch.org/documents/openflow-spec-v1.0.0.pdf Koide Toshio and Shimonishi, Hideyuki, "A Study on the Automatic Construction Mechanism of Control Network in OpenFlow-based Network", The Institute of Electronics, Information and Communication Engineers, IEICE Technical Report NS2009-165 (2010-3), Vol. 109, No. 448, pp. 19-24, March, 2010

The following analysis is given by the present invention. Henceforth, by using a method of Non Patent Literature 3 described above, it will be possible to build a network based on OpenFlow as described above, using an in-band secure channel, without preparing a network specially for control, in a business or home.

In order to have correct mutual recognition between a control device functioning as an OpenFlow controller and a forwarding node functioning as an OpenFlow switch via the abovementioned in-band secure channel so as to perform an exchange of control information, it is necessary that the control device and the forwarding node comprehend each other's addresses. For example, in a case of purchasing network equipment based on a specification of the OpenFlow switch of Non Patent Literature 2 and building a network, a task occurs of setting a unique address for a control channel in the network equipment and control device, respectively.

The present invention has been carried out in view of the abovementioned situation, and it is an object to provide a configuration and method that can reduce the task of setting addresses in a case of building a centrally controlled network as represented by OpenFlow, by using the abovementioned in-band secure channel.

According to a first aspect of the present invention there is provided a communication system comprising: a control device that controls a plurality of forwarding nodes, and forwarding nodes that process a received packet in accordance with control information received from the control device. The communication system further comprises; a channel establishing unit that establishes a control channel used in transmission of the control information between the control device and respective forwarding nodes, by using a network that comprises the control device and the respective forwarding nodes. An address conversion unit is arranged between the forwarding nodes and the control device, the address conversion unit executing a first conversion process of performing conversion such that control information transmitted via the control channel from the control device can be recognized as being control information received from a prescribed control device by the respective forwarding node(s), and a second conversion process of performing conversion such that control information transmitted via the control channel from any one of the forwarding nodes can be recognized as being control information received from a prescribed forwarding node by the control device.

According to a second aspect of the present invention there is provided a control information relay device arranged between a control device that controls a plurality of forwarding nodes, and a forwarding node(s) that processes a received packet in accordance with control information received from the control device. The control information relay device comprises: an address conversion unit that executes a first conversion process of performing conversion such that control information transmitted from the control device can be recognized as being control information received from a prescribed control device by the respective forwarding node(s), and a second conversion process of performing conversion such that control information transmitted from any one of the forwarding nodes can be recognized as being control information received from a prescribed forwarding node by the control device; wherein transfer (transmitting and receiving) of control information is realized via a control channel established between the respective forwarding node(s) and the control device, by using a network that comprises the control device and the respective forwarding node(s).

According to a third aspect of the present invention there is provided a control device comprising: a forwarding node control unit that, by transmitting control information to a forwarding node(s), causes the forwarding node(s) to process a received packet in accordance with the control information; a channel establishing unit that establishes a control channel used in transmission of the control information between the control device and respective forwarding node(s), by using a network that includes the control device and the respective forwarding node(s). The control device further comprises an address conversion unit disposed between the forwarding node(s) and the control device, the address conversion unit executing a first conversion process of performing conversion such that control information transmitted via the control channel from the control device can be recognized as being control information received from a prescribed control device by any one of the respective forwarding nodes, and a second conversion process of performing conversion such that control information transmitted via the control channel from any one of the forwarding nodes can be recognized as being control information received from a prescribed forwarding node by the control device.

According to a fourth aspect of the present invention there is provided a method of transmitting and receiving control information, the method comprising: a step of establishing a control channel used in transmission of the control information between a control device and respective forwarding node(s), by using a network that includes the control device and the respective forwarding node(s); a step of performing conversion, between the forwarding nodes and the control device, such that control information transmitted via the control channel from the control device can be recognized as being control information received from a prescribed control device, by the respective forwarding node(s). The method further comprises a step of performing conversion such that control information transmitted via the control channel from the forwarding nodes can be recognized as being control information received from a prescribed forwarding node, by the control device. The present method is linked with a specific apparatus, known as a communication system that comprises the control device and forwarding nodes, as described above.

According to a fifth aspect of the present invention there is provided a program executed on a computer provided between a control device that controls a plurality of forwarding nodes, and a forwarding node(s) that processes a received packet in accordance with control information received from the control device. The program executes: a process of performing conversion such that control information transmitted via the control channel from the control device can be recognized as being control information received from a prescribed control device by the respective forwarding node(s); and a process of performing conversion such that control information transmitted via the control channel from any one of the forwarding node(s) can be recognized as being control information received from a prescribed forwarding node, by the control device. It is to be noted that the program can be recorded in a computer readable storage medium which is typically non-transient. That is, the present invention can be embodied as a computer program product.

According to the present invention, it is possible to reduce the task of setting addresses upon establishing a centrally controlled network represented by OpenFlow, by using the in-band secure channel described above.

Fig. 1 is a diagram for describing an outline of a mode of the present disclosure; Fig. 2 is an example of an address conversion table for realizing address conversion shown in Fig. 1; Fig. 3 is a diagram showing a configuration of a first exemplary embodiment of the present disclosure; Fig. 4 is an example of an address conversion table held in an address conversion table holding unit of a control information relay device of the first exemplary embodiment; Fig. 5 is a flowchart for describing operation of the control information relay device of the first exemplary embodiment; Fig. 6 is another example of an address conversion table held in an address conversion table holding unit of a control information relay device of the first exemplary embodiment; Fig. 7 is another example of an address conversion table held in an address conversion table holding unit of a control information relay device of the first exemplary embodiment; Fig. 8 is another example of an address conversion table held in an address conversion table holding unit of a control information relay device of the first exemplary embodiment; Fig. 9 is a reference diagram for describing operations of the first exemplary embodiment; Fig. 10 is a reference diagram for describing operations of the first exemplary embodiment; Fig. 11 is a diagram showing a configuration of a second exemplary embodiment of the present disclosure; Fig. 12 is a reference diagram for describing operations of the second exemplary embodiment; Fig. 13 is a diagram showing a configuration of a third exemplary embodiment of the present disclosure; and Fig. 14 is a diagram representing a configuration of a flow entry described in Non Patent Literature 2.

First, an outline of a mode of the present disclosure is described, making reference to Fig. 1 and Fig. 2. It is to be noted that drawing reference symbols noted in this outline are added to respective elements for convenience, as an example to aid understanding, and are not intended to limit the invention to modes of the drawings shown.

As shown in Fig. 1, the present mode can be realized by a configuration in which are arranged: a control device 10 that controls a forwarding node 20, the forwarding node 20 that processes a received packet in accordance with control information received from the control device 10, and a control information relay device 30, arranged between the control device 10 and the forwarding node 20, which refers to an address conversion table to perform rewriting of a source and destination of the control information transferred in an in-band channel.

More specifically, the control information relay device 30 is configured by being provided with an address conversion unit that executes a first conversion process of performing conversion such that control information transmitted from the control device via the in-band channel can be recognized as being control information received from a prescribed control device, by the respective forwarding node(s), and a second conversion process of performing conversion such that control information transmitted from any one of the forwarding node(s) can be recognized as being control information received from a prescribed forwarding node, by the control device.

The address conversion unit, for example, performs conversion between address information included in control information transferred to or from the forwarding node 20 (corresponding to an IP address 192.168.0.1 of the forwarding node and an IP address 192.168.0.2 of the control device in Fig. 1), and address information included in control information transferred to or from the control device 20 (corresponding to an IP address 10.56.78.1 of the forwarding node and an IP address 10.56.78.90 of the control device in Fig. 1).

It is to be noted that establishment of an in-band secure channel by a channel establishing unit can be realized using a method of Non Patent Literature 3 or the like. (The disclosure of NPL 3 is herein incorporated by reference.)

Furthermore, the address conversion can be performed using the address conversion table shown in Fig. 2. The example in Fig. 2 has a table associating IP addresses or the like (obtainable from a packet received from forwarding node(s) 20) that are set on the side of the forwarding node(s) 20, and address information in order to that the control device 10 uniquely identifies the forwarding node 20 that is a source or destination of the control information.

By employing a configuration as described above, it is possible to perform transferring (transmitting and receiving) of control information via the in-band secure channel, without setting an IP address of the forwarding node 20 or the control device 10 in advance.

It is to be noted that the example of Fig. 2 has an address conversion table that converts sets of IP address and port number, but, as described in an exemplary embodiment to be described later, conversion of the port number can be omitted as appropriate (the port number is passed through).

(First Exemplary Embodiment)
Next, a detailed description is given concerning a first exemplary embodiment of the present disclosure, making reference to the drawings. Fig. 3 is a diagram showing a configuration of a communication system according to the first exemplary embodiment. Referring to Fig. 3, a configuration is shown that includes a control device 10, a plurality of forwarding nodes 20, and a control information relay device 30 arranged between the control device 10 and the plurality of forwarding nodes 20.

The control information relay device 30 is configured by being provided with an address conversion unit 31, a channel establishment unit 32,

interfaces

33 and 34, an address conversion table holding unit 35, and an address learning unit 36.

The channel establishment unit 32, for example, uses special frames disclosed in Non Patent Literature 3, and performs operations of searching a network topology configured by the respective forwarding nodes, and setting an in-band secure channel route. (The disclosure of NPL 3 is incorporated herein by reference.)

The interface 33 is a tunnel device connected to a virtual network interface on the side of the control device 10, and the interface 34 is an interface connected to a physical port on the side of the forwarding nodes 20.

The address learning unit 36 performs operations of issuing an IP address and port number to be recognized by the control device as an IP address and port number of a forwarding node in question, for each control channel ID, source IP address (srcIP), source port number (srcPort), destination IP address (dstIP), and destination port number (dstPort), included in special frames or the like transmitted from (any one of) the forwarding nodes 20 to the control device 10, to be recorded in the address conversion table holding unit 35. It is to be noted that in the present exemplary embodiment, ranges of IP addresses and port numbers that can be issued by the address learning unit 36 are set as 10.0.1.0 - 10.0.255.255/8, 10000 - 39999. The source IP address (srcIP) is an IP address that is set in a forwarding node 20 that transmits a special frame or the like with the control device 10 as a destination. Furthermore, the destination IP address (dstIP) is an IP address that is set as an address indicating the control device 10, to the forwarding node 20 in question. That is, in the forwarding node 20, an IP address corresponding to the destination IP address (dstIP) is recognized as an IP address of the control device 10.

Fig. 4 is a diagram showing an example of an address conversion table held in the address conversion holding unit 35. Referring to Fig. 4, the address conversion table is configured to associate address information on the side of the forwarding node(s) 20 obtained from the special frame described above, and address information on the side of the control device 10 (the IP address and port number of each forwarding node recognized by the control device). That is, the control device 10 recognizes that the IP address(es) of the forwarding node(s) 20 is (are) IP address(es) stored in the address information on the control device side. On the other hand, as described above, the IP address(es) that is (are) actually set in the forwarding node(s) 20 is (are) address(es) in the address information on the forwarding node side of the address conversion table. That is, the control device 10 and the forwarding nodes 20 have IP addresses recognized by each other that are different. The control information relay device 30 converts addresses in control information transmitted and received between the control device 10 and the forwarding nodes 20 using the address conversion table, and hides the difference between the addresses of the forwarding nodes 20 recognized by the control device 10 and the addresses of the forwarding nodes 20 recognized by the forwarding nodes 20. It is to be noted that in the example of Fig. 4, the 2 fields of the address information on the forwarding node side and the address information on the control device side respectively store detailed information of control channel IDs and subsequent information, but it is also possible to store each thereof in independent fields.

Furthermore, in the example of Fig. 4, the address information on the control device side does not contain an IP address of the control device 10 itself that is set in the control device 10. This is omitted because the IP address that is set in the control device 10 itself as an IP address indicating the control device 10, is fixed (for example, 10.56.78.90:6633. Refer to Fig. 9). In addition, in the example of Fig. 4, the IP address is not changed; this is because it is possible to identify each forwarding node by changing the port number.

The address conversion unit 31 refers to the address conversion table as described above, and performs mutual conversion of addresses of a control information storage packet (corresponding to a tunneling message in Non Patent Literature 3), exchanged between the control device 10 and the forwarding node(s) 20.

It is to be noted that functions equivalent to the address conversion unit 31 and the channel establishment unit 32 of the control information relay device 30 as described above can be realized by a program executed in a computer forming the control information relay device 30.

Next, a detailed description is given concerning operations of the present exemplary embodiment, making reference to the drawings. Fig. 5 is a flowchart for describing operations of the control information relay device of the first exemplary embodiment.

Referring to Fig. 5, the control information relay device 30 first uses a method of Non Patent Literature 3 or the like to perform an operation of searching a network topology configured by the respective forwarding nodes 20, and of setting a route of the in-band secure channel (step S001).

Next, the control information relay device 30 obtains address information of the control device 10 and the forwarding node(s) set on the side of the respective forwarding node(s) 20 (step S002).

Next, the control information relay device 30 assigns address information on the control device 10 side to address information set on the side of the respective forwarding nodes 20, based on a prescribed rule (step S003).

Next, the control information relay device 30 stores in the address conversion table holding unit 35 the address conversion table associating a set of address information set on the side of the respective forwarding nodes 20 and address information assigned to the control device side (step S004).

It is to be noted that the address information on the control device 10 side assigned in the abovementioned step S003 can be created using various methods, in accordance with an assignable address range of the control information relay device 30 or the number of forwarding nodes 20 that are to be managed.

For example, as shown in Fig. 4, in addition to a method of assigning new address information on the control device side for each control channel ID, source IP address (srcIP), source port number (srcPort), destination IP address (dstIP), and destination port number (dstPort), as shown in Fig. 6 it is possible to employ a method assigning the new address information on the control device side based on a combination with the exception of the source port number (srcPort). That is, outside of the source port number, it is possible to assign the new address information on the control device side for each combination of control channel ID, source IP address, destination IP address, and destination port number. Furthermore, in the example of Fig. 6, it is possible to reuse an IP address, as where "(reuse)" is noted in the lowest entry. In addition, in the example of Fig. 6, compared to Fig. 4, port numbers are omitted in the address information on the control device side; this is because only the IP address of a packet sent from a forwarding node 20 is converted, and a port number of the packet sent from the forwarding node 20 is used as it is (the port number is passed through).

In the same way, as shown in Fig. 7, it is possible to employ a method of assigning new address information on the control device side based on a combination with the exception of (i.e., without) the destination port number (dstPort). That is, other than the destination port number, it is possible to assign the new address information on the control device side, for each combination of control channel ID, source IP address, source port number, and destination IP address. Furthermore, in the example of Fig. 7, it is possible to reuse an IP address and port number set, as where "(reuse)" is noted in the second entry from the bottom.

In the same way, as shown in Fig. 8, it is possible to employ a method of assigning new address information on the control device side based on a combination with the exception of the source port number (srcPort) and the destination port number (dstPort). That is, other than the source port number and the destination port number, it is possible to assign the new address information on the control device side for each combination of control channel ID, source IP address, and destination IP address. Furthermore, in the example of Fig. 8, it is possible to reuse an IP address, as where "(reuse)" is noted in the first and second entries from the bottom. It is to be noted that the example of Fig. 8 is equivalent to assigning a new address for each channel ID.

According to the present exemplary embodiment operating as above, as shown in Fig. 9, for example, it is possible to perform identification according to difference in control channel IDs, and to exchange control information by performing necessary address conversion, even for forwarding nodes (forwarding nodes A and B in Fig. 9) in which the same IP address is set as an initial setting, in the control device 10 (refer to Fig. 10).

In the same way, according to the present exemplary embodiment, as in forwarding node C and forwarding node D in Fig. 9, it is possible to exchange control information by performing necessary address conversion, also for forwarding nodes with different subnets (refer to Fig. 10).

(Second Exemplary Embodiment)
Next, a description is given concerning a second exemplary embodiment of the present disclosure, in which a forwarding node 20 is made to operate as an address conversion unit as described above. Below, descriptions concerning portions that are in common with the first exemplary embodiment are omitted, and a description centered on points of difference thereof is given.

Fig. 11 is a diagram showing a configuration of the second exemplary embodiment. A point of difference in the configuration from the first exemplary embodiment shown in Fig. 3 is the point that a forwarding node 20A is provided instead of a control information relay device 30, and that a channel establishing unit 12 and an address learning unit 16 are provided on a control device 10A side.

The channel establishing unit 12 of the control device 10A performs an operation of establishing an in-band secure channel between the control device 10A and forwarding nodes 20, similar to a channel establishing unit 32 of the first exemplary embodiment described above. The address learning unit 16 of the control device 10A also performs an operation of creating an address conversion table to be recorded in an address conversion table holding unit 25, similar to an address learning unit 36 of the first exemplary embodiment described above.

Interfaces

23 and 24 of the forwarding node 20A respectively correspond to

interfaces

33 and 34 of the first exemplary embodiment described above.

An address conversion unit 21 and the address conversion table holding unit 25 of the forwarding node 20A perform an address conversion process based on the address conversion table, similar to an address conversion unit 31 and an address conversion table holding unit 35 of the first exemplary embodiment described above. It is to be noted that the address conversion table holding unit 25 of the forwarding node 20A can also be configured by a matching rule that identifies a packet that is a target for header rewriting, described in Non Patent Literature 2, and a flow table storing flow entries in which a header rewriting action is defined. Furthermore, in this case the address conversion unit 21 can also be configured by using a packet processing function of an OpenFlow switch of Non Patent Literature 2. In addition, with regard to recording of the address conversion table in the address conversion table holding unit 25 by the address learning unit 16, it is possible to use a flow entry setting message or the like provided in an OpenFlow controller of Non Patent Literature 2. (The disclosure of NPL 2 is incorporated herein by reference.)

According to the present exemplary embodiment as described above, it is possible for the forwarding node 20A to operate as the control information relay device, without providing the dedicated control information relay device 30, and as shown in Fig. 12, to perform necessary address conversion via the forwarding node 20A.

(Third Exemplary Embodiment)
Next, a description is given concerning a third exemplary embodiment of the present disclosure, in which a control device is made to operate as a control information relay device 30 as described above. Below, descriptions concerning portions that are in common with the first exemplary embodiment are omitted, and a description centered on points of difference thereof is given.

As shown in Fig. 13, it is possible to adopt a configuration embedding respective functions of the control information relay device 30 as described above, in a control device 10B (third exemplary embodiment). The functions of the control information relay device 30 embedded in the control device 10B may be similar to the abovementioned exemplary embodiments.

Furthermore, in the abovementioned exemplary embodiment a description has been given in which the control information relay device 30 or a control device 10 are provided with

address learning units

16 and 36, but it also possible to omit the

address learning units

16 and 36, in a case where it is possible to create an address conversion table at another stage.

A description has been given above of respective exemplary embodiments of the present invention, but the present invention is not limited to the abovementioned exemplary embodiments, and further modifications, substitutions and adjustments can be added, within a scope that does not depart from fundamental technological concepts of the invention. For example, in the abovementioned respective exemplary embodiments, a description has been given in which an IPv4 (Internet Protocol version 4) address is shown as an IP address, but application is also possible in the same way in a case of IPv6. It is to be noted that each disclosure of the abovementioned Patent Literatures and Non Patent Literatures is incorporated herein by reference. Modifications and adjustments of exemplary embodiments and examples are possible within the bounds of the entire disclosure (including the scope of the claims) of the present invention, and also based on fundamental technological concepts thereof. Furthermore, a wide variety of combinations and selections of various disclosed elements is possible within the scope of the claims of the present invention.

In the present disclosure, there are following modes.
(Mode 1)
A communication system set forth as the first aspect.
(Mode 2)
The communication system according to mode 1, wherein the address conversion unit may perform the first and second conversion processing by referring to an address conversion table that manages correspondence relationships between a group of addresses of the respective forwarding nodes and the control device as set in the respective forwarding nodes, an address of a forwarding node used by the control device as a control information destination, and the control channel.
(Mode 3)
The communication system according to mode 2, which may further comprise an address learning unit that creates an address conversion entry in the address conversion table, based on address information included in a packet received from the forwarding node via the control channel.
(Mode 4)
The communication system according to mode 3, wherein the address learning unit may create a new entry with respect to a combination in which the control channel established between the forwarding nodes and the control device, and a source IP address, a source port number, a destination IP address, and a destination port number, included in a packet transmitted from the forwarding nodes, are different.
(Mode 5)
The communication system according to mode 3, wherein the address learning unit may create a new entry with respect to a combination in which the control channel established between the forwarding nodes and the control device, and a source IP address, a destination IP address, and a destination port number, included in a packet transmitted from the forwarding nodes, are different.
(Mode 6)
The communication system according to mode 3, wherein the address learning unit may create a new entry with respect to a combination in which the control channel established between the forwarding nodes and the control device, and a source IP address, a source port number, and a destination IP address, included in a packet transmitted from the forwarding nodes, are different.
(Mode 7)
The communication system according to mode 3, wherein the address learning unit may create a new entry for each the control channel established between the forwarding nodes and the control device.
(Mode 8)
A control information relay device set forth as the second aspect.
(Mode 9)
The control information relay device according to mode 8, which may further comprises a channel establishing unit that establishes the control channel between the respective forwarding node(s) and the control channel, by using a network that includes the control device and the respective forwarding node(s).
(Mode 10)
A control device set forth as the third aspect.
(Mode 11)
A method of transmitting and receiving control information set forth as the fourth aspect.
(Mode 12)
A program executed on a computer set forth as the fifth aspect.
(Mode 13)
The control information relay device according to mode 8 or 9, wherein the address conversion unit may perform the first and second conversion processing by referring to an address conversion table that manages correspondence relationships between a group of addresses of the respective forwarding nodes and the control device as set in the respective forwarding nodes, an address of a forwarding node used by the control device as a control information destination, and the control channel.
(Mode 14)
The control information relay device according to mode 13, which may further comprises an address learning unit that creates an address conversion entry in the address conversion table, based on address information included in a packet received from the forwarding node via the control channel.
(Mode 15)
The control device according to mode 10, wherein the address conversion unit may perform the first and second conversion processing by referring to an address conversion table that manages correspondence relationships between a group of addresses of the respective forwarding nodes and the control device as set in the respective forwarding nodes, an address of a forwarding node used by the control device as a control information destination, and the control channel.
(Mode 16)
The control device according to mode 15, which may further comprises an address learning unit that creates an address conversion entry in the address conversion table, based on address information included in a packet received from the forwarding node via the control channel.

10, 10A, 10B control device
12, 32 channel establishing unit
16, 36 address learning unit
20, 20A forwarding node(s)
21, 31 address conversion unit
23, 24, 33, 34 interface
25, 35 address conversion table holding unit
30 control information relay device

Claims

A communication system, comprising:
a control device that controls a plurality of forwarding nodes, and a forwarding nodes that process a received packet in accordance with control information received from said control device;
said communication system further comprising:
a channel establishing unit that establishes a control channel used in transmission of said control information between said control device and respective forwarding nodes, by using a network that comprises said control device and said respective forwarding nodes; and
an address conversion unit arranged between said forwarding nodes and said control device, said address conversion unit executing a first conversion process of performing conversion such that control information transmitted via said control channel from said control device can be recognized as being control information received from a prescribed control device by said respective forwarding node(s), and a second conversion process of performing conversion such that control information transmitted via said control channel from any one of said forwarding nodes can be recognized as being control information received from a prescribed forwarding node by said control device.
The communication system according to claim 1, wherein said address conversion unit performs said first and second conversion processing by referring to an address conversion table that manages correspondence relationships between a group of addresses of said respective forwarding nodes and said control device as set in said respective forwarding nodes, an address of a forwarding node used by said control device as a control information destination, and said control channel.
The communication system according to claim 2, further comprising an address learning unit that creates an address conversion entry in said address conversion table, based on address information included in a packet received from said forwarding node via said control channel.
The communication system according to claim 3, wherein said address learning unit creates a new entry with respect to a combination in which said control channel established between said forwarding nodes and said control device, and a source IP address, a source port number, a destination IP address, and a destination port number, included in a packet transmitted from said forwarding nodes, are different.
The communication system according to claim 3, wherein said address learning unit creates a new entry with respect to a combination in which said control channel established between said forwarding nodes and said control device, and a source IP address, a destination IP address, and a destination port number, included in a packet transmitted from said forwarding nodes, are different.
The communication system according to claim 3, wherein said address learning unit creates a new entry with respect to a combination in which said control channel established between said forwarding nodes and said control device, and a source IP address, a source port number, and a destination IP address, included in a packet transmitted from said forwarding nodes, are different.
The communication system according to claim 3, wherein said address learning unit creates a new entry for each said control channel established between said forwarding nodes and said control device.
A control information relay device, arranged between a control device that controls a plurality of forwarding nodes, and a forwarding node(s) that processes a received packet in accordance with control information received from said control device;
said control information relay device comprising:
an address conversion unit that executes a first conversion process of performing conversion such that control information transmitted from said control device can be recognized as being control information received from a prescribed control device by said respective forwarding node(s), and a second conversion process of performing conversion such that control information transmitted from any one of said forwarding nodes can be recognized as being control information received from a prescribed forwarding node by said control device; wherein
transfer of control information is realized via a control channel established between said respective forwarding node(s) and said control device, by using a network that comprises said control device and said respective forwarding node(s).
The control information relay device according to claim 8, further comprising a channel establishing unit that establishes said control channel between said respective forwarding node(s) and said control channel, by using a network that includes said control device and said respective forwarding node(s).
A control device comprising:
a forwarding node control unit that, by transmitting control information to a forwarding node(s), causes said forwarding node(s) to process a received packet in accordance with said control information;
a channel establishing unit that establishes a control channel used in transmission of said control information between said control device and respective forwarding node(s), by using a network that includes said control device and said respective forwarding node(s); and
an address conversion unit, arranged between said forwarding node(s) and said control device, said address conversion unit executing a first conversion process of performing conversion such that control information transmitted via said control channel from said control device can be recognized as being control information received from a prescribed control device by any one of said respective forwarding nodes, and a second conversion process of performing conversion such that control information transmitted via said control channel from any one of said forwarding nodes can be recognized as being control information received from a prescribed forwarding node by said control device.
A method of transmitting and receiving control information, said method comprising:
a step of establishing a control channel used in transmission of said control information between a control device and respective forwarding node(s), by using a network that includes said control device and said respective forwarding node(s);
a step of performing conversion, between said forwarding node(s) and said control device, such that control information transmitted via said control channel from said control device can be recognized as being control information received from a prescribed control device, by said respective forwarding node(s); and
a step of performing conversion such that control information transmitted via said control channel from any one of said forwarding nodes can be recognized as being control information received from a prescribed forwarding node by said control device.
A program executed on a computer provided between a control device that controls a plurality of forwarding nodes, and a forwarding node(s) that processes a received packet in accordance with control information received from said control device,
said program executing:
a process of performing conversion such that control information transmitted via said control channel from said control device can be recognized as being control information received from a prescribed control device by said respective forwarding node(s); and
a process of performing conversion such that control information transmitted via said control channel from any one of said forwarding node(s) can be recognized as being control information received from a prescribed forwarding node, by said control device.
The control information relay device according to claim 8 or 9, wherein said address conversion unit performs said first and second conversion processing by referring to an address conversion table that manages correspondence relationships between a group of addresses of said respective forwarding nodes and said control device as set in said respective forwarding nodes, an address of a forwarding node used by said control device as a control information destination, and said control channel.
The control information relay device according to claim 13, further comprising an address learning unit that creates an address conversion entry in said address conversion table, based on address information included in a packet received from said forwarding node via said control channel.
The control device according to claim 10, wherein said address conversion unit performs said first and second conversion processing by referring to an address conversion table that manages correspondence relationships between a group of addresses of said respective forwarding nodes and said control device as set in said respective forwarding nodes, an address of a forwarding node used by said control device as a control information destination, and said control channel.
The control device according to claim 15, further comprising an address learning unit that creates an address conversion entry in said address conversion table, based on address information included in a packet received from said forwarding node via said control channel.