JP7002241B2 - Route inspection device, route inspection method and route inspection program - Google Patents

Description

The present invention relates to a technique for inspecting a route in a network.

Conventionally, a route (tree) used for multicast communication is formed by IGMP (Internet Group Management Protocol) in layer 2 and PIM (Protocol-Independent Multicast) in layer 3. When controlling and managing a tree of multicast communication, it is generally performed by actually measuring communication in the network using NetFlow or SNMP (Simple Network Management Protocol) (Patent Document 1).

In addition, SDN (Software Defined Networking) is a network technology that has been attracting attention in recent years. SDN is a technology for centrally controlling network devices by a single software, and can centrally control and manage communication devices and communication paths in the network with an SDN controller.

The tree of multicast communication can be controlled and managed even by using SDN. For example, by performing a route search with the SDN controller, it is possible to acquire a tree of multicast communication logically formed in the physical network. The SDN controller can also be used to configure each switch in the network with a flow entry through the desired multicast communication tree.

Japanese Patent No. 4627324

However, in the conventional SDN, it is not guaranteed that the previously set multicast communication tree is still used. Therefore, it cannot be detected that the flow is passing through a tree different from the expected tree for some reason, or that packets are lost in the middle of the tree that was set due to an error in the control program in the switch. There was a problem. Further, in Patent Document 1, since the tree in use is specified by measuring the actual communication, it is not possible to detect an abnormality in the communication on the server side.

The present invention has been made in view of the above circumstances, and an object thereof is to easily inspect a route (tree) in a network not only in multicast communication but also in SDN.

In order to solve the above problems, the route inspection device according to claim 1 is a route inspection device that inspects a route in a network using SDN (Software Defined Networking), and has a plurality of transfer devices through which packets pass and a route order. For the storage unit that stores the calculation tree that defines the above and a plurality of transfer devices that transfer packets according to the calculation tree, the identification information of the transfer device is added to the probe packet for inspection, and the identification information is used. A control unit that returns the assigned probe packet and transmits instruction information that defines an instruction to transfer the probe packet according to the calculation tree, and a transmission unit that transmits the inspection probe packet to the transfer device of the calculation tree. , Using the transfer device identification information attached to the reply probe packet returned from the transfer device of the calculation tree, a real tree including a plurality of transfer devices and the route order to which the probe packet for inspection has passed is created. It is characterized by including a generation unit to be generated and a comparison unit for comparing the real tree and the calculation tree.

The route inspection device according to claim 2 is the route inspection device according to claim 1. In the route inspection device according to claim 1, the instruction to give the identification information of the transfer device is a VLAN (Virtual Local Area Network) tag or MPLS (Virtual Local Area Network) tag or MPLS in the probe packet for the inspection. (Multi-Protocol Label Switching) It is an instruction to add a label and change the information contained in the VLAN tag or the MPLS label into the identification information of the transfer device.

The route inspection device according to claim 3 is the route inspection device according to claim 1, wherein the transmission unit adds time information to the probe packet for inspection and transmits the probe packet, and the generation unit is the generation unit. It is characterized in that the reply probe packet corresponding to the transmitted probe packet for inspection is specified based on the time information given to the reply probe packet.

The route inspection device according to claim 4 is the route inspection device according to any one of claims 1 to 3, wherein the storage unit defines the calculation tree for each multicast group.

The route inspection method according to claim 5 is a route inspection method performed by a route inspection device that inspects a route in a network using SDN (Software Defined Networking), wherein the route inspection device is a plurality of transfer devices through which packets pass. A storage step that stores a calculation tree that defines the route and the route order in the storage unit, and a transfer device identification information is added to the probe packet for inspection for a plurality of transfer devices that transfer packets according to the calculation tree. Then, the control step of returning the probe packet to which the identification information is added and transmitting the instruction information defining the instruction to transfer the probe packet according to the calculation tree, and the transfer device of the calculation tree for the probe packet for inspection. Using the transmission step to be transmitted to the transfer device and the identification information of the transfer device attached to the reply probe packet returned from the transfer device of the calculation tree, the plurality of transfer devices and the route order to which the probe packet for inspection has passed are used. It is characterized by performing a generation step of generating a real tree including the above, and a comparison step of comparing the real tree with the calculated tree.

The route inspection method according to claim 6 is the route inspection method according to claim 5, wherein the instruction to give the identification information of the transfer device is a VLAN (Virtual Local Area Network) tag or MPLS (Virtual Local Area Network) tag or MPLS in the probe packet for inspection. It is an instruction to add a (Multi-Protocol Label Switching) label and change the information contained in the VLAN tag or the MPLS label into the identification information of the transfer device.

The route inspection method according to claim 7 is the route inspection method according to claim 5, wherein in the transmission step, time information is added to the probe packet for inspection and transmitted, and in the generation step, the said. It is characterized in that the reply probe packet corresponding to the transmitted probe packet for inspection is specified based on the time information given to the reply probe packet.

The route inspection method according to claim 8 is the route inspection method according to any one of claims 5 to 7, characterized in that, in the storage step, the calculation tree is defined for each multicast group.

The route inspection program according to claim 9 is characterized in that a computer functions as the route inspection device according to any one of claims 1 to 4.

According to the present invention, the route (tree) in the network can be easily inspected in the SDN.

It is a figure which shows the whole structure of an open flow system. It is a figure which shows the functional block composition of the open flow controller. It is a sequence showing a route inspection processing procedure. It is a figure which shows the example of the calculation tree. It is a figure which shows the example of the flow table. It is a figure which shows the example of the tree management table. It is a figure which shows how the probe packet is returned. It is a figure which shows the structure of a reply probe packet. It is a figure which shows the search result of a real tree. It is a figure which shows the example of a real tree.

In the present invention, a probe packet is transmitted to a target multicast group or a unicast group (a plurality of unicast sets), and the packet header of the probe packet is marked to actually use the route. Find (tree). This makes it possible to check the current tree before starting multicast communication or unicast communication, which is generally assumed to be wideband.

Further, in the present invention, it is determined whether the obtained tree is the expected tree, and if an unexpected tree is used or the packet is discarded in the middle of the tree, correction / detour search / Make settings. This makes it possible to guarantee communication within the tree.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

In this embodiment, a case of inspecting a tree of multicast communication will be described. Further, in the present embodiment, it will be described using OpenFlow, which is one technique of SDN. In OpenFlow, the set of the header and output port of the packet flowing through the OpenFlow network OFN is called a flow. The open flow controller OFC can identify the flow of the packet via the open flow switch OFS based on the header information of the packet and control the target flow. For openflow, for example, "OpenFlow" (Japan Network Information Center, August 1, 2017 search, https://www.nic.ad.jp/ja/newsletter/No52/0800.html) It is explained in.

FIG. 1 is a diagram showing an overall configuration of an OpenFlow system according to the present embodiment. The open flow system includes an open flow controller OFC and an open flow network OFN.

The open flow network OFN is a physical network composed of a plurality of open flow switch OFS capable of intercommunication. Each of the plurality of OpenFlow switches OFS is connected to the OpenFlow controller OFC, and can communicate with each other even with the OpenFlow controller OFC.

In the open flow network OFN, one or more multicast groups are logically formed by using one or more open flow switch OFS. In FIG. 1, one multicast group is formed by six OpenFlow switches OFS1 to OFS6. In the multicast group, the video packet delivered from the video camera on the server side to the multicast group is forwarded to OFS1 → OFS5 → OFS6 → member terminal 1 of the multicast group, and OFS1 → OFS2 → OFS4 → member terminal. It has a tree consisting of a route to be transferred to 2 and a route to be transferred to OFS1 → OFS2 → OFS3 → member terminal 3.

Next, the OpenFlow controller OFC will be described. The OpenFlow controller OFC is a controller that manages and controls the OpenFlow switch OFS, and includes a route inspection device that inspects a route (tree) of multicast communication in the present embodiment.

FIG. 2 is a diagram showing a functional block configuration of the OpenFlow controller OFC according to the present embodiment. The OpenFlow controller OFC includes a data information storage unit 11, a switch control unit 12, a probe packet transmission unit 13, a probe packet reception unit 14, a real tree generation unit 15, a tree comparison unit 16, and a detour search unit. 17 and the like.

The data information storage unit 11 stores a calculation tree for each multicast group, which defines a plurality of OpenFlow switch OFS through which packets pass in a predetermined multicast group and a packet passage order in the plurality of open flow switch OFS. It is a functional part to keep.

The switch control unit 12 assigns the openflow switch OFS dpid (described later) to the probe packet for inspection to the plurality of openflow switch OFS that forward the packet according to the calculation tree, and the probe to which the dpid is assigned. It is a functional unit that returns a packet and sends a flow entry (command information) that defines a command to forward the probe packet according to the above calculation tree.

The probe packet transmission unit 13 is a functional unit that transmits a probe packet for inspection to the open flow switch OFS of the multicast group.

The probe packet receiving unit 14 is a functional unit that receives a reply probe packet returned from the OpenFlow switch OFS.

The real tree generation unit 15 uses the dpid of the open flow switch OFS attached to the received reply probe packet to use the plurality of open flow switch OFS via which the probe packet for inspection is passed and the plurality of open flow switch OFS. It is a functional part that generates a real tree including the order of packets in.

The tree comparison unit 16 is a functional unit that compares a real tree with a calculated tree.

The detour search unit 17 is a functional unit that searches and sets detours based on the comparison result between the real tree and the calculation tree.

Here, the dpid will be described. The dpid is information on the upper 16 bits of the DPID (Datapath ID) used in OpenFlow. In OpenFlow, the MAC address of the OpenFlow switch OFS is already assigned to the lower 48 bits of the fields given to the 64-bit DPID, so in this embodiment, the OpenFlow user can freely use it. Use the upper 16 bits possible. For example, a bit string for identifying the OpenFlow switch OFS is generated within a range of 16 bits, and is included in the upper 16 bits of the DPID for use.

Next, a communication route inspection method performed by the above-mentioned OpenFlow system will be described. Here, in a predetermined multicast group, it is verified whether the route (real tree) of the OpenFlow switch OFS that the packet is currently passing through matches the previously set route (calculation tree), and if it does not match. Realizes the guarantee of communication in the tree by setting the calculation tree again and setting a detour if it still does not match.

FIG. 3 is a sequence showing a route inspection processing procedure for multicast communication. It is assumed that the calculation tree illustrated in FIG. 4 is registered in advance in the data information storage unit 11. In the calculation tree of "No.1", for the multicast group of "239.0.0.1", the route of OFS1 → OFS2 → OFS3, the route of OFS1 → OFS2 → OFS4, and the route of OFS1 → OFS5 → OFS6 are set. Has been done.

Step S1;
First, the switch control unit 12 acquires a calculation tree corresponding to the multicast group designated by the user from the data information storage unit 11.

Step S2;
Next, the switch control unit 12 transmits a communication flow entry for forwarding a packet according to the calculation tree to a plurality of OpenFlow switch OFS defined in the acquired calculation tree. In the case of the "No. 1" calculation tree shown in FIG. 4, the switch control unit 12 transmits, for example, a communication flow entry for forwarding a packet to the open flow switch OFS 6 to the open flow switch OFS 5.

At this time, the switch control unit 12 instructs in the packet of the flow entry to register the first flow entry in the "flow table 1" in the open flow switch OFS. The flow table 1 of the OpenFlow switch OFS is illustrated in FIG. 5 (a). In the case of the open flow switch OFS5, "forwarding the packet to OFS6" is set in "GroupTable (1)". As a result, the OpenFlow switch OFS5 forwards the packet addressed to "239.0.0.1" to OFS6.

At the same time, the switch control unit 12 sends a packet (probe packet for inspection) whose source IP address is the OpenFlow controller OFC to the plurality of OpenFlow switch OFS defined in the calculation tree acquired in step S1. When received, an instruction to add a VLAN (Virtual Local Area Network) tag to the probe packet (PushVLAN), an instruction to change the default value of the VLAN tag to the dpid of the OpenFlow switch OFS (SetField (VLAN)), and An inspection flow entry including an instruction (Output (Controller)) for returning a probe packet including the dpid to the OpenFlow controller OFC and an instruction (GoToTable1) for executing the flow table 1 is transmitted.

Further, the switch control unit 12 sends packets that do not match the conditions of the flow table to the plurality of open flow switch OFS defined in the calculation tree acquired in step S1. As a flow entry for processing), each flow entry for table error including only the instruction (GoToTable1) for executing the flow table 1 is transmitted.

Then, the switch control unit 12 instructs to register the inspection flow entry and the table error flow entry in the "flow table 0" in the open flow switch OFS, respectively, in the packets of the two flow entries. However, since the probe packet does not need to be forwarded to the member terminal side, the inspection flow entry transmitted to the open flow switches OFS3, 4, 6 does not include the "instruction to execute the flow table 1 (GoToTable1)".

The flow table 0 of the OpenFlow switch OFS is illustrated in FIG. 5 (b). When each OpenFlow switch OFS receives a probe packet from the OpenFlow controller OFC based on the flow table 0, it adds a VLAN tag to the probe packet based on the PushVLAN Action, and adds a VLAN tag to the probe packet based on the SetField (VLAN) Action. The value is changed to the packet of the OpenFlow switch OFS, the VLAN tag is returned to the OpenFlow controller OFC based on the Output (Controller) Action, and the process set in "GroupTable (1)" based on the flow table 1 ( Packet transfer processing to another OpenFlow switch OFS) will be performed.

Step S3;
Next, the probe packet transmission unit 13 selects the calculation tree of the multicast group to be inspected from the data information storage unit 11, sets the IP address of the open flow controller OFC as the source, and sets the IP address of the selected multicast group as the source. Generate the RTP packet set as the destination, describe the time in the open flow controller OFC in the RTP time stamp (time information) in the RTP packet, and direct the RTP packet to the open flow switch OFS on the server side as a probe packet. And send.

For example, when the "No. 1" calculation tree is selected, the probe packet transmission unit 13 transmits the probe packet toward the OpenFlow switch OFS1. The probe packet transmission process follows the flow entry of the OpenFlow controller OFC.

At this time, the probe packet transmission unit 13 generates a tree management table in which the transmitted multicast address, the RTP time stamp, the calculation tree No., and the real tree No. are associated with each other, and stores the tree management table in the data information storage unit 11. .. For example, the tree management table illustrated in FIG. 6 is generated.

Steps S4 to S11;
Next, when each OpenFlow switch OFS on the tree receives the probe packet from the OpenFlow controller OFC, it performs the process registered in the flow tables 0 and 1. Specifically, each OpenFlow switch OFS assigns a VLAN tag, changes the value of the VLAN tag to the dpid of the own OpenFlow switch OFS, and returns a probe packet containing the dpid to the open flow controller OFC. At the same time, transmission is performed to the transfer destination OpenFlow switch OFS.

For example, as shown in FIGS. 7 (a) and 7 (b), the OpenFlow switch OFS1 opens a “probe packet + α” (FIGS. 8 (a) and 8 (b)) in which a VLAN tag of dpi1 is added to the probe packet. Along with replying to the flow controller OFC, it also sends to the open flow switches OFS2 and 5. Further, as shown in FIG. 7 (c), the OpenFlow switch OFS4 opens a “probe packet + β” (FIG. 8 (c)) in which a VLAN tag of dpi4 is further added to the probe packet from the open flow switch OFS2. Reply to the controller OFC. Similarly, as shown in FIG. 7 (c), the OpenFlow switch OFS6 opens the “probe packet + γ” (FIG. 8 (d)) in which the VLAN tag of dpid6 is further added to the probe packet from the open flow switch OFS5. Reply to the controller OFC.

Step S12;
Next, the probe packet receiving unit 14 receives the probe packet returned from the OpenFlow switch OFS, and the real tree generation unit 15 uses the dpid in the VLAN tag attached to the received probe packet to the server side. Generates a real tree with all OpenFlow switches OFS via the OpenFlow switch OFS.

For example, as shown in FIG. 9, the open flow switch OFS1 is used as the root of the tree, and a real tree (FIG. 10) including a route of OFS1 → OFS2 → OFS4 and a route of OFS1 → OFS5 → OFS6 is generated. Since the probe packet was not returned from the open flow switch OFS3, the route to the open flow switch OFS3 is not included.

Step S13;
Next, the tree comparison unit 16 identifies the tree to be compared using the tree management table after the probe packets are returned from all the OpenFlow switch OFS on the member terminal side or after the specified time has elapsed. , Compare the identified real tree with the calculated tree. As a result of the comparison, if the real tree and the calculated tree are equal, the process ends as it is.

Step S14;
On the other hand, as a result of the comparison in step S13, when the real tree and the calculation tree are not equal, the switch control unit 12 makes a flow entry (in the calculation tree) that is equal to the calculation tree for the open flow switch OFS at the unequal location. The flow entry) for setting the transfer destination OpenFlow switch OFS so as to match is transmitted, and the inspections in steps S3 to S13 are performed again. As a result of the inspection, if the real tree and the calculated tree are equal, the process is terminated.

Step S15;
On the other hand, if the actual tree and the calculation tree are not equal as a result of the inspection in step S14, the switch control unit 12 repeats step S14 a predetermined number of times and tries to match the original calculation tree as much as possible. If the real tree is still not equal to the calculated tree, the discrepancy is considered a failure.

Step S16;
After that, the detour search unit 17 searches for a detour that does not pass through the open flow switch OFS that is the target of failure, and changes the calculation tree using the searched detour. For example, when the open flow switch OFS 5 is regarded as a failure, another open flow switch OFS connecting between the open flow switch OFS 1 and the open flow switch OFS 6 is searched. Further, for example, when the packet has not reached all the OpenFlow switch OFS on the member terminal side, the detour that the packet arrives from the normal tree to the open flow switch OFS on the member terminal side other than all the open flow switch OFS. Is searched, and steps S1 and S2 are performed for the OpenFlow switch OFS on the searched detour. In this case as well, the inspection is performed using the probe packet.

When a plurality of calculation trees are selected in step S3 and a plurality of probe packets are continuously transmitted to a plurality of target multicast groups in a short time, the OpenFlow controller OFC is transmitted from the OpenFlow switch OFS. It may not be possible to determine which transmit probe packet the returned probe packet corresponds to. In this case, the OpenFlow controller OFC identifies the reply probe packet corresponding to the desired probe packet based on the RTP time stamp (time given for each probe packet) included in the returned probe packet.

From the above, according to the present embodiment, a calculation tree that defines a plurality of open flow switch OFS through which packets pass in a predetermined multicast group and a packet passage order in the plurality of open flow switch OFS is stored. To multiple open flow switch OFS that forward packets according to the calculation tree, the probe packet for inspection is given the identification information of the open flow switch OFS, and the probe packet with the identification information is returned, and the probe packet is returned. Sends a flow entry that defines the instruction to forward the packet according to the calculation tree, sends a probe packet for inspection to the open flow switch OFS of the multicast group, and assigns it to the reply probe packet returned from the open flow switch OFS of the multicast group. Using the identification information of the open flow switch OFS, a real tree containing a plurality of open flow switch OFS to which the probe packet for inspection has passed and the order of passing the packets in the plurality of open flow switch OFS is generated. Since the real tree and the calculated tree are compared, it is possible to easily check whether the intended route is used for the SDN network. In addition, based on the result of the inspection, the abnormal part can be automatically identified and the route can be corrected.

In the present embodiment, the case where each of the three flow entries is transmitted in step S2 has been described as an example, but the three flow entries may be collectively transmitted at one time.

Further, in the present embodiment, the case where the VLAN tag is used has been described as an example, but the MPLS (Multi-Protocol Label Switching) label may be used instead of the VLAN tag. Specifically, an MPLS label is added to the probe packet, and the value included in the MPLS label is changed to the dpid of the open flow switch OFS.

Further, in the present embodiment, the case of using dpid (upper 16 bits of DPID) has been described as an example, but when the open flow network OFN to be formed is a private network (for example, an in-house network), it is 64-bit. Since the DPID can be freely determined, the DPID itself may be used as the identification information of the OpenFlow switch OFS.

Further, in the present embodiment, the case of using a multicast group has been described as an example, but it can also be applied to a unicast group (a set of a plurality of unicasts). For example, a tree that passes through a plurality of target OpenFlow switch OFS is defined, and only the IP address of the server-side OpenFlow switch OFS is registered in the group address field of the calculation tree. This makes it possible to inspect the tree in the above unicast group in the same way. In normal route search (traceroute, etc.), packets are sent to each switch to inspect the tree, but probe packets need only be sent to the server-side OpenFlow switch OFS, so the number of packets should be limited to one. Can be done.

Further, in the present embodiment, the case where the multicast IP address is used has been described as an example, but the multicast MAC address may be used instead of the multicast IP address. This makes it possible to inspect the L2 multicast tree as well.

Further, in the present embodiment, the case of using OpenFlow has been described as an example, but it can be applied to other than OpenFlow. That is, it may be within the technical scope of SDN that centrally manages the network information in the physical network and collectively controls the route of the entire physical network by software using the network information.

Further, in the present embodiment, the case where a switch is used has been described as an example, but it can also be applied to a network formed by a transfer device such as a router.

Finally, the OpenFlow controller OFC (route inspection device) described in the present embodiment can be realized by a computer including a CPU and a memory. It is also possible to create a route inspection program for operating a computer as an OpenFlow controller OFC, and a storage medium for the route inspection program.

OFC ... Openflow controller OFN ... Openflow network OFS (OFS1 to OFS6) ... Openflow switch 11 ... Data information storage unit 12 ... Switch control unit 13 ... Probe packet transmission unit 14 ... Probe packet reception unit 15 ... Real tree generation unit 16 … Tree comparison unit 17… Detour search unit

Claims (7)

In a route inspection device that inspects routes in a network using SDN (Software Defined Networking)
A storage unit that stores a calculation tree that defines multiple transfer devices and the order in which packets pass.
To a plurality of transfer devices that transfer packets according to the calculation tree, the probe packet for inspection is given the identification information of the transfer device, the probe packet to which the identification information is added is returned, and the probe packet is transferred to the calculation tree. A control unit that sends command information that defines commands to be transferred according to
A transmitter that transmits the probe packet for inspection to the transfer device of the calculation tree,
Using the transfer device identification information attached to the reply probe packet returned from the transfer device of the calculation tree, a real tree including a plurality of transfer devices and the route order to which the probe packet for inspection has passed is generated. And the generator
A comparison unit for comparing the real tree and the calculated tree is provided.
The instruction to give the identification information of the transfer device is
A VLAN (Virtual Local Area Network) tag or an MPLS (Multi-Protocol Label Switching) label is added to the probe packet for inspection, and the information contained in the VLAN tag or the MPLS label is changed to the identification information of the transfer device. A route inspection device characterized by being an instruction . In a route inspection device that inspects routes in a network using SDN (Software Defined Networking)
A storage unit that stores a calculation tree that defines multiple transfer devices and the order in which packets pass.
To a plurality of transfer devices that transfer packets according to the calculation tree, the probe packet for inspection is given the identification information of the transfer device, the probe packet to which the identification information is added is returned, and the probe packet is transferred to the calculation tree. A control unit that transmits command information that defines commands to be transferred according to
A transmitter that transmits the probe packet for inspection to the transfer device of the calculation tree,
Using the transfer device identification information attached to the reply probe packet returned from the transfer device of the calculation tree, a real tree including a plurality of transfer devices and the route order to which the probe packet for inspection has passed is generated. And the generator
A comparison unit for comparing the real tree and the calculated tree is provided.
The transmitting unit adds time information to the probe packet for inspection and transmits the probe packet.
The generator is
A route inspection device for identifying a reply probe packet corresponding to a transmitted probe packet for inspection based on time information given to the reply probe packet. The storage unit is
The route inspection device according to claim 1 or 2, wherein the calculation tree is defined for each multicast group. In the route inspection method performed by the route inspection device that inspects the route in the network using SDN (Software Defined Networking).
The route inspection device is
A storage step that stores a calculation tree that defines multiple transfer devices through which packets pass and the order of passage in the storage unit, and
To a plurality of transfer devices that transfer packets according to the calculation tree, the probe packet for inspection is given the identification information of the transfer device, the probe packet to which the identification information is added is returned, and the probe packet is transferred to the calculation tree. A control step for transmitting instruction information that defines an instruction to be transferred according to
A transmission step of transmitting the probe packet for inspection to the transfer device of the calculation tree, and
Using the transfer device identification information attached to the reply probe packet returned from the transfer device of the calculation tree, a real tree including a plurality of transfer devices and the route order to which the probe packet for inspection has passed is generated. And the generation steps to do
A comparison step of comparing the real tree with the calculated tree is performed.
The instruction to give the identification information of the transfer device is
A VLAN (Virtual Local Area Network) tag or an MPLS (Multi-Protocol Label Switching) label is added to the probe packet for inspection, and the information contained in the VLAN tag or the MPLS label is changed to the identification information of the transfer device. A route inspection method characterized by being an instruction. In the route inspection method performed by the route inspection device that inspects the route in the network using SDN (Software Defined Networking).
The route inspection device is
A storage step that stores a calculation tree that defines multiple transfer devices through which packets pass and the order of passage in the storage unit, and
To a plurality of transfer devices that transfer packets according to the calculation tree, the probe packet for inspection is given the identification information of the transfer device, the probe packet to which the identification information is added is returned, and the probe packet is transferred to the calculation tree. A control step for transmitting instruction information that defines an instruction to be transferred according to
A transmission step of transmitting the probe packet for inspection to the transfer device of the calculation tree, and
Using the transfer device identification information attached to the reply probe packet returned from the transfer device of the calculation tree, a real tree including a plurality of transfer devices and the route order to which the probe packet for inspection has passed is generated. And the generation steps to do
A comparison step of comparing the real tree with the calculated tree is performed.
In the transmission step, time information is added to the probe packet for inspection and transmitted.
In the generation step,
A route inspection method comprising identifying a reply probe packet corresponding to a transmitted probe packet for inspection based on time information given to the reply probe packet. In the storage step,
The route inspection method according to claim 4 or 5, wherein the calculation tree is defined for each multicast group. A route inspection program comprising operating a computer as the route inspection apparatus according to any one of claims 1 to 3.

Images