Communication device and generation method

Abstract

A communication device according to the present invention is connected to not less than one link and comprises: an information update unit that, when a request via a layer 2 broadcast signal is received, adds, to an information element of the broadcast signal, additional information which includes collection information corresponding to the request and link information pertaining to a transmission source of the broadcast signal; a transfer unit that, when the broadcast signal satisfies a prescribed transfer condition, transfers, to a link other than the link via which the broadcast signal was received, the broadcast signal which includes the additional information; and a response unit that, when the broadcast signal does not satisfy the prescribed transfer condition, generates a response signal including the additional information which was added to the information element of the broadcast signal by one or more communication devices including the communication device, and responds to the request.

Description

Communication device and generation method

[0001] The present invention relates to a communication device and a generation method.

[0002] A network sonar is a mechanism in which a submarine or the like sends out a probe (sonar) and obtains information from its response by sending an information collection request to a network and obtaining information as a response. Also, for example, network map generation techniques for generating a network map using a network sonar or the like are known (see, for example, Non-Patent Documents 1 to 4).

[0003] Kazuki Iwasa, et al., "A study on the application of distributed tracing technology in network monitoring", 2024 IEICE General Conference, B-6-24. Network automatic generation software Codima Toolbox, <https: / / www.networkmap.jp / web-map / > RFC2991, "Multipath Issues in Unicast and Multicast Next-Hop Selection Status of this Memo", <https: / / datatracker.ietf.org / doc / html / rfc2991> RFC2992, "Analysis of an Equal-Cost Multi-Path Algorithm" <https: / / datatracker.ietf.org / doc / html / rfc2992>

[0004] In recent years, on-demand network services using technologies such as NFV (Network Function Virtualization) or SDN (Software Defined Network) have come to be provided. Also, in those networks, since the configuration changes moment by moment by user operation, an operation method corresponding to the change is required.

[0005] While network map generation technology supports the above operations, the conventional network map generation technology described above is based on TCP / IP (Transmission Control Protocol / Internet Protocol) technology and assumes that the nodes constituting the map have IP addresses and that these IP addresses are known. Therefore, it has the limitation that requests can only be sent to recipients with IP addresses, and destinations can only be specified using IP routing.

[0006] Embodiments of the present invention have been made in view of the above problems, and enable the detection of network status at the Layer 2 communication level without using IP addresses.

[0007] To solve the above problems, a communication device according to an embodiment of the present invention is a communication device connected to one or more links, and includes: an information update unit that, when it receives a request by a Layer 2 broadcast signal, adds to the information elements of the broadcast signal additional information including collected information corresponding to the request and link information of the source of the broadcast signal; a transfer unit that, when the broadcast signal satisfies predetermined transfer conditions, transfers the broadcast signal including the additional information to a link other than the link that received the broadcast signal; and a response unit that, when the broadcast signal does not satisfy the predetermined transfer conditions, generates a response signal including the additional information added to the information elements of the broadcast signal by one or more communication devices, including the communication device, and responds to the request.

[0008] According to one embodiment of the present invention, the network status can be detected at the Layer 2 communication level without using IP addresses.

[0009] This is a diagram illustrating the configuration and processing overview of the communication system according to this embodiment. This is diagram (1) illustrating the BC signal transfer conditions according to this embodiment. This is diagram (2) illustrating the BC signal transfer conditions according to this embodiment. This is diagram (3) illustrating the BC signal transfer conditions according to this embodiment. This is a diagram showing an example of the functional configuration of a communication node according to this embodiment. This is a diagram showing an example of the information elements of a BC signal (request) according to this embodiment. This is a diagram showing an example of the information elements of a response signal according to this embodiment. This is a flowchart showing an example of processing when a BC signal is received according to this embodiment. This is a flowchart showing an example of response processing according to this embodiment. This is a diagram showing an example of the functional configuration of a source node according to this embodiment. This is a diagram showing an example of the information elements of a BC signal (for network map generation) according to this embodiment. This is a flowchart showing an example of network map generation processing according to this embodiment. This is diagram (1) illustrating the network map generation processing according to this embodiment. This is diagram (2) illustrating the network map generation processing according to this embodiment. This is diagram (3) illustrating the network map generation processing according to this embodiment. This is diagram (4) illustrating the network map generation processing according to this embodiment. This is a diagram showing an example of the computer hardware configuration.

[0010] Hereinafter, embodiments of the present invention (this embodiment) will be described with reference to the drawings. The embodiments described below are merely examples, and the embodiments to which the present invention is applied are not limited to the embodiments described below.

[0011] <Overview> Network sonar is a system that sends information collection requests to a network and obtains information in response, similar to how submarines and other vessels transmit sonar signals and receive information from the response. Furthermore, network map generation technology is known, which uses network sonar and other technologies to generate network maps.

[0012] In recent years, on-demand network services using technologies such as NFV or SDN have become available. Furthermore, because the configuration of these networks changes constantly due to user operations, operational methods that can adapt to these changes are necessary.

[0013] Network map generation technology supports the above operations, but conventional network map generation technology is TCP / IP technology and assumes that the nodes that make up the map have IP addresses and that those IP addresses are known. However, this method has limitations, such as only being able to send requests to recipients with IP addresses, or only being able to specify destinations using IP routing.

[0014] This is because network topologies are almost always represented by the configuration of forwarding nodes and Layer 2 links, and it is difficult to automatically and accurately detect this network topology using only IP. For example, configurations with multiple paths, such as ECMP (Equal Cost Multi Path) load balancing, or configurations that include standby systems in IP-redundant systems, cannot be detected using IP-based network maps, and it is difficult to detect related network anomalies. Furthermore, the split-brain problem in redundant configurations is often caused by the fact that systems are physically connected or connected graphically between Layer 2 links and forwarding nodes, but not connected via IP, which is another problem that is difficult to detect with IP.

[0015] One possible solution to the above problems is to use Layer 2 instead of IP. However, Layer 2 does not fundamentally involve communication beyond Layer 3 nodes, and managing Layer 2 addresses is cumbersome and difficult for humans. Therefore, communication using Layer 2 addresses is not generally practiced.

[0016] In view of the above-mentioned problems, this embodiment requests information and obtains responses without using IP addresses and without being affected by IP routing. Furthermore, it provides a technology (network sonar) that can widely request information and obtain responses across the network. As a result, according to this embodiment, the state of the network can be detected more accurately at the Layer 2 communication level, which is a lower layer than IP.

[0017] <System Configuration> Figure 1 is a diagram illustrating the communication system and processing overview according to this embodiment. The communication system 1 according to this embodiment is a network composed of a plurality of communication nodes 100a, 100b, 100c, ... In the following description, when referring to any communication node among the plurality of communication nodes 100a, 100b, 100c, ..., the term "communication node 100" will be used.

[0018] A communication node (communication device) 100 is, for example, a router or a relay device such as a Layer 3 switch. Each communication node 100 is connected to a link 101, for example, a communication cable or wireless communication. Note that a communication node 100 is just one example of a communication device.

[0019] The source node 10 is an information processing device or various network devices, etc., equipped with the configuration of a computer.

[0020] (Processing Overview) The source node 10 sends a Layer 2 broadcast signal (hereinafter referred to as a BC signal) to the communication node 100a to request information. This BC signal is transmitted, for example, by broadcast communication without specifying a destination, or by unicast communication where the destination is specified after finding the recipient via broadcast and then sent to each recipient individually.

[0021] Communication node 100 forwards the received BC signal to other communication nodes 100, thereby expanding the request using the BC signal within the communication system 1, and the terminal or intermediate communication node 100 that received the BC signal returns a response signal.

[0022] The response signal can be returned by retracing the original route, or, if IP communication is possible, by using IP communication.

[0023] (Transfer Conditions) The transfer conditions (predetermined transfer conditions) for the BC signal (request) from the communication node 100 include the following (1) to (4).

[0024] (1) When the broadcast relay communication node 100 receives a BC signal (request), it forwards (transmits) the BC signal to a link other than the link that received the BC signal. For example, in Figure 2, when the communication node 100 receives a BC signal from link 101a, the communication node 100 forwards the received BC signal to the other links 101b, 101c, and 101d.

[0025] (2) Do not extend the same BC signal The information element of a BC signal (request) includes identification information (hereinafter referred to as signal ID) that identifies the BC signal, and if the communication node 100 receives a BC signal with the same signal ID multiple times, it will not forward the BC signal from the second time onward. For example, in Figure 3, when the communication node 100 receives the first BC signal (ID1) from link 101a, it forwards the received BC signal (ID1) to another node and stores the ID of the received BC signal for a predetermined time. Also, when the communication node 100 receives the second BC signal (ID1) from link 101b, it will not forward the BC signal (ID1) that was received the second time.

[0026] (3) Controlling the number of relays with TTL The information element of the BC signal (request) includes TTL (Time to Live), and when the communication node 100 forwards the BC signal, it decrements the TTL value by one. Also, when the TTL expires (when the number of forwardings has reached a predetermined number), the communication node 100 does not forward the BC signal.

[0027] (4) If there is no destination, the communication node 100 will not forward the signal. Even if the communication node 100 receives a BC signal (request), it will not forward the signal if there is no link to forward it to. For example, in Figure 4, if the communication node 100 receives a BC signal (request) from link 101a, it will not forward the BC signal because there is no other link 101 to forward it to.

[0028] In summary, the communication node 100 determines that the predetermined forwarding conditions are not met if any of the following conditions apply: the received BC signal (request) is a BC signal that has already been forwarded; the number of times the received BC signal (request) has been forwarded has reached a predetermined number; or there is no link to which the received BC signal (request) can be forwarded. This allows the communication node 100 to prevent the BC signal from spreading too much or surviving indefinitely.

[0029] <Functional Configuration> Figure 5 shows an example of the functional configuration of a communication node according to this embodiment.

[0030] The communication node (communication device) 100, for example, has the configuration of a computer, and by executing a predetermined program on the computer, it realizes the various functional configurations shown in Figure 5. In the example in Figure 5, the communication node 100 has various functional configurations such as a communication unit 501, an information update unit 502, a transfer unit 503, a response unit 504, and a storage unit 505. At least some of the above functional configurations may be realized by hardware.

[0031] The communication unit 501 performs basic communication processing such as receiving, transmitting, and forwarding signals. For example, if the communication node 100 is a router, the communication unit 501 implements the functions of a router. Also, if the communication node 100 is a Layer 3 switch, the communication unit 501 implements the functions of a Layer 3 switch.

[0032] When the information update unit 502 receives a request via a Layer 2 BC signal, it performs an information update process to add to the information elements of the BC signal the collected information corresponding to the request, and additional information including the link information of the source of the BC signal.

[0033] Figure 6 shows an example of information elements in a BC signal (request) according to this embodiment. This figure shows, for example, an example of a BC signal 600 transmitted from the nth-th stage (where n is an integer of 1 or more) communication node 100 to the (n+1)th-th stage communication node 100.

[0034] The BC signal (request) 600 includes, for example, information 601 indicating BC, BC source information 602, service information 603, signal ID 604, TTL 605, request content 606, source node ID 607, and additional information 610 as information elements.

[0035] Information 601 indicating BC is information indicating that the BC signal 600 is a broadcast signal. For example, in the case of Ethernet (registered trademark), setting the destination MAC address to "FFFFFF" can indicate that the BC signal 600 is a broadcast signal.

[0036] The BC source information 602 is the Layer 2 address of the nth-stage communication node 100 (the local node). The service information 603 sets information indicating, for example, that it is a network sonar. For example, if it is Ethernet, the service information 603 corresponds to the "type" which indicates the type of packet in the upper layer.

[0037] Signal ID 604 is identification information that identifies the BC signal 600. As mentioned above, TTL 605 is information that indicates the upper limit of the number of transmissions of the BC signal 600, or the remaining number of transmissions. When the communication node 100 transmits the BC signal 600, it subtracts 1 from the value of TTL 605, and when TTL 605 has expired (for example, when TTL = 0), it stops transmitting the BC signal.

[0038] Request content 606 indicates whether such information is to be collected. The source node ID 607 is identification information that identifies the communication node 100 (local node) that transmits the BC signal.

[0039] The additional information 610 is information that the communication node 100 adds when transferring the BC signal 600, such as the node ID 612, the source link information 613, and the collected information 614. The communication node 100 that first transfers the BC signal 600 adds the additional information 611-1 of the first stage node, and the communication node 100 that transfers the BC signal 600 for the nth time adds the additional information 611-n of the nth stage node to the information elements of the BC signal 600.

[0040] Node ID 612 is identification information that identifies the communication node 100. The source link information 613 includes the Layer 2 address of the link that received the BC signal and the Layer 2 address of the source of the BC signal. For example, in the additional information 611-n for the nth node, the source link information 613 includes the Layer 2 address of the link from which the BC signal was transmitted at the source (n-1th node) and the Layer 2 address of the link from which the BC signal was received at the local node (nth node). The collected information 614 is information collected by the communication node 100 in response to the request content 606.

[0041] For example, the information update unit 502 of the nth-stage communication node 100 adds the nth-stage node's additional information 611-n to the received BC signal.

[0042] If the received BC signal satisfies predetermined transfer conditions, the transfer unit 503 executes a transfer process to transfer the BC signal, including the additional information added by the information update unit 502, to a link other than the link to which the BC signal was received. For example, the transfer unit 503 determines that the predetermined transfer conditions are not met if: - The received BC signal is a broadcast signal that has already been transferred - The number of times the received BC signal has been transferred has reached a predetermined number of times - There is no link to which the received BC signal can be transferred and cancels the transfer of the received BC signal. On the other hand, if none of the above three conditions apply, the transfer unit 503 determines that the predetermined transfer conditions are met and transfers the BC signal, including the additional information added by the information update unit 502, to a link other than the link to which the BC signal was received.

[0043] When the received BC signal does not meet the predetermined transfer conditions, the response unit 504 generates a response signal including additional information added by one or more communication nodes 100 including the communication node 100 which is the self node, and executes a response process for responding. The method of responding to the response signal varies depending on the requirements, but the information returned to the requester includes the additional information 610 described in FIG. 6. This is the same regardless of the response method.

[0044] As a method of returning the response signal to the requester, for example, the following methods can be considered. (First method) Return by TCP or UDP. (Second method) In unicast of layer 2, the path through which the received BC signal traveled, such as from the nth stage -> n-1th stage, is traced back and returned.

[0045] Here, the second method will be described.

[0046] FIG. 7 is a diagram showing an example of response information elements according to the present embodiment. This figure shows an example of a response signal 700 generated by the communication node 100 at the nth stage in the second method (when returning the response of the BC signal by unicast of layer 2).

[0047] In this case, the response signal 700 includes, as information elements, for example, destination information (L2 address) 701, source information (L2 address) 702, service information 703, signal ID 704, source node ID 705, and additional information 610, etc.

[0048] The destination information (L2 address) 701 is the layer 2 address of the destination. The source information (L2 address) 702 is the layer 2 address of the source. Information indicating that it is a response of the network sonar is set in the service information 703. The signal ID 704 is identification information for identifying the response signal 700. The source node ID 705 is the node ID of the communication node 100 which is the self node. The additional information 610 may have the same content as the additional information 610 described in FIG. 6.

[0049] The storage unit 505 is realized, for example, by a program executed by a computer included in the communication node 100 and a storage device of the computer, etc., and stores various information, data, etc.

[0050] <Processing Flow> Next, the processing flow of the communication method according to this embodiment will be explained.

[0051] (Processing upon reception of BC signal) Figure 8 is a flowchart showing an example of processing upon reception of a BC signal according to this embodiment. This processing shows an example of processing performed when a communication node 100 having the functional configurations described in Figure 5 receives a BC signal (request).

[0052] In step S801, when the communication unit 501 receives a BC signal (request) from the source node 10 or another communication node 100, the communication node 100 executes the processing from step S802 onward.

[0053] In step S802, the information update unit 502 adds additional information, including the source link information and the collected information corresponding to the request, to the information elements of the BC signal. For example, if the communication node 100 is the nth stage communication node 100, a BC signal 600 is generated with the additional information 611-n of the nth stage node added, as shown in Figure 6.

[0054] In step S803, the transfer unit 503 determines whether the TTL has expired. For example, the transfer unit 503 determines that the TTL has expired if the value of the TTL 605 of the received BC signal is "0". If the TTL has expired, the transfer unit 503 proceeds to step S804. On the other hand, if the TTL has not expired, the transfer unit 503 proceeds to step S805.

[0055] When the process moves to step S804, the response unit 504 generates a response signal and responds to the request via the BC signal. For example, if the communication node 100 is the nth-th stage communication node 100, the response unit 504 generates the response signal 700 described in Figure 7 and transmits the generated response signal 700 to the (n-1)th stage communication node 100.

[0056] On the other hand, when the process moves to step S805, the transfer unit 503 determines whether the received BC signal (request) is a BC signal that has already been transferred. For example, if the signal ID 604 of the received BC signal matches a stored signal ID, the transfer unit 503 determines that the received BC signal is a BC signal that has already been transferred. If it is a BC signal that has already been transferred, the transfer unit 503 proceeds to step S804 described above. On the other hand, if it is not a BC signal that has already been transferred, the transfer unit 503 proceeds to step S806.

[0057] When the process moves to step S806, the transfer unit 503 determines whether there is a destination link to which the communication node 100 can transfer the received BC signal. If there is no destination link, the transfer unit 503 proceeds to step S804 described above. On the other hand, if there is a destination link, the transfer unit 503 proceeds to step S807.

[0058] When the process moves to step S807, the transfer unit 503 transfers the BC signal, which includes the additional information added by the information update unit 502, to a link other than the link that received the BC signal. For example, the transfer unit 503 subtracts 1 from the TTL of the BC signal 600 as shown in Figure 6, and broadcasts it to the destination (or, after finding the destination by broadcasting, unicasts it to the found destination).

[0059] (Response Processing) Figure 9 is a flowchart showing an example of response processing according to this embodiment. This process shows an example of response processing that is executed when a communication node 100 receives a response signal from another communication node 100 and returns the path that the received BC signal followed in reverse, such as nth stage -> n-1th stage, using Layer 2 unicast.

[0060] In step S901, the response unit 504 determines which stage node its own node is based on the node IDs of each stage of the received response signal and its own node ID.

[0061] In step S902, the response unit 504 obtains the source link information 613 from the node information of the stage corresponding to its own node.

[0062] In step S903, the response unit 504 determines the link to which the response signal will be transmitted based on the acquired source link information, and sets the destination information (L2 address) 701 and source information (L2 address) 702 for the response signal 700. The response unit 504 also transmits the generated response signal 700 as a Layer 2 unicast to the determined destination link.

[0063] Each communication node 100 that receives a response signal can forward the response signal to the source node 10 that initially sent the BC signal (request) by executing the response processing shown in Figure 9.

[0064] <Network Map Generation Process> Next, we will explain the method for automatically generating a network map using network sonar.

[0065] (Functional Configuration) Figure 10 is a diagram showing an example of the functional configuration of a source node according to this embodiment. The source node 10 has the configuration of a computer, and by executing a predetermined program on the computer, it realizes each of the functional configurations shown in Figure 10, for example. In the example of Figure 10, the source node 10 has a transmission unit 1001, a receiving unit 1002, a generation unit 1003, and a storage unit 1004, etc.

[0066] The transmitting unit 1001 performs a transmission process to send a BC signal for network map generation to the communication node 100 (communication node 100a in the example of Figure 1).

[0067] Figure 11 shows an example of information elements of a BC signal (for network map generation) according to this embodiment. Each information element of the BC signal (for network map generation) 1100 corresponds to each information element of the BC signal (request) 600 described in Figure 6.

[0068] In the example shown in Figure 11, the service information 1101 of the BC signal 1100 contains information indicating that it is a BC signal for collecting L2 (Layer 2) address information. The request content 1102 contains information indicating that network map information is to be collected. Furthermore, the source link information 613 of the additional information 611-1 of the first-stage node contains the source L2 address 1111 and the receiving L2 address 1112. The source L2 address 1111 is the Layer 2 address of the link from which the BC signal was transmitted at the communication node 100 that sent the received BC signal. The receiving L2 address 1112 is the Layer 2 address of the link from which the BC signal was received at the communication node 100, which is the local node.

[0069] Furthermore, the collected information 614 of the additional information 611-1 of the first-stage node contains L2 address information 1121. The L2 address information 1121 contains the Layer 2 addresses of each link of the communication node 100, which is the node itself. In addition, the additional information of the second-stage and subsequent nodes also stores information corresponding to the additional information 611-1 of the first-stage node.

[0070] The additional information 610 is information that each stage's communication node 100 adds when transferring the BC signal 1100.

[0071] The receiving unit 1002 performs a receiving process to receive a response signal in response to the BC signal for network map generation transmitted by the transmitting unit 1001. The received response signal includes additional information 610, similar to the BC signal 1100 for network map generation described in Figure 11.

[0072] The generation unit 1003 executes a generation process to generate a network map and the like based on the response information received by the receiving unit 1002.

[0073] The memory unit 1004 is implemented, for example, by a program executed by a computer on the source node 10, and the storage device of that computer, and stores various information and data.

[0074] (Processing Flow) Figure 12 is a flowchart showing an example of the network map generation process according to this embodiment. This process shows an example of the network map generation process executed by the source node 10.

[0075] In step S1201, the transmitting unit 1001 of the source node 10 transmits a BC signal for network map generation to the communication node 100 (communication node 100a in the example of Figure 1).

[0076] In step S1202, the receiving unit 1002 of the transmitting node 10 receives a plurality of response signals in response to the transmitted BC signal for network map generation.

[0077] In step S1203, the generation unit 1003 of the source node 10 decomposes the additional information 610 contained in the received response signal for each communication node 100, for example, as shown in Figure 13.

[0078] In step S1204, the generation unit 1003 organizes the decomposed additional information for each communication node 100. For example, as shown in Figure 14, if the generation unit 1003 has information 1401 of a communication node (node ​​IDx) obtained from one response signal and information 1402 of a communication node (node ​​IDx) obtained from another response signal, it merges the source link information 613 of both to generate information 1403 of a single communication node (node ​​IDx).

[0079] The information 1403 for this communication node (node ​​IDx) indicates, for example, the state 1500 of the communication node IDx, as shown in Figure 15.

[0080] In step S1205, the generation unit 1003 executes the process of step S1211 for all communication nodes 100.

[0081] In step S1211, the generation unit 1003 searches for the source L2 address (Layer 2 address) of other communication nodes and determines the source node ID.

[0082] For example, by performing the process in step S1211 on the communication node with node IDx shown in Figure 15, the node IDs v and w of the source communication node 100 and the links 1601 and 1602 between them are determined, as shown in Figure 16.

[0083] Similarly, by performing the process in step S1211 on the communication node of node IDy, the link 1603 between the communication node of node IDy and the communication node of node IDx is also confirmed. Furthermore, by performing the process in step S1211 on the communication node of node IDz, the link 1604 between the communication node of node IDz and the communication node of node IDx is also confirmed.

[0084] In step S1206, the generation unit 1003 compiles the link information between each communication node 100 determined in step S1205 and generates a network map of the entire communication system 1.

[0085] As shown in Figure 12, the source node 10 can generate a network map of the communication system 1 at the Layer 2 communication level without using an IP address. Note that the generation of a network map is one example of detecting the state of the network.

[0086] <Hardware Configuration> The communication node 100 and the source node 10 have, for example, the hardware configuration of a computer 1700 as shown in Figure 17. Note that the communication node 100 or the source node 10 may be implemented using multiple computers 1700. Furthermore, the computers may be virtual computers on the cloud, etc.

[0087] Figure 17 shows an example of a computer hardware configuration. In the example in Figure 17, the computer 1700 includes a processor 1701, memory 1702, storage device 1703, communication device 1704, input device 1705, output device 1706, and bus B, etc.

[0088] The processor 1701 is a computing device such as a CPU (Central Processing Unit) that realizes various functions by executing a predetermined program. The memory 1702 is a storage medium that can be read by the computer 1700, and includes, for example, RAM (Random Access Memory) and ROM (Read Only Memory). The storage device 1703 is a large-capacity storage medium that can be read by the computer, and may include, for example, an HDD (Hard Disk Drive), an SSD (Solid State Drive), various optical discs, and magneto-optical discs.

[0089] The communication device 1704 includes one or more hardware components (communication devices) for communicating with other devices via a wireless or wired network. The input device 1705 is an input device that accepts external input (e.g., a keyboard, mouse, microphone, switch, button, sensor, etc.). The output device 1706 is an output device that outputs to the outside (e.g., a display, speaker, LED lamp, etc.).

[0090] Bus B is connected to all of the above components in common and transmits, for example, address signals, data signals, and various control signals. Note that the processor 1701 is not limited to a CPU, but may be other processors such as a DSP (Digital Signal Processor), a PLD (Programmable Logic Device), or an FPGA (Field Programmable Gate Array).

[0091] (Supplement) In this embodiment, the communication node 100 and the source node 10 are not limited to being implemented by dedicated devices, but may also be implemented by a general-purpose computer. In that case, the program for implementing this function may be recorded on a computer-readable recording medium, and the program recorded on this recording medium may be loaded into a computer system and executed. The term "computer system" as used herein includes hardware such as the OS and peripheral devices.

[0092] Furthermore, "computer-readable recording media" includes various storage devices such as flexible disks, magneto-optical disks, ROMs, CD-ROMs, and other portable media, as well as storage devices built into computer systems. In addition, "computer-readable recording media" may also include those that dynamically hold programs for a short period of time, such as communication lines used when transmitting programs over networks such as the Internet or communication lines such as telephone lines, and those that hold programs for a certain period of time, such as volatile memory inside computer systems that act as servers or clients in such cases.

[0093] Furthermore, the above program may be for the purpose of realizing some of the functions described above, or it may be able to realize the above functions in combination with a program already recorded in the computer system, or it may be implemented using hardware such as a PLD or FPGA.

[0094] <Effects of the Embodiment> According to this embodiment, the network status can be detected at the Layer 2 communication level without using IP addresses. For example, the source node 10 can generate a network map of the communication system 1 at the Layer 2 communication level without using IP addresses.

[0095] Furthermore, this embodiment also provides the following advantages: • Information requests can be expanded and responses obtained without being affected by IP routing. • Information can be requested without specifying an address, and information can be collected from the entire network in the response. • Network maps can be generated even in cases where IP-based network map generation cannot correctly investigate. • Since Layer 2 network maps can be automatically generated from the collected information, the workload of maintenance personnel can be reduced.

[0096] <Summary of Embodiments> This specification discloses at least the following communication devices, generation methods, and communication methods: (Section 1) A communication device connected to one or more links, comprising: an information update unit that, upon receiving a request by a Layer 2 broadcast signal, adds to the information elements of the broadcast signal a collection information corresponding to the request and additional information including the link information of the source of the broadcast signal; a transfer unit that, when the broadcast signal satisfies predetermined transfer conditions, transfers the broadcast signal including the additional information to a link other than the link that received the broadcast signal; and a response unit that, when the broadcast signal does not satisfy the predetermined transfer conditions, generates a response signal including the additional information added to the information elements of the broadcast signal by one or more communication devices, including the communication device, and responds to the request. (Section 2) The communication device according to Section 1, wherein the source link information includes the Layer 2 address of the link that received the broadcast signal and the Layer 2 address of the link from which the broadcast signal was transmitted by the communication device that transmitted the broadcast signal. (3) The communication device according to paragraph 1 or 2, wherein the transfer unit determines that the predetermined transfer conditions are not met if the broadcast signal is a broadcast signal that has already been transferred, if the number of times the broadcast signal has been transferred has reached a predetermined number of times, or if there is no link to which the broadcast signal can be transferred. (4) A generation method, wherein a computer connected to a network composed of communication devices according to any one of paragraphs 1 to 3 performs the following: a transmission process that sends a request using a Layer 2 broadcast signal to the communication device; a reception process that receives a plurality of response signals from the communication device in response to the request; and a generation process that generates a network map of the network based on the collected information corresponding to the request and the link information of the source of the broadcast signal included in the plurality of response signals.(Clause 5) A communication method comprising: an information update process in which, when a communication device connected to one or more links receives a request via a Layer 2 broadcast signal, additional information including collected information corresponding to the request and link information of the source of the broadcast signal is added to the information elements of the broadcast signal; a transfer process in which, if the broadcast signal satisfies predetermined transfer conditions, the broadcast signal including the additional information is transferred to a link other than the link that received the broadcast signal; and a response process in which, if the broadcast signal does not satisfy the predetermined transfer conditions, one or more communication devices, including the communication device, generate a response signal including the additional information added to the information elements of the broadcast signal and respond to the request.

[0097] Although this embodiment has been described above, the present invention is not limited to this specific embodiment, and various modifications and changes are possible within the scope of the gist of the invention as described in the claims.

[0098] 1 Communication System 10 Source Nodes 100, 100a, 100b, 100c Communication Nodes (Communication Devices) 101 Link 501 Communication Unit 502 Information Update Unit 503 Transfer Unit 504 Response Units 505, 1004 Storage Unit 1001 Transmission Unit 1002 Receiving Unit 1003 Generation Unit 1700 Computer

Claims

1. A communication device connected to one or more links, comprising: an information update unit that, upon receiving a request via a Layer 2 broadcast signal, adds to the information elements of the broadcast signal additional information including collected information corresponding to the request and link information of the source of the broadcast signal; a transfer unit that, if the broadcast signal satisfies predetermined transfer conditions, transfers the broadcast signal including the additional information to a link other than the link that received the broadcast signal; and a response unit that, if the broadcast signal does not satisfy the predetermined transfer conditions, generates a response signal including the additional information added to the information elements of the broadcast signal by one or more communication devices, including the communication device, and responds to the request.

2. The communication device according to claim 1, wherein the source link information includes the Layer 2 address of the link that received the broadcast signal and the Layer 2 address of the link on which the broadcast signal was transmitted in the communication device that transmitted the broadcast signal.

3. The communication device according to claim 1, wherein the transfer unit determines that the predetermined transfer conditions are not met if the broadcast signal is a broadcast signal that has already been transferred, if the number of times the broadcast signal has been transferred has reached a predetermined number of times, or if there is no link to which the broadcast signal can be transferred.

4. A generation method comprising: a computer connected to a network comprising a communication device according to any one of claims 1 to 3, performing a transmission process to send a request to the communication device using a Layer 2 broadcast signal; a reception process to receive a plurality of response signals from the communication device in response to the request; and a generation process to generate a network map of the network based on collected information corresponding to the request and link information of the source of the broadcast signal, which are included in the plurality of response signals.

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