JP5640853B2 - Communication system, router, switching hub, and program - Google Patents

Description

This invention is a LAN (Local
The present invention relates to priority control of various data communications performed via a communication network such as an area network.

  In recent years, corporations have established LANs (hereinafter referred to as local LANs) at each base such as a branch office, and connected these local LANs to an IP (Internet Protocol) network such as the Internet via a router. Building is generally done. Such a local LAN is often configured by cascading a plurality of switching hubs, and a communication terminal used by each user (for example, a company employee) is connected to any one of those switching hubs. Here, the router is a relay device that performs transfer control of packets (data transmission / reception unit in the third layer) according to the communication protocol of the third layer (network layer) in the OSI (Open Systems Interconnection) reference model. The switching hub is a relay device that performs transfer control of a frame (data transmission / reception unit in the second layer) according to the communication protocol of the second layer (data link layer) in the OSI reference model, and is also called an L2 switch.

  In general, in-house information systems perform various types of data communication such as voice data transmission / reception according to VoIP (Voice Over Internet Protocol) and text data transmission / reception according to HTTP (Hyper Text Transport Protocol). . For example, voice data is transmitted / received according to VoIP in a remote conference between bases, and text data is transmitted / received when browsing or writing an in-house bulletin board. As described above, when various types of data communication can be performed simultaneously and in parallel, a priority is determined in advance for each type of data communication, and high-priority data communication is performed by low-priority data communication. It is necessary not to be disturbed. For example, the priority of data communication performed according to VoIP is set higher than the priority of data communication performed according to HTTP so that the former is not hindered by the latter. This is because if the former is hindered by the latter, the voice representing the speech of each conference participant in the remote conference is reproduced intermittently, and the operation of the conference is hindered.

  As an example of a technique for predetermining a priority for each type of data communication so that data communication with high priority is not hindered by data communication with low priority, QoS (Quality of Service) is cited. QoS means that, when each switching hub performs frame transfer control, frame transfer related to data communication with a high priority is preferentially performed over other frames. In the case of the in-house information system as described above, the operation manager of each local LAN directly connects to each switching hub included in the local LAN what type of data communication terminal is connected. It is necessary to know whether it is connected or indirectly (that is, via another switching hub) and then perform complicated operations such as setting QoS appropriately in relation to the priority of the data communication. It must be made. For this reason, various techniques for reducing the complexity related to the QoS setting have been proposed, and an example thereof is the technique disclosed in Patent Document 1. In the technique disclosed in Patent Document 1, the MAC (Media Access Control) address of a communication terminal that transmits and receives audio data is associated with the setting contents of QoS at the time of transfer control of a frame that includes the audio data. Store in advance in the switching hub. Then, when the MAC address is stored in the MAC address table of the own device, each switching hub is caused to execute processing for applying the setting to the communication port corresponding to the MAC address.

JP 2005-184192 A

  According to the technique disclosed in Patent Document 1, the workload of the operation manager is reduced in that it is not necessary to know in advance the connection relationship between a communication terminal that performs voice data communication and each switching hub. However, in the technique disclosed in Patent Document 1, the MAC address of the communication terminal that performs voice data communication and the QoS setting contents are stored in association with each other for all switching hubs included in the LAN. Need to be performed in advance, and the workload of the operation manager is not sufficiently reduced.

  The present invention has been made in view of the above problems, and allows each switching hub to perform transfer control according to the priority of data communication executed by each communication terminal while reducing the complexity of setting work. The aim is to provide technology that makes it possible.

  In order to solve the above problems, the present invention provides a router for connecting a subordinate network and another network, a plurality of switching hubs included in the network under the router, and any one of the plurality of switching hubs. In a communication system including a plurality of connected communication terminals, the router transmits priority data indicating priority of data communication performed by the communication terminal to each of the plurality of communication terminals and the communication terminal. Requesting transmission of adjacent device information indicating the communication device that has transferred the frame, and requesting each of the plurality of switching hubs to transmit a request frame requesting transmission of adjacent device information about the switching hub A first means for giving a communication address of the own device as an identifier and multicasting to the network; A priority notification frame returned from each of the communication terminals to notify the priority and neighboring device information about the communication terminal, and neighboring device information about the switching hub from each of the plurality of switching hubs. The adjacent device notification frame returned for notification is received, the switching hub on the communication path from the router to each of the plurality of communication terminals is specified for each communication terminal, and the switching hub on each communication path is specified. On the other hand, the priority data of the communication terminal located at the end of the communication path and the information indicating the communication path are transmitted, and the frame transmitted / received along the communication path (that is, the communication located at the end of the communication path) An instruction is given to perform transfer control of a frame having a terminal as a transmission destination or transmission source at the priority indicated by the priority data. Each of the plurality of switching hubs, wherein each of the plurality of switching hubs stores an adjacent device table that stores adjacent device information indicating a communication device that has transferred a frame to the own device, and a transfer source in the received frame If an identifier is assigned, the transfer source identifier is written in the adjacent device table as neighbor device information, and then the transfer source identifier is rewritten to the communication address of the own device to perform transfer control according to the destination of the frame. If the received frame is the request frame, the third means to perform, generate an adjacent device notification frame in which the adjacent device information stored in the adjacent device table is written, and transfer the communication address of its own device A fourth means for giving and returning as an identifier, and transfer control of frames transmitted and received along the communication path indicated by the information received from the router. And a fifth means for switching a frame transfer control mode in the switching hub so as to be performed with the priority indicated by the priority data received together with the information, and each of the plurality of communication terminals includes the Sixth means for storing the transfer source identifier given to the request frame as reception of the request frame as neighboring device information for the communication device, and priority data indicating the priority of data communication performed by the terminal itself And a seventh means for replying with the communication address of the own apparatus as a transfer source identifier.

  In such a communication system, if priority data indicating the priority of data communication performed by the communication terminal is stored in advance in each communication terminal, each switching hub on the communication path from the router to the communication terminal is stored. The priority setting in the frame transfer control is automatically changed. Therefore, according to the above communication system, each switching hub can be controlled to perform transfer control according to the priority of data communication performed by each communication terminal without performing special setting work for each switching hub. It becomes possible.

  In a more preferred aspect, when the fifth means receives a frame originating from a communication terminal located at the end of the communication path indicated by the information received from the router, the fifth means is written in the payload portion of the frame. It is characterized in that the header portion of the packet is rewritten so that the packet transfer control in the third layer with respect to the received packet is performed according to the priority indicated by the priority data. According to such an aspect, it is expected that a packet transmitted from the router to another network is preferentially handled in the third layer transfer control in the other network. Here, as a specific example of rewriting the header part of the packet so that the priority at the time of transfer control in the third layer becomes high, a DSCP (Diff Serv Code Point) value, a CoS value or a TOS value is high It can be rewritten to a value representing priority.

  Further, in order to solve the above-described problem, the present invention transmits, to each of a plurality of switching hubs included in a subordinate network, transmission of adjacent device information indicating a communication device that has transferred a frame to the switching hub. Requesting each communication terminal connected to each of the plurality of switching hubs to transmit priority data indicating the priority of data communication performed by the communication terminal and neighboring device information about the communication terminal. A multicast unit that assigns the communication address of its own device as a transfer source identifier to a request frame to be transmitted and multicasts to the network, and notifies the priority and neighboring device information about the communication terminal from each of the plurality of communication terminals For receiving the priority notification frame and each of the plurality of switching hubs. Receiving a neighboring device notification frame returned to notify neighboring device information about the switching hub, specifying a switching hub on a communication path from the router to each of the plurality of communication terminals, for each communication terminal; The priority data of the communication terminal located at the end of the communication path and information indicating the communication path are transmitted to the switching hub on each communication path, and transfer control of frames transmitted and received along the communication path is performed. There is provided a router characterized by having priority setting control means for instructing to perform at the priority indicated by the priority data. This is because the communication system can be configured by combining such a router with the switching hub and the communication terminal.

  As another aspect of the present invention, an aspect of providing a program that causes a computer to function as the multicast means and the priority setting control means is also conceivable. This is because by installing such a program on a general computer and operating the control unit of the computer according to the program, the computer can function as the router of the present invention. In addition, by installing the above program in a general router and operating the routing control unit of the router according to the above program, it is possible to give the general router a function that significantly shows the characteristics of the router of the present invention. It becomes possible. In addition, as a concrete supply mode of the above-mentioned program, for example, a mode in which the program is written and distributed on a computer-readable recording medium such as a CD-ROM (Compact Disk-Read Only Memory) and a DVD (Digital Versatile Disc), the Internet A mode of distribution by downloading via a telecommunication line is conceivable.

  In order to solve the above-described problem, the present invention provides an adjacent device table for storing adjacent device information indicating a communication device that has transferred a frame to the own device, and performs transfer control of the received frame according to the destination. And when the transfer source identifier is given to the received frame, the transfer source identifier is written in the adjacent device table as adjacent device information, and then the transfer source identifier is set to the communication address of the own device. To the frame transfer control means for performing transfer control according to the destination of the frame, and the switching hub for requesting the transmission of the adjacent device information indicating the communication device that has received the frame transferred to the switching hub. In the case of a request frame transmitted from a router that connects a network to another network, A neighboring device notification means for generating a neighboring device notification frame in which the neighboring device information stored in the network is written, giving the communication address of the own device as a transfer source identifier, and returning, and communication indicated by the information received from the router Priority setting change means for switching a frame transfer control mode in the switching hub so that transfer control of frames transmitted / received along the path is performed with the priority indicated by the priority data received together with the information. A switching hub is provided. This is because the communication system can be configured by combining such a switching hub with the router having the multicast unit and the priority setting control unit and the communication terminal. Further, in another aspect of the present invention, an aspect is conceivable in which a program for causing a computer to function as storage means for storing adjacent device information, frame transfer control means, adjacent device notification means, and priority setting change means is provided.

It is a figure which shows the structural example of the information system in a company of 1st Embodiment of this invention. It is a figure which shows the structural example of the communication terminal 40 contained in the system. It is a flowchart which shows the flow of the priority notification process which the control part 410 of the communication terminal 40 performs. It is a figure which shows an example of the data structure of the flame | frame transmitted / received in the network under the router 60 contained in the system. It is a figure which shows the structural example of the switching hub 50 contained in the system. It is a flowchart which shows the flow of the process which the switching engine part 520 of the switching hub 50 performs according to a firmware. 3 is a diagram illustrating a configuration example of the router 60. FIG. It is a flowchart which shows the flow of the priority setting control processing which the routing engine part 620 of the router 60 performs according to a firmware. It is a figure which shows an example of the connection relation of each apparatus in LAN1A. It is a figure for demonstrating the operation | movement of this embodiment. It is a figure for demonstrating the operation | movement of this embodiment. It is a figure for demonstrating the effect of this embodiment. It is a figure which shows the structural example of LAN1C of 2nd Embodiment of this invention. It is a figure for demonstrating the network topology of LAN1C grasped | ascertained from the topology data which the router 60A produces | generates.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<A: First Embodiment>
<A-1: Configuration>
FIG. 1 is a diagram illustrating a configuration example of a communication system according to an embodiment of the present invention. This communication system is the above-described in-company information system, and is configured by connecting LANs 1A and 1B, which are local LANs installed at bases such as branch offices, to an IP network such as the Internet. As shown in FIG. 1, the LAN 1A includes a router 60A, two switching hubs (switching hubs 50A and 50B), and three communication terminals (communication terminals 40A, 40B, and 40C). It is connected to the IP network via 60A. As shown in FIG. 1, a switching hub 50A is connected to the router 60A, and a switching hub 50B and a communication terminal 40A are connected to the switching hub 50A. Communication terminals 40B and 40C are connected to the switching hub 50B. On the other hand, the LAN 1B includes a router 60B, a switching hub 50C, and three communication terminals (communication terminals 40D, 40E, and 40F), and is connected to the IP network via the router 60B. As shown in FIG. 1, a switching hub 50C is connected to the router 60B, and each of the communication terminals 40D, 40E, and 40F is connected to the switching hub 50C.

  The six communication terminals shown in FIG. 1 are personal computers, for example, and all have the same configuration. Below, when it is not necessary to distinguish each of these 6 communication terminals, it describes with the "communication terminal 40". The three switching hubs shown in FIG. 1 all have the same configuration, and when it is not necessary to distinguish each of these three switching hubs, they are denoted as “switching hub 50”. Similarly, each of the routers 60A and 60B shown in FIG. 1 has the same configuration, and when it is not necessary to distinguish each of these two routers, they are denoted as “router 60”.

  The communication terminal 40 is a switching hub 50 included in a network under the router 60 (a network connected to the IP network by the router 60 and using the router 60 as a default gateway, LAN 1A if the router 60A, LAN 1B if the router 60B). It is accommodated in the said network by connecting to. The communication terminal 40 accommodated in the network under the router 60 is connected to another communication device (for example, another communication terminal accommodated in the LAN 1A, a communication terminal accommodated in another local LAN, or an IP network). Data communication is performed with a connected WWW server or the like. More specifically, among the six communication terminals shown in FIG. 1, each of the communication terminals 40A, 40B, 40D, and 40E is a VoIP terminal that transmits and receives voice packets according to VoIP. Here, the voice packet is a packet in which voice data representing the voice of the terminal user is compressed and encoded and written in the payload portion. Of these four VoIP terminals, the communication terminals 40B and 40E are used for general voice communication such as a remote conference, and the communication terminals 40A and 40D are used only for emergency voice communication such as a fire report. The communication terminals 40C and 40F are terminals that transmit / receive data other than voice data, for example, transmit / receive text data according to HTTP.

  The switching hub 50 is a relay device that relays data communication in the second layer, and performs transfer control based on a frame destination MAC address. The router 60 is a relay device that relays data communication in the third layer. For example, if the destination IP address of the packet received from the IP network is that of the communication terminal 40 accommodated in the subordinate network, the router 60 transfers the packet to the subordinate network, and the destination IP address Is not the one of the communication terminal 40 accommodated in the subordinate network, it is transferred to another router according to the stored contents of the routing table.

  As described above, in each of the LAN 1A and the LAN 1B shown in FIG. 1, each communication terminal 40 performs three types of data communication such as general voice communication, emergency voice communication, and data communication other than voice communication. These three types of data communication have different priorities. Specifically, the priority of emergency voice communication performed by the communication terminal 40A or 40D is the highest, followed by the priority of voice communication performed by the communication terminal 40B or 40E, and the priority of data communication performed by the communication terminal 40C or 40F. Is the lowest. For this reason, in LAN 1A (or LAN 1B), transfer of frames transmitted and received by communication terminal 40A (or communication terminal 40D) is performed with the highest priority, and transfer of frames transmitted and received by communication terminal 40B (or communication terminal 40E) is performed. The frame transfer control setting in each switching hub 50 needs to be set so as to be performed with the next highest priority, and the same applies to the packet transfer control setting in the router 60.

  Conventionally, these settings are generally performed manually by an operation manager of the LAN 1A (or LAN 1B). On the other hand, in the present embodiment, by causing each of the communication terminal 40, the switching hub 50, and the router 60 to execute processing that clearly shows the characteristics of the present embodiment, the frame transfer control setting for the switching hub 50, and The packet transfer control setting for the router 60 is automatically performed. Hereinafter, the communication terminal 40, the switching hub 50, and the router 60 will be described in detail.

<A-1-1: Configuration of the communication terminal 40>
FIG. 2 is a block diagram illustrating a configuration of the communication terminal 40. As shown in FIG. 2, the communication terminal 40 mediates data exchange between the control unit 410, a communication interface (hereinafter referred to as I / F) unit 420, a user I / F unit 430, a storage unit 440, and these components. A bus 450 is included. The control unit 410 is a CPU, and functions as a control center of the communication terminal 40 by executing a program stored in the storage unit 440. The communication I / F unit 420 is, for example, a NIC (Network Interface Card). The communication I / F unit 420 receives the data transferred from the switching hub 50 that is the connection destination and transfers the data to the control unit 410, while sending the data transferred from the control unit 410 toward the switching hub 50. .

  The user I / F unit 430 includes a voice input / output unit for inputting / outputting a voice, a display unit for displaying various screens, and an operation unit for allowing a user to input various data such as a numeric keypad (both not shown). ) Is included. In communication terminals 40A, 40B, 40D, and 40E, the user's voice is input via user I / F unit 430, and the voice of the other party is output. In communication terminals 40C and 40F, various data (such as text data to be transmitted to the other party) is input / output via user I / F unit 430.

  As shown in FIG. 2, the storage unit 440 includes a nonvolatile storage unit 442 and a volatile storage unit 444. The nonvolatile storage unit 442 is, for example, a hard disk. The non-volatile storage unit 442 stores a communication program (not shown in FIG. 2) for performing voice communication according to VoIP and text data transmission / reception according to HTTP. The nonvolatile storage unit 442 includes a priority notification program for causing the control unit 410 to execute the priority notification process illustrated in FIG. 3 and priority data indicating the priority of data communication performed by the communication terminal 40. And are stored. The processing contents of this priority notification processing will be clarified later. In the present embodiment, data having a value of “0”, “1”, or “2” is used as the priority data. More specifically, the communication terminals 40A and 40D have “0” as priority data, the communication terminals 40B and 40E have “1” as priority data, and the communication terminals 40C and 40F have “0” as priority data. 2 "is stored in advance. That is, the priority data of this embodiment represents a higher priority as the value is smaller. If the priority data is written to the non-volatile storage unit 442, for example, the user of the communication terminal 40 or the operation manager of the network that houses the communication terminal 40 may be performed in advance by operating the user I / F unit 430. good.

  The volatile storage unit 444 is, for example, a RAM (Random Access Memory), and is used as a work area when executing various programs such as a communication program and a priority notification program. The volatile storage unit 444 stores adjacent device information as shown in FIG. Here, the adjacent device information is information indicating the relay device that has transferred the frame to the communication terminal 40 (in this embodiment, the MAC address of the switching hub 50 to which the communication terminal 40 is connected). . Although details will be described later, the neighboring device information is written to the volatile storage unit 444 in the course of executing the priority notification program. In the following, prior to a detailed description of the processing contents of the priority notification process executed in accordance with the priority notification program, the data structure of frames transmitted and received in the network under the router 60 will be described.

  FIG. 4A is a diagram illustrating a data structure of a general frame transmitted / received in the network under the router 60. As shown in FIG. 4A, the frame has a header portion and a payload portion. The header part stores a transmission destination MAC address, a transmission source MAC address, and a type identifier. The transmission destination MAC address is the MAC address of the device that is the destination of the frame, and the transmission source MAC address is the MAC address of the device that transmitted the frame. The type identifier is data indicating the type of the frame (for example, what type of packet is written in the payload portion).

  Of the frames transmitted and received in the network under the router 60, the features of the present embodiment are remarkably shown in the following four types: request frame, priority notification frame, adjacent device notification frame, and setting change instruction frame. It is done. For these four types of frames, common values (values different from those related to voice communication and text data data communication) are written as type identifiers. The request frame means that the router 60 returns a priority notification frame to the communication terminal 40 accommodated in the subordinate network, and returns a neighboring device notification frame to the switching hub 50 included in the network. , A frame that is multicast to the subordinate network for each request. The priority notification frame is a frame that the communication terminal 40 returns (unicast) as a response to the request frame, and the adjacent device notification frame is a transmission source of the request frame as a response to the request frame by the switching hub 50. This is a frame to reply to (unicast). Hereinafter, when there is no need to distinguish between the adjacent device notification frame and the priority notification frame, they are simply referred to as “notification frame”. The setting change instruction frame is a frame transmitted by the router 60 to instruct the switching hub 50 included in the subordinate network to change the priority setting in the frame transfer control.

  FIG. 4B is a diagram illustrating the data structure of the payload portion of the request frame. As shown in FIG. 4B, a destination MAC address, a source MAC address, a message type identifier, and a transfer source identifier are written in the payload portion of the request frame. The destination MAC address of the payload portion of the request frame is the same as the destination MAC address written in the header portion of the frame, and the same applies to the source MAC address of the payload portion. In the message type identifier, a value indicating which of the above four types of frames is set. For example, when character code data is used as a message type identifier, a character code indicating “1” (or “A”) as a message type identifier in the request frame, and “2” as a message identifier in the priority notification frame. (Or “B”), a character code indicating “3” (or “C”) as a message identifier in the adjacent device notification frame, and “4” (as a message type identifier in the setting change instruction frame) Alternatively, a character code indicating “D”) is set. The transmission source identifier is set with the MAC address of the transmission source when the request frame is transmitted, and rewritten to the MAC address of the switching hub 50 that performed the transfer every time the switching hub 50 transfers the frame. It is done. Although details will be described later, when the switching hub 50 and the communication terminal 40 receive the request frame, the switching hub 50 and the communication terminal 40 transfer the request frame to their own devices by referring to the transfer source identifier of the request frame. The relay device can be specified.

  FIG. 4C is a diagram illustrating the data structure of the payload portion of the adjacent device notification frame. As shown in FIG. 4C, in the payload portion of the adjacent device notification frame, the adjacent device information list is written in addition to the transmission destination MAC address, the transmission source MAC address, the message type identifier, and the transfer source identifier. Although details will be described later, the adjacent device information list is a correspondence relationship between the MAC address of the device that has transferred the frame to the switching hub that is the transmission source of the adjacent device notification frame and the communication port that has received the frame Is information. FIG. 4D is a diagram illustrating the data structure of the payload portion of the priority notification frame. As shown in FIG. 4D, in the payload portion of the priority notification frame, in addition to the transmission destination MAC address, the transmission source MAC address, the message type identifier, and the transfer source identifier, the transmission source of the priority notification frame The adjacent device information and priority data of the communication terminal 40 are written. Although details will be described later, when the router 60 and the switching hub 50 receive these notification frames, the router 60 and the switching hub 50 transfer the notification frame to their own devices by referring to the transfer source identifier of the notification frame. The device can be specified.

  FIG. 4E shows the data structure of the payload portion of the setting change instruction frame. As shown in FIG. 4E, in the payload portion of the setting change instruction frame, the transmission destination MAC address, the transmission source MAC address, and the message type identifier are written, and setting change instruction data is written. The setting change instruction data includes a port identifier indicating a communication port whose priority setting should be changed for the switching hub 50 that is the transmission destination of the setting change instruction frame, and priority data indicating the priority. . The above is the data structure of the frame transmitted / received in the network under the router 60.

Next, details of the priority notification process will be described with reference to FIG. This priority notification process is executed when a request frame is received. Here, whether or not the received frame is a request frame may be determined by referring to the message type identifier written in the payload portion of the received frame. As shown in FIG. 3, in the priority notification process, the control unit 410 first writes the transfer source identifier written in the payload portion of the received request frame in the volatile storage unit 444 as neighboring device information (step SA100). ). Next, the control unit 410 generates the above-described priority notification frame and returns (unicasts) it to the transmission source of the request frame (step SA110). In the payload portion of the priority notification frame returned by the control unit 410 in step SA110, the MAC address of the communication terminal 40 is written as the transfer source identifier, and the adjacent device information stored in the volatile storage unit 444 is stored. , And the priority data stored in the nonvolatile storage unit 442 is written.
The above is the configuration of the communication terminal 40.

<A-1-2: Configuration of the switching hub 50>
FIG. 5 is a block diagram showing the configuration of the switching hub 50. As illustrated in FIG. 5, the switching hub 50 includes a communication I / F unit 510, a switching engine unit 520, and a storage unit 530. Communication I / F unit 510 has a plurality of communication ports. Each of the plurality of communication ports is connected to another communication device (in this embodiment, the router 60, another switching hub 50, or the communication terminal 40) via a communication cable such as 100BASE-T. Each of the plurality of communication ports is assigned a unique port identifier (for example, a port number) for each communication port, and each communication port can be uniquely identified using this port identifier. The communication I / F unit 510 provides a frame received via each communication port to the switching engine unit 520, and transmits a frame provided from the switching engine unit 520 from a communication port instructed by the switching engine unit 520.

  The storage unit 530 includes, for example, a volatile memory such as a RAM and a nonvolatile memory such as an EPROM (Erasable Programmable Read Only Memory) (none of which is shown in FIG. 5). In this nonvolatile memory, firmware (program) for causing the switching engine unit 520 to execute processing that clearly shows the characteristics of the switching hub of the present invention is stored in advance. On the other hand, the volatile memory is used by the switching engine unit 520 as a work area when executing the firmware. The volatile memory serves as a buffer for temporarily storing frames received by the communication I / F unit 510, and the volatile memory further includes a MAC address table in FIG. And the adjacent device table of FIG. 5 are stored.

  The MAC address table of FIG. 5 is not particularly different from that of a conventional switching hub. This MAC address table stores the port identifier of the communication port that received the frame in association with the transmission source MAC address of the frame received by the communication I / F unit 510. The writing of the MAC address and the port identifier to the MAC address table is performed in accordance with frame transfer control described later. For example, in the transfer process of a frame (a frame in which an ARP (Address Resolution Protocol) packet is written in the payload portion) transmitted from the communication terminal 40 for resolving the MAC address of the router 60, the transmission source MAC address (that is, the frame) , The MAC address of the communication terminal 40) and the port identifier of the receiving port of the frame are associated and written into the MAC address table. On the other hand, in the transfer process of the response frame to the frame, a process of writing the transmission source MAC address of the frame (that is, the MAC address of the router 60) and the port identifier of the reception port of the frame in association with each other is performed. Is called. The stored contents of the MAC address table are used when frame transfer control based on the destination MAC address is performed.

  In the adjacent device table, a connection destination identifier that uniquely indicates a communication device that is a transfer source of a frame received via the communication port in association with each port identifier of the plurality of communication ports that the communication I / F unit 510 has. (In this embodiment, the MAC address of the communication device) is stored. The adjacent device table is generated in a state where each connection destination identifier is NULL (0x00) when a power source (not shown) of the switching hub 50 is turned on. Then, as the switching hub 50 relays a predetermined specific frame (in this embodiment, the request frame and the notification frame described above), the stored contents of the table are updated (that is, these frames are received). The connection destination identifier corresponding to the port identifier of the communication port is rewritten with the transfer source identifier of the frame).

  The switching engine unit 520 is, for example, a CPU. The switching engine unit 520 functions as a control center of the switching hub 50 by executing the firmware stored in the storage unit 530. Each time the switching engine unit 520 operating in accordance with the firmware receives a frame via any communication port, the switching engine unit 520 writes the frame to a buffer in the volatile memory, and the flow chart of FIG. The process shown in is executed. As shown in FIG. 6, there are three processes executed by the switching engine unit 520 according to the firmware: a frame transfer control process, an adjacent device notification frame transmission process, and a priority setting change process.

  As shown in FIG. 6, the switching engine unit 520 first determines whether or not the received frame is a setting change instruction frame transmitted to its own device, with the transmission destination MAC address in the header part of the received frame. The determination is made with reference to the message type identifier of the payload part (step SB100). In other words, when the transmission destination MAC address is the MAC address of the own device and the message type identifier indicates the setting change instruction frame, the determination result in Step SB100 is “Yes”. When the determination result in step SB100 is “Yes”, switching engine unit 520 executes the priority setting change process (step SB110), and conversely, the determination result in step SB100 is “No”. In this case, a frame transfer control process is executed.

  The frame transfer control process executed when the determination result in step SB100 is “No” includes a process (step SB190) for performing transfer control of the received frame based on the destination MAC address of the received frame. Here, the transfer control based on the transmission destination MAC address of the received frame is a unicast address in which the transmission destination MAC address is not a unicast address or the transmission destination MAC address is not stored in the MAC address table. In this case, the received frame is flooded, while when the destination MAC address is a unicast address stored in the MAC address table, it is stored in the MAC address table in association with the MAC address. The received frame is transmitted only from the communication port indicated by the port identifier. Here, a MAC address that is not a unicast address includes a multicast address or a broadcast address. Also, flooding means sending the received frame from all communication ports other than the communication port that received the received frame. The transfer control based on the destination MAC address is not particularly different from that in the conventional switching hub. In other words, in the conventional switching hub, only the transfer control based on the destination MAC address (that is, the process of step SB190) is executed as the frame transfer control process.

  The priority setting change process executed when the determination result of step SB100 is “Yes” is the priority when the process of step SB190 is performed on each of the frames stored in the buffer in the volatile memory. Is changed in accordance with an instruction given from the router 60. The priority setting change process of the present embodiment includes a change in VLAN (Virtual Local Area Network) setting and a change in QoS setting. Here, the VLAN setting is to virtually separate the network segment by excluding the communication port instructed to change the priority setting from the router 60 from the flooding target. Since the multicast frame received via the communication port of the other network segment is not sent to the communication port separated from the network segment by the VLAN setting, the data communication performed through the communication port is performed by the transfer of the multicast frame. It will not be disturbed. On the other hand, when QoS is performed in step SB190, a frame having a higher priority than the frame is accumulated in the buffer when the frame is transmitted to the communication port corresponding to the destination. Is to postpone sending. By performing such QoS, it is possible to avoid that the transfer control of a frame assigned with a high priority is hindered by the transfer control of a frame with a low priority. In the priority setting change process according to the present embodiment, the switching engine unit 520 performs network segment separation based on the VLAN setting described above for the communication port instructed that the priority should be “0”, and The highest priority in QoS is set for a frame received via a communication port (or a frame transmitted to the communication port). For the communication port instructed to set the priority to “1”, the switching engine unit 520 only changes the QoS setting and sets the QoS priority to the second highest.

  The frame transfer control process of this embodiment includes the processes of steps SB120 to SB160 in addition to the process of step SB190 described above. As shown in FIG. 3, the switching engine unit 520 first determines whether or not the transfer source identifier is written in the payload portion of the received frame (step SB120). Here, various methods for determining whether or not the transfer source identifier is written in the payload portion of the received frame can be considered. For example, it may be a mode in which the corresponding area of the payload portion of the received frame is directly referred to and determined based on whether or not a MAC address is written. The received frame is a request frame, an adjacent device notification frame. Alternatively, the determination may be made according to whether the frame is one of the priority notification frames. As described above, among the frames transmitted / received in the network under the router 60, the transfer source identifier is written in the payload portion because there are only three types of request frames, adjacent device notification frames, and priority notification frames. is there. For example, in the case of the latter mode, the type identifier written in the header portion of the received frame indicates the above four types of frames, and the message type identifier written in the payload portion is a request frame, If it indicates either the adjacent device notification frame or the priority notification frame, the determination result in step SB120 is “Yes”.

  If the determination result in step SB120 is “No”, the switching engine unit 520 causes the received frame to be transmitted from the subordinate network to the IP network for voice communication (that is, in the payload part). It is determined with reference to the transmission destination MAC address and type identifier of the header portion of the received frame (step SB130). For example, when the destination MAC address of the received frame is not the MAC address of the communication terminal 40 accommodated in the network under its own apparatus, and the type identifier of the received frame indicates VoIP, step SB130 The determination result is “Yes”. When the determination result in step SB130 is “Yes”, the switching engine unit 520 rewrites the DSCP value of the voice packet written in the payload part of the voice communication frame according to the priority of the transmission source ( Step SB140), and then the process of step SB190 is executed. Conversely, when the determination result in step SB130 is “No”, the switching engine unit 520 executes the process in step SB190 without performing the process in step SB140. The DSCP value is a value indicating the priority when performing voice packet transfer control in the third layer. Although details will be described later, by rewriting the DSCP value in the switching hub 50, the packet transfer control in the IP network is performed by the packet transfer control in the IP network for the voice packet transmitted from the router 60 to the IP network. It is expected to be performed according to the priority of the terminal 40. In the present embodiment, for voice packets sent from the router 60 to the IP network, packet transfer control in the IP network is performed according to the priority of the communication terminal 40 that is the transmission source. Although the DSCP value has been rewritten, it is of course possible to use other indices such as the CoS value and the TOS value.

On the other hand, when the determination result in step SB120 is “Yes” (that is, when the received frame is any one of the request frame, the priority notification frame, and the adjacent device notification frame), the switching engine unit 520 The adjacent device identifier stored in the adjacent device table in association with the port identifier of the communication port that received the received frame is rewritten with the transfer source identifier of the received frame (step SB150), and the received frame is transferred. The original identifier is rewritten to the MAC address of the own device (step SB160). Next, the switching engine unit 520 determines whether or not the received frame is a request frame with reference to the message type identifier of the payload part of the received frame (step SB170), and when the determination result is Yes, After executing the adjacent device notification frame transmission process (step SB170), the process of step SB190 is executed. In the adjacent device notification frame transmission process, the switching engine unit 520 generates the above-described adjacent device notification frame and returns (unicast) it to the transmission source of the request frame. In the payload portion of the adjacent device notification frame, the stored content of the adjacent device table updated by the processing of step SB150 is written as an adjacent device information list. Conversely, if the determination result in step SB170 is “No”, the switching engine unit 520 executes the process in step SB190 without executing the process in step SB180.
The above is the configuration of the switching hub 50.

<A-1-3: Configuration of Router 60>
FIG. 7 is a block diagram showing the configuration of the router 60. As illustrated in FIG. 7, the router 60 includes a communication I / F unit 610, a routing engine unit 620, and a storage unit 630. The communication I / F unit 610 has a plurality of ports like the communication I / F unit 510 of the switching hub 50, and a unique port identifier is assigned to each port. For example, in the router 60A, the IP network and the switching hub 50A are connected to two of the plurality of ports, respectively. Similar to communication I / F unit 510, communication I / F unit 610 provides a frame received via each communication port to routing engine unit 620, while a frame provided from routing engine unit 620 is provided by routing engine unit 620. Send out from the specified communication port.

  Similarly to the storage unit 530 of the switching hub 50, the storage unit 630 includes a volatile memory such as a RAM and a nonvolatile memory such as an EPROM (not shown). Firmware is stored in the nonvolatile memory. In the present embodiment, by operating the routing engine unit 620 according to this firmware, the function of the router 60 that significantly shows the features of the present embodiment is realized. On the other hand, the volatile memory is used by the routing engine unit 620 as a work area when executing the firmware, and serves as a buffer for temporarily storing received frames (or packets). . The volatile memory stores the routing table shown in FIG. 7, the MAC address table for the router 60, and the adjacent device table.

  The routing engine unit 620 is a CPU, like the switching engine unit 520 of the switching hub 50. The routing engine unit 620 executes firmware stored in the storage unit 630 and functions as a control center of the router 60. The routing engine unit 620 executes four types of processing, that is, packet transfer control processing, multicast processing, connection relationship identification processing, and priority setting control processing, according to the firmware. Of these four processes, the packet transfer control process is not particularly different from the conventional process. Therefore, the following description will focus on multicast processing, connection relationship identification processing, and priority setting control processing.

  The multicast process is a process of multicasting the request frame toward the network under the router 60 (LAN1A if the router 60A, LAN1B if the router 60B). Although details will be described later, in this embodiment, this multicast processing is periodically executed every time a predetermined time T (for example, 3 seconds) elapses after the power of the router 60 (not shown) is turned on.

  In the connection relationship specifying process, the routing engine unit 620 first, in response to the reception of the notification frame transmitted from each switching hub 50, associates it with the port identifier of the communication port that has received the notification frame in the adjacent device table. The stored connection destination identifier is rewritten to the transfer source identifier written in the payload portion of the frame. Then, the routing engine unit 620 subordinates the content stored in the adjacent device table of its own device, the adjacent device information list returned from each switching hub 50, and the adjacent device information returned from the communication terminal 40. Topology data representing the connection relationship (network topology) of each device in the network is generated.

  More specifically, the routing engine unit 620 includes the stored contents of the adjacent device table of its own device, the adjacent device information list returned from the switching hub 50, the adjacent device information returned from the communication terminal 40, For each of the own device, each switching hub 50 and each communication terminal 40, the first pointer indicating the upstream neighboring device (for example, the port identifier of the communication port connected to the upstream neighboring device and the upstream Data indicating the MAC address of the side neighboring device) and one or more second pointers indicating the downstream side neighboring device (for example, the port identifier of the communication port connected to the downstream side neighboring device and the downstream side neighboring device) Structure data with a bidirectional list structure consisting of data indicating the MAC address of the device) A set of concrete body data to the above-mentioned topology data. Here, the upstream adjacent device is an adjacent device on the side close to the router 60, and the downstream adjacent device is an adjacent device on the side far from the router 60. For example, in the LAN 1A of FIG. 1, the upstream adjacent device of the switching hub 50A is the router 60, and the downstream adjacent devices are the communication terminal 40A and the switching hub 50B. In the structure data for a device that does not have an upstream adjacent device such as the router 60 in FIG. 1, NULL may be set in the first pointer, and similarly, the communication terminal 40 in FIG. Thus, in the structure data for a device that does not have a downstream adjacent device, NULL may be set in the second pointer.

  When a set of structure data having a bidirectional list structure as described above is used as topology data, the two pointers that are adjacent to each other can be traced using the second pointer from the upstream side, or the first pointer can be viewed from the downstream side. It is necessary that no contradiction arises even if traced using. For example, in the topology data related to the LAN 1A in FIG. 1, the switching hub 50B is indicated by the second pointer of the structure data corresponding to the switching hub 50A, and the first pointer of the structure data corresponding to the switching hub 50B. The switching hub 50A needs to be indicated by. Therefore, for example, when there is a contradiction that the switching hub 50B is not notified of the switching hub 50B as an adjacent device even though the switching hub 50A is notified of the adjacent device as the adjacent device, The routing engine unit 620 generates topology data only to the extent that no contradiction occurs.

Next, the processing content of the priority setting control processing will be described with reference to FIG. This priority setting control process is a process executed in response to reception of a priority notification frame. FIG. 8 is a flowchart showing the flow of priority setting control processing. As shown in FIG. 8, the routing engine unit 620 first refers to the topology data to determine whether or not the communication path between the communication terminal 40 that is the transmission source of the priority notification frame and its own device is specified. Determination is made (step SC100). More specifically, if the router 60 can be reached by following the first pointer in order from the structure data corresponding to the communication terminal 40 that is the transmission source of the priority notification frame, the process proceeds to step SC100. The determination result is “Yes”. When the determination result in step SC100 is “Yes”, the routing engine unit 620 sets the priority setting in the packet transfer control of the own device in the priority level written in the payload portion of the priority notification frame. The setting is changed according to the priority represented by the data (step SC110), and a setting change instruction frame is transmitted (unicast) to each of the switching hubs 50 on the communication path (SC120).
The above is the configuration of the router 60.

<A-2: Operation>
Hereinafter, the operation of the present embodiment will be described by taking as an example the case where the router 60 and the switching hub 50 each have eight communication ports and are connected to each other in the LAN 1A as shown in FIG. . In FIG. 9, the communication port is indicated by a black circle, and the port number of the communication port is indicated by a number with #. As shown in FIG. 9, a switching hub 50A is connected to the communication port of port number = 1 of the router 60A. From the viewpoint of the switching hub 50A, the router 60A is connected to the communication port of port number = 2 of the switching hub 50A. Has been. As shown in FIG. 9, the communication terminal 40A is connected to the communication port of port number = 3 of the switching hub 50A, and the switching hub 50B is connected to the communication port of port number = 4. When viewed from the switching hub 50B, the switching hub 50A is connected to the communication port of port number = 5 of the switching hub 50B, and the communication terminal 40B is connected to the communication port of port number = 6 of the switching hub 50B. A communication terminal 40C is connected to the communication port. At the start of the operation described below, the connection destination identifiers in the adjacent device tables of the router 60 and the switching hub 50 are NULL cleared.

  The routing engine unit 620 of the router 60A multicasts the request frame at a time T0 when a predetermined time T has elapsed after the power (not shown) of the router 60A is turned on. The request frame multicasted from the router 60A in this way is first received by the switching hub 50A. The switching engine unit 520 of the switching hub 50A receives the request frame via the communication port with port number = 2, and executes each process of steps SB150, SB160, SB180, and SB190 in FIG. This is because the determination result of step SB100 is “No” and the determination results of SB120 and SB170 are “Yes” because the received frame is a request frame.

  Since the process of step SB150 is executed, the connection destination identifier stored in the adjacent device table of the switching hub 50A in association with the port number = 2 is the transfer source identifier (that is, the router 60) assigned to the received frame. Of the MAC address). Further, the transfer source identifier of the received frame is rewritten to the MAC address of the switching hub 50A by the process of step SB160. In step SB180, the adjacent device notification frame in which the stored content of the updated adjacent device table by the processing in step SB150 is written as the adjacent device information list is unicast from the switching hub 50A to the router 60. In step SB190, the request frame in which the transfer source identifier has been rewritten by the processing in step SB160 is flooded. This is because the destination MAC address of the request frame is a multicast address as described above. The request frame flooded in this way is received by each of the communication terminal 40A and the switching hub 50B.

  When receiving the request frame via the communication I / F unit 420, the control unit 410 of the communication terminal 40A executes the above-described priority notification process (see FIG. 3). More specifically, the control unit 410 writes the transfer source identifier (that is, the MAC address of the switching hub 50A) written in the payload portion of the request frame in the volatile storage unit 444 as adjacent device information (FIG. 3). : Step SA100). Next, the control unit 410 generates a priority notification frame having the transmission source MAC address (that is, the MAC address of the router 60A) of the request frame as a transmission destination MAC address, and transmits the priority notification frame (FIG. 3). : Step SA110). In the payload portion of the priority notification frame, the MAC address of the communication terminal 40A is written as a transfer source identifier, and the priority data and adjacent device information of the communication terminal 40A are written.

  When the switching engine unit 520 of the switching hub 50B receives the request frame transferred from the switching hub 50A, the switching engine unit 520 performs the processes of steps SB150, SB160, SB180, and SB190 of FIG. 6 in the same manner as the switching engine unit 520 of the switching hub 50A. Run. More specifically, the switching engine unit 520 of the switching hub 50B transfers the connection destination identifier corresponding to the port number = 5 in the adjacent device table of its own device to the request frame transferred from the switching hub 50A. The renewal is performed using the original identifier (that is, the MAC address of the switching hub 50A), and the adjacent device notification frame in which the stored content of the rewritten adjacent device table is written as the adjacent device information list is unicast to the router 60. In addition, the switching engine unit 520 of the switching hub 50B performs flooding of a request frame in which the transfer source identifier is rewritten to the MAC address of the switching hub 50B.

  The request frame flooded in this way is received by each of the communication terminals 40B and 40C. The control unit 410 of the communication terminal 40B (or communication terminal 40C) executes priority notification processing (see FIG. 3) in the same manner as the control unit 410 of the communication terminal 40A, triggered by reception of the request frame. As a result, the MAC address of the switching hub 50B is written as adjacent device information in the volatile storage unit 444 of the communication terminal 40B (or 40C), and the adjacent device information and the priority data of the communication terminal 40B (or 40C) Is sent back to the router 60. As a result of executing the operation described above, the storage contents of the adjacent device table of the switching hubs 50A and 50B and the adjacent device information of the communication terminals 40A, 40B and 40C are in the state shown in FIG.

  Next, the update of the adjacent device table performed in accordance with the notification frame transfer control will be described. When the switching engine unit 520 of the switching hub 50B receives the priority notification frame unicast from the communication terminal 40B (or communication terminal 40C) to the router 60 via the communication port of port number = 6 (or 7), Steps SB150, SB160, and SB190 of FIG. 6 are executed. This is because the determination result of steps SB100 and SB170 is “No” and the determination result of step SB120 is “Yes” because the received frame is a priority notification frame.

  Since the process of step SB150 is executed, the connection destination identifier stored in the adjacent device table of the switching hub 50B in association with the port identifier of the communication port that has received the priority notification frame is given to the received frame. The transfer source identifier (that is, the MAC address of the communication terminal 40B (or communication terminal 40C)) is rewritten, and the transfer source identifier of the received frame is rewritten to the MAC address of the switching hub 50B by the process of step SB160. In step SB190, the priority notification frame in which the transfer source identifier has been rewritten by the process in step SB160 is transmitted via the communication port with port number = 5.

  The switching engine unit 520 of the switching hub 50A includes a priority notification frame transmitted from the communication terminal 40A or a notification frame transferred from the switching hub 50B (that is, an adjacent device notification frame transmitted from the switching hub 50B or a switching hub). When the priority notification frame (transferred by 50B) is received, the processing of steps SB150, SB160, and SB190 in FIG. 6 is similarly performed. The switching hub 50A sets the connection destination identifier corresponding to the communication port that has received these notification frames as the transfer source identifier assigned to the notification frame (if the notification frame is transferred by the switching hub 50B, the switching hub 50B The MAC address or the priority notification frame transmitted from the communication terminal 40A is rewritten with the MAC address of the communication terminal 40A), and the transfer source identifier of the notification frame is rewritten with the MAC address of the own device and transferred to the router 60. When the router 60 receives the notification frame transferred from the switching hub 50A via the communication port having the port number = 1, the router 60 sets the connection destination identifier corresponding to the port number in the adjacent device table of the own device to the transfer source identifier of the frame. Rewrite with. As a result of the operation described above being executed, the contents stored in the adjacent device tables of the router 60 and the switching hubs 50A and 50B are updated from the state shown in FIG. 10 to the state shown in FIG. As is apparent from FIG. 11, the stored contents of the adjacent device table and the adjacent device information of each communication terminal 40 represent the network topology in the LAN 1A without contradiction.

  It should be noted that the adjacent device information list written in the adjacent device notification frame received by the router 60A from the switching hubs 50A and 50B in the operation described above is stored in the adjacent device table shown in FIG. This corresponds to not the contents but the contents stored in the adjacent device table shown in FIG. In the stored contents of each adjacent device table shown in FIG. 10, only the connection relationship between the router 60A and the switching hub 50A is represented without contradiction. For this reason, when the notification frame for the request frame multicasted at time T0 is received, the routing engine unit 620 generates topology data representing only the connection relationship between the router 60A and the switching hub 50A.

  When a predetermined time T further elapses from time T0, the routing engine unit 620 multicasts the request frame, and each of the switching hubs 50A and 50B performs the same processing as described above. An adjacent device information list corresponding to the stored contents of the adjacent device table shown in FIG. 11 is written in each of the adjacent device notification frames returned by the switching hubs 50A and 50B as a response to the request frame transmitted from the router 60A at time T0 + T. It is. Therefore, the routing engine unit 620 receives the adjacent device notification frame returned for the request frame multicasted at time T0 + T (that is, the second multicast if the multicast at time T0 is the first). Then, topology data representing the connection relationship between the own device and all the communication devices under its control is generated. The operation manager of the LAN 1A can grasp the network topology of the LAN 1A by referring to the topology data generated in this way.

  The routing engine unit 620 of the router 60A executes the above-described priority setting control process (see FIG. 8) every time the priority notification frame returned from each of the communication terminals 40A, 40B, and 40C is received. As described above, in the priority setting control process, the routing engine unit 620 refers to the topology data to determine whether or not the communication path between the own device and the transmission source of the priority notification frame can be specified. (Step SC100). As described above, when a notification frame returned in response to the multicast request frame is received at time T0, topology data representing only the connection relationship between the router 60A and the switching hub 50A (that is, corresponding to the router 60A). Only structure data and structure data corresponding to the switching hub 50A) are generated. Thus, at the time of receiving the priority notification frame returned to the multicast request frame at time T0, the structure data corresponding to each of the communication terminals 40A, 40B and 40C is not generated, and step SC100. The determination result is “No”. In other words, the processing after step SC110 is not executed when the priority notification frame returned for the request frame multicasted at time T0 is received.

  On the other hand, at the time of receiving the priority notification frame returned to the multicast request frame at time T0 + T, as described above, the router 60A, the switching hubs 50A and 50B, and the communication terminals 40A, 40B and 40C. Structure data corresponding to each of the above is generated. Therefore, for example, when the priority notification frame transmitted from the communication terminal 40B is received, the routing engine unit 620 refers to the first pointer of the structure data corresponding to the communication terminal 40B, and performs the communication. The connection destination of the terminal 40B is specified as the switching hub 50B, and the communication terminal 40B refers to the second pointer of the structure data corresponding to the switching hub 50B so that the communication terminal 40B becomes the communication port of port number = 6 of the switching hub 50B. Identify that it is connected. Also, the routing engine unit 620 refers to the first pointer of the structure data corresponding to the switching hub 50B, specifies that the switching hub 50B is connected to the switching hub 50A, and corresponds to the switching hub 50A. With reference to the second pointer of the structure data, it is specified that the switching hub 50B is connected to the communication port of port number = 4 of the switching hub 50A. Then, the routing engine unit 620 refers to the first pointer of the structure data corresponding to the switching hub 50A, specifies that the switching hub 50A is connected to the own device, and the structure corresponding to the own device. With reference to the second pointer of data, it is specified that the switching hub 50A is connected to the communication port of port number = 1. As a result, the communication path between the router 60A and the communication terminal 40B is specified.

  Since the communication path between the own device and the communication terminal 40B is specified in this way, the determination result in step SC100 is “Yes”, and the processing after step SC110 is executed. As described above, priority data indicating that the priority is “1” is written in the priority notification frame transmitted from the communication terminal 40B. For this reason, in step SC110, unless there is a packet transmitted from a communication terminal (in this embodiment, communication terminal 40A) that performs data communication with priority “0” (highest priority), communication terminal 40B The transmitted packet is sent to the IP network with the highest priority, and when a packet addressed to the communication terminal 40B is received via the IP network, the communication terminal that performs data communication with a priority of “0” is set as the destination. As long as there is no packet to be transmitted, priority setting of packet transfer control is performed so that the packet is transmitted to the switching hub 50A with the highest priority. In step SC120, for each switching hub 50 (that is, switching hubs 50A and 50B) on the communication path from router 60A to communication terminal 40B, the communication port to which communication terminal 40B is connected and the communication port. A setting change instruction frame in which setting change instruction data indicating that the priority of data communication performed through the communication is “1” is written is transmitted. Specifically, for the switching hub 50A, setting change instruction data indicating that the priority of data communication performed through the communication port of port number = 4 and the port number is “1” is set in the payload portion. The setting change instruction frame written in is sent. On the other hand, for the switching hub 50B, setting change instruction data indicating that the priority of data communication performed via the communication port of port number = 6 and the port number is “1” is written in the payload portion. A setting change instruction frame is transmitted.

  When the switching engine unit 520 of the switching hub 50A or 50B receives the setting change instruction frame transmitted from the router 60 (step SB100: Yes in FIG. 6), the setting change instruction data written in the payload portion of the setting change instruction frame The priority setting for the frame transfer control is changed according to the contents indicated by (step SB110 in FIG. 6). Since the priority indicated by the setting change instruction data written in the payload portion of the setting change instruction frame is “1”, the switching engine unit 520 only changes the QoS setting for the communication port indicated by the setting change instruction data. I do. Specifically, unless there is a frame received via a communication port with a priority “0” (or a frame transmitted to a communication port with a priority “0”), the communication port indicated by the setting change instruction data The QoS setting is changed so that transfer of a frame received via the network (or a frame transmitted to the communication port) has the highest priority.

  In contrast, when the routing engine unit 620 receives the priority notification frame transmitted from the communication terminal 40A, the routing engine unit 620 sets the priority of data communication performed through the communication port of port number = 3 and the port number to “0”. A setting change instruction frame in which setting change instruction data indicating "" is written is transmitted to the switching hub 50A. When the switching engine unit 520 of the switching hub 50A receives this setting change instruction frame, the switching engine unit 520 changes the priority setting in the frame transfer control as follows. That is, since the priority indicated by the setting change instruction data written in the payload portion of the setting change instruction frame is “0”, the network segment of the communication port indicated by the setting change instruction data and the network of the other communication port Segments are separated by VLAN settings, and QoS settings are changed. Specifically, the QoS setting is changed so that transfer of a frame received via the communication port (or a frame transmitted to the communication port) has the highest priority. As a result of such VLAN setting, the LAN 1A is virtually divided into a network segment to which only the communication terminal 40A belongs and a network segment to which the switching hub 50B and the communication terminals 40B and 40C belong, as indicated by a dotted line in FIG. Therefore, it is possible to reliably prevent the voice communication performed by the communication terminal 40A from being obstructed by the data communication performed by the communication terminal 40B or 40C.

  As described above, in this embodiment, if the priority of data communication performed by the communication terminal 40 is set for the communication terminal 40 accommodated in the network under the router 60, each switching hub 50 is set. The priority setting of the frame transfer control is automatically changed. In the present embodiment, since there is no need to store the MAC address of the communication terminal 40 that transmits and receives voice data, the QoS setting contents, and the like in advance in association with the switching hub 50, the setting work of the operation manager Is less complicated. That is, according to the present embodiment, it is possible to cause each switching hub 50 to perform transfer control according to the priority of data communication executed by each communication terminal while reducing the complexity of the setting work. In the operation example described above, priority control in the LAN 1A has been described, but the same applies to priority control in the LAN 1B.

  Further, according to the present embodiment, the network topology of the network under the router 60 can be easily grasped by referring to the topology data generated based on the neighboring device information returned from the switching hub 50 and the communication terminal 40. You can also Here, the data size of the neighboring device information transmitted from each switching hub 50 is determined according to the number of relay devices connected to the switching hub 50, and the data size according to the number of communication ports that the switching hub 50 has. No more. In other words, even if the number of switching hubs 50 included in the LAN 1A increases, the data size of the payload portion of the notification frame in the present embodiment does not increase without limit. For this reason, even if the scale of the LAN 1A is increased, an excessive load is not applied to the LAN 1A for specifying the network topology.

  Furthermore, since the router 60 of the present embodiment periodically multicasts the request frame every time the predetermined time T elapses, for example, the network topology is changed such that the switching hub 50 (or the communication terminal 40) is newly connected. Even when the network topology is changed, topology data that accurately represents the network topology after the change without any contradiction is generated by multicasting the second request frame from the connection of the new switching hub. That is, according to the present embodiment, it is possible to detect a change in the network topology without delay while avoiding an excessive load on the LAN 1A.

<B: Second Embodiment>
FIG. 13 is a block diagram illustrating a configuration example of the LAN 1C according to the second embodiment of this invention.
As apparent from a comparison between FIG. 13 and FIG. 1, the LAN 1C is different from the LAN 1A in that it includes a switching hub 500 instead of the switching hub 50B. The switching hub 500 is a conventional switching hub, and differs from the switching hub 50 in that only the frame transfer control based on the transmission destination MAC address of the received frame (that is, the process of step SB190 in FIG. 6) is executed.

  In the LAN 1C, the request frame transferred from the switching hub 50A to the switching hub 500 is transferred to the communication terminals 40B and 40C without rewriting the transfer source identifier. Therefore, the MAC address of the switching hub 50A is written as adjacent device information in the volatile storage unit 444 of the communication terminals 40B and 40C. Similarly, the priority notification frames transmitted from each of the communication terminals 40B and 40C are also transferred to the switching hub 50A by the switching hub 500 without rewriting the transfer source identifier. Therefore, in the adjacent device table of the switching hub 50A, either the MAC address of the communication terminal 40B or the MAC address of the communication terminal 40C is associated with the port identifier of the communication port to which the switching hub 500 is connected. Written. This is because of the priority notification frames transmitted from each of the communication terminals 40B and 40C, the one received earlier is rewritten by the transfer identifier received later.

  As a result of the MAC address being written to the adjacent device table in the manner described above, the router 60A generates topology data representing the network topology shown in FIG. 14 (A) or FIG. 14 (B). FIG. 14A shows a network topology represented by topology data generated when the switching hub 50A receives the latter of the priority notification frames transmitted from the communication terminals 40B and 40C first. FIG. 14B shows a network topology represented by topology data generated when the switching hub 50A receives the former first. As apparent from a comparison between FIG. 14 (A) or FIG. 14 (B) and FIG. 13, the switching hub 500 does not appear in the network topology shown in FIG. 14 (A) or FIG. 14 (B). Also, only one of the communication terminals 40B and 40C appears, which is different from the actual network topology of the LAN 1C.

  Thus, when the conventional switching hub is included in the network under the router 60, the connection between the conventional switching hub and other devices (that is, the router 60, the switching hub 50, and the communication terminal 40). The relationship cannot be grasped, and priority control for data communication performed by a communication terminal connected to a conventional switching hub may be hindered. For example, when topology data representing the network topology shown in FIG. 14A is generated, priority control for data communication performed by the communication terminal 40C cannot be performed, and conversely, FIG. 14B When the topology data representing the network topology shown in FIG. 2 is generated, priority control for data communication performed by the communication terminal 40B cannot be performed. However, also in the LAN 1C, it is possible to grasp a rough connection relationship between the router 60 and the switching hub 50 and to perform priority control for the communication terminal 40 connected to the switching hub 50.

  Needless to say, if all of the switching hubs included in the network under the router 60 are conventional, it is impossible to grasp the network topology in the network and to control the priority for each data communication. However, if at least one switching hub 50 according to the present invention is included in a plurality of switching hubs included in the network under the router 60, the connection relationship between the router 60 and the switching hub 50 (that is, general General network topology excluding typical conventional switching hubs) can be grasped, and priority control for data communication performed by the communication terminal 40 connected to the switching hub 50 can be performed. It can be done.

<C: Deformation>
Although the embodiment of the present invention has been described above, it is needless to say that the following modifications may be added to this embodiment.
(1) In each of the above-described embodiments, a request frame for requesting transmission of a notification frame is periodically multicast to the router 60 at predetermined time intervals, but triggered by reception of a predetermined type of packet. The request frame may be multicast to the router 60. For example, the request frame is transmitted to the router 60 when the ARP packet is received. The fact that an ARP packet is newly transmitted means that a new communication terminal 40 is connected to the network under the router 60, and there is a possibility that the network topology has changed due to the connection of the new communication terminal. There is also a possibility that the priority of frame transfer control needs to be changed. If the router 60 is made to transmit a request frame in response to reception of a new ARP packet, a change in the network topology associated with the connection of a new communication terminal is detected without waiting for the elapse of a predetermined time, and further frame transfer control is performed. The priority setting can be changed without waiting for the predetermined time to elapse.

  When the router 60 also serves as a DHCP server, the request frame may be multicast when triggered by the reception of a packet requesting IP address assignment from a subordinate communication terminal. When the router 60 executes the process of periodically multicasting the request frame at a predetermined time interval and the process of multicasting the request frame triggered by reception of a specific type of packet, the latter multicast is performed. You may make it measure the progress of the said predetermined time again from the time as the starting point. Similarly for control frames, in addition to periodic multicast (or in place of periodic multicast), reception of a predetermined type of packet such as an ARP packet or a packet requesting IP address assignment is received. As an opportunity, the router 60 may be multicast.

(2) In each of the embodiments described above, the adjacent device notification frame is transmitted to the switching hub 50 in response to the reception of the request frame. However, the adjacent device notification frame is periodically transmitted to the switching hub 50 at predetermined time intervals. Anyway. Similarly, the priority notification frame may be periodically transmitted to the communication terminal 40 at predetermined time intervals. Thus, in the aspect of periodically transmitting the notification frame, it is not necessary to multicast the request frame from the router 60, and a predetermined part of the frames to be multicast from the router 60 to the subordinate network. The transfer source identifier may be assigned to and multicasted.

(3) In each embodiment described above, every time a request frame is received, the adjacent device notification frame in which the adjacent device information list is written in the payload is returned to each switching hub 50. However, if there is no change in the stored contents of the adjacent device table between the reception of the N (natural number) request frame and the reception of the (N + 1) th request frame, a response is made to the request frame received at the (N + 1) th time. In this case, instead of the adjacent device information list, a notification frame in which data indicating that there is no change in the adjacent device information list is written in the payload portion may be returned.

(4) In each of the embodiments described above, the type of data communication performed by the communication terminal 40 is predetermined for each communication terminal 40, and priority data indicating the priority of the data communication is stored in the nonvolatile storage unit. 442 was previously written. However, each of the communication terminals 40 may perform a plurality of types of data communication, and priority data indicating the priority of the data communication being performed may be written in the nonvolatile storage unit 442. Such a thing is realizable in the following ways. That is, a plurality of types of communication programs are stored in each communication terminal 40, and a priority table that associates each of the communication programs with the priority of data communication performed according to the communication program is stored in each communication terminal 40. Remember. Then, in response to an instruction to execute one of the communication programs, the priority corresponding to the communication program is specified by referring to the stored contents of the priority table, and priority data indicating the priority is nonvolatile. The control unit 410 is caused to execute processing for writing to the property storage unit 442.

(5) In each of the above-described embodiments, the multicast processing and the priority setting control processing that clearly show the characteristics of the router of the present invention are realized by software. However, of course, each of the multicast means for realizing the multicast processing and the priority setting control means for executing the priority setting control processing may be realized by hardware such as an electronic circuit. Similarly, for the switching hub 50, the frame transfer control process, the adjacent device notification frame transmission process, and the priority setting change process may be realized by hardware such as an electronic circuit.

(6) In each of the embodiments described above, the priority of emergency voice communication is the highest, the priority of general voice communication is the next highest, and the priority of data communication other than voice communication is the lowest. However, it is desirable to increase the priority even for data communication other than voice communication, for example, if the data communication needs to be performed at a high capacity and at high speed, such as daily upload of data to a database server. Needless to say. In the above-described embodiment, the priority setting is performed for each communication port. However, the priority setting may be performed for each communication terminal located at the end of the communication path (that is, each MAC address of each communication terminal). . For this reason, the priority data and the MAC address of the communication terminal that is the transmission source of the priority data are used as the setting change instruction data, and the priority setting change process is executed in the switching hub 50 according to the setting change instruction data. You can make it.

  1A, 1B, 1C ... LAN, 40A, 40B, 40C, 40D, 40E, 40F ... Communication terminal, 50A, 50B, 50C, 50D, 500 ... Switching hub, 60 ... Router, 410 ... Control unit, 420, 510, 610 ... Communication I / F part, 430 ... User I / F part, 520 ... Switching engine part, 440, 530, 630 ... Memory part, 442 ... Nonvolatile memory part, 444 ... Volatile memory part, 620 ... Routing engine part, 450 ... Bus.

Claims (7)

Communication including a router connecting a subordinate network and another network, a plurality of switching hubs included in the network subordinate to the router, and a plurality of communication terminals respectively connected to any of the plurality of switching hubs In the system,
The router
For each of the plurality of communication terminals, priority data indicating the priority of data communication performed by the communication terminal, and transmission of adjacent device information indicating the communication apparatus that has transferred the frame to the communication terminal. To each of the plurality of switching hubs, assigning a communication address of the own device as a transfer source identifier to a request frame for requesting transmission of neighboring device information about the switching hub, and multicasting to the network A first means;
A priority notification frame returned from each of the plurality of communication terminals to notify the priority and adjacent device information for the communication terminal, and an adjacent device for the switching hub from each of the plurality of switching hubs The adjacent device notification frame returned to notify the information is received, the switching hub on the communication path from the router to each of the plurality of communication terminals is specified for each communication terminal, and the switching on each communication path is performed. The priority data of the communication terminal located at the end of the communication path and information indicating the communication path are transmitted to the hub, and the transfer control of the frame transmitted / received along the communication path is indicated by the priority data. And a second means for instructing to do with priority,
Each of the plurality of switching hubs is
An adjacent device table that stores adjacent device information indicating a communication device that has transferred a frame to the own device;
When a transfer source identifier is given to the received frame, the transfer source identifier is written in the adjacent device table as adjacent device information, and then the transfer source identifier is rewritten to the communication address of the own device, and the destination of the frame A third means for performing transfer control according to
If the received frame is the request frame, an adjacent device notification frame in which adjacent device information stored in the adjacent device table is written is generated, and the communication address of the own device is assigned as a transfer source identifier and returned. A fourth means;
A mode of frame transfer control in the switching hub is performed so that transfer control of frames transmitted and received along the communication path indicated by the information received from the router is performed with the priority indicated by the priority data received together with the information. A fifth means for switching,
Each of the plurality of communication terminals is
Sixth means for storing a transfer source identifier assigned to the request frame as reception of the request frame as neighboring device information for the communication device;
And a seventh means for giving a reply with the communication address of the own apparatus as a transfer source identifier to the priority notification frame in which priority data indicating the priority of data communication performed by the own terminal is written. Communications system.   2. The fifth means according to claim 1, wherein at least one of QoS (Quality of Service) setting and VLAN (Virtual Local Area Network) setting is switched according to priority data received from the router. Communication system.   When the fifth means receives a frame originating from a communication terminal located at the end of the communication path indicated by the information received from the router, the fifth means 3. The communication system according to claim 1, wherein a header portion of the packet is rewritten so that packet transfer control in the three layers is performed according to the priority indicated by the priority data. For each of the plurality of switching hubs included in the subordinate network, the switching hub is requested to transmit adjacent device information indicating the communication device that has transferred the frame, and connected to each of the plurality of switching hubs. For each communication terminal to be transmitted, the communication address of the own device is assigned to a request frame for requesting transmission of priority data indicating the priority of data communication performed by the communication terminal and neighboring device information for the communication terminal. A multicast means for granting and multicasting to the network as
A priority notification frame returned from each of the plurality of communication terminals to notify the priority and adjacent device information for the communication terminal, and an adjacent device for the switching hub from each of the plurality of switching hubs The adjacent device notification frame returned to notify the information is received, the switching hub on the communication path from the own apparatus to each of the plurality of communication terminals is specified for each communication terminal, and the switching on each communication path is performed. The priority data of the communication terminal located at the end of the communication path and information indicating the communication path are transmitted to the hub, and the transfer control of the frame transmitted / received along the communication path is indicated by the priority data. A router having priority setting control means for instructing to perform with priority. An adjacent device table that stores adjacent device information indicating a communication device that has transferred a frame to the own device;
A means for performing transfer control of a received frame according to its destination, and when a transfer source identifier is given to the received frame, the transfer source identifier is written in the adjacent device table as adjacent device information Frame transfer control means for performing transfer control according to the destination of the frame by rewriting the transfer source identifier later with the communication address of the own device;
When the received frame is a request frame transmitted from a router that connects a network including the own device to another network in order to request transmission of neighboring device information indicating the communication device that has transferred the frame to the own device , An adjacent device notification means for generating an adjacent device notification frame in which the adjacent device information stored in the adjacent device table is written, giving a communication address of the own device as a transfer source identifier, and sending back;
Switch the mode of frame transfer control in the own device so that transfer control of frames transmitted and received along the communication path indicated by the information received from the router is performed with the priority indicated by the priority data received together with the information. Priority setting change means;
A switching hub comprising: Computer
Each of a plurality of switching hubs included in a network connected to another network using the computer as a router requests transmission of adjacent device information indicating a communication device that has transferred the frame to the switching hub. A request frame for requesting transmission of priority data indicating the priority of data communication performed by the communication terminal and adjacent device information for the communication terminal to each communication terminal connected to each of the plurality of switching hubs Multicast means for giving a communication address of its own device as a transfer source identifier and multicasting to the network;
A priority notification frame returned from each of the plurality of communication terminals to notify the priority and adjacent device information for the communication terminal, and an adjacent device for the switching hub from each of the plurality of switching hubs The adjacent device notification frame returned to notify the information is received, the switching hub on the communication path from the router to each of the plurality of communication terminals is specified for each communication terminal, and the switching on each communication path is performed. The priority data of the communication terminal located at the end of the communication path and information indicating the communication path are transmitted to the hub, and the transfer control of the frame transmitted / received along the communication path is indicated by the priority data. A program which functions as a priority setting control means for instructing to perform with priority. Computer
Storage means for storing adjacent device information indicating a communication device that has transferred a frame to the computer;
A means for performing transfer control of a received frame according to its destination, and when a transfer source identifier is given to the received frame, after writing the transfer source identifier as neighbor device information in the storage means Frame transfer control means for rewriting the transfer source identifier to the communication address of its own device and performing transfer control according to the destination of the frame;
When the received frame is a request frame transmitted from a router that connects a network including the computer to another network in order to request transmission of neighboring device information indicating the communication device that transferred the frame to the computer, An adjacent device notification unit that generates the adjacent device notification frame in which the adjacent device information stored in the storage unit is written, and gives a communication address of the own device as a transfer source identifier;
Switch the frame transfer control mode in the computer so that the transfer control of the frames transmitted and received along the communication path indicated by the information received from the router is performed with the priority indicated by the priority data received together with the information. Priority setting change means;
A program characterized by functioning as

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