WO2012111833A1 - Système de communication, routeur, concentrateur de commutation et procédé de communication - Google Patents

Système de communication, routeur, concentrateur de commutation et procédé de communication Download PDF

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Publication number
WO2012111833A1
WO2012111833A1 PCT/JP2012/053889 JP2012053889W WO2012111833A1 WO 2012111833 A1 WO2012111833 A1 WO 2012111833A1 JP 2012053889 W JP2012053889 W JP 2012053889W WO 2012111833 A1 WO2012111833 A1 WO 2012111833A1
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Prior art keywords
switching hub
relay device
router
communication
communication port
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PCT/JP2012/053889
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English (en)
Japanese (ja)
Inventor
博之 新井田
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ヤマハ株式会社
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Application filed by ヤマハ株式会社 filed Critical ヤマハ株式会社
Priority to CN201280009491.5A priority Critical patent/CN103503383B/zh
Publication of WO2012111833A1 publication Critical patent/WO2012111833A1/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks

Definitions

  • This invention relates to a technology for supporting operation management of a LAN (Local Area Network).
  • local LANs In recent years, companies have established LANs (hereinafter referred to as local LANs) at each branch office, etc., and connected these local LANs to an IP (Internet Protocol) network such as the Internet via a router. Building is generally done.
  • IP Internet Protocol
  • 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.
  • 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.
  • Patent Document 1 discloses a technique for delivering a MAC (Media Access Control) address table between switching hubs included in a LAN and searching for a communication terminal by referring to the stored contents of the MAC address table.
  • the MAC address is a hardware identifier that uniquely identifies each communication device in the second layer of the OSI reference model.
  • the MAC address table is a table provided in a relay device such as a switching hub or router, and 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 relay device. Is to do.
  • a larger LAN includes a larger number of communication terminals and switching hubs, and the connection relationship between the switching hubs is often complicated. For this reason, the importance of searching for communication terminals increases as the LAN becomes larger.
  • the technique disclosed in Patent Document 1 has a problem that application becomes more difficult as the LAN becomes larger. This is because as the size of a LAN increases and the number of switching hubs included in the LAN increases, the load due to the transfer of the MAC address table between the switching hubs increases, and the original data communication performed via the LAN (for example, This is because there is a high possibility of adversely affecting data communication between communication terminals accommodated in the LAN.
  • the present invention has been made in view of the above problems, and grasps to which switching hub a communication terminal accommodated in the network is connected without applying an excessive load to the network under the router.
  • the purpose is to provide a technology that makes this possible.
  • an aspect of the present invention provides a communication system including a router as a relay device and one or more switching hubs as a relay device included in a network under the router.
  • At least one of the plurality of switching hubs and each of the routers each include a hardware identifier for uniquely identifying a communication terminal that has transmitted a frame addressed to itself and a port identifier of a communication port that has received the frame
  • an adjacent relay device table that stores a hardware identifier of a relay device that is a transfer source of a frame received via the communication port in association with a port identifier of the communication port.
  • the router communicates with the at least one switching hub.
  • the router Based on the adjacent relay device information storage processing means for acquiring and storing the stored contents of the device table and the hardware identifier indicating the communication terminal to be searched or another identifier uniquely converted to the hardware identifier, the router A communication port specifying means for specifying a communication port corresponding to the communication terminal from the stored contents of the address table of the router, and whether or not a switching hub is connected to the communication port specified by the communication port specifying means. If the connection destination of the communication port is determined not to be a switching hub, the search target communication terminal is connected to the router. A first connection relay device determining means for informing the communication port and a communication port specified by the communication port specifying means.
  • Connection destination candidate selecting means for selecting the switching hub as a connection destination candidate of the search target communication terminal when it is determined by the first connection relay device determining means that the connection destination is a switching hub
  • Inquiry means for querying the switching hub selected by the connection destination candidate selection means for the communication port corresponding to the communication terminal to be searched in the switching hub, and a response from the switching hub of the inquiry destination by the inquiry means Determining whether or not the connection destination of the communication port is another switching hub with reference to the storage content of the adjacent relay device table acquired by the adjacent relay device information storage means from the switching hub of the inquiry destination, If the connection destination of the communication port is not another switching hub, the search While the target communication terminal notifies that it is connected to the switching hub of the inquiry destination, when the connection destination of the communication port is another switching hub, the other switching hub is set as a new candidate.
  • Second connection relay device determination means for reselecting and performing processing by the inquiry means, and the at least one switching hub stores the contents stored in the adjacent relay device table of the at least one switching hub
  • the communication port corresponding to the communication terminal for the inquiry is specified from the stored contents of the address table of the at least one switching hub.
  • a communication port notifying means for returning the communication.
  • the router determines whether or not the search target terminal is connected to each of the switching hubs on the communication path from the router to the search target communication terminal, thereby determining the connection destination of the communication terminal.
  • a switching hub is identified.
  • the MAC address table is not transferred between the router and the switching hub, and an excessive load is not applied to the network under the router.
  • the hardware identifier is a MAC (Media Access Control) address
  • the other identifier uniquely converted to the hardware identifier is an IP (Internet Protocol) address
  • the router is a subordinate A DHCP (Dynamic Host Configuration Protocol) server means for assigning an IP address to a communication terminal accommodated in the network and performing mutual conversion between the IP address and the MAC address of the communication terminal;
  • the communication port specifying means converts the IP address of the communication terminal to be searched into a MAC address by the DHCP server means, and specifies the communication port corresponding to the communication terminal from the MAC address and the contents stored in the address table of the router. It is characterized by doing.
  • the hardware identifier is a MAC (Media Access Control) address
  • the other identifier uniquely converted to the hardware identifier is a host name
  • the router is a subordinate network.
  • a DHCP (Dynamic Host Configuration Protocol) server means for allocating an IP (Internet Protocol) address to a communication terminal accommodated in the communication terminal and performing mutual conversion between the IP address and the MAC address of the communication terminal; DNS (Domain Name System) server means for performing mutual conversion between the host name of the terminal and the IP address, and the address address reference means determines the host name of the communication terminal to be searched by the DNS server means.
  • the IP address is converted into an IP address, and the IP address is converted to M by the DHCP server means.
  • Into a C address and identifies the communication port corresponding to the communication terminal and a corresponding MAC address and store the contents of the router in the address table.
  • an IP address is easier for a person to understand than a MAC address
  • a host name is easier for a person to understand than an IP address.
  • the communication terminal to be searched can be specified by an IP address or host name that is easier to understand than the MAC address, an advantage that convenience is improved can be obtained.
  • the one or more switching hubs may include a switching hub that does not have the adjacent relay device table.
  • a conventional switching hub is included in the network, it is possible to search for communication terminals connected to the switching hub having the adjacent relay device table.
  • another aspect of the present invention provides a communication system including a router as a relay device and one or more switching hubs as a relay device included in a network under the router.
  • At least one of the one or more switching hubs and each of the routers includes a hardware identifier for uniquely identifying a communication terminal that has transmitted a frame addressed to the own device, and a communication port that has received the frame
  • An address table for storing the port identifiers in association with each other, an adjacent relay device table for storing the hardware identifier of the relay device that is the transfer source of the frame received via the communication port in association with the port identifier of the communication port, and
  • the router has a hardware identifier indicating a communication terminal to be searched Or a first communication port specifying means for specifying a communication port corresponding to the communication terminal in the router from the stored contents of the address table of the router, based on another identifier uniquely converted into the hardware identifier.
  • the first connection relay device determining means for notifying that the communication terminal to be searched is connected to the router, and the first communication port specifying means
  • the first connection relay device determining means determines that the connection destination of the communication port specified by is a switching hub
  • Connection destination candidate selection means for selecting the switching hub as a connection destination candidate for the search target communication terminal, and whether or not the search target communication terminal is connected to the switching hub selected by the connection destination candidate selection means
  • Inquiry means for inquiring and a switching hub to which the inquiry means inquires that the communication terminal to be searched is connected, the connection destination of the communication terminal to be searched is the switching hub If there is a response indicating that another switching hub should be a new inquiry destination, the other switching hub is selected as a connection destination candidate of the search target communication terminal.
  • Second connection relay device determination means that performs the processing by the inquiry means again, and the at least one switching hub has a front
  • a second communication port specifying means for specifying a communication port corresponding to the communication terminal involved in the inquiry from the stored contents of the address table of the at least one switching hub, and the second communication It is determined whether another switching hub is connected to the communication port specified by the port specifying means based on the stored contents of the adjacent relay device table of the at least one switching hub, and the other switching hub is connected If it is determined that the other switching hub should be a new inquiry destination, the router is returned to the router. If it is determined that the other switching hub is not connected, the search target A communication terminal responding to the router that it is connected to the at least one switching hub.
  • Communication system comprising: the cause determining means, and to provide.
  • another aspect of the present invention is a router as a relay device that has a switching hub as a relay device in a subordinate network and connects the network and another network,
  • a communication interface unit having a plurality of communication ports, a hardware identifier that uniquely identifies a communication terminal that has transmitted a frame addressed to the router, and a port identifier of the communication port that has received the frame are stored in association with each other.
  • An address table a neighboring relay device table storing a hardware identifier of a relay device that is a transfer source of a frame received via the communication port in association with a port identifier of each of the plurality of communication ports, the router, From a switching hub having the same type of address table and adjacent relay device table, the switch Based on the storage means for acquiring and storing the stored contents of the adjacent relay device table of the mobile hub and the hardware identifier indicating the communication terminal to be searched or another identifier uniquely converted to the hardware identifier.
  • Communication port specifying means for specifying the corresponding communication port from the stored contents of the address table, and whether or not the connection destination of the communication port specified by the communication port specifying means is a switching hub included in the subordinate network Is determined based on the contents stored in the adjacent relay device table, and if it is determined that the communication terminal is not a switching hub, a first notification that the search target communication terminal is connected to the router is performed.
  • connection destination of the communication port specified by the connection relay device determining means and the communication port specifying means is a switching hub If it is determined by the first connection relay device determination means, the connection destination candidate selection means for selecting the switching hub as a connection destination candidate of the communication terminal to be searched, and the connection relay device determination means Inquiry means for inquiring a communication port corresponding to the communication terminal to be searched for the selected switching hub, and the connection destination of the communication port returned from the inquiry destination switching hub is the other switching hub.
  • a router characterized by
  • the communication system described above can be configured by combining such a router with a switching hub having the address table and the adjacent relay device table and having the adjacent relay device notification means and the communication port notification means. Further, as another aspect of the present invention, an aspect in which a communication method having the same steps as the above-described units can be considered.
  • another aspect of the present invention is a switching hub as a relay device included in a network under a router as a relay device, and a communication interface unit having a plurality of communication ports;
  • An address table that stores a hardware identifier that uniquely identifies a communication terminal that has transmitted a frame addressed to the switching hub and a port identifier of a communication port that has received the frame, and the plurality of communication ports.
  • the adjacent relay device table storing the hardware identifier of the relay device that is the transfer source of the frame received via the communication port in association with each port identifier of the frame, and the stored contents of the adjacent relay device table are notified to the router
  • Adjacent relay device notification means and an inquiry frame transmitted from the router, Identifying the corresponding communication port from the stored contents of the address table, triggered by the reception of an inquiry frame containing the hardware identifier of the communication terminal to be searched and inquiring the reception port of the frame transmitted from the communication terminal
  • a communication port notifying means for returning the specified result to the router
  • FIG. 6 is a diagram for describing frame transfer control processing, adjacent relay device notification frame transmission processing, and communication port notification frame transmission processing executed by a switching engine unit 520 of the switching hub 50.
  • FIG. It is a figure which shows the data structure of the flame
  • 6 is a flowchart showing a flow of terminal search processing executed by a routing engine unit 620 of a router 60.
  • FIG. 5 is a diagram for explaining operations of a switching hub 50 and a router 60.
  • FIG. 5 is a diagram for explaining operations of a switching hub 50 and a router 60.
  • It is a figure which shows an example of the storage content of the MAC address table of the switching hub 50 and the router 60.
  • FIG. It is a figure which shows an example of the communication sequence in the search process of a communication terminal. It is a figure which shows the structural example of LAN1B of 2nd Embodiment of this invention.
  • FIG. 1 is a diagram illustrating a configuration example of a LAN 1A that is a communication system according to a first embodiment of this invention.
  • the LAN 1A is a local LAN laid at a company branch, for example, and is connected to an IP network (not shown) such as the Internet by a router 60.
  • the LAN 1A serves as a communication system in the branch, and constitutes an in-company information system in the company together with the LAN in the base laid in another branch. As shown in FIG.
  • the LAN 1A includes four switching hubs (switching hubs 50A, 50B, 50C, and 50D), two communication terminals (communication terminals 40A and 40B), and one operation terminal 30. , Including. As shown in FIG. 1, a switching hub 50A and an operation terminal 30 are connected to the router 60, and a switching hub 50B is connected to the switching hub 50A. Switching hubs 50C and 50D are connected to switching hub 50B. Communication terminal 40A is connected to switching hub 50C, and communication terminal 40B is connected to switching hub 50D.
  • Each of the operation terminal 30 and the communication terminals 40A and 40B is, for example, a personal computer.
  • the operation terminal 30 is used to cause the operation manager of the LAN 1A to perform various operations for operation management of the LAN 1A.
  • the communication terminals 40A and 40B are accommodated in the LAN 1A by being connected to any switching hub included in the LAN 1A.
  • Each of the communication terminals 40A and 40B accommodated in the LAN 1A 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). Packet communication in accordance with the IP.
  • FIG. 1 illustrates the case where two communication terminals 40 are accommodated in the network under the router 60 (ie, LAN 1A), three or more communication terminals 40 may be accommodated in the LAN 1A. Of course, only one communication terminal 40 may be accommodated.
  • the switching hub 50 is a relay device that relays data communication in a second layer (data link layer) that is a protocol layer lower than IP.
  • the router 60 is a relay device that relays data communication in the network layer, and serves as a default gateway of the LAN 1A. If the destination IP address of the packet received from the IP network is one of the communication terminals 40A or 40B, the router 60 transfers the packet to the subordinate LAN 1A, and the destination IP address is the communication terminal 40A.
  • the router 60 functions as a default gateway of the LAN 1A as described above, the LAN 1A may be hereinafter referred to as a “network under the router 60”.
  • the router 60 in FIG. 1 has a DHCP server function and a DNS server function. With this DHCP server function, the router 60 assigns an IP address to each of the terminals when the operation terminal 30 or the communication terminal 40 is connected to the LAN 1A, and performs mutual conversion between the IP address and the MAC address of each terminal. The router 60 performs mutual conversion between the host name and the IP address assigned to the operation terminal 30 or the communication terminal 40 by the DNS server function.
  • each relay device that is, the router 60 and the switching hub 50 included in the LAN 1A is executed in the process of executing data communication (that is, frame transmission / reception and transfer control) according to the communication protocol of the second layer. )
  • the adjacent relay device is another relay device that has transferred a frame to the relay device
  • the adjacent relay device for the router 60 is the switching hub 50A
  • the adjacent relay devices for the switching hub 50A are the router 60 and the switching hub 50B.
  • the adjacent relay devices for the switching hub 50B are the switching hubs 50A, 50C and 50D
  • the adjacent relay device for the switching hub 50C (or 50D) is the switching hub 50B.
  • each of the switching hubs 50 detects the adjacent relay device of its own device and notifies the router 60 of the detection result, while the router 60 indicates the adjacent relay device of each switching hub 50.
  • Information is stored for each switching hub 50.
  • the operation manager operates the MAC address, IP address, or host name of the terminal (in this embodiment, communication terminal 40A or communication terminal 40B: hereinafter, search target terminal) for which the connection destination is desired to be specified.
  • the router 60 is instructed via the terminal 30, the router 60 communicates with each switching hub 50 to identify the connection destination of the search target terminal, and informs the operation terminal 30 of the identification result. Thereby, the said operation manager can grasp
  • the search target terminal can be specified by the IP address or the host name, the convenience is improved as compared with the mode in which the search target terminal can be specified only by the MAC address.
  • the switching hub 50 and the router 60 that clearly show the features of the present embodiment will be mainly described.
  • FIG. 2 is a block diagram showing the configuration of the switching hub 50.
  • the switching hub 50 includes a communication interface (hereinafter referred to as I / F) unit 510, a switching engine unit 520, and a storage unit 530.
  • I / F communication interface
  • the 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, either the router 60, another switching hub 50, or the communication terminal 40) via a communication cable such as 100BASE-T. Is done. 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 the 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 (Random Access Memory) and a non-volatile memory such as an EPROM (Erasable Programmable Read Only Memory) (none of which is shown in FIG. 2).
  • a volatile memory such as a RAM (Random Access Memory)
  • a non-volatile memory such as an EPROM (Erasable Programmable Read Only Memory) (none of which is shown in FIG. 2).
  • 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.
  • 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. 2 and the adjacent relay apparatus table of FIG. 2 are stored.
  • the MAC address table in FIG. 2 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 along with the frame transfer control.
  • 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.
  • 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.
  • a connection destination identifier is stored in association with each port identifier of a plurality of communication ports included in the communication I / F unit 510.
  • the connection destination identifier indicates whether or not the connection destination of the communication port associated with the connection destination identifier is an adjacent relay device, and when the connection destination is an adjacent relay device, This is information that uniquely indicates an adjacent relay device.
  • the adjacent relay device is another relay device (in this embodiment, the router 60 or another switching hub 50) that has transferred a frame to the switching hub 50.
  • the port identifier of the communication port connected to the adjacent relay device is associated with the MAC address of the adjacent relay device as a connection destination identifier, and other communication devices other than the adjacent relay device (in this embodiment)
  • the communication port to which the communication terminal 40) is connected or the communication port not connected to another communication device is associated with NULL (0x00) as the connection destination identifier.
  • This adjacent relay device table is generated in a state where each connection destination identifier is set to NULL when a power source (not shown) of the switching hub 50 is turned on. Then, along with relaying a predetermined specific frame, the stored contents of the table are updated (that is, the connection destination identifier corresponding to the port identifier of the communication port to which the adjacent relay device is connected is set to the adjacent Rewriting to the MAC address of the relay device).
  • the adjacent relay device notification frame transmitted by each switching hub 50 to notify the router 60 of the stored contents of the adjacent relay device table as the specific frame, and the adjacent relay Two types of request frames that the router 60 multicasts to the subordinate LAN 1A to request transmission of the device notification frame are determined in advance.
  • the switching engine unit 520 is, for example, a CPU (Central Processing Unit).
  • 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.
  • the switching engine unit 520 operating according to this firmware executes the processing shown in the flowchart of FIG. 3 every time a frame is received via any one of the communication ports.
  • FIG. 3 there are three processes executed by the switching engine unit 520 in accordance with the firmware: a frame transfer control process, an adjacent relay device notification frame transmission process, and a communication port notification frame transmission process.
  • a data structure of a frame transmitted / received in the LAN 1A will be described.
  • FIG. 4A is a diagram showing a data structure of a general frame transmitted / received in the LAN 1A.
  • 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 multicast address is set as the destination MAC address
  • the MAC address of the router 60 is set as the source MAC address. This is because the request frame is multicast from the router 60 toward the subordinate LAN 1A.
  • the MAC address of the router 60 is set as the transmission destination MAC address, and the MAC address of the switching hub 50 of the transmission source is set as the transmission source MAC address. This is because the adjacent relay device notification frame is unicast from the switching hub 50 to the router 60 as described above.
  • the type identifier is an identifier indicating the type of data (packet) stored in the payload portion.
  • the features of the present embodiment are remarkably shown in addition to the request frame and the adjacent relay device notification frame, Communication port notification frame.
  • the inquiry frame is a frame that the router 60 unicasts to inquire the switching hub 50 of the port identifier of the communication port corresponding to the communication terminal designated as the search target, and the communication port notification frame is the inquiry frame. This is a frame returned (unicast) by the switching hub 50 to the router 60 as a response to the frame.
  • a value (0xe812) for distinguishing these four types of frames from other frames is set in the header portions of the four types of frames that clearly show the features of the present embodiment.
  • the request frame and the adjacent relay device notification frame may be collectively referred to as “adjacent relay device information collection frame”.
  • FIG. 4B shows the data structure of the payload portion of the request frame.
  • the destination MAC address, the source MAC address, the frame type identifier, and the transfer source identifier are written in the payload portion of the request frame.
  • the destination MAC address and source MAC address written in the payload portion of the request frame are the same as those written in the header portion of the request frame.
  • the frame type identifier is an identifier indicating which of the above-described four types of frames. A different value is set in the frame type identifier for each of the four types of frames.
  • a value indicating a request frame is set in the frame type identifier of the payload portion of the request frame.
  • the transmission source identifier is set with the MAC address of the transmission source when the request frame is transmitted, and is rewritten to the MAC address of the switching hub 50 that performed the transfer every time the frame is transferred by the switching hub 50. It is done.
  • FIG. 4C is a diagram showing the data structure of the payload portion of the adjacent relay device notification frame.
  • adjacent relay device information is written in the payload portion of the adjacent relay device notification frame in addition to the transmission destination MAC address, the transmission source MAC address, the frame type identifier, and the transfer source identifier. .
  • the frame type identifier of the payload portion of the adjacent relay device notification frame a value that clearly indicates that the frame is the adjacent relay device notification frame is set.
  • the adjacent relay device information in the payload portion includes the stored contents of the adjacent relay device table of the switching hub 50 that is the transmission source of the adjacent relay device notification frame at the time of transmission of the adjacent relay device notification frame (that is, the switching hub).
  • a list of port identifiers for all 50 communication ports and connection destination identifiers corresponding to the port identifiers) is written.
  • the transmission destination MAC address, transmission source MAC address, and transfer source identifier written in the payload portion of the adjacent relay device notification frame are the same as those in the request frame.
  • FIG. 4D shows the data structure of the payload portion of the inquiry frame.
  • a destination MAC address, a source MAC address, a frame type identifier, and a search target identifier are written in the payload portion of the inquiry frame.
  • a value that clearly indicates that the frame is an inquiry frame is set in the frame type identifier of the payload portion of the inquiry frame.
  • the search target identifier is an identifier for uniquely identifying a communication terminal designated as a search target (in this embodiment, the MAC address of the communication terminal).
  • FIG. 4E shows the data structure of the payload portion of the communication port notification frame. As shown in FIG.
  • the destination MAC address, the source MAC address, the frame type identifier, and the connection destination port identifier are written in the payload portion of the communication port notification frame.
  • a value that clearly indicates that the frame is a communication port notification frame is set in the frame type identifier of the payload portion of the communication port notification frame.
  • the communication port notification frame is a frame returned by the switching hub 50 that has received the inquiry frame as a response to the inquiry frame, and is a port associated with the search target identifier in the MAC address table of the switching hub.
  • An identifier is written as the connection destination port identifier.
  • the destination MAC address and the source MAC address written in the payload portion of these inquiry frame and communication port notification frame were also written in the respective header portions as in the request frame (or the adjacent relay device notification frame). Is the same.
  • the above is the data structure of the frame transmitted / received in the LAN 1A.
  • step SA100 processing contents of the frame transfer control process, the adjacent relay device notification frame transmission process, and the communication port notification frame transmission process.
  • step SA100 When the determination result in step SA100 is “Yes”, switching engine unit 520 executes the communication port notification frame transmission process (step SA110), and conversely, the determination result in step SA100 is “No”. In some cases, a frame transfer control process is executed as shown in FIG. Prior to step SA100, it is determined whether or not the received frame is any of the above-described four types of frames (that is, whether or not the type identifier of the header portion of the received frame is 0xe812).
  • step SA100 may be performed when the type identifier of the received frame is 0xe812.
  • the frame transfer control process includes transfer control based on the destination MAC address (step SA170).
  • 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.
  • 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.
  • a MAC address that is not a unicast address includes a multicast address or a broadcast address.
  • 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 (the process of step SA170) is executed as the frame transfer control process.
  • the frame transfer control process of the present embodiment includes the processes of steps SA120 to SA140 in addition to the process of step SA170.
  • the switching engine unit 520 first determines whether the received frame is an adjacent relay device information collection frame (that is, a request frame or an adjacent relay device notification frame). It is determined by referring to the frame type identifier of the payload portion of the received frame (step SA120). Specifically, when the frame type identifier of the received frame is a value indicating a request frame or a value indicating an adjacent relay device notification frame, the switching engine unit 520 is an adjacent relay device information collection frame. Judge that there is.
  • step SA120 When the determination result in step SA120 is “No”, the switching engine unit 520 executes the process in step SA170 described above to end the frame transfer control process, and conversely, the determination result in step SA120. Is “Yes”, the processing after step SA130 is executed.
  • step SA130 executed when the determination result in step SA120 is “Yes”, the switching engine unit 520 associates the adjacent relay device information collection frame with the port identifier of the communication port that has received the adjacent relay device information collection frame in the adjacent relay device table.
  • the stored connection destination identifier is rewritten with the transfer source identifier written in the payload portion of the frame.
  • the switching engine unit 520 rewrites the transfer source identifier of the received adjacent relay device information collection frame with the MAC address of the own device (step SA140).
  • the switching engine unit 520 determines whether or not the received frame is a request frame with reference to the frame type identifier of the payload portion of the received frame (step SA150), and the determination result If Yes, the adjacent relay device notification frame transmission process (step SA160) is further executed. In this adjacent relay device notification frame transmission process, the switching engine unit 520 generates the above-described adjacent relay device notification frame and transmits (unicasts) it to the router 60.
  • the switching engine unit 520 displays the inquiry frame.
  • the MAC address table of the own device is searched using the search target identifier written in the payload part of the search key as a search key, and the port identifier stored in the MAC address table is specified in association with the MAC address indicated by the search target identifier .
  • the switching engine unit 520 generates a communication port notification frame in which the port identifier is written as a connection destination port identifier in the payload portion, and returns (unicast) the inquiry frame to the transmission source of the inquiry frame.
  • the port identifier and the MAC address are written to the MAC address table in accordance with the frame transfer control.
  • the communication terminal 40 When the communication terminal 40 is connected to the LAN 1A, the communication terminal 40 always multicasts (or broadcasts) an ARP frame for specifying the MAC address of the router 60 as a default gateway. For this reason, the MAC address of the communication terminal 40 is always registered in the MAC address table of each switching hub 50. Therefore, as long as the communication terminal 40 is designated as a search target, in this communication port notification frame transmission process, the communication port corresponding to the search target identifier is always specified.
  • the above is the configuration of the switching hub 50.
  • FIG. 5 is a block diagram showing a configuration of the router 60.
  • 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.
  • An IP network (not shown in FIG. 1), the switching hub 50A, and the operation terminal 30 are connected to three of the plurality of ports. 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.
  • 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.
  • 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. 5, the MAC address table for the router 60, and the adjacent relay device table.
  • the routing engine unit 620 is a CPU (Central Processing Unit) 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 DHCP server processing, DNS server processing, packet transfer control processing, multicast processing, adjacent relay device information storage processing, and terminal search processing according to the firmware.
  • the DHCP server process is a process for realizing the DHCP server function
  • the DNS server process is a process for realizing the DNS server function
  • the packet transfer control process is a process for transferring the packet based on the transmission destination IP address of the packet received via the communication I / F unit 610 and the stored contents of the routing table.
  • the multicast process is a process of multicasting the request frame to the network under the router 60 (that is, the LAN 1A). 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.
  • a predetermined time T for example, 3 seconds
  • the adjacent relay device information storage process is executed every time an adjacent relay device notification frame is received.
  • the routing engine unit 620 uses the connection destination identifier stored in the adjacent relay device table of the own device in association with the port identifier of the communication port that received the adjacent relay device notification frame. Overwrite with the transfer source identifier of the relay device notification frame, and use the adjacent relay device information written in the payload portion of the adjacent relay device notification frame as the adjacent relay device table of the transmission source of the frame, the transmission source MAC address of the frame And is written in the storage unit 630 (if already written, it is overwritten with new neighboring relay device information).
  • the adjacent relay device table of each switching hub 50 stored in the storage unit 630 in this way is used in terminal search processing described later.
  • FIG. 6 is a flowchart showing the flow of the terminal search process.
  • This terminal search process is a process that is executed when a search target terminal is designated by an operation on the operation terminal 30, and is searched for in any of the relay devices (that is, the router 60 and the switching hub 50) included in the LAN 1A. This is processing for identifying whether the target terminal is connected.
  • the routing engine unit 620 first stores the contents stored in the adjacent relay device table of the own device and the adjacent relay device table of each switching hub 50 written in the storage unit 630 by the adjacent relay device information storage process. It is determined whether or not there is a contradiction in the connection relationship between the relay devices represented by the contents (step SB100).
  • the adjacent relay device table of the switching hub 50A includes A state in which the MAC address of the switching hub 50B is not stored.
  • step SB100 When the determination result in step SB100 is “Yes” (that is, when there is a contradiction), the routing engine unit 620 notifies the operation terminal 30 of a message that preparation for enabling terminal search is in progress. (Step SB170) and the execution of the terminal search process is terminated. On the other hand, when the determination result in step SB100 is “No”, the routing engine unit 620 executes the processing after step SB110 in FIG. Thus, the reason why the processing after step SB110 is not executed when there is a contradiction in the connection relationship of each relay device is to avoid erroneous determination of the connection destination of the search target terminal due to the contradiction. . This point will be described in detail in the operation example of this embodiment.
  • step SB110 which is subsequently executed when the determination result in step SB100 is “No”, the routing engine unit 620 determines whether or not there is a communication port corresponding to the search target terminal. The determination is made based on the stored contents. As described above, as a method of specifying the search target terminal, there are a mode in which the terminal is specified by the MAC address, a mode in which the IP address is specified, and a mode in which the host name is specified. When the search target terminal is designated by the MAC address, the communication port corresponding to the search target terminal depends on whether or not there is a communication port whose port identifier is stored in the MAC address table in association with the MAC address. What is necessary is just to determine the presence or absence.
  • the IP address is converted into a MAC address by the DHCP server function described above, and a port identifier is stored in the MAC address table in association with the MAC address. It may be determined whether or not there is a communication port.
  • the host name is converted into an IP address by the DNS server function, and further, the MAC address table is converted by the DHCP server function into a MAC address. The presence / absence of the corresponding communication port may be determined by referring to the stored contents.
  • step SB110 determines whether the search target terminal is connected to the candidate relay device. If the determination result in step SB110 is “No”, the routing engine unit 620 informs the operation terminal 30 that the search target terminal is not accommodated in the subordinate network (step SB180), and this terminal The search process is terminated. On the other hand, if the determination result in step SB110 is “Yes”, the routing engine unit 620 selects the port identifier of the communication port as a candidate port identifier, and selects its own device as a connection destination candidate of the search target terminal. (Hereinafter referred to as a candidate relay device) is selected (step SB120). Then, the routing engine unit 620 searches the adjacent relay device table of the candidate relay device using the candidate port identifier as a search key (step SB130), and determines whether the search target terminal is connected to the candidate relay device.
  • a candidate relay device search key
  • Step SB140 More specifically, the routing engine unit 620 associates with the same port identifier as the candidate port identifier, and if the connection destination identifier stored in the adjacent relay device table of the candidate relay device is NULL, the search target terminal It is determined that the candidate relay device is connected.
  • step SB140 When the determination result in step SB140 is “Yes” (that is, when it is determined that the search target terminal is connected to the candidate relay device), the routing engine unit 620 connects the search target terminal to the candidate relay device. The operation terminal 30 is notified (step SB190) that this is done, and the terminal search process is terminated. On the other hand, when the determination result in step SB140 is “No”, the routing engine unit 620 reselects the relay device indicated by the connection destination identifier as a new candidate relay device, and the new candidate relay device. An inquiry frame is transmitted to the apparatus (step SB150).
  • the routing engine unit 620 updates the candidate port identifier with the connection destination port identifier written in the payload portion of the communication port notification frame returned from the new candidate relay device (step SB160), and after step SB130.
  • steps SB120 to SB140 are executed only once without executing steps SB150 and SB160. It is notified that (router 60) is connected to the search target terminal (first connection relay device determination).
  • step SB150 and step SB160 are executed at least once to reselect candidate relay devices.
  • step SB190 it is notified that one of the switching hubs 50 is connected to the search target terminal (second connection relay device determination).
  • the above is the configuration of the router 60.
  • FIG. 7 the communication port is indicated by a black circle, and the port number of the communication port is indicated by a number with #.
  • the connection destination identifiers in the adjacent relay device tables of the router 60 and each switching hub 50 are NULL cleared.
  • the connection destination of the search target terminal is specified based on the contents stored in the MAC address table and the adjacent relay device table of the router 60 and each switching hub 50. Therefore, prior to specifying the connection destination of the search target terminal, the MAC address of each adjacent relay device is stored in the adjacent relay device table, and the stored contents of the adjacent relay device table of each switching hub 50 are notified to the router 60. It is necessary to keep it.
  • the router 60 and each switching hub 50 to perform the operation described below, the MAC address of the adjacent relay device is stored in each adjacent relay device table, and each switching hub 50 to the router 60 is stored. Notification of the stored contents of the adjacent relay device table is realized.
  • the routing engine unit 620 of the router 60 multicasts the request frame at a time T0 when a predetermined time T has elapsed after the power (not shown) of the router 60 is turned on.
  • the request frame multicasted from the router 60 in this manner is first received by the switching hub 50A.
  • the reason is as follows.
  • the frame received by the switching hub 50A from the router 60 is a request frame, and a value indicating that the frame is the request frame is set in the frame type identifier of the payload portion. Therefore, the determination result of step SA100 in FIG. 3 is “No”, the determination result of step SA120 is “Yes”, and the determination result of step SA150 is also “Yes”. Therefore, the processes of steps SA130, SA140, SA160 and SA170 in FIG. 3 are executed.
  • step SA160 the adjacent relay device notification frame in which the stored content of the updated adjacent relay device table by the processing in step SA130 is written as adjacent relay device information is unicast from the switching hub 50A to the router 60.
  • step SA170 the request frame in which the transfer source identifier has been rewritten by the processing in step SA140 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 the switching hub 50B.
  • the adjacent relay device notification frame which is rewritten by the transfer source identifier (that is, the MAC address of the switching hub 50A) and in which the stored contents of the rewritten adjacent relay device table is written as the adjacent relay device information, is unicast to the router 60.
  • 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 frames flooded in this way are received by the switching hubs 50C and 50D, respectively.
  • the adjacent relay device notification frame written as is unicast to the router 60.
  • the switching hubs 50C and 50D also perform a process of flooding a request frame in which the transfer source identifier is rewritten to the MAC address of the own device. However, since the switching hub is not connected to the downstream side of the switching hubs 50C and 50D, the request frames are not transferred thereafter.
  • the contents stored in the adjacent relay device table of each of the switching hubs 50A, 50B, 50C, and 50D are in the state shown in FIG.
  • An adjacent relay device notification frame in which the stored contents of each adjacent relay device table is written as adjacent relay device information is unicast from each switching hub 50 to the router 60.
  • the stored contents of the adjacent relay device table of each switching hub 50 are indicated by balloons (the same applies to FIG. 9).
  • the process of SA170 is executed.
  • the frame received by the switching hub 50B from the switching hub 50C is an adjacent relay device notification frame, and a value indicating that the frame is an adjacent relay device notification frame is set in the frame type identifier of the payload portion. ing. Therefore, in the process executed by the switching engine unit 520 when the frame is received (the process shown in the flowchart of FIG. 3), the determination result in step SA100 is “No”, while the determination result in step SA120 is “ Yes, and the determination result in step SA150 is “No”. Therefore, the processes of steps SA130, SA140, and SA170 in FIG. 3 are executed.
  • the MAC address of the hub 50C 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 SA140.
  • the switching engine unit 520 of the switching hub 50B executes the processes of steps SA130, SA140, and SA170 in FIG. .
  • the switching engine unit 520 of the switching hub 50A When the switching engine unit 520 of the switching hub 50A receives the adjacent relay device notification frame transmitted from the switching hub 50B (or the adjacent relay device notification frame transferred by the switching hub 50B), the switching engine unit 520 similarly performs step SA130 of FIG. , SA140 and SA170 are executed.
  • the transfer source identifier of the adjacent relay device notification frame is rewritten to the MAC address of the own device and transferred to the router 60.
  • the adjacent relay device information written in the adjacent relay device notification frame received by the router 60 from each switching hub 50 is stored in the adjacent relay device table shown in FIG. This corresponds to not the stored contents but the stored contents of the adjacent relay apparatus table shown in FIG. Only the connection relationship between the router 60 and the switching hub 50A is represented in a consistent manner between the stored contents of the adjacent relay apparatus table of the router 60 shown in FIG. 9 and the stored contents of the adjacent relay apparatus table of each switching hub 50 shown in FIG. And other connections are inconsistent. For example, although the MAC address of the switching hub 50B is not stored in the adjacent relay device table of the switching hub 50A, the MAC address of the switching hub 50A is stored in the adjacent relay device table of the switching hub 50B.
  • step SB100 Becomes “Yes”, and only notification that preparation is in progress is made.
  • each switching hub 50 executes the same processing as described above.
  • the adjacent relay device information corresponding to the stored contents of the adjacent relay device table shown in FIG. Has been written. Therefore, when the adjacent relay device notification frame for the request frame multicasted at time T0 + T (that is, the second multicast if the multicast at time T0 is the first) is received, it is stored in the storage unit 630 of the router 60.
  • the adjacent relay device table (the adjacent relay device table of the router 60 and the adjacent relay device table of each switching hub 50) represents the connection relationship between the router 60 and each switching hub 50 without contradiction.
  • the determination result in step SB100 is “No”, and the routing engine unit 620 executes the processing after step SB110.
  • ⁇ A-2-2 Communication terminal search operation>
  • the search of the communication terminal 40A is performed under the situation where the stored contents of the adjacent relay device table of the router 60 and each switching hub 50 are in the state shown in FIG. An operation performed by the hub 50 will be described.
  • the contents stored in the MAC address tables of the router 60 and the switching hub 50 are controlled by the transfer control of the ARP packet transmitted from the communication terminal 40A for MAC address resolution of the router 60. Is as shown in FIG.
  • the routing engine unit 620 automatically stores the contents stored in the adjacent relay device table of each switching hub 50 stored in the storage unit 630. It is determined whether or not there is a contradiction in the connection relationship represented by the stored contents of the adjacent relay device table of the device (step SB100). As described above, if the stored contents of the adjacent relay device tables of the router 60 and each switching hub 50 are in the state shown in FIG. 9, there is no contradiction in the connection relationship represented by these adjacent relay device tables. Therefore, the determination result in step SB100 is “No”, and the processing after step SB110 is executed. As shown in FIG.
  • step SB110 the routing engine unit 620 executes the processing after step SB120.
  • step SB130 the routing engine unit 620 searches the adjacent relay device table of the candidate relay device (that is, the adjacent relay device table of the router 60), and acquires the connection destination identifier corresponding to the candidate port identifier.
  • step SB140 the routing engine unit 620 reselects the switching hub 50A as a candidate relay device and transmits an inquiry frame (step SB150). That is, in this operation example, as shown in FIG. 11, the inquiry frame Q010 is transmitted from the router 60 to the switching hub 50A. In the payload portion of the inquiry frame Q010, the MAC address of the communication terminal 40A is written as a search target identifier.
  • the switching engine unit 520 of the switching hub 50A executes communication port notification frame transmission processing (FIG. 3: step SA110).
  • step SA110 communication port notification frame transmission processing
  • the determination in step SB100 is performed in order to avoid such an erroneous determination. In this embodiment, in order to avoid the occurrence of the erroneous determination as described above, the routing engine unit 620 performs the determination in step SB100.
  • step SB100 and the notification process (step SB170) when the determination result is Yes may be omitted.
  • the MAC address of the communication terminal 40A is written as a search target identifier, as in the inquiry frame Q010.
  • the routing engine unit 620 When receiving the communication port notification frame R020 returned from the switching hub 50B, the routing engine unit 620 connects to the connection destination written in the payload portion of the communication port notification frame R020 as in the case of receiving the communication port notification frame R010.
  • the routing engine unit 620 is written in the payload portion of the communication port notification frame R030 in the same manner as when the communication port notification frame R010 or R020 is received.
  • step SB140 executed for the fourth time in this operation example is “Yes”, and the routing engine unit 620 indicates that the search target terminal (that is, the communication terminal 40A) is connected to the switching hub 50C.
  • Step SB190 the operation manager of the LAN 1A grasps that the search target terminal (communication terminal 40A) is connected to the switching hub 50C.
  • the MAC address table is not transferred between the router 60 and each switching hub 50, an excessive load is not applied to the network under the router 60.
  • FIG. 12 is a block diagram illustrating a configuration example of the LAN 1B according to the second embodiment of this invention.
  • LAN 1B differs from LAN 1A in that it has a switching hub 500 in place of switching hub 50B and that communication terminal 40C is connected to switching hub 500.
  • the switching hub 500 is a conventional switching hub, and is different 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 SA170 in FIG. 3) is executed.
  • the communication terminal 40C is a general personal computer like the communication terminal 40A and the communication terminal 40B.
  • the request frame transferred from the switching hub 50A to the switching hub 500 is transferred to the switching hubs 50C and 50D without rewriting the transfer source identifier. Therefore, the MAC address of the switching hub 50A is written in the adjacent relay device table of each of the switching hubs 50C and 50D in association with the port identifier of the communication port to which the switching hub 500 is connected.
  • the adjacent relay device notification frame returned from each of the switching hubs 50C and 50D to the router 60 is transferred to the switching hub 50A by the switching hub 500 without rewriting the transfer source identifier.
  • the switching engine unit 520 of the switching hub 50A receives the adjacent relay device notification frame transmitted from each of the switching hubs 50C and 50D via the communication port to which the switching hub 500 is connected, and these adjacent relay device notification frames.
  • the content stored in the adjacent relay device table is updated every time. That is, the content of the update performed in response to the previously received one of the adjacent relay device notification frames transmitted from each of the switching hubs 50C and 50D depends on the content of the update performed in response to the one received later. Overwritten.
  • the switching hub 50D is included in the port identifier of the communication port to which the switching hub 500 is connected.
  • the MAC address of the switching hub 50A is associated with the port identifier of the communication port to which the switching hub 500 is connected. That is, a contradiction arises in the connection relationship between the switching hub 50A and the switching hub 50C.
  • the switching hub 50A when the latter of the adjacent relay device notification frames returned by each of the switching hubs 50C and 50D in response to the request frame multicasted first from the router 60 reaches the switching hub 50A first.
  • the port identifier of the communication port to which the switching hub 500 is connected is the switching hub. Only 50C MAC addresses are associated.
  • the MAC address of the switching hub 50A is associated with the port identifier of the communication port to which the switching hub 500 is connected. That is, a contradiction arises in the connection relationship between the switching hub 50A and the switching hub 50D.
  • step SB100 in FIG. 6 it is possible to specify the connection destination of either the communication terminal 40A or the communication terminal 40B.
  • the connection destination of the communication terminal 40A cannot be specified accurately. The reason is as follows.
  • the port identifier of the communication port to which the switching hub 500 is connected is stored in association with the MAC address of the communication terminal 40A. This is because the ARP frame transmitted from the communication terminal 40A reaches the switching hub 50A through flooding by the switching hub 500. Therefore, when the router 60 transmits an inquiry frame in which the MAC address of the communication terminal 40A is written as a search target identifier to the switching hub 50A, the switching hub 50A sets the port identifier of the communication port to which the switching hub 500 is connected to the connection destination. The communication port notification frame written as the port identifier is returned to the router 60.
  • the MAC address of the switching hub 50D is stored in the adjacent relay device table of the switching hub 50A in association with the port identifier. Therefore, the router 60 transmits an inquiry frame in which the MAC address of the communication terminal 40A is written as a search target identifier to the switching hub 50D.
  • the port identifier of the communication port to which the switching hub 500 is connected is stored in association with the MAC address of the communication terminal 40A.
  • the ARP frame transmitted from the communication terminal 40A reaches the switching hub 50D through flooding by the switching hub 500. Therefore, the switching hub 50D returns a communication port notification frame in which the port identifier of the port identifier of the communication port to which the switching hub 500 is connected as a connection destination port identifier is written back to the router 60.
  • the MAC address of the switching hub 50A is stored in the adjacent relay device table of the switching hub 50D in association with the port identifier, an inquiry frame has already been transmitted to the switching hub 50A, and again the switching hub 50A.
  • the connection destination of the communication terminal 40B is accurately set. It cannot be specified. Similarly, the communication terminal 40C connected to the switching hub 500 cannot be searched.
  • a conventional switching hub when included in the network under the router 60, a communication terminal connected to the conventional switching hub cannot be searched, but the network is connected to the switching hub 50. It does not mean that the search for a communication terminal that is present cannot be performed at all.
  • the search for the communication terminals accommodated in the network cannot be performed at all. If at least one switching hub 50 according to the present invention is included, a search for a communication terminal connected to the switching hub 50 can be performed. Also in this embodiment, since the MAC address table is not transferred between the router 60 and each switching hub 50, an excessive load is not applied to the network under the router 60.
  • the router 60 periodically executes request frame multicasting at predetermined time intervals, while the switching hub 50 sends the adjacent relay device notification frame to the router 60 when the request frame is received.
  • the request frame may be multicast to the router 60 when a predetermined type of packet is received.
  • the router 60 is caused to transmit a request frame when receiving the ARP packet for resolving the MAC address of the own device.
  • the fact that a new ARP packet has been received means that a new communication terminal has been connected to the network under the router 60.
  • the new switching hub 50 is connected to the existing switching hub 50, and the new communication terminal is connected to the new switching hub 50.
  • the router 60 is made to transmit a request frame when a new ARP packet is received, even if a new switching hub 50 is added as a new communication terminal is connected, It becomes possible to search for the new communication terminal.
  • the router 60 also serves as a DHCP server as in each of the above embodiments, a request frame is triggered when a packet requesting IP address assignment is received from a subordinate communication terminal. You may make it multicast.
  • the adjacent relay device notification frame is transmitted to the switching hub 50 when the request frame is received.
  • the adjacent relay device notification frame may be transmitted to the switching hub 50 periodically at predetermined time intervals.
  • a transfer source identifier may be assigned to a predetermined part and multicasted. This is because each switching hub 50 stores the MAC address of the adjacent relay device on the upstream side (the side close to the router 60) in the adjacent relay device table.
  • the router 60 selects a new candidate relay device, but the switching hub 50 can also perform the selection.
  • the switching engine unit 520 performs the following processing. That is, the switching engine unit 520 searches the MAC address table of its own device using the search target identifier written in the payload portion of the inquiry frame as a search key, and stores the MAC address table in association with the search target identifier. Get the port identifier. Next, the switching engine unit 520 searches its own MAC address table using the port identifier as a search key, and acquires a connection destination identifier corresponding to the port identifier.
  • the switching engine unit 520 unicasts to the router 60 the communication port notification frame in which the connection destination identifier is written in the payload portion. If the connection destination identifier written in the payload portion of the communication port notification frame is NULL in the router 60, the search target terminal is connected to the switching hub 50 that is the transmission source of the communication port notification frame. If the connection destination identifier is a value other than NULL, an inquiry frame is transmitted using the switching hub 50 indicated by the connection destination identifier as a new candidate relay device. The process is executed. In such an aspect, it is not essential to store the adjacent relay device table of each switching hub 50 in the router 60.
  • the routing engine unit 620 determine whether the contents stored in the adjacent relay device table of each switching hub 50 are inconsistent with each other (that is, determine whether the communication terminal can be searched).
  • the adjacent relay device table of each switching hub 50 may be stored in the router 60.
  • the processing load in the switching hub 50 is higher than that in each of the above embodiments by the amount of searching for the adjacent relay device table, the switching hub 50 having a sufficiently high processing capability is used. Needless to say, there is a need.
  • the adjacent relay device notification frame in which the adjacent relay device information is written in the payload portion is returned to each switching hub 50.
  • the request frame received for the (N + 1) th request frame When responding, an adjacent relay device notification frame in which data indicating that there is no change in the adjacent relay device information instead of the adjacent relay device information is written in the payload portion may be returned.
  • the router 60 has a DHCP server function and a DNS server function. However, if a DHCP server and DNS server separate from the router 60 are provided in the network under the router 60 and the router 60 can access these servers, the router 60 functions as a DHCP server. It is not necessary to have a DNS server function. That is, the DHCP server function and the DNS server function are not essential for the router of the present invention.
  • the IP address is dynamically allocated to each communication terminal 40 by the DHCP server function of the router 60. . Even when the IP address is fixedly assigned to each communication terminal 40 and the search target terminal is designated by the fixedly assigned IP address, the communication is started from the IP address by using the ARP.
  • the MAC address of the terminal can be obtained. Further, in each of the above-described embodiments, the MAC address is used as a hardware identifier for uniquely identifying each communication device in the second layer. However, a new hardware identifier different from the MAC address is defined, and the identifier May be used.
  • the frame transfer control processing, the adjacent relay device notification frame transmission processing, and the communication port notification frame transmission processing that clearly show the characteristics of the switching hub of the present invention are realized by software.
  • each of the frame transfer control means for executing the frame transfer control process, the adjacent relay apparatus notification means for executing the adjacent relay apparatus notification frame transmission process, and the communication port notification means for executing the communication port notification frame transmission process is used as an electronic circuit or the like.
  • the switching hub 50 may be configured by incorporating these units in place of the switching engine unit 520.
  • the multicast processing, the adjacent relay device storage processing, and the terminal search processing may be realized by hardware such as an electronic circuit.
  • the frame is adjacent based on the frame type identifier written in the payload portion of the frame (or based on the type identifier of the header portion and the frame type identifier of the payload portion).
  • the determination may be performed depending on whether or not a transfer source identifier is assigned. For example, when collecting neighboring relay device information using frames transmitted and received according to the existing communication protocol in the second layer, based on the frame type identifier (or the header type identifier and the payload frame This is because the above determination cannot be made (based on the type identifier).
  • the transfer source identifier (or the transfer source identifier and the adjacent relay device information) may be written in an empty area of the header portion of the frame.

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Abstract

La présente invention a pour objectif d'identifier un concentrateur de commutation d'une destination de connexion d'un terminal de communication hébergé dans un réseau desservi par un routeur sans placer une charge excessive sur le réseau. Une table de dispositifs intermédiaires adjacents est stockée par rapport à chaque routeur et à chacun des concentrateurs de commutation desservis par le routeur. Le routeur se réfère à une table d'adresses MAC pour identifier un port de communication correspondant à un terminal à rechercher et se réfère à la table de dispositifs intermédiaires adjacents du routeur pour identifier un concentrateur de commutation correspondant au port de communication. Ensuite, le routeur ayant le concentrateur de commutation en tant que candidat de destination de connexion interroge le port de communication correspondant au terminal et se réfère aux contenus stockés de la table de dispositifs intermédiaires adjacents du concentrateur de commutation pour estimer si la destination de connexion du port de communication est un autre concentrateur de commutation. Ensuite, si la destination de connexion est l'autre concentrateur de commutation, une interrogation est effectuée de nouveau avec l'autre concentrateur de commutation en tant que nouveau candidat de destination de connexion.
PCT/JP2012/053889 2011-02-18 2012-02-17 Système de communication, routeur, concentrateur de commutation et procédé de communication WO2012111833A1 (fr)

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