JP6579025B2 - Packet relay device, packet relay control device, packet relay system, and packet relay method - Google Patents

Description

  The present invention relates to a packet relay device that relays packets between a backbone network and a subnet, a packet relay control device that forms part of the packet relay device, a packet relay system, and a packet relay method.

  When communication is performed between a terminal device existing in the backbone network and a plurality of terminal devices existing in the subnet via the packet relay device, the terminal device exists in the backbone network and the terminal device even if the subnet is divided. There is a method of redundantly connecting a backbone network and a subnet with a plurality of packet relay devices in order to enable communication with a terminal device (for example, Patent Document 1).

  Conventionally, in the packet relay device of Patent Document 1, when an abnormality occurs in a line in a subnet and the network is divided, the host route for each terminal device existing in the divided subnet is advertised to the router of the backbone network. Routers and other packet relay devices have a routing table in which host routes are stored. When a host route of a terminal device is advertised, the host routes in the routing table for all advertised terminal devices are updated. save.

JP 2004-357194 A

  However, in the conventional packet relay device described above, when the division within the subnet is detected, the host routes of all the terminal devices existing in the divided subnet are advertised to the backbone network router and other packet relay devices. It was. For this reason, there has been a problem of increasing the amount of data stored in the routing tables of the router and the packet relay device.

  The present invention has been made to solve the above-described problems, and in the case where a subnet is divided, a packet relay device, a packet relay control device, and a packet relay that can suppress an increase in the amount of data stored in a routing table. It is an object to provide a system and a packet relay method.

  The packet relay apparatus according to the present invention, together with other packet relay apparatuses, connects a backbone network in which terminal apparatuses exist and a subnet in which a plurality of other terminal apparatuses exist through a router having a routing table for storing and updating host routes. In a redundantly connected packet relay device, a detection unit that detects a disconnection of communication with another packet relay device within a subnet, a search unit that searches for address information of other terminal devices that can communicate within the subnet, and a search Receiving a table for storing address information of other terminal devices that can be searched, and a transmission packet transmitted from the terminal device to the other terminal device, and instructing an advertisement of a host route for updating the routing table A packet transmission / reception unit for transmitting / receiving an instruction packet to / from another packet relay device; If the address information of another communicable terminal device corresponding to the address information of the transmission packet received by the packet transmission / reception unit is not in the table after the detection of the division by the detection unit, the instruction corresponding to the address information of the transmission packet A reception packet processing unit that generates a packet and transmits the generated instruction packet to the packet transmission / reception unit.

  According to the present invention, when a host route is advertised from another packet relay device after detection of the division of the subnet, an instruction packet corresponding to the address information of the received transmission packet is transmitted to the other packet relay device, and the backbone Since the host route is advertised and the routing table of the backbone network is updated when the communication from the network to the terminal device in the subnet occurs, an increase in the amount of data stored in the routing table can be suppressed.

It is a schematic block diagram of the packet relay system which concerns on Embodiment 1 of this invention. It is a functional block diagram of the packet relay apparatus according to Embodiment 1 of the present invention. It is the figure which showed an example of the ARP table preserve | saved at the table which concerns on Embodiment 1 of this invention, (a) is the figure which showed the ARP table before a subnet division | segmentation, (b) is after a subnet division | segmentation It is the figure which showed the ARP table. It is the figure which showed an example of the IP datagram of the instruction | indication packet which concerns on Embodiment 1 of this invention. It is the figure which showed an example of the IP datagram of the host route advertisement packet which concerns on Embodiment 1 of this invention. It is a hardware block diagram of the packet relay apparatus concerning Embodiment 1 of this invention. It is a flowchart which shows operation | movement of the reception packet process part which concerns on Embodiment 1 of this invention. It is a flowchart which shows operation | movement of the detection part which concerns on Embodiment 1 of this invention. It is a flowchart which shows operation | movement of the search part which concerns on Embodiment 1 of this invention. It is a flowchart which shows operation | movement of the host route advertisement part which concerns on Embodiment 1 of this invention. It is the figure which showed an example of the routing table which concerns on Embodiment 1 of this invention, (a) is the figure which showed the routing table before host route advertisement, (b) is the routing table after host route advertisement. FIG. It is the figure which showed an example of the IP datagram of the instruction | indication packet which concerns on Embodiment 2 of this invention. It is a flowchart which shows operation | movement of the reception packet process part which concerns on Embodiment 2 of this invention. It is a schematic block diagram of the packet relay system which concerns on Embodiment 3 of this invention. It is a functional block diagram of the packet relay apparatus which concerns on Embodiment 3 of this invention.

Embodiment 1 FIG.
FIG. 1 is a schematic configuration diagram of a packet relay system according to Embodiment 1 of the present invention.

  In FIG. 1, a backbone network 101 that constructs an IP (Internet Protocol) network and a subnet 102 are redundantly connected by a packet relay device 200 and a packet relay device 220, and are connected via the packet relay device 200 and the packet relay device 220. Communicate. In the first embodiment, for convenience of explanation, one subnet 102 is connected to the backbone network 101. However, the present invention is not limited to this, and a plurality of subnets 102 may be connected.

  In the backbone network 101, there are a router 111, a router 112 connected to the router 111, and a terminal device 113 connected to the router 111. The router 111, the router 112, and the terminal device 113 are connected via a line 126, respectively. Within the backbone network 101, the packet relay device 200 is connected to the router 111 via the line 126, and the packet relay device 220 is connected to the router 112 via the line 126.

  The router is one of the relay devices of the network, and is a device that determines the destination of the packet based on the data of the third layer, which is the network layer of the OSI (Open Systems Interconnection) reference model, and transfers it. For example, a layer 3 switch may be used instead of the router.

  Within the subnet 102, a layer 2 switch 121, a layer 2 switch 122 connected to the layer 2 switch 121, a layer 2 switch 123 connected to the layer 2 switch 122, and a terminal device 124 connected to the layer 2 switch 121. And a terminal device 125 connected to the layer 2 switch 123 exists. The layer 2 switches 121, 122, 123 and the terminal devices 124, 125 are connected via a line 126, respectively. In the subnet 102, the packet relay apparatus 200 is connected to the layer 2 switch 121 via the line 126, and the packet relay apparatus 220 is connected to the layer 2 switch 123 via the line 126.

  The layer 2 switch is one of the relay devices of the network, and is a device that determines the destination of the packet based on the data of the second layer that is the data link layer of the OSI reference model and transfers the packet.

  Here, the packet relay device 200 and the packet relay device 220 are made redundant by using, for example, a VRRP (Virtual Router Redundancy Protocol) protocol defined by RFC2338. Assume that the packet relay apparatus 200 is a VRRP working router and the packet relay apparatus 220 is a VRRP standby router. That is, in a state where the subnet 102 is not divided, for example, packets addressed to the terminal device 124 and the terminal device 125 from the terminal device 113 are relayed via the packet relay device 200.

  Further, the packet relay apparatus 200, the packet relay apparatus 220, the router 111, and the router 112 set OSPF (Open Shortest Path First) defined by RFC (Request for Comments) 2328 as a routing protocol, and calculate the shortest path. Suppose that Further, it is assumed that the packet relay apparatus 200 performs route advertisement of the subnet 102. Instead of OSPF, RIP (Routing Information Protocol) or EIGRP (Enhanced Interior Gateway Routing Protocol) may be used.

  FIG. 2 is a functional block diagram of packet relay apparatus 200 according to Embodiment 1 of the present invention. The packet relay device 200 and the packet relay device 220 are similar functional block diagrams.

  The packet relay device 200 detects a packet transmission / reception unit 210 that transmits / receives a packet to / from the backbone network 101, a subnet transmission / reception unit 211 that transmits / receives a packet to / from the subnet 102, and a detection that detects a disconnection of communication with the packet relay device 220 in the subnet 102. A search unit 213 that searches for address information of a terminal device that can communicate with the packet relay device 200 within the subnet 102, a table 214 that stores address information of the terminal device that can be searched for by the search unit 213, A packet relay control apparatus 300 that performs processing based on the received packet.

  The detection unit 212 uses, for example, ICMP (Internet Control Message Protocol) to detect a disconnection of communication with the packet relay device 220 within the subnet 102. The detection unit 212 continues to periodically transmit an Echo Request packet to the packet relay device 220 via the subnet 102, for example, every second, and receives an Echo Reply packet from the packet relay device 220 as a response. If this response cannot be received, it is determined that the subnet 102 has been divided. The detection unit 212 stores a determination result as to whether the state of the subnet 102 is divided or undivided. For example, the transmission is performed periodically every 1 second, but it is detected every 0.1 second, every 1 minute, or from the received packet processing unit 302a (to be described later) of the packet relay control device 300 as a trigger. May be.

  Further, instead of ICMP, it may be determined by an inquiry and response of a protocol mechanism of ARP (Address Resolution Protocol). Further, in the OSPF Hello packet and the VRRP Hello packet, it may be determined whether or not a periodically transmitted packet is received. Or, create and judge inquiry and response packets using a unique protocol mechanism using TCP (Transmission Control Protocol) and UDP (User Datagram Protocol), or create periodically sent packets and create periodic It may be determined whether or not a packet to be transmitted is received.

  The search unit 213 uses, for example, an ARP request packet to search for address information of a terminal device that can communicate with the packet relay device 200 within the subnet 102. The search unit 213 transmits an ARP Request packet to all destination IP address information that may exist on the IP address information space in the subnet 102. When the search unit 213 receives the ARP reply packet, the search unit 213 determines that the terminal device that is the destination of the ARP request packet is a terminal device that can communicate with the packet relay device 200 within the subnet 102, and the IP stored in the ARP reply packet. Address information and MAC (Media Access Control) address information are stored in the table 214 as an ARP table.

  The search unit 213 transmits an ARP Request packet triggered by, for example, the division of the subnet 102, and updates the ARP table of the table 214 as shown in FIG. For example, the ARP request packet is transmitted when the subnet 102 is divided as a trigger. However, the ARP request packet may be transmitted periodically such as every one minute or every ten minutes. In this case, information indicating whether the subnet 102 is divided or time information is linked and stored in the table 214.

  FIG. 3 is a diagram showing an example of the ARP table stored in the table 214 according to Embodiment 1 of the present invention. FIG. 3A is a diagram showing the ARP table 401 before the subnet 102 is divided. b) is a diagram showing the ARP table 402 after the subnet 102 is divided. As shown in FIG. 3, the ARP table 401 and the ARP table 402 are tables that store IP address information and MAC address information corresponding to the IP address information. For example, in the packet relay device 200, when the subnet 102 is not divided, the packet relay device 200 can communicate with the terminal device 124 and the terminal device 125. Therefore, the table 214 is stored in the terminal device 124 as shown in FIG. In addition, the IP address information and the MAC address information of the terminal device 125 are stored. Here, the IP address information of the terminal device 124 is 124a, the MAC address information is 124A, the IP address information of the terminal device 125 is 125a, and the MAC address information is 125A.

  Next, in the packet relay apparatus 200, when the subnet 102 is divided due to a failure of the layer 2 switch 122, the packet relay apparatus 200 can communicate with the terminal apparatus 124. Therefore, the table 214 is shown in FIG. Thus, the IP address information and the MAC address information of the terminal device 124 are stored. Since the packet relay device 200 cannot communicate with the terminal device 125, the packet relay device 200 cannot receive the ARP Reply packet from the terminal device 125, and the IP address information and the MAC address information of the terminal device 125 cannot be registered.

  The packet relay control device 300 includes a received packet processing unit 302a that processes a packet received by the packet transmission / reception unit 210, and a host route advertisement unit 301 that advertises a host route.

  Based on the received packet, the reception packet processing unit 302a determines whether to relay a transmission packet that is a packet transmitted from, for example, the terminal device 113 existing in the backbone network 101 to the terminal device 124 or 125 existing in the subnet 102, for example. The host route advertisement notification is determined, and the instruction packet 403a that is a packet for instructing the host route advertisement to be transmitted to the packet relay apparatus 220 is generated and transmitted.

  FIG. 4 is a diagram showing an example of an IP datagram of the instruction packet 403a according to Embodiment 1 of the present invention. The IP datagram of the instruction packet 403a includes an IP header 501 and a data part 502, as shown in FIG. The IP header is a header conforming to the RFC 791 standard, and stores source IP address information 503, destination IP address information 504, and the like. Data section 502 stores data to be transmitted such as IP address information 505a of the destination terminal device. Note that “˜” in the figure may store data related to transmission / reception, data to be transmitted / received, and the like. Here, for example, when the subnet 102 is divided due to a failure of the layer 2 switch 122 in the subnet 102, the terminal device 113 existing in the backbone network 101 is changed from the terminal device 125 existing in the subnet 102. Consider a case where a transmission packet is transmitted and the instruction packet 403a is transmitted from the packet relay apparatus 200 to the packet relay apparatus 220. The instruction packet 403a generated by the received packet processing unit 302a of the packet relay apparatus 200 includes the IP address information 200a assigned to the input / output port corresponding to the packet transmission unit 210 of the packet relay apparatus 200 to the source IP address information 503 of FIG. In the destination IP address information 504, the IP address information 220a assigned to the input / output port corresponding to the packet transmission unit 210 of the packet relay device 220 is stored. Further, the IP address information 125a of the terminal device 125 is stored in the IP address information 505a of the destination terminal device. The instruction packet 403a is transmitted, for example, from an input / output port corresponding to the packet transmission / reception unit 210 of the packet relay apparatus 200 to the input / output port corresponding to the packet transmission / reception unit 210 of the packet relay apparatus 220 via the backbone network 101. The IP address information 220a stored in the destination IP address information 504 of the instruction packet 403a is set in advance.

  The host route advertisement unit 301 generates a host route advertisement packet 404 as shown in FIG. 5, which is a packet for advertising the host route, and transmits the host route advertisement packet 404 to the backbone network 101 via the packet transmission / reception unit 210. Advertise host routes with. Here, the host route advertisement packet 404 is a packet depending on the format of the routing protocol used to construct the host route of the backbone network 101. In the example of the first embodiment, since the routing protocol OSPF is used, the host route is advertised by an LSA (Link State Advertisement) packet conforming to RFC2328.

  FIG. 5 is a diagram showing an example of an IP datagram of the host route advertisement packet according to Embodiment 1 of the present invention. FIG. 5 is a diagram illustrating an example of an IP datagram of the host route advertisement packet 404 transmitted from the host route advertisement unit 301 of the packet relay apparatus 220 to the router 112. The IP datagram of the host route advertisement packet 404 includes an IP header 501 and a data part 502 as shown in FIG. Regarding “˜” in the figure, data related to transmission / reception, data to be transmitted / received, and the like may be stored. Here, for example, when the subnet 102 is divided due to a failure of the layer 2 switch 122 in the subnet 102, the terminal device 113 existing in the backbone network 101 is changed from the terminal device 125 existing in the subnet 102. The transmission packet is transmitted, the instruction packet 403a is transmitted from the packet relay apparatus 200 to the packet relay apparatus 220, and the packet relay apparatus 220 uses the host route advertisement packet 404 as the router 111 and the router 112 in which the OSPF existing in the backbone network 101 operates. Consider a case where the host route of the terminal device 125 is advertised to the packet relay device 200. First, the host route advertisement packet 404 generated by the host route advertisement unit 301 of the packet relay device 220 is added to the input / output port corresponding to the packet transmission unit 210 of the packet relay device 220 in the source IP address information 503 of FIG. The multicast address information of OSPF predetermined by RFC2328 is stored in the IP address information 220a and the destination IP address information 504, and the routing protocol information 505b is stored in the data portion 502. Further, information for calculating the host route of the terminal device 125 is stored in the routing protocol information 505b. In this way, the host route advertisement packet 404 is created, and the host route advertisement packet 404 is transmitted from the packet relay apparatus 220 to the router 112.

  Here, the router 112 generates a host route advertisement packet based on the received host route advertisement packet 404 and transmits information for calculating the host route of the terminal 125 to the router 111 which is an adjacent OSPF operation router. . Similarly, the router 111 transmits a host route advertisement packet 404 to the packet relay device 200. Then, the router 111, the router 112, and the packet relay apparatus 200 calculate the host route of the terminal 125 based on information obtained from the adjacent router.

  FIG. 6 is a hardware configuration diagram of the packet relay apparatus 200 according to Embodiment 1 of the present invention. Note that the packet relay device 200 and the packet relay device 220 have the same hardware configuration.

  In FIG. 6, the packet relay apparatus 200 is configured by a computer. A computer constituting the packet relay device 200 includes a bus 205, a main storage device 204 that stores an ARP table, an external storage device 202 that stores a program, and a processor that reads and executes a program of the external storage device 202 loaded in the main storage device 204. 201, a communication interface 203 that transmits and receives a transmission packet, an instruction packet 403a, and a host route advertisement packet 404.

  A bus 205 is a signal path for electrically connecting the devices and exchanging information.

  The main storage device 204 functions as a work area for loading a program stored in the external storage device 202. The main storage device 204 is, for example, a RAM (Random Access Memory). The main storage device 204 stores IP address information and MAC address information stored in the ARP table. The table 214 is realized by the main storage device 204.

  The external storage device 202 stores programs such as search and detection of division. The external storage device 202 is, for example, a ROM (Read Only Memory), a flash memory, or an HDD (Hard Disk Drive). The external storage device 202 also stores an OS (Operating System).

  The processor 201 is connected to other devices via the bus 205 and controls these other devices. The processor 201 reads and executes the program of the external storage device 202 loaded in the main storage device 204. The processor 201 loads at least a part of the OS stored in the external storage device 202 into the main storage device 204, and executes the program while executing the OS. The processor 201 is an integrated circuit (IC) that performs processing. The processor 201 is, for example, a CPU (Central Processing Unit). The detection unit 212, the search unit 213, the host route advertisement unit 301, and the received packet processing unit 302 a are realized by reading and executing the program of the external storage device 202 loaded into the main storage device 204 by the processor 201.

  The packet transmission / reception unit 210 and the subnet transmission / reception unit 211 are realized by the communication interface 203.

  Information, data, signal values, variable values, and the like indicating the results of each device are stored in the main storage device 204, the external storage device 202, or a register or cache memory in the processor 201.

  Further, the program may be stored in a portable recording medium such as a magnetic disk, a flexible disk, an optical disk, a compact disk, or a DVD (Digital Versatile Disc).

  Next, the operation of the packet relay apparatus 200 according to Embodiment 1 of the present invention will be described.

  FIG. 7 is a flowchart showing the operation of the received packet processing unit 302a according to Embodiment 1 of the present invention. The operation of the received packet processing unit 302a will be described below with reference to FIG.

  In step S101, the received packet processing unit 302a receives the packet received from the backbone network 101 by the packet transmitting / receiving unit 210. The received packet processing unit 302a determines whether the received packet is a transfer packet or an instruction packet 403a based on the destination IP address information of the packet.

  Specifically, for example, when a transmission packet is transmitted from the terminal device 113 in the backbone network 101 to the terminal device 124 or the terminal device 125 in the subnet 102, the destination IP address information of the received packet is the terminal device 124 or the terminal device. 125 IP address information is stored. On the other hand, when the instruction packet 403a shown in FIG. 4 is transmitted from the packet relay apparatus 220 to the packet relay apparatus 200, the destination IP address information 504 of the received packet is given to the input / output port corresponding to the packet transmission unit 210 of the packet relay apparatus 200. IP address information 200a is stored. If the destination IP address information 504 of the received packet is the IP address information 200a of the packet relay device 200, the received packet processing unit 302a determines that the instruction packet 403a is obtained, and the result is Yes in step S101. If the destination IP address information of the received packet is other than the IP address information 200a of the packet relay device 200, the received packet processing unit 302a determines that the packet is a transfer packet, and the result is No in step S101.

  The received packet processing unit 302a determines whether the received packet is a transfer packet or an instruction packet 403a based on the destination IP address information of the packet. However, the received packet processing unit 302a may determine from the information stored in the data unit.

  In step S102, the received packet processing unit 302a transmits the received instruction packet 403a to the host route advertisement unit 301 to notify the backbone network 101 that the host route is advertised. The processing of the host route advertisement unit 301 will be described later.

  On the other hand, in step S <b> 103, the received packet processing unit 302 a acquires information on whether or not communication with the packet relay apparatus 220 is disconnected in the subnet 102 from the detection unit 212. A process in which the detection unit 212 detects the disconnection of communication with the packet relay device 220 in the subnet 102 will be described later. If the received packet processing unit 302a obtains information from the detection unit 212 that communication with the packet relay device 220 is disconnected within the subnet 102, the process proceeds to step S103: Yes. When the received packet processing unit 302a acquires information from the detection unit 212 that communication with the packet relay device 220 is not divided in the subnet 102, the received packet processing unit 302a determines that communication with the terminal device having the destination IP address information of the transfer packet is possible. Step S103: No.

  In step S104, the received packet processing unit 302a transmits the received transmission packet to the subnet 102 via the subnet transmission / reception unit 211. When transmitting to the subnet 102, the MAC address information of the terminal device having the destination IP address information of the transmission packet designated as the destination MAC address information of the transmission packet is acquired from the ARP table 401 shown in FIG. To do.

  Here, the case of step S104 is, for example, the case where the subnet 102 is not divided in FIG. 1 and the terminal device 113 transmits a transfer packet to the terminal device 124 or the terminal device 125. The router 111 receives the transmission packet addressed to the terminal device 124 or the terminal device 125 transmitted by the terminal device 113. Since the router 111 stores the route to the subnet 102 advertised from the packet relay device 200, the router 111 relays the received transmission packet to the packet relay device 200. In the packet relay apparatus 200, the packet transmission / reception unit 210 receives the transmission packet, and the packet transmission / reception unit 210 transmits the transmission packet to the reception packet processing unit 302a. Since the received packet processing unit 302a is in a state where the subnet 102 is not divided, the received transmission packet is transmitted to the subnet 102 via the subnet transmission / reception unit 211, and the transmission packet is transmitted to the destination terminal device 124 or the terminal device 125. Send. When transmitting to the subnet 102, the MAC address information of the terminal device 124 or the terminal device 125 specified as the destination MAC address information of the transfer packet is acquired from the ARP table 401 shown in FIG.

  On the other hand, in step S105, the received packet processing unit 302a acquires the address information of the terminal device that can communicate with the packet relay device 200 in the subnet 102 from the table 214, and communicates with the terminal device having the destination IP address information of the transfer packet. Determine if it is possible.

  Specifically, the received packet processing unit 302a acquires the ARP table 402 as shown in FIG. 3B of the address information of the terminal device that can communicate with the packet relay device 200 within the subnet 102 from the table 214, It is determined whether there is IP address information that matches the destination IP address information of the transmission packet. If there is IP address information that matches the destination IP address information of the transfer packet, the received packet processing unit 302a determines that communication with the terminal device having the destination IP address information of the transfer packet is possible, and the result of step S105 is Yes. If there is no IP address information that matches the destination IP address information of the transfer packet, the received packet processing unit 302a determines that communication with the terminal device having the destination IP address information of the transfer packet is impossible, and the result of step S105 is No. . A process in which the search unit 213 searches for address information of a terminal device that can communicate with the packet relay device 200 in the subnet 102 will be described later.

  In step S106, the received packet processing unit 302a transmits the received transmission packet to the subnet 102 via the subnet transmission / reception unit 211, as in step S104. When transmitting to the subnet 102, the MAC address information of the terminal device having the destination IP address information of the transmission packet designated as the destination MAC address information of the transmission packet is acquired from the ARP table 402 shown in FIG. 3B. To do.

  Here, the case of step S106 is, for example, the case where the subnet 102 is divided due to the failure of the layer 2 switch 122 in FIG. 1, and the terminal device 113 transmits a transfer packet to the terminal device 124. Is the case. The transmission packet addressed to the terminal device 124 transmitted by the terminal device 113 is received by the packet transmission / reception unit 210 of the packet relay device 200 as in the case where the subnet 102 in step S104 is not divided, and the packet transmission / reception unit 210 transmits the transmission packet. Is sent to the received packet processing unit 302a. The detection unit 212 detects the division of the subnet 102 by each of the packet relay devices 200 and 220 and notifies the search unit 213 of it. The search unit 213 searches for address information of a terminal device that can communicate with the packet relay device 200 in the subnet 102 using the notification of division by the detection unit 212 as a trigger, and stores the address information in the table 214. The received packet processing unit 302a acquires the ARP table 402 as shown in FIG. 3B of the address information of the communicable terminal device stored from the table 214, and includes the destination IP address information of the transfer packet and the ARP table 402 therein. It is determined that matching IP address information exists. The reception packet processing unit 302 a transmits the received transmission packet to the subnet 102 via the subnet transmission / reception unit 211, and transmits the transmission packet to the destination terminal device 124.

  On the other hand, in step S107, the received packet processing unit 302a generates an instruction packet 403a for instructing the packet relay apparatus 220 as shown in FIG. 4 to advertise the host route.

  In step S108, the received packet processing unit 302a transmits the generated instruction packet 403a to the packet transmitting / receiving unit 210, and transmits the instruction packet 403a to the packet relay apparatus 220 via the backbone network 101. When the packet relay apparatus 220 receives the instruction packet 403a, the packet relay apparatus 220 executes Step S102.

  Here, the case of step S108 is, for example, the case where the subnet 102 is divided due to the failure of the layer 2 switch 122 in FIG. 1, and the terminal device 113 transmits a transfer packet to the terminal device 125. Is the case. The transmission packet addressed to the terminal device 125 transmitted by the terminal device 113 is received by the packet transmission / reception unit 210 of the packet relay device 200 as in the case where the subnet 102 in step S104 is not divided, and the packet transmission / reception unit 210 transmits the transmission packet. Is sent to the received packet processing unit 302a. Similarly to step S106, the detection unit 212 and the search unit 213 search for the address information of the terminal device that can detect and communicate with the division, and store the search result in the table 214. The received packet processing unit 302a acquires the ARP table 402 as shown in FIG. 3B of the address information of the communicable terminal device stored from the table 214, and includes the destination IP address information of the transfer packet and the ARP table 402 therein. It is determined that there is no matching IP address information. The received packet processing unit 302 a generates an instruction packet 403 a as shown in FIG. 4 so that the packet relay device 220 advertises the host route, and transmits the instruction packet 403 a to the packet relay device 220 via the packet transmitting / receiving unit 210 and the backbone network 101. An instruction packet 403a is transmitted. The packet relay apparatus 220 executes step S102 and advertises the host route to the backbone network 101.

  FIG. 8 is a flowchart showing the operation of the detection unit 212 according to Embodiment 1 of the present invention. The operation of the detection unit 212 will be described below with reference to FIG.

  In step S <b> 201, the detection unit 212 uses ICMP to transmit an Echo Request packet to the packet relay device 220 via the subnet 102 via the subnet transmission / reception unit 211 every second.

  In step S202, the detection unit 212 confirms whether an Echo Reply packet is received as a response from the packet relay apparatus 220 via the subnet transmission / reception unit 211 within one second, for example. If the detection unit 212 receives an Echo Reply packet from the packet relay device 220 as a response within one second, the detection unit 212 returns Yes in step S202. If the detection unit 212 does not receive an Echo Reply packet from the packet relay apparatus 220 within 1 second as a response, the determination result in step S202 is No. It should be noted that, for example, whether or not a response is received within 1 second, but may be 0.1 second, 1 minute, or the like as long as it is a fixed time.

  In step S203, when the detection unit 212 receives an Echo Reply packet from the packet relay device 220 as a response within one second, the detection unit 212 determines that the packet is not divided from the packet relay device 220, and stores the determination result.

  In step S204, if the detection unit 212 does not receive an Echo Reply packet from the packet relay device 220 within 1 second as a response, the detection unit 212 determines that the packet is disconnected from the packet relay device 220, and stores the determination result.

  In step S <b> 205, the detection unit 212 transmits a determination result indicating that it is divided to the search unit 213 to notify it.

  FIG. 9 is a flowchart showing the operation of the search unit 213 according to Embodiment 1 of the present invention. The operation of the search unit 213 will be described below using FIG.

  In step S301, when the search unit 213 receives a determination result indicating that it is divided from the detection unit 212, all the destinations that can exist in the IP address information space in the subnet 102 via the subnet transmission / reception unit 211. An ARP Request packet is transmitted for the IP address information.

  In step S302, the search unit 213 confirms whether, for example, the ARP reply packet is received as a response via the subnet transmission / reception unit 211 within one second. When the search unit 213 receives an ARP Reply packet as a response within one second, the search unit 213 makes a step S302: Yes. If the search unit 213 does not receive the ARP Reply packet within 1 second as a response, the search unit 213 determines that there is no terminal device that can communicate with the packet relay device 200, and the process ends in step S302: No. It should be noted that, for example, whether or not a response is received within 1 second, but may be 0.1 second, 1 minute, or the like as long as it is a fixed time.

  In step S303, the search unit 213 determines that the terminal device that is the destination of the ARP Request packet is a terminal device that can communicate with the packet relay device 200 in the subnet 102, and the IP address information and the MAC stored in the ARP Reply packet. The address information is stored in the table 214 as the ARP table 402.

  FIG. 10 is a flowchart showing the operation of the host route advertisement unit 301 according to Embodiment 1 of the present invention. The operation of the host route advertisement unit 301 will be described below with reference to FIG.

  In step S401, when the host route advertisement unit 301 receives the instruction packet 403a from the received packet processing unit 302a, the host route advertisement unit 301 obtains the ARP table 402 of the address information of the terminal device that can communicate with the packet relay device 220 within the subnet 102 from the table 214. Then, it is determined whether or not communication with the terminal device having the destination IP address information 504 stored in the instruction packet 403a is possible. A specific method is the same as that in step S105. The host route advertisement unit 301 has the destination IP address information 504 stored in the instruction packet 403a when the IP address information matching the destination IP address information 504 stored in the instruction packet 403a exists in the ARP table 402. It is determined that communication with the terminal device is possible, and step S401 is Yes. When there is no IP address information in the ARP table 402 that matches the destination IP address information 504 stored in the instruction packet 403a, the host route advertising unit 301 has the destination IP address information 504 stored in the instruction packet 403a. It is determined that communication with the terminal device is impossible, and step S401: No, and the flowchart ends.

  In step S402, the host route advertisement unit 301 generates a host route advertisement packet 404 corresponding to the destination IP address information 504 stored in the instruction packet 403a as shown in FIG.

  In step S <b> 403, the host route advertisement unit 301 transmits the generated host route advertisement packet 404 to the backbone network 101 via the packet transmission / reception unit 210.

  When the packet relay device 220 advertises the host route of the terminal device 125 having the destination IP address information of the transfer packet, the router 111, the router 112, the packet relay device 200, and the packet relay device 220 have the routing table as shown in FIG. Update. Thereby, the terminal device having the destination IP address information of the transmission packet that has already been transmitted is relayed by the shortest route thereafter.

  FIG. 11 is a diagram illustrating an example of the routing table according to the first embodiment of the present invention, where (a) illustrates the routing table 406 before the host route advertisement of the router 111, and (b) illustrates It is the figure which showed the routing table 407 after host route advertisement of the router 111. FIG. As shown in FIG. 11, the routing table 406 and the routing table 407 are tables that store destination network information and transfer destination information. The destination network information stores a set of IP address information and a subnet mask. For example, the subnet 102 stored in the destination network information of the routing table 406 indicates a set of IP address information and subnet mask of the subnet 102. The router 111 does not divide the subnet 102 and before the advertisement of the host route, the IP address information 200a of the destination packet relay apparatus 200 corresponding to the IP address information of the terminal apparatus existing in the subnet 102 is shown in FIG. It is registered in the routing table 406 shown in a). Therefore, when the subnet 102 is not divided, the router 111 transmits all transmission packets addressed to the terminal devices existing in the subnet 102 to the packet relay device 200.

  Here, for example, due to a failure of the layer 2 switch 122 in the subnet 102, the subnet 102 is divided, a transmission packet is transmitted from the terminal device 113 to the terminal device 125, and a host route advertisement transmitted from the packet relay device 220. Consider a case where the router 404 receives the packet 404 via the router 112. After the host route is advertised, the router 111 calculates the host route based on the routing protocol information 505b in the host route advertisement packet 404 received from the packet relay device 220 via the router 112, and the destination network information. The IP address information and subnet mask 125a of the terminal device 125 and the IP address information 112a of the router 112 are stored in the routing table 407 shown in FIG. Here, the route indicated by the combination of the destination network information 125a and the transfer destination 112a is a host route indicating a route addressed to a specific terminal device 125. The destination network information 125a of the terminal device 125 is stored as a set of the IP address information of the specific terminal device 125 and a 32-bit subnet mask. The router 112, the packet relay device 200, and the packet relay device 220 store information in the routing table in the same manner. In the routing table, when a plurality of routes corresponding to a certain destination are registered, a route with a long subnet mask is prioritized. Specifically, for example, consider a case where a transfer packet is transmitted from the terminal device 113 to the terminal device 125 after the host route advertisement and the router 111 receives the transfer packet. Here, since the terminal device 125 is a terminal device existing in the subnet 102, in the routing table 407, the route indicated by the combination of the subnet 102 of the destination network information and the forwarding destination 200a, and the destination network information 125a Both of the routes indicated by the pair with the forwarding destination 112a correspond to the destination. Here, when the subnet mask of the subnet 102 of the destination network information in the routing table 407 after the host route advertisement is 24 bits and the subnet mask of 125a is 32 bits, a route with a long subnet mask is given priority, so transmission to the terminal device 125 is performed. For the packet, priority is given to the transfer destination of the IP address information 112a of the router 112 whose subnet mask is 32 bits.

  By repeating the above processing until there is a processing termination trigger such as turning off the power or performing a termination operation, an increase in the amount of data stored in the routing table can be suppressed when the subnet is divided . Although the above processing is repeated, it may be performed only once without repeating.

  As described above, in the packet relay apparatus 200 and the packet relay apparatus 220 according to the first embodiment, when advertising the host route from the packet relay apparatus 220 after detecting the division of the subnet 102, the address information of the received transmission packet is included. The corresponding instruction packet 403a is transmitted to the packet relay device 220, and when the communication from the backbone network 101 to the terminal device in the subnet 102 occurs, the host route is advertised and the router of the backbone network 101 and the packet relay device Since the routing table is updated, communication from the backbone network 101 to the subnet 102 is enabled, and the OPSF processing load of the router and the packet relay device is increased and the routing table size is increased. It is possible to suppress. As a result, stable network operation is possible.

  Further, in the packet relay device 200 and the packet relay device 220 of the first embodiment, the host route is advertised only for the destination IP address information 504 of the instruction packet 403a, so it is necessary to transmit a transfer packet It is not necessary to register all the terminal devices all at once until appears. Therefore, communication from the backbone network 101 to the subnet 102 can be performed, and an increase in the OPSF processing load of the router and the packet relay device and an increase in the routing table size can be suppressed. As a result, stable network operation is possible.

  In the packet relay device 200 and the packet relay device 220 of the first embodiment described above, the case where there are two packet relay devices has been described, but the number of packet relay devices may be two or more.

Embodiment 2. FIG.
In the first embodiment, the received packet processing unit 302a generates the instruction packet 403a and transmits the instruction packet 403a when the communication from the backbone network 101 to the terminal device in the subnet 102 occurs. In the second embodiment, as illustrated in FIGS. 12 to 13, the received packet processing unit 302 b generates an instruction packet 403 b including a transfer packet. Therefore, for example, when the instruction packet 403b is transmitted from the packet relay apparatus 200 to the packet relay apparatus 220, the transfer packet is also transmitted to the packet relay apparatus 220, and the transfer packet is transmitted to the destination terminal apparatus. The rest is the same as in the first embodiment.

  In the second embodiment, a received packet processing unit 302b is added as a functional block diagram instead of the received packet processing unit 302a in FIG. 2 of the first embodiment.

  In addition to the function of the received packet processing unit 302a of the first embodiment, the received packet processing unit 302b performs encapsulation for generating an IP packet in which the transmission packet is stored in the data unit 502, and performs transmission as illustrated in FIG. An instruction packet 403b which is a capsule packet including the packet is generated.

  FIG. 12 shows an example of an IP datagram of instruction packet 403b according to Embodiment 2 of the present invention. The IP datagram of the instruction packet 403b is an IP packet including an IP header 501 and a data part 502 as shown in FIG. Regarding “˜” in the figure, data related to transmission / reception, data to be transmitted / received, and the like may be stored. The data part 502 stores a transmission packet, and other than that is the same as the instruction packet 403a of the first embodiment. Here, as in the first embodiment, for example, when the subnet 102 is divided due to a failure of the layer 2 switch 122 in the subnet 102, the terminal device 113 existing in the backbone network 101 enters the subnet 102. Consider a case in which a transfer packet is transmitted to an existing terminal device 125 and an instruction packet 403b is transmitted from the packet relay device 200 to the packet relay device 220. The instruction packet 403b generated by the received packet processing unit 302b of the packet relay device 200 includes the source IP address information 503, the IP address information 220a assigned to the input / output port corresponding to the packet transmitting / receiving unit 210 of the packet relay device 220, and the destination IP. This is a capsule packet in which the IP address information 200a assigned to the input / output port corresponding to the packet transmitting / receiving unit 210 of the packet relay apparatus 200 is stored in the address information 504 and the transmission packet is stored in the data unit 502, respectively.

  When receiving the capsule packet via the packet transmission / reception unit 210, the reception packet processing unit 302b transmits the transmission packet included in the capsule packet to the subnet 102 via the subnet transmission / reception unit 211, and transmits the transmission packet to the destination terminal. Send to device. The rest is the same as in the first embodiment.

  The hardware configuration diagram of the packet relay apparatus 200 according to the second embodiment of the present invention is the same as that of FIG. 6 according to the first embodiment. The hardware configuration of the received packet processing unit 302b is the same as that of the received packet processing unit 302a.

  FIG. 13 is a flowchart showing the operation of the received packet processing unit 302b according to Embodiment 2 of the present invention. The operation of the received packet processing unit 302b will be described with reference to FIG. In the following description, the configurations and operations already described are denoted by the same reference numerals, and redundant description is omitted.

  In step S501, the received packet processing unit 302b receives a packet in the same manner as in step S101 of the first embodiment. The received packet processing unit 302b determines whether the received packet is a capsule packet. If the received packet is a capsule packet, the received packet processing unit 302b determines that the received packet is the instruction packet 403b, and the result of step S501 is Yes. If the received packet is not a capsule packet, the received packet processing unit 302b determines that the packet is a transfer packet, and the result of step S501 is No.

  Step S502 is the same as step S102 of the first embodiment.

  In step S503, the received packet processing unit 302b acquires the address information of the terminal device that can communicate in the subnet 102 from the table 214, as in step S105 of the first embodiment, and the destination of the transfer packet included in the capsule packet. It is determined whether or not communication with a terminal device having IP address information is possible. When there is IP address information that matches the destination IP address information of the transmission packet included in the capsule packet in the ARP table 402 acquired from the table 214, the reception packet processing unit 302b receives the destination IP address of the transmission packet included in the capsule packet. It is determined that communication with the terminal device having the information is possible, and step S503 is Yes. When there is no IP address information that matches the destination IP address information of the transfer packet included in the capsule packet in the ARP table 402 acquired from the table 214, the reception packet processing unit 302b receives the destination IP address of the transfer packet included in the capsule packet. It is determined that communication with the terminal device having the information is impossible, and step S503: No, and the flowchart ends.

  In step S504, the received packet processing unit 302b transmits the transfer packet included in the capsule packet to the subnet 102 via the subnet transmission / reception unit 211, as in step S106 of the first embodiment.

  Step S505, step S506, step S507, and step S508 are the same as step S103, step S104, step S105, and step S106 of the first embodiment.

  In step S509, the received packet processing unit 302b generates an instruction packet 403b for instructing the packet relay apparatus 220 to advertise the host route. As shown in FIG. 12, the received packet processing unit 302b encapsulates the transfer packet and generates an instruction packet 403b that is a capsule packet including the transfer packet.

  In step S <b> 510, the received packet processing unit 302 b transmits the generated capsule packet instruction packet 403 b to the packet transmission / reception unit 210, and transmits the instruction packet 403 b to the packet relay device 220 via the backbone network 101. When receiving the instruction packet 403b, the packet relay device 220 executes steps S502 to S504.

  By repeating the above processing until there is a processing termination trigger such as turning off the power or performing a termination operation, an increase in the amount of data stored in the routing table can be suppressed when the subnet is divided . Although the above processing is repeated, it may be performed only once without repeating.

  As described above, in the packet relay apparatus 200 and the packet relay apparatus 220 according to the second embodiment, when advertising a host route from the packet relay apparatus 220 after detecting the division of the subnet 102, the address information of the received transmission packet is included. The corresponding instruction packet 403b is transmitted to the packet relay device 220, and when the communication from the backbone network 101 to the terminal device in the subnet 102 occurs, the host route is advertised and the routing table of the backbone network 101 is updated. As a result, communication from the backbone network 101 to the subnet 102 can be performed, and an increase in the OPSF processing load of the router and the packet relay device and an increase in the routing table size can be suppressed. As a result, stable network operation is possible.

  In the packet relay apparatus 200 and the packet relay apparatus 220 according to the second embodiment, the host route is advertised only for the address information of the transfer packet stored in the instruction packet 403b, so the transfer packet is transmitted. It is not necessary to register all the terminal devices at once until it is necessary to do so. Therefore, communication from the backbone network 101 to the subnet 102 can be performed, and an increase in the OPSF processing load of the router and the packet relay device and an increase in the routing table size can be suppressed. As a result, stable network operation is possible.

  Furthermore, in packet relay apparatus 200 and packet relay apparatus 220 of the second embodiment, received packet processing section 302b generates instruction packet 403b including a transfer packet. Therefore, for example, when the instruction packet 403b is transmitted from the packet relay apparatus 200 to the packet relay apparatus 220, the transfer packet is also transmitted to the packet relay apparatus 220, and the transfer packet can be transmitted to the destination terminal apparatus.

Embodiment 3 FIG.
In the first embodiment, transmission / reception of the instruction packet 403 a between the packet relay apparatus 200 and the packet relay apparatus 220 is performed via the backbone network 101. In the third embodiment, as shown in FIGS. 14 to 15, a dedicated line 127 is provided between the packet relay device 200 and the packet relay device 220 to relay the instruction packet 403a. For this reason, an increase in communication processing load of the backbone network 101 can be suppressed. The rest is the same as in the first embodiment.

  FIG. 14 is a schematic configuration diagram of a packet relay system according to Embodiment 3 of the present invention. In the following description, the configurations and operations already described are denoted by the same reference numerals, and redundant description is omitted.

  The dedicated line 127 is an IP network different from the backbone network 101 and the subnet 102, and connects the packet relay apparatus 200 and the packet relay apparatus 220.

  FIG. 15 is a functional block diagram of packet relay apparatus 200 according to Embodiment 3 of the present invention. The packet relay device 200 and the packet relay device 220 are similar functional block diagrams.

  The packet relay control device 300 includes a dedicated transmission / reception unit 303 in addition to the configuration of the first embodiment. The dedicated transmission / reception unit 303 transmits / receives the instruction packet 403a to / from the packet relay apparatus 220. The dedicated transmission / reception unit 303 is an input / output port.

  The hardware configuration diagram of the packet relay apparatus 200 according to the third embodiment of the present invention is the same as that of FIG. 6 according to the first embodiment. The hardware configuration of the dedicated transmission / reception unit 303 is realized by the communication interface 203.

  The operation of the third embodiment is the same as the operation of FIGS. 7 to 10 of the first embodiment. However, in step S101, the received packet processing unit 302a does not receive the transmission packet and the instruction packet 403a received by the packet transmitting / receiving unit 210 from the backbone network 101, but receives the instruction packet 403a from the dedicated transmitting / receiving unit 303. The method for transmitting / receiving the transmission packet is the same as that in the first embodiment. In step S108, the received packet processing unit 302a transmits the generated instruction packet 403a to the packet transmitting / receiving unit 210, and does not transmit the instruction packet 403a to the packet relay apparatus 220 via the backbone network 101. The instruction packet 403a is transmitted to the packet relay apparatus 220 via the dedicated transmission / reception unit 303.

  As described above, in the packet relay device 200 and the packet relay device 220 according to the third embodiment, when advertising the host route from the packet relay device 220 after detecting the division of the subnet 102, the address information of the received transmission packet is included. The corresponding instruction packet 403a is transmitted to the packet relay device 220, and when the communication from the backbone network 101 to the terminal device in the subnet 102 occurs, the host route is advertised and the routing table of the backbone network 101 is updated. As a result, communication from the backbone network 101 to the subnet 102 can be performed, and an increase in the OPSF processing load of the router and the packet relay device and an increase in the routing table size can be suppressed. As a result, stable network operation is possible.

  Further, in the packet relay device 200 and the packet relay device 220 according to the third embodiment, since the host route is advertised only for the destination IP address information 504 of the instruction packet 403a, it is necessary to transmit a transmission packet. It is not necessary to register all the terminal devices all at once until appears. Therefore, communication from the backbone network 101 to the subnet 102 can be performed, and an increase in the OPSF processing load of the router and the packet relay device and an increase in the routing table size can be suppressed. As a result, stable network operation is possible.

  Furthermore, in the packet relay device 200 and the packet relay device 220 according to the third embodiment, a dedicated line 127 is provided between the packet relay device 200 and the packet relay device 220 to relay the instruction packet 403a. For this reason, an increase in communication processing load of the backbone network 101 can be suppressed.

  By the way, the packet relay device, the packet relay control device, the packet relay system, and the packet relay method described in the above-described embodiments are merely examples, and can be appropriately combined and configured. It is not restricted to the structure of.

101 backbone network, 102 subnets,
111, 112 routers, 113, 124, 125 terminal devices,
127 dedicated line, 200, 220 packet relay device,
201 processor, 202 external storage device, 203 communication interface,
204 main storage device, 210 packet transmission / reception unit,
212 detection units, 213 search units, 214 tables,
300 packet relay control device, 301 host route advertisement section,
302a, 302b Received packet processor, 303 dedicated transceiver.

Claims (14)

In a packet relay device that redundantly connects a backbone network in which a terminal device exists and a subnet in which a plurality of other terminal devices exist via a router having a routing table that stores and updates a host route, together with other packet relay devices,
A detection unit for detecting a division of communication with the other packet relay device in the subnet;
A search unit for searching for address information of the other terminal device capable of communicating in the subnet;
A table for storing address information of the other terminal devices capable of communication searched by the search unit;
A packet that receives a transmission packet to be transmitted from the terminal device to the other terminal device and transmits / receives an instruction packet for instructing an advertisement of the host route for updating the routing table to / from the other packet relay device. A transceiver unit;
When the address information of the other communicable terminal device corresponding to the address information of the transmission packet received by the packet transmission / reception unit is not in the table after the detection of the division by the detection unit, A packet relay apparatus comprising: a reception packet processing unit that generates the instruction packet corresponding to address information and transmits the generated instruction packet to the packet transmitting / receiving unit. When the packet transmission / reception unit receives the instruction packet from the other packet relay device, the address information of the other terminal device capable of communication corresponding to the address information of the transfer packet is detected after the detection unit detects the division. 2. The packet relay device according to claim 1, further comprising: a host route advertisement unit that advertises the host route corresponding to the address information of the transfer packet to the router via the packet transmission / reception unit. The packet relay device according to claim 2, wherein the host route advertisement unit advertises only the host route corresponding to the address information of the transmission packet. The packet relay apparatus according to claim 1, wherein the instruction packet generated by the received packet processing unit includes the transfer packet. 5. The packet relay device according to claim 1, wherein the packet transmission / reception unit includes a dedicated transmission / reception unit that is directly connected to the other packet relay device and transmits / receives the instruction packet. A backbone network in which terminal devices exist and a subnet in which a plurality of other terminal devices exist are redundantly connected together with other packet relay devices via a router having a routing table for storing and updating host routes, and within the subnet A detection unit that detects a disconnection of communication with the other packet relay device, a search unit that searches for address information of the other terminal device that can communicate within the subnet, and the communicable device that is searched by the search unit A table for storing address information of another terminal device, and an instruction packet for instructing advertisement of the host route for receiving the transmission packet transmitted from the terminal device to the other terminal device and updating the routing table. A packet comprising a packet transmitting / receiving unit for transmitting / receiving to / from the other packet relay device The packet relay control unit constituting a part of the joining device,
When the address information of the other communicable terminal device corresponding to the address information of the transfer packet received by the packet transmitting / receiving unit is not in the table after the detection of the division by the detection unit, the transfer packet A packet relay control device comprising: a reception packet processing unit that generates the instruction packet corresponding to the address information of the packet and transmits the generated instruction packet to the packet transmitting / receiving unit. When the packet transmission / reception unit receives the instruction packet from the other packet relay device, the address information of the other terminal device capable of communication corresponding to the address information of the transfer packet is detected after the detection unit detects the division. 7. The packet relay control device according to claim 6, further comprising: a host route advertisement unit that advertises the host route corresponding to the address information of the transmission packet to the router via the packet transmission / reception unit. The packet relay control device according to claim 7, wherein the host route advertisement unit advertises only the host route corresponding to the address information of the transmission packet. A backbone network in which a terminal device exists via a router having a routing table for storing and updating host routes;
A subnet in which a plurality of other terminal devices exist, and
A plurality of packet relay devices that redundantly connect the backbone network and the subnet;
Each of the plurality of packet relay devices includes:
A detection unit for detecting a disconnection of communication with each of the other packet relay devices in the subnet;
A search unit for searching for address information of the other terminal device capable of communicating in the subnet;
A table for storing address information of the other terminal devices capable of communication searched by the search unit;
An instruction packet instructing advertisement of the host route for receiving the transmission packet to be transmitted from the terminal device to the other terminal device and updating the routing table is transmitted between the other packet relay devices. A packet transmitting and receiving unit for transmitting and receiving;
When the address information of the other communicable terminal device corresponding to the address information of the transmission packet received by the packet transmission / reception unit is not in the table after the detection of the division by the detection unit, A packet relay system comprising: a reception packet processing unit that generates the instruction packet corresponding to address information and transmits the generated instruction packet to the packet transmitting / receiving unit. Each of the plurality of packet relay devices includes:
When the packet transmission / reception unit receives the instruction packet from each of the plurality of other packet relay devices, the address information of the other communicable terminal device corresponding to the address information of the transmission packet is divided by the detection unit. The packet relay according to claim 9, further comprising: a host route advertisement unit that advertises the host route corresponding to the address information of the transfer packet to the router via the packet transmission / reception unit. system. The packet relay system according to claim 10, wherein the host route advertisement unit of each of the plurality of packet relay devices advertises only the host route corresponding to the address information of the transfer packet. The packet relay device and other packet relay devices are connected redundantly to the backbone network in which the terminal device exists and the subnet in which multiple other terminal devices exist through a router having a routing table that stores and updates the host route. In the packet relay method to
Detecting a disconnection of communication between the packet relay device and the other packet relay device in the subnet;
Searching for address information of the other terminal device capable of communicating with the packet relay device in the subnet;
Storing address information of other terminal devices capable of communicating with the searched packet relay device;
An instruction packet for receiving an advertisement of the host route for receiving a transmission packet to be transmitted from the terminal device to the other terminal device and updating the routing table is transmitted between the packet relay device and the other packet relay device. Sending and receiving between,
The address information of the other terminal device communicable with the packet relay device corresponding to the received address information of the transfer packet is stored in the other terminal device communicable with the packet relay device after detection of the stored division. A packet relay method comprising: generating the instruction packet corresponding to the address information of the transmission packet and transmitting the generated instruction packet when the address packet is not included in the address information. When the instruction packet is received from the other packet relay device, the address information of another terminal device that can communicate with the packet relay device corresponding to the address information of the transmission packet is the detected information after the detection of the fragmentation. 13. The packet relay method according to claim 12, further comprising the step of advertising the host route corresponding to the address information of the transfer packet to the router if it is in the address information of another terminal device that can communicate with the packet relay device. The packet relay method according to claim 13, wherein the advertising step advertises only the host route corresponding to the address information of the transmission packet.

Images