JP5497697B2 - Communications system - Google Patents

Description

  The present invention relates to a stacked communication system.

  Communication devices are used to control packet transfer between terminals connected to a network. The communication device can operate as a communication system that is a virtual one communication device by connecting to a plurality of other communication devices. For example, Patent Document 1 discloses a technique related to packet transfer using a stack communication system.

  When using a communication system, in order for a plurality of communication devices to operate as a single virtual communication device, the performance of the plurality of connected communication devices (can be stored in a MAC address table provided in the communication device) The number of MAC address entries, etc. (hereinafter also referred to as “accommodating conditions”) is preferably the same. This is because the performance of the entire communication system may be degraded by a communication device with low performance. Therefore, conventionally, the types of communication devices that can constitute a stack are limited.

JP 2006-42368 A JP 2007-124673 A

  Considering the above-mentioned problems, the problem to be solved by the present invention is that when a stacked communication system is constructed by communication apparatuses having different performances, the performance of the entire communication system is affected by the communication apparatus having a low performance. It is to provide a technology that suppresses this.

SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.
A first aspect of the present invention is a communication system including a first communication device and a second communication device, and the communication system includes a plurality of the second communication devices connected in a ring shape. The first communication device is connected to at least two of the plurality of second communication devices,
The first communication device includes a plurality of first ports for transmitting and receiving packets each including a source terminal address and a destination terminal address, and any one of the plurality of first ports. A first packet with reception port information added with reception port information for identifying the received port to an original packet that is a layer 2 packet or a layer 3 packet received via the first communication device; A transfer control unit, wherein the second communication device receives a source packet with receiving port information from the first communication device, the plurality of first ports, and the plurality of ports. A first storage unit storing a first address table storing at least a correspondence relationship with a terminal connected to each of the first ports;
Terminals connected to each of the plurality of first ports and the plurality of first ports based on the reception port information included in the received original packet with reception port information and the address of the transmission source terminal Based on the learning unit that learns the correspondence relationship with the first address table and records it in the first address table, the address of the destination terminal included in the received original packet with the reception port information, and the first address table A transmission port specifying unit that specifies, from among the plurality of first ports, a first port that transmits the original packet transferred from the first communication device, and the specified transmission port information It includes a second transfer control unit for transferring the source packet with the transmission port information added to the original packet to the first communication device, wherein the first communication device, the plurality Further comprising a second storage unit in which the second address table is stored corresponding relationship between the addresses of terminals connected to the respective first port and said plurality of first ports has been recorded, the The first transfer control unit of the first communication device receives the original packet with the transmission port information, and from the first port corresponding to the transmission port information included in the original packet with the transmission port information, The original packet is transmitted when the first port that transmits the original packet is identified from among the plurality of first ports based on the second address table. If the first port for transmitting the original packet is not identified from the plurality of first ports, the original port with the reception port information is transmitted. When the communication between the at least two second communication devices is detected and a failure has occurred in the connection between the at least two second communication devices. The number of correspondences that can be stored in the second storage unit of the first communication device can be stored in the first storage unit of the second communication device by relaying packets that flow between them wherein less than the number of correspondence relations is communication system.
With such a configuration, the reception port information added to the original packet that is the layer 2 packet or the layer 3 packet received by the first transfer control unit included in the first communication device, and the address of the transmission source terminal Based on the above, the second communication device learns the correspondence between the plurality of first ports and the terminals connected to each of the plurality of first ports, and records them in the first address table. In addition, the transmission port identification unit included in the second communication device identifies the first port that transmits the original packet from the plurality of first ports based on the first address table, and identifies the identified transmission. The original packet with the port information added is transferred to the first communication device, and the first communication device transmits the original packet from the first port corresponding to the transmission port information. Therefore, even when a stack communication system is constructed by communication devices having different performances, the second communication device can take charge of learning regarding the packet received by the first communication device and specifying the transmission port. Therefore, it is possible to suppress the performance of the communication system from being affected by a low-performance communication device, and to manage a wide range of networks collectively by the communication system and transmit packets. Further, the first communication device includes a second address table in which a correspondence relationship with the address of the terminal connected to each of the first ports is recorded. Therefore, the first communication device can perform part of learning and transmission port specification performed by the second communication device. Therefore, the burden on learning and transmission port specification performed by the second communication device is reduced, and the accommodation conditions of the entire communication system can be improved. Furthermore, even when a failure occurs in the connection between the second communication devices, the first communication device can relay the packets flowing between the second communication devices. Redundancy can be realized and the availability of the communication system can be increased.

[Application Example 1] A communication system including a first communication device and a second communication device, wherein the first communication device transmits a packet including an address of a source terminal and an address of a destination terminal. Receiving port information for identifying the received port is added to a plurality of first ports for performing transmission and reception and an original packet which is a packet received via any of the plurality of first ports. A first transfer control unit configured to transfer the original packet with reception port information to the second communication device, wherein the second communication device receives the original packet with reception port information from the first communication device. A first address table storing at least correspondence between the second port to receive, the plurality of first ports, and the terminals connected to each of the plurality of first ports is stored. 1 of the plurality of first ports and the plurality of first ports based on the reception port information included in the received original packet with the reception port information and the address of the transmission source terminal. A learning unit that learns a correspondence relationship with each connected terminal and records it in the first address table; an address of the destination terminal included in the received source packet with the reception port information; and the first A transmission port specifying unit for specifying, from among the plurality of first ports, a first port for transmitting the original packet transferred from the first communication device based on an address table; A second transfer control unit configured to transfer an original packet with transmission port information obtained by adding the transmitted port information to the original packet to the first communication device, and the first communication A first transfer control unit configured to receive the original packet with the transmission port information and transmit the original packet from the first port corresponding to the transmission port information included in the original packet with the transmission port information. A communication system.

  With such a configuration, the second communication is performed based on the reception port information added to the original packet received by the first transfer control unit included in the first communication device and the address of the transmission source terminal. The device learns the correspondence between the plurality of first ports and the terminals connected to each of the plurality of first ports, and records them in the first address table. In addition, the transmission port identification unit included in the second communication device identifies the first port that transmits the original packet from the plurality of first ports based on the first address table, and identifies the identified transmission. The original packet with the port information added is transferred to the first communication device, and the first communication device transmits the original packet from the first port corresponding to the transmission port information. Therefore, even when a stack communication system is constructed by communication devices having different performances, the second communication device can take charge of learning regarding the packet received by the first communication device and specifying the transmission port. Therefore, it is possible to suppress the performance of the communication system from being affected by a low-performance communication device, and to manage a wide range of networks collectively by the communication system and transmit packets.

Application Example 2 In the communication system according to Application Example 1, the first communication device is further configured by a terminal connected to each of the plurality of first ports and the plurality of first ports. A second storage unit storing a second address table in which a correspondence relationship with the address is recorded, and the first transfer control unit transmits the original packet based on the second address table. When the first port for performing the identification is specified from among the plurality of first ports, the original packet is transmitted from the identified first port, and the original packet is transmitted. A communication system that transfers the original packet with reception port information to the second communication device when the port cannot be identified from the plurality of first ports.

  With such a configuration, the first communication apparatus includes a second address table in which a correspondence relationship with the address of the terminal connected to each of the first ports is recorded. Therefore, the first communication device can perform part of learning and transmission port specification performed by the second communication device. Therefore, the burden on learning and transmission port specification performed by the second communication device is reduced, and the accommodation conditions of the entire communication system can be improved.

Application Example 3 The communication system according to Application Example 1 or Application Example 2, wherein the communication system includes a plurality of the second communication devices connected in a ring shape, and the first communication device includes: , Being connected to at least two of the plurality of second communication devices, wherein the first transfer control unit of the first communication device is connected to the at least two second communication devices. A communication system that relays packets flowing between the at least two second communication devices when it is detected that a failure has occurred.

  With such a configuration, when a failure occurs in the connection between the communication devices, the first transfer control unit included in the first communication device transmits packets between at least two second communication devices. Relay. Therefore, redundancy of the network system can be realized and the availability of the communication system can be increased.

Application Example 4 The communication system according to any one of Application Examples 1 to 3, wherein the communication system is cascade-connected between the first communication device and the second communication device. A communication system comprising at least one third communication device, wherein the third communication device integrally comprises the first communication device and the second communication device.

  With such a configuration, a part of packet transfer processing performed by the second communication device is performed using the third communication device that integrally includes the first communication device and the second communication device. be able to. Furthermore, since a communication system connected in multiple stages can be constructed, the network can be expanded and packet transfer processing can be performed.

[Application Example 5] In the communication system according to any one of application examples from Application Example 1 to Application Example 4, the second communication apparatus stores at least an address of a terminal that performs packet reception restriction. A first transfer control unit of the first communication device acquires at least a part of the access control list, and for the terminal connected to the first port, A communication system that limits reception.

  With such a configuration, based on at least a part of the access control list provided in the second communication device, the original communication packet reception restriction for the terminal connected to the first port by the first communication device. To do. Therefore, the burden related to the packet reception restriction performed by the second communication apparatus is reduced. Therefore, a wide range of networks with different accommodation conditions can be collectively managed by the communication system based on the access control list, and packet reception can be restricted.

[Application Example 6] The communication system according to any one application example from Application Example 1 to Application Example 5, in which the second communication device is information for classifying terminals into virtual groups. A VLAN table in which certain group information is defined, wherein the first transfer control unit of the first communication device obtains at least a part of the VLAN table, and a group related to a terminal connected to the first port; A communication system for controlling packet forwarding based on information.

  With such a configuration, at least a part of the VLAN table included in the second communication apparatus is acquired, and packet transfer is controlled based on group information regarding the terminal connected to the first port. Therefore, a burden related to packet transfer control performed by the second communication apparatus is reduced. For this reason, it is possible to collectively control a wide range of networks by a communication system based on the VLAN table by using communication apparatuses having different accommodation conditions, and to control packet transfer.

Application Example 7 The communication system according to any one application example from Application Example 1 to Application Example 6, wherein the original packet is a layer 2 packet or a layer 3 packet. With such a configuration, a wide range of networks can be collectively managed by the communication system to control transfer of layer 2 packets or layer 3 packets.

  In addition to the configuration as the communication system described above, the present invention can also be configured as a communication device, a packet transfer method, and a computer program included in the communication system. Such a computer program may be recorded on a computer-readable recording medium. As the recording medium, for example, various media such as a flexible disk, a CD-ROM, a DVD-ROM, a magneto-optical disk, a memory card, and a hard disk can be used.

It is a figure which shows roughly the structure of the network using the communication system in 1st Example of this invention. It is the figure which showed schematic structure of the leaf and the node. It is the figure which showed an example of the address table recorded by the learning part. It is a flowchart of the packet transfer process repeatedly performed in a communication system. It is a figure which shows the data structure of an original packet and an encapsulation packet. It is a figure which shows an example of the address table after learning. It is a figure which shows an example of port bitmap information. It is the figure which showed schematic structure of the leaf and node in case a leaf has a learning part, a transmission port specific | specification part, a memory | storage part, and an address table like a node. It is the figure which showed an example of the address table with which a leaf is provided. It is a flowchart of the transfer process of the packet in 2nd Example. It is a figure which shows the structure of the network using the communication system connected in the cascade type. It is the figure which showed schematic structure of the leaf in the communication system connected in cascade, the node leaf, and the node. It is the figure which showed an example of the address table with which a node leaf is provided. It is the figure which showed an example of the address table with which a node is provided. 1 is a diagram showing a network in which a plurality of nodes are connected in a ring shape. It is the figure which showed the state in which the failure occurred in communication in the ring-shaped network. It is a flowchart which shows the transfer process of the packet in a ring. It is a flowchart which shows the transfer process of the packet in a ring performed by the leaf which received failure occurrence information. It is a figure which shows an example of the access control list with which a node is provided.

A. First embodiment:
FIG. 1 is a diagram schematically showing the configuration of a network 10 using a communication system 100 in the first embodiment of the present invention. The network 10 includes a plurality of terminal devices (hereinafter also simply referred to as “terminals”) 300, a plurality of first communication devices SW1 to which the terminal devices 300 are connected, and a plurality of to which the first communication devices SW1 are connected. And a second communication device SW2. Hereinafter, the first communication device is also referred to as “leaf”, and the second communication device is also referred to as “node”. In this embodiment, the network 10 includes a stacked communication system 100 in which each of a plurality of nodes SW2 connected in a ring shape is connected to a leaf SW1. Each terminal 300 in the network 10 is connected to a communication device, and each communication device is connected by, for example, a UTP cable, an STP cable, an optical fiber, or the like.

  The terminal device 300 is an information processing device used by a user, and is configured by, for example, a personal computer (PC). The leaf SW1 and the node SW2 are devices that transfer packets in the network 10. At least one leaf SW1 in the network 10 is, for example, a communication device that does not include a MAC address table or has fewer MAC address entries than the node SW2 that can be stored in the MAC address table. That is, the accommodation condition of at least one leaf SW1 in the network 10 is lower than the accommodation condition of the node SW2.

The leaf SW1 and the node SW2 function as a communication device that transfers a layer 2 (L2) packet that is a second layer (data link layer) packet in the OSI reference model. The layer 2 packet is also called an Ethernet (registered trademark) frame. The leaf SW1 and the node SW2 can also function as a communication device that transfers a layer 3 (L3) packet that is a third layer (network layer) packet in the OSI reference model. Therefore, the communication system 100 to which the leaf SW1 and the node SW2 are connected can function as one virtual communication device that transfers layer 2 packets or one virtual communication device that transfers layer 3 packets. Is possible.

  FIG. 2 is a diagram showing a schematic configuration of the leaf SW 11 and the node SW 21 using a part of the network 15 of the network 10 shown in FIG. The leaf SW 11 transfers a packet with a plurality of first ports (1a, 1b, 1c, 1d, etc.) to which cables for connecting to a plurality of terminal devices including the terminals 301, 302, and 303 and the node SW21 are connected. And a first control unit 110 for controlling the above. The leaf SW11 has a MAC address “MAC1”, and the node SW21 has a MAC address “MAC2”. The terminal 301 has a MAC address “MAC3”, the terminal 302 has a MAC address “MAC4”, and the terminal 303 has a MAC address “MAC5”. Hereinafter, the configuration of the leaf SW 11 and the node SW 21 will be described using an example in which a packet is transferred with the terminal 301 as a transmission source terminal and the terminal 302 as a destination terminal. However, each terminal also transmits as a destination terminal. It can also function as the original terminal.

  The first port included in the leaf SW11 includes a port 1a connected to the terminal 301, a port 1b connected to the terminal 302, a port 1c connected to the terminal 303, a port 1d connected to the node SW21, And a plurality of ports (not shown).

  The first control unit 110 includes a first transfer control unit 115. The first transfer control unit 115 is configured by, for example, an ASIC (Application Specific Integrated Circuit). The first transfer control unit 115 adds identification information (hereinafter referred to as reception port information) of the port (hereinafter referred to as reception port) that has received the packet to the packet (hereinafter also referred to as original packet) received from the terminal 301. Then, the data is transferred to the node SW21 through the port 1d. Hereinafter, adding information to an original packet is also referred to as “encapsulation”, and a packet to which information is added is also referred to as “encapsulated packet”. Further, the first transfer control unit 115 receives the packet encapsulated by the node SW21, and sets a plurality of first ports for transmitting the packet based on the transmission port information included in the encapsulated packet. Specify from among the ports.

  The node SW21 includes a plurality of second ports (2a, 2b, 2c, 2d, etc.) to which a cable for connecting to a plurality of terminal devices, other nodes and leaf SW11 (not shown), and the second control unit 210 are connected. And a storage unit 220.

  The second control unit 210 includes a learning unit 211, a transmission port specifying unit 213, and a second transfer control unit 215. The learning unit 211, the transmission port specifying unit 213, and the second transfer control unit 215 are configured by an ASIC, for example.

  The second transfer control unit 215 extracts information on the address of the terminal 302 that is the destination of the original packet included in the encapsulated packet received from the leaf SW 11 from the encapsulated packet. Hereinafter, taking out the information added to the original packet from the encapsulated packet is also referred to as “decapsulation”. The extracted information is used for learning by the learning unit 211 described later and for specifying a transmission port by the transmission port specifying unit 213. Further, the second transfer control unit 215 adds the transmission port information specified by the transmission port specifying unit 213 described later to the original packet and encapsulates it. The second transfer control unit 215 transfers the encapsulated packet to the leaf SW11 via the second port 2d connected to the leaf SW11.

  The transmission port identification unit 213 identifies, from the address table 221, the first port (port connected to the terminal 302) 1 b for the leaf SW 11 to transmit the original packet. Details of the address table 221 will be described later.

  The storage unit 220 includes an address table 221 and other access control lists and VLAN tables used for packet transfer processing (not shown). The storage unit 220 corresponds to the first storage unit of the present invention. The access control list and VLAN table will be described later.

  The learning unit 211 learns the correspondence between the reception port information added to the original packet received from the leaf SW 11 via the second port 2d and the terminal 301 that is the source of the original packet, and the address table 221 To record.

  FIG. 3 is a diagram illustrating an example of the address table 221 recorded by the learning unit. The address table 221 stores a MAC address, port information of a leaf to which a terminal or a communication apparatus having the MAC address is connected, and port information of a node to which the leaf is connected. The port information is port identification information included in each communication device, and is used as the above-described reception port information and transmission port information. In the address table 221 shown in FIG. 3, for example, MAC4 that is the MAC address of the terminal 302, 1b that is port information of the leaf SW11 connected to the terminal 302, and the port of the node SW21 that is connected to the leaf SW11 Information 2d is stored in association with each other. The address table 221 corresponds to the first address table of the present invention.

  FIG. 4 is a flowchart of packet transfer processing that is repeatedly executed in the communication system 100. The packet transfer process is a process in which the leaf SW 11 and the node SW 21 relay communication between terminal devices connected to respective ports. In FIG. 4, the process executed by the leaf SW 11 is shown separately on the left side of the broken line, and the process executed by the node SW 21 is shown separately on the right side of the broken line. Hereinafter, a case where a packet is transferred from the terminal 301 to the terminal 302 will be described using the network 15 shown in FIGS. 1 and 2 as an example.

  When the packet transfer process is started, the leaf SW 11 receives the original packet from the terminal 301 (step S10). When the original packet 410 is received, the first transfer control unit 115 included in the leaf SW 11 encapsulates the original packet 410 based on the received port information (step S14).

  FIG. 5 shows the data structure of the original packet and the encapsulated packet. As shown in FIG. 5A, the source packet received from the terminal 301 includes a destination MAC address 401 that is the MAC address of the destination terminal, and a source MAC address 402 that is the MAC address of the terminal serving as the transmission source. , And a payload check 403 and an FCS (Frame Check Sequence) 404. When the packet is transferred from the terminal 301 to the terminal 302 illustrated in FIG. 2, the MAC address corresponding to the destination MAC address 401 is “MAC4”, and the MAC address corresponding to the transmission source MAC address 402 is “MAC3”.

As shown in FIG. 5B, the encapsulated packet 420 is unique to the original packet 410, indicating that the received port information 406 is communication between the leaf SW11 and the node SW21. Type 405 is added. In this embodiment, the reception port information 406 added to the original packet 410 is the port information “1a” of the first port to which the terminal 301 that is the transmission source is connected. The destination MAC address 411 of the encapsulated packet 420 is “MAC2” that is the MAC address of the node SW21, and the source MAC address 412 is “MAC1” that is the MAC address of the leaf SW11.

  When the original packet 410 is encapsulated, the first transfer control unit 115 transmits the encapsulated packet 420 to the node SW21 via the port 1d connected to the node SW21 (step S15).

  When the node SW21 receives a packet from the leaf SW11 via the second port 2d connected to the first port 1d (step S21), the second transfer control unit 215 included in the second control unit 210 receives the packet. It is determined whether the received packet is an encapsulated packet (step S22).

  When the received packet is an encapsulated packet (step S22: Yes), the second transfer control unit 215 extracts the reception port information 406 from the encapsulated packet 420 by decapsulation (step S23). In this embodiment, the reception port information 406 extracted from the encapsulated packet 420 is “1a”.

  When the reception port information 406 is extracted, the learning unit 211 included in the second control unit 210 of the node SW21 executes a learning process (step S24). The learning process is a process in which the learning unit 211 stores, in the address table 221, a combination of a MAC address and port information that is not stored in the address table 221. Specifically, when the combination of the source MAC address 402, the reception port information 406 of the leaf SW11 obtained by decapsulation, and the port information of the node SW21 that received the packet is not stored in the address table 221. The combination is stored in the address table 221. When the packet received from a communication device or terminal (not shown) connected to any of the second ports by the node SW21 is not the encapsulated packet 420 (step S22: No), that is, when the original packet is received from the terminal device The learning unit 211 performs the learning process in the same manner. However, in this case, since the node SW 21 directly receives the original packet from the terminal, the leaf port information is not stored in the address table 221.

  FIG. 6 is a diagram illustrating an example of the address table 221 after learning. As shown in FIG. 6, the address table 221 includes the MAC address “MAC3” of the terminal 301 and the received port information acquired by decapsulation by the learning process in step S24 (for the port to which the terminal 301 is connected). Port information) “1a” and the correspondence between the port information “2d” of the node SW 21 that received the packet are newly stored. When the association is stored, or when the association is already stored, the learning unit 211 ends the learning process and proceeds to the next step.

  When the learning process is completed, the transmission port specifying unit 213 included in the node SW21 determines whether or not the destination MAC address 401 of the decapsulated original packet 410 corresponds to the leaf SW11 (step S25). “Destination MAC address 401 corresponds to leaf SW11” means that port information corresponding to destination MAC address 401 is stored in address table 221 or that destination MAC address 401 is a multicast address or a broadcast address. Say. Multicast refers to copying and distributing packets having the same contents to a plurality of destinations registered in advance. Broadcast refers to copying and distributing packets of the same content to all terminals, nodes, and leaves on a network. That is, if the destination MAC address 401 corresponds to the leaf SW 11, the original packet 410 can be transferred using any one of the plurality of first ports included in the leaf SW 11.

  If the destination MAC address 401 does not correspond to the leaf SW11 (step S25: No), the node SW21 transfers the packet by a general switching process (step S26). The general switching process is an operation for acquiring an association between a MAC address that has not been acquired and port information by an ARP (Address Resolution Protocol) process, or an original packet to another node or terminal connected to the node SW21. 410 is transferred.

  When the destination MAC address 401 corresponds to the leaf SW 11 (step S25: Yes), the transmission port specifying unit 213 determines that the original packet 410 is a broadcast packet based on the destination MAC address 401 or the destination IP address of the original packet 410. Or it is judged whether it is a multicast packet (step S27).

  When the original packet 410 is not a broadcast packet or a multicast packet (step S27: No), the transmission port specifying unit 213 specifies port information corresponding to the destination MAC address 401 from the address table 221. When the port information corresponding to the destination MAC address 401 is specified, the second transfer control unit 215 performs the encapsulation by adding the transmission port information 407 to the original packet 410, and encapsulates the packet 430 (see FIG. 5 (c)) is transferred (step S29). In this embodiment, the destination MAC address 401 is “MAC4” which is the MAC address of the terminal 302, and the transmission port information 407 added to the original packet is the port information “MAC4” corresponding to the MAC address “MAC4” of the terminal 302. 1b ". The destination MAC address 413 of the encapsulated packet 430 is “MAC1” which is the MAC address of the leaf SW11, and the source MAC address 414 is “MAC2” which is the MAC address of the node SW21.

  When the original packet 410 is a broadcast packet or a multicast packet (step S27: Yes), the second transfer control unit 215 adds a port bitmap information (PBM information) 408 to the original packet 410 to create a new capsule. Packet 440 (see FIG. 5D) is created and transferred to the leaf SW 11 via the second port 2d (step S28).

  FIG. 7 is a diagram illustrating an example of the port bitmap information 408. The port bitmap information 408 is information including a bit string for indicating which port is used to transfer a packet from among a plurality of first ports included in the leaf SW 11. FIG. 7A shows an example of the port bitmap information 408 when the original packet 410 is a multicast packet. For example, in this embodiment, among the four ports 1a, 1b, 1c, and 1d included in the leaf SW 11, when a packet is transferred from the ports 1b and 1c, the bit in the column corresponding to the ports 1b and 1c is represented as 1. . When the original packet 410 is a broadcast packet, the port bit map information 408 indicates that the bit of the column corresponding to the ports 1a, 1b, and 1c included in the leaf SW11 is 1, as shown in FIG. Port bitmap information 408 shown in FIG. 7B represents that the original packet 410 is transferred from a port other than the port 1d connected to the node SW21 among the four ports included in the leaf SW11.

  When the leaf SW11 receives the encapsulated packet 430 or 440 transferred via the second port 2d included in the node SW21 (step S30), the first transfer control included in the leaf SW11. The unit 115 decapsulates the encapsulated packet 430 or 440 and takes out the transmission port information 407 or the port bitmap information 408 (step S31).

  When the encapsulated packet 430 or 440 is decapsulated and the transmission port information 407 or the port bitmap information 408 is taken out, the first transfer control unit 115 outputs the first port corresponding to the transmission port information 407 or the port bitmap information 408. The original packet 410 is transferred from the port to the destination terminal (step S32). Specifically, when the transmission port information 407 is “1b” and the destination MAC address 401 is “MAC4”, which is the MAC address of the terminal 302, the first transfer control unit 115 sets the first port The original packet 410 is transferred from the inside to the terminal 302 via the port 1b. When the port bitmap information 408 is added, as shown in FIGS. 7A and 7B, the original packet 410 is transmitted from the first port corresponding to the bit to which 1 is attached. Forward.

  In the communication system 100 as described above, even when the leaf SW 11 has lower accommodation conditions than the node SW 21 and cannot store the MAC address or the like, the node SW 21 learns and transmits the packet received by the leaf SW 11. Can be specified. Therefore, the communication system 100 including the leaf SW 11 can be constructed as one virtual communication device, and packet transfer processing can be performed collectively. Therefore, according to the present embodiment, even when there is a communication device having inferior accommodation conditions, it is possible to effectively use the communication device to collectively manage a wide range of networks and perform packet transfer processing. it can.

B. Second embodiment:
In the packet transfer process of the first embodiment described above, the leaf SW 11 does not perform the learning process, and the transmission port is specified on the node SW 21 side. On the other hand, in the present embodiment, the leaf SW 11b specifies a transmission port based on the address table 121 provided in the leaf SW 11b, and performs part of the packet transfer based on its own judgment, like the node SW21.

  FIG. 8 is a diagram illustrating a schematic configuration of the leaf SW 11b and the node SW21 when the leaf SW 11b includes the learning unit 111, the transmission port specifying unit 113, the storage unit 120, and the address table 121 included in the storage unit 120 in the same manner as the node SW21. It is. In the present embodiment, the accommodation condition of the leaf SW11b is lower than that of the node SW21. In other words, the storage capability of the address table 121 included in the leaf SW 11b (the number of MAC address entries that can be stored in the MAC address table) is inferior to the storage capability of the address table 221b included in the node SW21.

  FIG. 9 is a diagram illustrating an example of the address table 121 included in the storage unit 120 included in the leaf SW 11b. As shown in FIG. 9, in the address table 121, the MAC address and the port information of the leaf SW 11b to which the terminal having the MAC address is connected are stored in association with each other. The storage unit 120 corresponds to the second storage unit of the present invention, and the address table 121 corresponds to the second address table of the present invention.

  FIG. 10 is a flowchart of packet transfer processing in the second embodiment. In FIG. 10, the processing executed by the leaf SW 11b is shown separately on the left side of the broken line, and the processing executed by the node SW 21 is shown separately on the right side of the broken line. Hereinafter, a case where a packet is transferred from the terminal 301 connected to the leaf SW 11b illustrated in FIG. 8 to the terminal 302 will be described. In FIG. 10, the same step numbers are assigned to the same processing contents as the processing shown in FIG.

  When the packet transfer process is started, the leaf SW 11b illustrated in FIG. 8 receives the original packet 410 from the terminal 301 (step S10).

  When the leaf SW 11b receives the original packet 410 from the terminal 301, the learning unit 111 included in the first control unit 110 included in the leaf SW 11b performs a learning process (step S12). The learning process performed in the learning unit 111 included in the first control unit 110 is the same as the learning process performed in the learning unit 211 included in the second control unit 210 included in the node SW21 (the learning process performed in step S23). It is processing. However, the port information of the node SW 21 is not stored in the address table 121.

  When the learning process ends, the transmission port specifying unit 113 of the leaf SW 11b determines whether or not the destination MAC address 401 is a learned destination (step S13). The “learned destination” refers to a destination MAC address 401 in which correspondence with port information is stored in the address table 121.

When the port information corresponding to the destination MAC address 401 is stored in the address table 121 (step S13: Yes), the transmission port specifying unit 113 stores the MAC address “MAC4 of the destination terminal 302 from the address table 121. Port information “1b” corresponding to “” is specified. The first transfer control unit 115 transfers the original packet 410 to the destination from the specified port (step S32). That is, the first transfer control unit 115 has the same function as the function of the second transfer control unit 215 included in the node SW21 in the first embodiment described above.

  In step S13, when the destination MAC address 401 is not a learned destination (step S13: No), the transmission port specifying unit 113 sets the transmission port for sending the original packet from the plurality of first ports to the leaf SW 11b. It cannot be specified based on the address table 121 provided. Therefore, the first transfer control unit 115 adds the reception port information 406 to the original packet 410 and a unique ether type 405 indicating that this packet is communication between the leaf SW 11b and the node SW 21 to encapsulate the original packet 410. (Step S14), and transfers the encapsulated packet 420 to the node SW21 via the first port 1d (step S15). Thereafter, processing similar to the packet transfer processing in the flowchart shown in FIG. 4 (processing from step S21 to step S32) is executed, and the original packet 410 is transferred to the destination terminal 302.

  Note that, in the above-described step S13, even when the destination is a learned destination, the first transfer control unit 115 can encapsulate the received original packet 410 with the reception port information and transfer it to the node. By doing so, the correspondence between the MAC address and the port information can be stored in the address table 221b of the node SW21. Further, the leaf SW 11b may be in a form that does not include the learning unit 111. That is, the leaf SW 11b does not execute the learning process, and executes step S13 based on the address table 121 recorded in advance or the address table 121 acquired from the node SW 21 at a predetermined timing such as at the time of activation or every time of learning. It may be in the form of

  In the communication system as described above, even when the leaf SW 11b has the address table 121 having a MAC address storage capability lower than that of the node SW21, the node SW21 learns about the packet received by the leaf SW11b and the transmission port. Can take on a specific part. Therefore, it is possible to construct a communication system including the leaf SW 11b and perform packet transfer processing as one virtual communication device. In addition, by using a communication device with inferior accommodation conditions, it is possible to perform part of the learning and transmission port specification that the node SW 21 performed in the first embodiment. Therefore, the burden on the node SW21 is reduced, and the storage capability such as the MAC address table of the leaf SW 11b can be incorporated in the communication system, and the accommodation conditions can be improved as the entire communication system.

C. Third embodiment:
In the first and second embodiments, a communication device (leaf) is connected to each node in only one stage. In contrast, in the third embodiment, communication devices are connected to each node in multiple stages, that is, in cascade. FIG. 11 is a diagram illustrating a configuration of the network 14 using the communication system 101 connected in a cascade manner. The network 14 includes a plurality of terminal devices 300, a plurality of leaf SW1 to which the terminal device 300 is connected, a plurality of third communication devices SW3 to which the leaf SW1 is connected, and a third communication device SW3. And a plurality of nodes SW2. Similar to the network 10 described above, the network 14 constitutes a stacked communication system 101 in which the node SW2 is connected to the third communication device SW3 and the leaf SW1. This is a communication device that integrally combines the functions of the node SW2 and the leaf SW1 (details will be described later). Hereinafter, the third communication device SW3 is also referred to as a node leaf SW3.

  The leaf SW1, the node leaf SW3, and the node SW2 function as communication devices that transfer layer 2 packets in the same manner as in the first embodiment described above. Further, the leaf SW1, the node / leaf SW3, and the node SW2 can also function as a communication device that transfers layer 3 packets. Accordingly, the stack communication system 101 can function as one virtual communication device that transfers layer 2 packets or one virtual communication device that transfers layer 3 packets.

  FIG. 12 is a diagram showing a schematic configuration of the leaf SW11, the node / leaf SW31, and the node SW21 in the communication system 101 connected in cascade using the network 16 which is a part of the network 14 shown in FIG. . The configuration of the leaf SW11 is the same as that of the leaf SW11 in the first embodiment described above. The configuration of the node SW21 is the same as that of the node SW21 in the first embodiment described above, except for the address table 221c included in the node SW21. The address table 221c included in the node SW21 will be described later.

  The node / leaf SW31 includes a plurality of third ports (3a, 3b, 3c, 3d, etc.) to which a plurality of terminal devices and other communication devices (not shown) and cables for connecting to the leaf SW11 and the node SW21 are connected. And a third control unit 310 and a storage unit 320.

  The third control unit 310 includes a learning unit 311, a transmission port specifying unit 313, and a third transfer control unit 315. The learning unit 311, the transmission port specifying unit 313, and the third transfer control unit 315 are configured by, for example, an ASIC.

  The learning unit 311 learns and stores the correspondence between the reception port information 406 added to the original packet 410 received from the leaf SW 11 via the third port 3d and the terminal 301 that is the transmission source of the original packet 410. The data is recorded in the address table 321 stored in the unit 320.

  FIG. 13 is a diagram showing an example of the address table 321 included in the node / leaf SW 31. The address table 321 stores a MAC address, port information of a leaf to which the MAC address is connected, and port information of a node / leaf to which the leaf is connected in association with each other.

  The transmission port identifying unit 313 decapsulates the received encapsulated packet 420 and identifies the first port for transmitting a packet corresponding to the address of the terminal 302 from the address table 321.

  The third transfer control unit 315 adds the specified transmission port information to the original packet 410 to create an encapsulated packet 430, and transfers the packet to the leaf SW11 via the third port 3d connected to the leaf SW11. . In addition, when the third transfer control unit 315 receives the encapsulated packet 420 to which the reception port information is added from the leaf SW 11, the third transfer control unit 315 confirms that this packet is communication between the node / leaf SW 31 and the node SW 21. It is also possible to transfer the data to the node SW21 via the third port 3a which is encapsulated by adding the unique ether type 405 shown and connected to the node SW21.

  FIG. 14 is a diagram illustrating an example of the address table 221c included in the node SW21 illustrated in FIG. The address table 221c includes the MAC address, the port information of the leaf to which the MAC address is connected, the port information of the node and leaf to which the leaf is connected, and the port information of the node to which the node leaf is connected. Are stored in association with each other. Therefore, in this embodiment, the transmission port specifying unit 213 provided in the node SW 21 specifies the port for transmitting the original packet based on the address table 221 from among the plurality of ports provided in the node leaf SW 31 and the leaf SW 11. can do.

  In the communication system 101 of the present embodiment, the node SW21, the node leaf SW31, and the leaf SW11 are connected in this way, and thus the node leaf SW31 that integrally combines the functions of the node SW21 and the leaf SW11. However, a part of the transfer processing performed by the node SW21 can be performed. In addition, since a communication system connected in multiple stages in a cascade type can be constructed, a wider range of network 14 and packet transfer processing can be performed.

D. Fourth embodiment:
In the first to third embodiments, each leaf is connected to one node. On the other hand, in the fourth embodiment, the communication path is made redundant by connecting each leaf to two or more nodes. FIG. 15 is a diagram showing a network in which a plurality of nodes SW2 are connected in a ring shape. In the network shown in FIG. 15, a leaf SW1 is connected to a plurality of nodes SW2 by link aggregation in order to increase the bandwidth and make a redundant communication. Each node SW2 shown in FIG. 15 is assigned a node number (node number: 1, 2, 3, 4, etc.) that is a number for identifying the other node SW2. A plurality of leaves SW1 are connected to each node SW2, and leaf numbers (leaf numbers: 1, 2, 3, 4, etc.), which are numbers for distinguishing from other leaf SW1, are attached. Hereinafter, the node SW2 with the node number “1” is referred to as “node (1)”, and the leaf SW1 with the leaf number “1” is referred to as “leaf (1)”. In the network shown in FIG. 15, when each node SW2 receives a packet, if the packet is not a packet corresponding to the own device, the node SW2 connected to the own device has a node number larger than that of the own device. Transfer the packet to SW2. For example, when the node (2) receives the packet, the node (2) transfers the packet to the node (3). Hereinafter, the packet transferred in the ring is also referred to as “in-ring packet”.

  FIG. 16 is a diagram showing a state in which a communication failure has occurred in the ring network shown in FIG. As shown in FIG. 16, when a communication failure occurs between two nodes SW2 connected in a ring network, it has a transmission source port connected to the communication path in which the failure has occurred. The node SW2 notifies the “failure occurrence information”, which is information of the connection location where the failure has occurred, to the other nodes SW2 and leaf SW1 connected to the node SW2 by the second transfer control unit 215. To do. For example, when the link connection between the node SW2 and the node SW2 connected to the back (the node SW2 connected to the back of the node (2) indicates the node (3) in this embodiment) is disconnected. It can be determined that a failure has occurred.

  FIG. 17 is a flowchart showing the transfer process of the intra-ring packet. In the network notified of the “failure occurrence information” shown in FIG. 16, the node SW2 having the transmission source port connected to the communication path in which the failure has occurred is the leaf SW1 connected to the own device or the other The packet is received from the node SW2 (step S110).

When the node SW2 receives a packet from the leaf SW1 or another node SW2, the node SW2 that has received the packet determines whether or not the packet is a packet received from the leaf SW1 (step S115).

  When the node SW2 receives a packet from the leaf SW1 (step S115: Yes), the node SW2 determines whether there is one leaf SW1 that can be a detour path (step S120). The leaf SW1 that can be a detour path is a leaf SW1 that is also connected to a node SW2 other than the node SW2 that has received the packet among the plurality of leaf SW1 that are connected to the node SW2 that has received the packet. For example, when the node (2) shown in FIG. 16 receives a packet from the leaf (2), the leaf SW1 that can be a detour route is the leaf (1), the leaf (2), the leaf (3), and the leaf (4). There are four.

  When there are two or more leaf SW1 that can be a detour path (step S120: No), the node SW2 is a leaf that is a transmission source when a packet is received in step S110 among two or more leaf SW1 that can be a detour path. It is determined whether or not there is a leaf SW1 having a larger leaf number than SW1 (step S130). For example, when the node (2) receives a packet from the leaf (2), the leaf (1), the leaf (2), the leaf (3), and the leaf (4), which can be a detour path, than the leaf (2) Leafs SW1 having large leaf numbers are leaf (3) and leaf (4).

  If there is a leaf SW1 having a leaf number larger than the leaf SW1 that is the transmission source among the two or more leaf SW1 that can be a detour path (step S130: Yes), the leaf SW1 is the node (2 It is determined whether or not it is connected to the node SW2 with a larger node number (step S150). When there are a plurality of “leaf SW1 having a leaf number larger than the leaf SW1 as the transmission source”, the leaf SW1 to which the smallest leaf number is attached is assigned a node number larger than that of the node (2). It is determined whether or not it is connected to the node SW2. Therefore, when the node (2) receives a packet from the leaf (2), the “leaf SW1 having a leaf number larger than the leaf SW1 as the transmission source” is the leaf (3).

  When there is no leaf SW1 having a leaf number larger than that of the leaf SW1 that is the transmission source (step S130: No), or when the node SW2 receives a packet from the node SW2 immediately before the own device (step S115). : No) The node SW2 selects the leaf SW1 with the smallest leaf number from the leaf SW1 that can be a detour path (step S140), and the selected leaf SW1 has a node number larger than the node SW2. It is determined whether or not the node SW2 is connected (step S150). When the node (2) receives a packet from the leaf (2) or the node (1), the leaf (3) is connected to the node (3) with a node number higher than that of the node (2). In step S150, “Yes” is determined.

  When the leaf SW1 selected in step S130 and step S140 is not connected to the node SW2 assigned a node number larger than the node SW2 (step S150: No), the node SW2 is the leaf number of the selected leaf SW1. The leaf having the next largest leaf number is selected (step S160), and the process of step S150 is executed again.

  When the leaf SW1 selected in step S130 and step S140 is connected to the node SW2 assigned with a node number larger than that of the node (2) (step S150: Yes), or one leaf can be a detour route. If there is (step S120: Yes), the node SW2 transfers the packet to the selected leaf SW1 (step S170). According to such processing, even when the node SW2 receives a packet when a failure occurs, the packet transfer is executed without being stopped.

  FIG. 18 is a flowchart showing the intra-ring packet transfer process executed by the leaf SW 1 that has received the failure occurrence information. In the network shown in FIG. 16, the leaf SW1 receives a packet from the node SW2 that is the transmission source of the failure occurrence information (step S210).

  When the leaf SW1 receives a packet from the node SW2 that is the transmission source of the failure occurrence information, the leaf SW1 has a node SW2 that has a larger node number than the node SW2 that is the transmission source when receiving the packet in step S210. Is determined (step S230). For example, when leaf (3) receives a packet from node (2), node (3) with a larger node number than node (2) that is the packet transmission source is connected to leaf (3). Therefore, “Yes” is determined in step S230.

  When there is no node SW2 having a larger node number than the node SW2 that is the transmission source when the packet is received in step S210 (step S230: No), the leaf SW1 is assigned the smallest node number among the connected nodes SW2. The selected node SW2 is selected (step S240).

  When node SW2 is selected in step S230 and step S240, leaf SW1 transfers the packet to the selected node SW2 (step S270).

  According to the fourth embodiment described above, a network in which one leaf SW1 is connected to a plurality of nodes SW2 is constructed using a communication system, so that even when a failure occurs, the leaf SW1 passes through the leaf SW1. The packet can be transferred between the nodes SW2. Therefore, the availability of the communication system can be increased.

E. Example 5:
The node SW 21 can also include an access control list 223 in the storage unit 220. FIG. 19 is a diagram illustrating an example of the access control list 223 included in the node SW21. The node SW 21 can perform packet transfer processing in the network based on the access control list 223 in each of the embodiments described above.

  In addition, the node SW 21 may include a VLAN (Virtual Local Area Network) table in the storage unit 220. In the VLAN table, group information for dividing a plurality of terminals and communication devices on the network into virtual groups is defined. In each of the embodiments described above, the node SW 21 can perform packet transfer processing in the network based on the group information in the VLAN table.

  When the node SW21 includes an access control list and a VLAN table, as shown in FIGS. 8 and 12, when the leaf SW11b and the node / leaf SW31 include a storage unit, the node SW21 moves to the leaf SW11b and the node / leaf SW31. Information related to the terminals connected to the leaf SW 11b and the node / leaf SW 31 from the access control list and the VLAN table is transmitted at a predetermined timing such as at the time of activation or every learning. The leaf SW 11b and the node leaf SW 31 shown in FIG. 8 and FIG. 12 record the related information in an access control list and a VLAN table provided in the own device, and transfer packets in the network based on the access control list and the VLAN table. Processing can be performed.

F. Variations:
Although various embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various configurations can be adopted without departing from the spirit of the present invention. For example, a function realized by hardware may be realized by software, and vice versa. In addition, the following modifications are possible.

  In the above-described embodiments, the communication device and the communication system including the communication device may be a switch and a switch system including the switch, respectively.

  As the ports provided in each communication device, a dedicated port for stack connection may be prepared. Also, by entering a configuration command that instructs each communication device to use a given port for stack connection, specify one of the ports to use as a stack connection port. Is also possible.

  In the embodiment described above, the terminal 300 is an example of a personal computer. However, the terminal 300 is not limited thereto, and various electronic devices having an Ethernet port can be used. As such an electronic device, for example, a personal computer peripheral device, an AV device, a telephone, various home appliances (for example, a television, a Blu-ray player, etc.) can be used. The terminal 300 may be configured to have a router function and be connectable to an external network.

  The accommodation conditions of each leaf SW1 shown in the network in the embodiment described above may be different. Further, the leaf SW1 may be used in a mixture of a leaf having a learning unit and a leaf not having the learning unit.

1a, 1b, 1c, 1d ... first port 2a, 2b, 2c, 2d ... second port 3a, 3b, 3c, 3d ... third port 10, 14, 15, 16 ... network 100, 101 ... communication System 110 ... first control unit 111 ... learning unit 113 ... transmission port specifying unit 115 ... first transfer control unit 120 ... storage unit 121 ... address table 210 ... second control unit 211 ... learning unit 213 ... transmission port specifying unit 215 ... second transfer control unit 220 ... storage unit 221,221b, 221c ... address table 223 ... access control list 300, 301, 302, 303 ... terminal 310 ... third control unit 311 ... learning unit 313 ... transmission port specifying unit 315 ... Third transfer control unit 320 ... Storage unit 321 ... Address table 401 ... Destination MAC address 402 Source MAC address 403 ... Payload 405 ... Ether type 406 ... Reception port information 407 ... Transmission port information 408 ... Port bitmap information 410 ... Original packet 411 ... Destination MAC address 412 ... Source MAC address 413 ... Destination MAC address 414 ... Transmission Original MAC address 420, 430, 440 ... Encapsulated packet SW11, SW11b ... Leaf SW21 ... Node SW31 ... Node leaf SW1 ... First communication device (leaf)
SW2 ... Second communication device (node)
SW3 ... Third communication device (node / leaf)

Claims (3)

A communication system including a first communication device and a second communication device,
The communication system includes a plurality of the second communication devices connected in a ring shape,
The first communication device is connected to at least two of the plurality of second communication devices,
The first communication device is:
A plurality of first ports for transmitting and receiving packets each including a source terminal address and a destination terminal address;
An original packet with reception port information obtained by adding reception port information for identifying a received port to an original packet that is a layer 2 packet or a layer 3 packet received via any of the plurality of first ports. A first transfer control unit for transferring to a second communication device,
The second communication device is:
A second port for receiving the original packet with the reception port information from the first communication device;
A first storage unit storing a first address table in which at least correspondences between the plurality of first ports and terminals connected to the plurality of first ports are recorded;
Terminals connected to each of the plurality of first ports and the plurality of first ports based on the reception port information included in the received original packet with reception port information and the address of the transmission source terminal A learning unit that learns the correspondence relationship between the first address table and the learning unit;
Based on the address of the destination terminal and the first address table included in the received original packet with the receiving port information, a first packet is transmitted that transmits the original packet transferred from the first communication device. A transmission port specifying unit for specifying a port from among the plurality of first ports;
A second transfer control unit configured to transfer the original packet with transmission port information obtained by adding the specified transmission port information to the original packet to the first communication device;
The first communication device stores a second address table in which a correspondence relationship between the plurality of first ports and addresses of terminals connected to the plurality of first ports is recorded. 2 storage units,
The first transfer control unit of the first communication device is
Receiving the original packet with the transmission port information, transmitting the original packet from the first port corresponding to the transmission port information included in the original packet with the transmission port information ;
When the first port for transmitting the original packet is specified from the plurality of first ports based on the second address table, the original packet is specified as the specified first port. And when the first port for transmitting the original packet cannot be identified from the plurality of first ports, the original packet with reception port information is transferred to the second communication device,
Relaying packets flowing between the at least two second communication devices when it detects that a failure has occurred in the connection between the at least two second communication devices;
The number of correspondence relationships that can be stored in the second storage unit of the first communication device is less than the number of correspondence relationships that can be stored in the first storage unit of the second communication device.
Communications system. The communication system according to claim 1 ,
Comprising at least one third communication device cascade-connected between the first communication device and the second communication device;
The third communication device integrally includes the first communication device and the second communication device.
Communications system. A communication system according to claim 1 or claim 2 , wherein
The second communication device is:
Comprising transmission / reception control information for controlling at least one of transmission and reception of packets concerning a plurality of terminals
The first transfer control unit of the first communication device is
Obtaining at least part of the transmission / reception control information, and controlling at least one of transmission and reception of the original packet based on the part of the information;
Communications system.

Images