Frame transfer device, frame transfer method, and frame transfer program

Abstract

To provide a frame forwarding device, a frame forwarding method, and a frame forwarding program that can suppress the execution of unnecessary flooding processing.SOLUTION: A frame forwarding device includes forwarding means for forwarding a received frame on the basis of an MAC address table that stores entry information that associates a port of the device with the MAC (Media Access Control) address of a node connected to the port, and management means for storing the entry information stored in the MAC address table in a storage unit different from the MAC address table. When the entry information corresponding to the destination MAC address of the received frame is not stored in either the MAC address table or the storage unit, the forwarding means executes flooding processing of the received frame.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present disclosure relates to a frame forwarding device, a frame forwarding method, and a frame forwarding program. [Background technology]

[0002] Patent Document 1 describes a Layer 2 switch that exchanges frames in a frame switching network. The frame exchange unit of the Layer 2 switch described in Patent Document 1 determines the port to output a MAC frame to be forwarded according to a combination of a destination MAC address and an output port stored in a MAC (Media Access Control) table. Furthermore, if a MAC entry related to the destination MAC address of the MAC frame to be forwarded is not stored in the MAC table, the flooding processing unit performs flooding processing of the MAC frame. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-045657 Summary of the Invention [Problem to be solved by the invention]

[0004] Generally, when a frame forwarding device such as a Layer 2 switch is applied to a large-scale network, it is configured to dynamically learn MAC addresses and manage a table (e.g., equivalent to the MAC table described in Patent Document 1). Furthermore, when the frame forwarding device receives a frame addressed to a MAC address that does not exist in the table, it executes a flooding process to forward the received frame to all ports.

[0005] For example, consider a case where a node connected to such a frame forwarding device becomes unable to communicate due to a failure or other reason, but then recovers and becomes able to communicate. In this case, the frame forwarding device detects the link down of the node, deletes the entry from the table, and then detects the link up. However, unless the node voluntarily transmits a frame, the frame forwarding device cannot learn the MAC address of the node. As a result, when the frame forwarding device receives a frame addressed to the MAC address of the node (i.e., an unlearned MAC address), it executes a flooding process even though the node is able to communicate. In other words, unnecessary flooding is executed.

[0006] An object of the present disclosure is to provide a frame forwarding device, a frame forwarding method, and a frame forwarding program that can suppress the execution of unnecessary flooding processes. [Means for solving the problem]

[0007] A frame forwarding device according to the present disclosure includes a forwarding means for forwarding a received frame based on a MAC address table that stores entry information associating a port of the device with a MAC (Media Access Control) address of a node connected to the port, and a management means for storing the entry information stored in the MAC address table in a memory unit different from the MAC address table, and the forwarding means performs flooding processing of the received frame if entry information corresponding to the destination MAC address of the received frame is not stored in either the MAC address table or the memory unit.

[0008] The frame forwarding method disclosed herein forwards a received frame based on a MAC address table that stores entry information that associates a port of the device with the MAC (Media Access Control) address of a node connected to that port, stores the entry information stored in the MAC address table in a memory unit different from the MAC address table, and performs flooding processing on the received frame if entry information corresponding to the destination MAC address of the received frame is not stored in either the MAC address table or the memory unit.

[0009] The frame forwarding program according to the present disclosure causes a computer to perform a forwarding process for forwarding a received frame based on a MAC address table that stores entry information that associates a port of the device with the MAC (Media Access Control) address of a node connected to that port, and a management process for storing the entry information stored in the MAC address table in a storage unit different from the MAC address table, and if, during the forwarding process, entry information corresponding to the destination MAC address of the received frame is not stored in either the MAC address table or the storage unit, the computer performs a flooding process for the received frame. [Effects of the Invention]

[0010] According to the present disclosure, it is possible to suppress the execution of unnecessary flooding processes. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a block diagram illustrating a functional configuration of a frame forwarding device. [Figure 2] 10 is a flowchart illustrating an operation of the frame forwarding device. [Figure 3] 10 is a flowchart illustrating an operation of the frame forwarding device. [Figure 4] 3A and 3B are explanatory diagrams illustrating examples of the configuration of a MAC address table and a registration history table. [Figure 5]3A and 3B are explanatory diagrams illustrating examples of the configuration of a MAC address table and a registration history table. [Figure 6] 3A and 3B are explanatory diagrams illustrating examples of the configuration of a MAC address table and a registration history table. [Figure 7] 3A and 3B are explanatory diagrams illustrating examples of the configuration of a MAC address table and a registration history table. [Figure 8] FIG. 1 is a block diagram illustrating a configuration of a computer. [Figure 9] 1 is a block diagram illustrating a main part of a frame forwarding device. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each drawing, the same or corresponding elements are designated by the same reference numerals, and duplicate explanations will be omitted as necessary for clarity. Unless otherwise specified, predetermined values ​​such as predetermined values ​​and threshold values ​​are stored in advance in a storage device accessible from a device that uses the values. Furthermore, unless otherwise specified, the storage unit is composed of one or any number of storage devices.

[0013] The functional configuration of the frame forwarding device will be described below with reference to Fig. 1. Fig. 1 is a block diagram illustrating the functional configuration of the frame forwarding device.

[0014] The frame forwarding device 100 includes a frame forwarding unit 110 , a table management unit 120 , a link detection unit 130 , a MAC address table 140 , and a registration history table 150 .

[0015] The frame forwarding device 100 is a device that forwards frames over a layer 2 network such as Ethernet (registered trademark). The frame forwarding device 100 is realized by a device that communicates over a layer 2 network, such as a layer 2 switch, a general-purpose server, or a personal computer.

[0016] The frame forwarding unit 110 forwards the received frame based on a MAC address table 140 that stores entry information that associates a port of its own device (i.e., the frame forwarding device 100) with the MAC address of a node connected to that port. Note that the nodes connected to the frame forwarding device 100 may include various devices that communicate over a Layer 2 network, in addition to general-purpose servers and personal computers.

[0017] The frame forwarding unit 110 determines, for example, whether or not entry information corresponding to the destination MAC address of the received frame is stored in the MAC address table 140. If entry information corresponding to the destination MAC address is stored in the MAC address table 140, the frame forwarding unit 110 forwards the received frame to the port associated with the destination MAC address in the entry information.

[0018] If the entry information corresponding to the destination MAC address of the received frame is not stored in the MAC address table 140, the frame forwarding unit 110 determines whether the entry information corresponding to the destination MAC address is stored in the registration history table 150.

[0019] If it is determined that entry information corresponding to the destination MAC address of the received frame is stored in the registration history table 150, the frame forwarding unit 110 determines the link state of the port associated with the destination MAC address in the entry information. If it is determined that the link state of the port is a link up state, the frame forwarding unit 110 forwards the received frame to the port. On the other hand, if it is determined that the link state of the port is a link down state, the frame forwarding unit 110 discards the received frame.

[0020] If it is determined that entry information corresponding to the destination MAC address of the received frame is not stored in the registration history table 150, the frame forwarding unit 110 executes a flooding process to forward the received frame to all ports. That is, if entry information corresponding to the destination MAC address of the received frame is not stored in either the MAC address table 140 or the registration history table 150, the frame forwarding unit 110 executes a flooding process for the received frame.

[0021] The table management unit 120 includes a MAC address table management unit 121 that manages the MAC address table 140 and a registration history table management unit 122 that manages the registration history table 150 .

[0022] The MAC address table 140 stores entry information that associates a port of the device with the MAC address of a node connected to that port.

[0023] When the frame forwarding device 100 receives a frame, the MAC address table management unit 121 performs MAC address learning, which learns the MAC address of the source node and registers it in the MAC address table 140. Specifically, the MAC address table management unit 121 stores entry information that associates the MAC address of the source node with the port to which the source node is connected in the MAC address table 140. Note that if the same entry information is already stored in the MAC address table 140, the MAC address table management unit 121 does not register new entry information.

[0024] The MAC address table management unit 121 deletes entry information stored in the MAC address table 140 when a predetermined condition is met. For example, the MAC address table management unit 121 deletes entry information when a frame with a matching source MAC address is not received within a predetermined period of time (hereinafter also referred to as aging time) since the entry information was registered. Also, for example, the MAC address table management unit 121 deletes entry information when a link-down of a port corresponding to the entry information is detected.

[0025] The registration history table 150 stores the entry information stored in the MAC address table 140. The registration history table 150 also stores link information indicating the link state of a port as entry information (or in addition to the entry information).

[0026] For example, based on the detection of a link down, the registration history table management unit 122 stores entry information corresponding to the port where the link down was detected in the registration history table 150. At this time, the registration history table management unit 122 stores information indicating a link down state as link information for the port in the registration history table 150. Note that if the same entry information is already stored in the registration history table 150, the registration history table management unit 122 does not execute these processes.

[0027] The registration history table management unit 122 stores all entry information stored in the MAC address table 140 at any timing, such as every predetermined period, in the registration history table 150. At this time, the registration history table management unit 122 stores information indicating that each port is in a link-up state in the registration history table 150 as link information for each port.

[0028] Based on the detection of a link-up, the registration history table management unit 122 stores information indicating a link-up state as link information for the port where the link-up was detected in the registration history table 150. Note that if the registration history table 150 does not store entry information corresponding to the port, the registration history table management unit 122 does not execute these processes.

[0029] For example, the registration history table management unit 122 deletes from the registration history table 150 entry information that matches the entry information stored in the MAC address table 140 in either the MAC address or the port but does not match the other entry information. For example, the registration history table management unit 122 may be configured to execute such processing at predetermined intervals.

[0030] For example, after entry information is stored in the MAC address table 140 by MAC address learning, the registration history table management unit 122 deletes from the registration history table 150 entry information whose MAC address matches the entry information.

[0031] For example, after entry information is stored in the MAC address table 140 by MAC address learning, the registration history table management unit 122 deletes from the registration history table 150 entry information whose port matches the entry information.

[0032] The link detection unit 130 detects the link state of each port. For example, the link detection unit 130 detects that the link state of a port has changed from a link up state to a link down state. Also, for example, the link detection unit 130 detects that the link state of a port has changed from a link down state to a link up state. The link detection unit 130 determines the link state by, for example, monitoring the continuity state of Ethernet (registered trademark) link pulses.

[0033] Next, a description will be given of the operation of the frame forwarding device 100. Figures 2 and 3 are flowcharts illustrating the operation of the frame forwarding device.

[0034] 2 shows an example of processing executed to manage the registration history table. The link detection unit 130 determines whether a link down has been detected (step S101). When a link down is detected, the registration history table management unit 122 stores entry information corresponding to the port in which the link down has been detected in the registration history table 150 (step S102). At this time, the registration history table management unit 122 stores information indicating a link down state as link information for the port in which the link down has been detected in the registration history table 150.

[0035] The link detection unit 130 determines whether a link-up has been detected (step S103). When a link-up is detected, the registration history table management unit 122 updates the entry information in the registration history table 150 corresponding to the port in which the link-up has been detected (step S104). Specifically, the registration history table management unit 122 updates the link information of the port in which the link-up has been detected to a link-up state.

[0036] When the frame forwarding device 100 receives a frame, the MAC address table management unit 121 performs MAC address learning. When MAC address learning is performed (Y in step S105), the registration history table management unit 122 deletes from the registration history table any entry information whose MAC address matches the entry information added to the MAC address table (step S106). In addition, the registration history table management unit 122 deletes from the registration history table any entry information whose port matches the entry information added to the MAC address table (step S107).

[0037] 2 does not limit the operation of the frame forwarding device 100 of the present disclosure. For example, the processing of steps S1 to S2, the processing of steps S3 to S4, and the processing of steps S5 to S7 may be executed in the reverse order or in parallel.

[0038] Further, for example, instead of or in addition to the processing of steps S1 to S2, a process may be executed in which all entry information stored in the MAC address table 140 is stored in the registration history table 150 at any timing, such as every predetermined period.

[0039] Furthermore, for example, instead of or in addition to the processing of steps S5 to S7, the following processing may be executed. For example, the registration history table management unit 122 determines whether or not there is any entry information stored in the registration history table 150 that matches the entry information stored in the MAC address table 140 in either the MAC address or the port, but not in the other. Then, the registration history table management unit 122 deletes the corresponding entry information from the registration history table 150. The registration history table management unit 122 executes this processing at predetermined intervals.

[0040] 3 shows an example of processing executed when a frame is received. The frame forwarding unit 110 of the frame forwarding device 100 receives a frame from a source node (step S201).

[0041] Next, the frame forwarding unit 110 determines whether or not entry information corresponding to the destination MAC address of the received frame is stored in the MAC address table 140 (step S202).

[0042] If the entry information corresponding to the destination MAC address is stored in the MAC address table 140, the frame forwarding unit 110 forwards the received frame to the port associated with the destination MAC address in the entry information (step S203).

[0043] If the entry information corresponding to the destination MAC address is not stored in the MAC address table 140, the frame forwarding unit 110 determines whether the entry information corresponding to the destination MAC address is stored in the registration history table 150 (step S204).

[0044] If it is determined that the entry information corresponding to the destination MAC address is stored in the registration history table 150, the frame forwarding unit 110 determines the link state of the port associated with the destination MAC address in the entry information (step S205).

[0045] If it is determined that the link state of the port is a link up state, the frame forwarding unit 110 forwards the received frame to the port (step S206). On the other hand, if it is determined that the link state of the port is a link down state, the frame forwarding unit 110 discards the received frame (step S207).

[0046] If it is determined that the entry information corresponding to the destination MAC address is not stored in the registration history table 150, the frame forwarding unit 110 executes a flooding process to forward the received frame to all ports (step S208).

[0047] The frame forwarding device 100 can execute the process shown in Fig. 2 and the process shown in Fig. 3 in parallel. Note that the operation example shown in Fig. 3 does not limit the operation of the frame forwarding device 100 of the present disclosure.

[0048] Next, the configurations of the MAC address table 140 and the registration history table 150 will be described. Figures 4 to 7 are explanatory diagrams illustrating examples of the configurations of the MAC address table and the registration history table. Note that the configuration examples of the MAC address table and the registration history table shown in Figures 4 to 7 do not limit the configuration and operation of the frame forwarding device 100 of the present disclosure.

[0049] The MAC address table 140 shown in Fig. 4 stores entry information that associates MAC addresses with port numbers. Fig. 4 illustrates an example of MAC address table 140 in which first entry information of MAC address: A, port number: 1, second entry information of MAC address: B, port number: 2, and third entry information of MAC address: C, port number: 3 are registered.

[0050] The registration history table 150 shown in FIG. 4 stores entry information that associates a MAC address, a port number, and a link state.

[0051] 4 illustrates an example of a case where link down of port 1 is detected. In this embodiment, based on the detection of link down, the registration history table management unit 122 stores entry information corresponding to port 1 where link down was detected in the registration history table 150. At this time, the registration history table management unit 122 stores information indicating a link down state ("Down" in the example of FIG. 4) as link information for port 1 in the registration history table 150. Therefore, FIG. 4 illustrates an example of the registration history table 150 that stores entry information of MAC address: A, port number: 1, and link information: Down.

[0052] The state of the registration history table 150 shown in FIG. 4 is realized by the frame forwarding device 100 executing the processes of steps S101 to S102 shown in FIG.

[0053] 5 shows a case where port 1 temporarily goes down due to a momentary interruption or the like, and then goes up. In the example shown in FIG. 5, the states transition in the order of (a), (b), and (c).

[0054] Figure 5(a) illustrates a state in which link down of port 1 is detected due to a momentary interruption or the like. The MAC address table 140 and registration history table 150 in Figure 5(a) are the same as the MAC address table 140 and registration history table 150 shown in Figure 4. Therefore, a detailed description of Figure 5(a) will be omitted.

[0055] Figure 5(b) illustrates a state in which a link-up of port 1 is detected after a link-down of port 1 is detected. Note that in the state shown in Figure 5(b), MAC address learning of port 1 has not yet been performed. Therefore, Figure 5(b) illustrates an example of the MAC address table 140 in which the first entry information corresponding to port 1 has been deleted in response to the detection of link-down.

[0056] In this embodiment, when a link-up of port 1 is detected, the registration history table management unit 122 updates the entry information in the registration history table 150 corresponding to port 1. Specifically, the registration history table management unit 122 updates the link information of port 1 to information indicating a link-up state ("UP" in the example of FIG. 5). Therefore, FIG. 5(b) illustrates an example of the registration history table 150 that stores entry information of MAC address: A, port number: 1, and link information: UP.

[0057] The state of the registration history table 150 shown in Fig. 5(b) is realized, for example, by the frame forwarding device 100 executing the processes of steps S103 to S104 shown in Fig. 2. In the state shown in Fig. 5(b), when a frame with destination MAC address: A is received, the frame forwarding unit 110 forwards the frame to port 1 (corresponding to the process of step S206).

[0058] 5(c) illustrates a state in which MAC address learning has been performed for port 1. When the MAC address table management unit 121 receives a frame, it performs MAC address learning, learning the MAC address of the source node and registering it in the MAC address table 140. Therefore, FIG. 5(c) illustrates an example of the MAC address table 140 that stores entry information for MAC address: A, port number: 1.

[0059] Furthermore, in this embodiment, after entry information is stored in the MAC address table 140 by MAC address learning, the registration history table management unit 122 deletes entry information whose MAC address or port matches the entry information from the registration history table 150. Therefore, Fig. 5(c) illustrates an example of the registration history table 150 from which the entry information of MAC address: A, port number: 1, and link information: UP has been deleted.

[0060] Fig. 6 shows a case where the device connection is changed from port 1 to port 4. In the example shown in Fig. 6, the state transitions in the order of (a), (b), and (c).

[0061] Figure 6(a) illustrates a state in which a device (MAC address: A) that was connected to port 1 is removed and a link down of port 1 is detected. The MAC address table 140 and the registration history table 150 in Figure 6(a) are the same as the MAC address table 140 and the registration history table 150 shown in Figure 4. Therefore, a detailed description of Figure 6(a) will be omitted.

[0062] 6(b) illustrates a state in which MAC address learning is performed after a device (MAC address: A) that was connected to port 1 is connected to port 4. Therefore, FIG. 6(b) illustrates a MAC address table 140 that stores entry information for MAC address: A, port number: 4.

[0063] 6(c) illustrates an example of a state in which the registration history table 150 is updated after MAC address learning has been performed. After entry information is stored in the MAC address table 140 through MAC address learning, the registration history table management unit 122 deletes entry information whose MAC address matches the entry information from the registration history table 150. Therefore, FIG. 6(c) illustrates an example of the registration history table 150 from which the entry information of MAC address: A, port number: 1, and link information: Down has been deleted.

[0064] Figure 7 shows a case where a device is replaced and connected to a port. In the example shown in Figure 7, the state transitions in the order of (a), (b), and (c).

[0065] Figure 7(a) illustrates a state in which a device (MAC address: A) that was connected to port 1 is removed and a link down of port 1 is detected. The MAC address table 140 and the registration history table 150 in Figure 7(a) are the same as the MAC address table 140 and the registration history table 150 shown in Figure 4. Therefore, a detailed description of Figure 7(a) will be omitted.

[0066] 7(b) illustrates a state in which MAC address learning is performed after a new device (MAC address: D) is connected to port 1. Therefore, FIG. 7(b) illustrates a MAC address table 140 that stores entry information for MAC address: D, port number: 1.

[0067] In this embodiment, when a link-up is detected, the registration history table management unit 122 stores information indicating a link-up state as link information for the port where the link-up is detected in the registration history table 150. Therefore, Fig. 7(b) shows an example of the registration history table 150 that stores entry information of MAC address: A, port number: 1, and link information: UP.

[0068] 7(c) illustrates an example of a state in which the registration history table 150 has been updated after MAC address learning has been performed. After entry information is stored in the MAC address table 140 through MAC address learning, the registration history table management unit 122 deletes entry information whose port matches the entry information from the registration history table 150. Therefore, FIG. 7(c) illustrates an example of the registration history table 150 from which the entry information of MAC address: A, port number: 1, and link information: UP has been deleted.

[0069] Next, the effects of this embodiment will be described. In this embodiment, if entry information corresponding to the destination MAC address of a received frame is not stored in the MAC address table 140, the frame forwarding unit 110 determines whether the entry information is stored in the registration history table 150. If entry information corresponding to the destination MAC address is stored in the registration history table 150, the frame forwarding unit 110 determines the link state of the port associated with the destination MAC address in the entry information. If the port is in a link-up state, the frame forwarding unit 110 forwards the received frame to the port. If the port is in a link-down state, the frame forwarding unit 110 discards the received frame. Then, if entry information corresponding to the destination MAC address is not stored in either the MAC address table 140 or the registration history table 150, the frame forwarding unit 110 executes flooding processing for the received frame. This configuration makes it possible to suppress unnecessary flooding processing. As a result, congestion in the network can be suppressed.

[0070] The frame forwarding device 100 of this embodiment is applicable to a network that communicates at Layer 2. In particular, the frame forwarding device 100 is suitable for a network in which connected devices do not generally change and devices or cables cannot be easily replaced in the event of a failure. The frame forwarding device 100 can prevent flooding from occurring when a link down occurs in such a network due to a failure of a connected device or a cable break. As a result, the frame forwarding device 100 can reduce the time required for recovery when restoring the link up state.

[0071] The frame forwarding device 100 can be suitably applied to a network to which devices with low communication frequency are connected. In such a network, the frame forwarding device 100 can communicate without causing flooding by forwarding frames based on the entry information stored in the registration history table 150.

[0072] 8 is a block diagram illustrating the configuration of a computer according to the present disclosure. A CPU 1000 executes processing in accordance with a frame forwarding program stored in a storage device 1001, thereby realizing the functions of the frame forwarding device 100 in the above embodiment.

[0073] That is, the CPU 1000 executes processing in accordance with the frame forwarding program stored in the memory device 1001, thereby realizing the functions of the frame forwarding unit 110, table management unit 120 (including the MAC address table management unit 121 and the registration history table management unit 122), and link detection unit 130 of the frame forwarding device 100 shown in FIG. 1.

[0074] The storage device 1001 is, for example, a non-transitory computer readable medium. The non-transitory computer readable medium includes various types of tangible storage media. Specific examples of the non-transitory computer readable medium include semiconductor memory (for example, mask ROM, PROM (Programmable ROM), EPROM (Erasable PROM), and flash ROM). The storage device 1001 implements, for example, the MAC address table 140 and the registration history table 150 in the above embodiment.

[0075] The memory 1002 is realized by, for example, a RAM (Random Access Memory), and is a storage means for temporarily storing data when the CPU 1000 executes processing.

[0076] Next, an overview of the present disclosure will be described. FIG. 9 is a block diagram illustrating a main part of a frame forwarding device. The frame forwarding device 10 shown in FIG. 9 includes a forwarding unit 11 (implemented by the frame forwarding unit 110 in the embodiment) that forwards a received frame based on a MAC address table (e.g., corresponding to the MAC address table 140) that stores entry information associating ports of the device with MAC (Media Access Control) addresses of nodes connected to the ports, and a management unit 12 (implemented by the table management unit 120 in the embodiment) that stores the entry information stored in the MAC address table in a storage unit (e.g., corresponding to the registration history table 150) different from the MAC address table. If entry information corresponding to the destination MAC address of the received frame is not stored in either the MAC address table or the storage unit, the forwarding unit 11 executes flooding processing for the received frame (e.g., corresponding to the part where the frame forwarding unit 110 executes step S208 after N in steps S202 and N in S204). This configuration can prevent unnecessary flooding processing from being executed. As a result, congestion can be prevented from occurring in the network.

[0077] Furthermore, if entry information corresponding to the destination MAC address of the received frame is not stored in the MAC address table but is stored in the storage unit, and the link status of the port associated with the destination MAC address is a link-up status, the forwarding means 11 forwards the received frame to the port (e.g., this corresponds to the process of N in step S202, Y in S204, and Y in S205, followed by the frame forwarding unit 110 executing step S206). This configuration makes it possible to prevent unnecessary flooding processing from being executed. As a result, it is possible to prevent congestion from occurring in the network.

[0078] Furthermore, if entry information corresponding to the destination MAC address of the received frame is not stored in the MAC address table but is stored in the storage unit, and the link status of the port associated with the destination MAC address is a link down status, the forwarding unit discards the received frame (e.g., this corresponds to the part where, after N in step S202, Y in S204, and N in S205, the frame forwarding unit 110 executes step S207). With this configuration, it is possible to prevent unnecessary flooding processing from being executed. As a result, it is possible to prevent congestion from occurring in the network.

[0079] Although the present disclosure has been described above with reference to the embodiments, the present disclosure is not limited to the above-described embodiments. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present disclosure within the scope of the present disclosure. Each embodiment can be combined with other embodiments as appropriate.

[0080] Each drawing is merely an example for describing one or more embodiments. Each drawing may relate not only to one particular embodiment, but also to one or more other embodiments. As will be understood by those skilled in the art, various features or steps described with reference to any one drawing can be combined with features or steps shown in one or more other drawings to create, for example, an embodiment not explicitly shown or described. Not all features or steps shown in any one drawing are necessary to describe an exemplary embodiment, and some features or steps may be omitted. The order of steps described in any drawing may be changed as appropriate.

[0081] A part or all of the above-described embodiments can be described as, but not limited to, the following supplementary notes.

[0082] (Appendix 1) a forwarding means for forwarding a received frame based on a MAC address table that stores entry information that associates a port of the device with a MAC (Media Access Control) address of a node connected to the port; a management unit for storing entry information stored in the MAC address table in a storage unit different from the MAC address table; The forwarding means executes flooding processing for the received frame when entry information corresponding to the destination MAC address of the received frame is not stored in either the MAC address table or the storage unit. A frame forwarding device characterized by:

[0083] (Appendix 2) The forwarding means forwards the received frame to a port when entry information corresponding to the destination MAC address of the received frame is not stored in the MAC address table but is stored in the storage unit, and the link state of the port associated with the destination MAC address is a link up state. 2. The frame forwarding apparatus of claim 1.

[0084] (Appendix 3) The forwarding means discards the received frame when entry information corresponding to the destination MAC address of the received frame is not stored in the MAC address table but is stored in the storage unit, and the link status of the port associated with the destination MAC address is a link down status. 3. The frame forwarding device according to claim 1 or 2.

[0085] (Appendix 4) The management means, based on the detection of link down, stores entry information corresponding to the port in which link down has been detected in the storage unit. 4. A frame forwarding device according to any one of claims 1 to 3.

[0086] (Appendix 5) The management means stores all entry information stored in the MAC address table in the storage unit at any timing. 5. A frame forwarding device according to any one of claims 1 to 4.

[0087] (Appendix 6) The management means deletes from the storage unit entry information in which either the MAC address or the port matches the entry information stored in the MAC address table but the other does not match. 6. A frame forwarding device according to any one of Supplementary Note 1 to Supplementary Note 5.

[0088] (Appendix 7) After entry information is stored in the MAC address table by MAC address learning, the management means deletes entry information whose MAC address matches the entry information from the storage unit. 7. A frame forwarding device according to any one of claims 1 to 6.

[0089] (Appendix 8) After entry information is stored in the MAC address table by MAC address learning, the management means deletes entry information whose port matches the entry information from the storage unit. 8. A frame forwarding device according to any one of Supplementary Note 1 to Supplementary Note 7.

[0090] (Appendix 9) forwarding the received frame based on a MAC address table that stores entry information that associates a port of the device with a MAC (Media Access Control) address of a node connected to the port; storing entry information stored in the MAC address table in a storage unit different from the MAC address table; If entry information corresponding to the destination MAC address of the received frame is not stored in either the MAC address table or the storage unit, a flooding process is performed for the received frame. A frame transfer method comprising:

[0091] (Appendix 10) On the computer, a forwarding process for forwarding the received frame based on a MAC address table that stores entry information that associates a port of the device with a MAC (Media Access Control) address of a node connected to the port; a management process for storing entry information stored in the MAC address table in a storage unit different from the MAC address table; In the forwarding process, if entry information corresponding to the destination MAC address of the received frame is not stored in either the MAC address table or the storage unit, a flooding process of the received frame is executed. A frame forwarding program for

[0092] Some or all of the elements (e.g., configurations and functions) described in Supplementary Notes 2 to 8 that are dependent on Supplementary Note 1 may also be dependent on Supplementary Notes 9 and 10 in the same dependency relationship as Supplementary Notes 2 to 8. Some or all of the elements described in any Supplementary Note may be applied to various hardware, software, recording means for recording software, systems, and methods. [Explanation of symbols]

[0093] 10,100 Frame Transfer Device 11 Transfer Methods 12 Control measures 110 Frame Transfer Unit 120 Table Management Section 121 MAC address table management section 122 Registration History Table Management Unit 130 Link detector 140 MAC Address Table 150 Registration History Table 1000 CPU 1001 Storage device 1002 memory

Claims

1. a forwarding means for forwarding a received frame based on a MAC address table that stores entry information that associates a port of the device with a MAC (Media Access Control) address of a node connected to the port; a management unit for storing entry information stored in the MAC address table in a storage unit different from the MAC address table; The forwarding means executes flooding processing for the received frame when entry information corresponding to the destination MAC address of the received frame is not stored in either the MAC address table or the storage unit. A frame forwarding device characterized by:

2. The forwarding means forwards the received frame to a port when entry information corresponding to the destination MAC address of the received frame is not stored in the MAC address table but is stored in the storage unit, and the link status of the port associated with the destination MAC address is a link-up status.

2. The frame forwarding device according to claim 1.

3. The forwarding means discards the received frame when entry information corresponding to the destination MAC address of the received frame is not stored in the MAC address table but is stored in the storage unit, and the link status of the port associated with the destination MAC address is a link down status.

3. The frame transfer device according to claim 1.

4. The management means, based on the detection of link down, stores entry information corresponding to the port in which link down has been detected in the storage unit.

3. The frame transfer device according to claim 1.

5. The management means stores all entry information stored in the MAC address table in the storage unit at any timing.

3. The frame transfer device according to claim 1.

6. The management means deletes from the storage unit entry information that matches either the MAC address or the port with the entry information stored in the MAC address table but does not match the other.

3. The frame transfer device according to claim 1.

7. After entry information is stored in the MAC address table by MAC address learning, the management means deletes entry information whose MAC address matches the entry information from the storage unit.

3. The frame transfer device according to claim 1.

8. After entry information is stored in the MAC address table by MAC address learning, the management means deletes entry information whose port matches the entry information from the storage unit.

3. The frame transfer device according to claim 1.

9. forwarding the received frame based on a MAC address table that stores entry information that associates a port of the device with a MAC (Media Access Control) address of a node connected to the port; storing entry information stored in the MAC address table in a storage unit different from the MAC address table; If entry information corresponding to the destination MAC address of the received frame is not stored in either the MAC address table or the storage unit, a flooding process is performed for the received frame. A frame transfer method comprising:

10. On the computer, a forwarding process for forwarding the received frame based on a MAC address table that stores entry information that associates a port of the device with a MAC (Media Access Control) address of a node connected to the port; a management process for storing entry information stored in the MAC address table in a storage unit different from the MAC address table; In the forwarding process, if entry information corresponding to the destination MAC address of the received frame is not stored in either the MAC address table or the storage unit, a flooding process of the received frame is executed. A frame forwarding program for

Images