COMMUNICATION SYSTEM, COMMUNICATION METHOD, NETWORK DEVICE, AND PROGRAM

Abstract

The objective of the present disclosure is to suppress duplicate distribution of Broadcast, Unknown Unicast, Multicast (BUM), while transferring unicast via a boundary device that is geographically close to a user device, even in communication from an L2 network to an Ethernet Virtual Private Network (EVPN).　In a communication system according to the present disclosure, in which a first network and a second network are connected by a plurality of pathways, the plurality of pathways are provided with a transfer inhibiting unit which inhibits the transfer of broadcast frames, unknown unicast frames and multicast frames from the second network to the first network, and only a specific pathway among the plurality of pathways transfers broadcast frames, unknown unicast frames, and multicast frames from the second network to the first network.

Description

[Technical field]

[0001] The present disclosure relates to a network device that connects a plurality of networks. [Background technology]

[0002] In network systems, there is a demand for networks to be interconnected at multiple locations to improve reliability and avoid connections that require large detours. When connecting an EVPN (Ethernet VPN (Virtual Private Network)) to a normal L2 network with multiple border devices, by utilizing the DF (Designated Forwarder) selection function, which is a basic function of EVPN, it is possible to suppress duplicate distribution of BUM (Broadcast, Unknown Unicast, Multicast) for communication from EVPN to the L2 network while communicating unicast with all-act settings.

[0003] However, in the conventional technology, only the same setting is possible for communication from the L2 network to EVPN, regardless of whether it is unicast or BUM. Therefore, there were problems such as the all-act setting causing duplicate delivery of BUM via multiple border devices, and the single-act setting causing both unicast and BUM to be forwarded via a border device geographically distant from the user device (making a large detour around the network). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-146045 A Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure aims to prevent duplicate delivery of BUM while forwarding unicast via a border device geographically close to the user device, even in communication from an L2 network to an EVPN. [Means for solving the problem]

[0006] The communication system according to the present disclosure includes: A communication system in which a first network and a second network are connected by a plurality of paths, the plurality of paths each include a forwarding suppression unit configured to suppress forwarding of a broadcast frame, an unknown unicast frame, and a multicast frame from a second network to a first network; Only a specific route among the plurality of routes disables the forwarding inhibition unit and forwards broadcast frames, unknown unicast frames, and multicast frames from the second network to the first network.

[0007] The communication method according to the present disclosure includes: A communication method executed by a communication system in which a first network and a second network are connected by a plurality of network devices, comprising: the plurality of paths each include a forwarding suppression unit configured to suppress forwarding of a broadcast frame, an unknown unicast frame, and a multicast frame from a second network to a first network; Only a specific route among the plurality of routes disables the forwarding inhibition unit and forwards broadcast frames, unknown unicast frames, and multicast frames from the second network to the first network.

[0008] A network device according to the present disclosure comprises: A network device connected to a boundary between a first network and a second network, a forwarding suppression unit that suppresses forwarding of broadcast frames, unknown unicast frames, and multicast frames from the second network to the first network; a BUM communication availability determination unit that obtains identification information of a network device installed at a boundary between the first network and the second network via the first network, and determines whether the forwarding inhibition unit is enabled using the obtained information; a forwarding inhibition enabling unit that enables the forwarding inhibition unit according to a determination by the BUM communication availability determining unit; Equipped with.

[0009] The program of the present disclosure is a program for causing a computer to realize each functional unit of a network device of the present disclosure, and is a program for causing a computer to execute each step of a communication method performed by an device of the present disclosure. Effect of the Invention

[0010] According to this invention, even in communication from an L2 network to an EVPN, it is possible to prevent duplicate delivery of BUM frames while forwarding unicast via a border device that is geographically close to the user device. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing a state in which networks are connected via a plurality of network devices. [Diagram 2] 1 is a diagram illustrating a network device that prevents duplicate distribution in the direction from NW#2 to NW#1. [Diagram 3] FIG. 2 is an explanatory diagram showing an example of the operation of the system of the present disclosure. [Figure 4] FIG. 1 is a diagram showing a state in which networks are connected via a plurality of network devices. [Diagram 5] 13 is a diagram showing a network device installed on the NW#1 side when preventing duplicate delivery from NW#2 to NW#1 using multiple devices. FIG. [Figure 6] 13 is a diagram showing a network device installed on the NW#2 side when preventing duplicate delivery in the direction from NW#2 to NW#1 by using multiple devices. FIG. [Figure 7] FIG. 2 is an explanatory diagram showing an example of the operation of the system of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, a network system that interconnects networks via a plurality of network devices according to the present invention, transmits unicast frames via all of the network devices, and prevents duplicate delivery of BUM frames will be described with reference to the drawings. Note that in the following embodiments, parts with the same numbers perform the same operations, and repeated explanations will be omitted. Note that the network system that interconnects networks via a plurality of network devices according to the present disclosure, transmits unicast frames via all of the network devices, and prevents duplicate delivery of BUM frames can be applied to the information and communications industry.

[0013] Hereinafter, a communication network that enables direct or indirect traffic communication between multiple devices will be called a network. Also, a network device installed at the edge of any network, or in other words, an edge device, will be simply called a border device.

[0014] FIG. 1 shows an example of a system configuration of the present disclosure. The communication system of the present disclosure uses multiple border devices to connect networks 10 and 20. For example, as shown in FIG. 1, multiple border devices 11 and 12 are provided between network 10, which is a first network (hereinafter referred to as NW#1), and network 20, which is a second network (hereinafter referred to as NW#2). This provides multiple paths connecting networks 10 and 20. Border device 11 and border device 12 do not necessarily directly connect networks 10 and 20, and communication is possible in networks 10 and 20 by passing through multiple devices.

[0015] The network connection between the border device 11 and the border device 12 allows communication to continue unless multiple border devices fail at the same time. In addition, by installing the border device 11 at a base where a user device is installed and the border device 12 at a base where another user device is installed, communication between users via the network 10 and the network 20 becomes possible without passing through geographically distant bases.

[0016] On the other hand, when the networks are each an Ethernet (trademark registered) service, a problem arises in the method of using multiple border devices to connect the networks as described above. In Fig. 1, it is assumed that networks 10 and 20 are both services that provide communication at layer 2 of the OSI (Open Systems Interconnection) reference model, such as Ethernet. In this case, traffic (frames) that arrives at network 20 from network 10 via border device 11 may flow back into network 10 via border device 12. As a countermeasure to such a problem, for example, prior art document 1 is available.

[0017] Another problem is the duplicated delivery of BUM frames. BUM is a general term for broadcast, unknown unicast, and multicast, and these frames are forwarded to all reachable devices in the L2 network. That is, a BUM frame transmitted from a user device 23 connected to the network 20 reaches both the border device 11 and the border device 12. Now, when both the border device 11 and the border device 12 forward the BUM frame to the network 10, the frame reaches each of the user devices 13 connected to the network 10. This means that a single BUM traffic transmitted from the user device 23 is multiplexed and delivered to the user devices 13 by forwarding it via multiple border devices.

[0018] In order to avoid such a problem, it is possible to limit the number of border devices that can forward traffic from network 20 to network 10 to one. That is, among multiple border devices that connect the networks, only one network device is set to the Active state, and at a certain time, only the network device in the Active state is used. However, in an L2 network, only the same setting is possible regardless of unicast / BUM. For example, in an all-active setting, all traffic passes through, and in a single-active setting, all unicast / BUM traffic passes through only one border device. For this reason, if only network devices in the Active state are used, the number of border devices that can travel between the two networks is limited, and it may become necessary to pass through geographically distant locations.

[0019] The present disclosure has been made in light of the above-mentioned circumstances. The present disclosure has the following components. The communication system according to the present disclosure includes: At the border device, the DF selection function and the filter function in the direction from EVPN to the L2 network are combined, In the direction from the L2 network to EVPN, all-act is set, If the border device is the DF in the direction from EVPN to the L2 network, it also forwards the BUM. If the border device in the direction from EVPN to the L2 network is a non-DF, the transfer of BUM is suppressed. In this disclosure, an edge device that is a DF is called a specific network device, and a route connected by a specific network device is called a specific route.

[0020] More specifically, the network device according to the present disclosure comprises: A border device connected to the edge of the networks 10 and 20, a forwarding determination unit that determines a network device capable of transmitting a broadcast frame, an unknown unicast frame, or a multicast frame in a direction from NW#1 to NW#2 based on a result of transmitting and receiving information about the network device via NW#1; a forwarding inhibition unit that inhibits forwarding in a direction from NW#2 to NW#1; The forwarding inhibition unit in the direction from NW2 to NW1 is enabled based on a forwarding determination unit that determines a network device that can transmit frames in the direction from NW#1 to NW#2. Hereinafter, the direction from NW#1 to NW#2 will be referred to as the NW#1→NW#2 direction, and the direction from NW#2 to NW#1 will be referred to as the NW#2→NW#1 direction.

[0021] [First embodiment] 2 shows an example of the configuration of the boundary device 11 according to this embodiment. The boundary device 11 according to this embodiment is a boundary device having a NW#2 side physical port 111, a NW#1 side physical port 112, a NW#2 side port frame receiver 113, a NW#2→NW#1 direction transfer inhibition unit 114, a NW#1 side port frame transmitter 115, a NW#1 side port frame receiver 116, a NW#1→NW#2 direction transfer inhibition unit 117, a NW#2 side port frame transmitter 118, a NW#1→NW#2 direction BUM communication possibility determination unit 119, a transfer inhibition activation unit 11a, and a boundary device information DB 11b. The boundary device 12 also has a similar configuration to the boundary device 11.

[0022] In this embodiment, the border devices 11 and 12 are provided with these configurations, thereby preventing frames from traveling between the networks 10 and 20 while connecting the networks to each other, and preventing duplicate delivery of frames. The border devices 11 and 12 can also be realized by a computer and a program, and the program can be recorded on a recording medium or provided through a network. Note that this embodiment targets a network system of Layer 2 of the OSI reference model, as typified by Ethernet (registered trademark).

[0023] In this embodiment, information on the border device between NW#1 and NW#2 is exchanged via NW#1. Specifically, the border device information DB11b of each border device holds border device information indicating that the device is installed on the border between NW#1 and NW#2, and the held border device information is exchanged via NW#1. The border device information is any information that can determine which device the DF is (whether the DF is the own device or another border device), such as identification information of the DF device. The border device information may include identification information of the own device, identification information of the border device of the connection destination, and port numbers of the connected own device and the connection destination device. The identification information is, for example, a MAC address and a node ID defined in the network.

[0024] In the present disclosure, this information exchange determines that there are multiple border devices that span between NW#1 and NW#2. At this time, if each of the border devices forwards the BUM traffic, multiplexing occurs in the direction from NW#1 to NW#2, so it is necessary to uniquely determine the border device that can forward the BUM traffic. If the border device that spans between NW#1 and NW#2 is shared among all the border devices, it is also possible to uniquely determine the border device that can forward the BUM traffic by a predetermined calculation method. This calculation method can employ any method that can determine a unique border device, and for example, the border device with the smaller node ID can be set as the DF.

[0025] As a method for sharing border device information and selecting a single border device that transmits BUM traffic from NW#1 to NW#2 as described above, for example, NW#1 may use EVPN (Ethernet VPN) technology. By utilizing the DF (Designated Forwarder) selection function of EVPN, multiplexing of BUM traffic from NW#1 to NW#2 can be suppressed. For example, the NW#1 → NW#2 BUM communication availability determination unit 119 provided in the border devices 11 and 12 selects the border device 12 as a DF using the DF function provided in EVPN, and determines whether to enable / disable the NW#2 → NW#1 forwarding suppression unit 114.

[0026] When the border device 11 is a non-DF, the NW#1→NW#2 direction BUM communication determination unit 119 included in the border device 11 determines not to forward the BUM traffic. In this case, the forwarding inhibition activation unit 11a included in the border device 11 activates the NW#2→NW#1 forwarding inhibition unit 114. This makes it possible to inhibit forwarding in the NW#2→NW#1 direction at the border device 11, as in the border device 11 shown in FIG.

[0027] When the border device 12 is the DF, the NW#1→NW#2 direction BUM communication availability determination unit 119 included in the border device 12 determines that the BUM traffic can be forwarded. In this case, the forwarding inhibition activation unit 11a included in the border device 12 disables the NW#2→NW#1 forwarding inhibition unit 114. This allows the border device 12 to perform forwarding in the NW#2→NW#1 direction, as in the border device 12 shown in FIG.

[0028] When the border device 11 is a non-DF, the processing procedure of the border device 11 for receiving a frame from NW#2, i.e., network 20 in Figure 1, at the NW#2 side physical port 111 and transmitting the received frame to NW#1, i.e., network 10 in Figure 1, is shown below.

[0029] When a frame arrives at the NW#2 side physical port 111 of the boundary device 11, the frame is passed to the NW#2 side port frame receiver 113. The NW#2 side port frame receiver 113 judges whether the received frame is a BUM frame, i.e., a broadcast frame, an unknown unicast frame, a multicast frame, or a unicast frame. If the frame corresponds to a BUM frame, it transmits the frame to the NW#2 → NW#1 direction transfer suppression unit 114. In the case of a unicast frame, the NW#2 side port frame receiver 113 selects a port to transmit the frame according to the processing of the layer 2 network system, i.e., the learning status of the MAC address, and transmits the frame from the selected port.

[0030] When the NW#2→NW#1 direction transfer inhibition unit 114 receives an instruction to inhibit frame transfer in the NW#2→NW#1 direction from the transfer inhibition enabling unit 11a, it inhibits the transfer of BUM frames. A method of inhibiting transfer may be to use a filter function for BUM frames, or to discard frames by setting the buffer length for temporarily holding BUM frames to 0. The conditions for issuing an instruction to inhibit frame transfer in the NW#2→NW#1 direction from the transfer inhibition enabling unit 11a will be described later.

[0031] When the boundary device 11 is a DF and the forwarding suppression enabling unit 11a does not give an instruction to suppress the BUM frame forwarding in the NW#2→NW#1 direction, the NW#2→NW#1 direction forwarding suppression unit 114 selects a physical port for transmitting the BUM frame according to the processing of the network system of layer 2. In this embodiment, in order to describe a case where the NW#1 side physical port 112 exists as one of the physical ports for transmitting the BUM frame, the BUM frame is transmitted to the NW#1 side port frame transmitting unit 115.

[0032] The NW#1 side port frame transmitter 115 transmits the BUM frame from the NW#1 side physical port 112.

[0033] When the border device 11 is not a DF, the border device 11 receives a frame from NW#1, i.e., the network 10 in Fig. 1, at the NW#1 side physical port 112 and transmits the received frame to NW#2, i.e., the network 20 in Fig. 1. The processing procedure of the border device 11 is shown below. Note that the DF function of EVPN may be used for BUM frame forwarding from NW#1 to NW#2.

[0034] When a frame arrives at the NW#1 side physical port 112 of the boundary device 11, the frame is passed to the NW#1 side port frame receiver 116. The NW#1 side port frame receiver 116 judges whether the received frame is a BUM frame, i.e., a broadcast frame, an unknown unicast frame, a multicast frame, or a unicast frame. If it is a BUM frame, it transmits the frame to the NW#1 → NW#2 direction transfer suppression unit 117. If it is a unicast frame, it selects a port to transmit the frame according to the processing of the layer 2 network system, i.e., the learning status of the MAC address, and transmits the frame from the selected port.

[0035] The NW#2 → NW#1 direction forwarding inhibition unit 117 inhibits forwarding of BUM frames in accordance with an instruction from the forwarding inhibition activation unit 11a based on the determination result of the NW#1 → NW#2 direction BUM communication availability determination unit 119. In the border device that has determined that forwarding of BUM traffic is not possible, that is, in the border device other than the device selected as the DF in the EVPN, the forwarding inhibition activation unit 11a activates the NW#1 → NW#2 direction forwarding inhibition unit 117, and the NW#1 → NW#2 direction forwarding inhibition unit 117 inhibits forwarding of BUM traffic.

[0036] On the other hand, in the border device 12 that has determined that the BUM traffic can be forwarded, that is, the border device 12 that has been selected as the DF in the EVPN, the forwarding suppression enabling unit 11a disables the function of the NW#1→NW#2 direction forwarding suppression unit 117 based on the determination of the NW#1→NW#2 direction BUM communication enablement unit 119. Therefore, the border device 12 forwards the BUM traffic.

[0037] In this case, the NW#1 → NW#2 direction forwarding suppression unit 117 of the boundary device 12 selects a physical port for transmitting the BUM frame in accordance with the processing of the network system of Layer 2. In this embodiment, in order to describe a case where the NW#2 side physical port 111 exists as one of the physical ports for transmitting the BUM frame, the BUM frame is transmitted to the NW#2 side port frame transmitting unit 118.

[0038] The NW#2 side port frame transmitter 118 of the boundary device 12 transmits the BUM frame from the NW#2 side physical port 111.

[0039] The feature of this embodiment is that the suppression of forwarding in the NW#2→NW#1 direction is controlled by using information of the NW#1→NW2 direction BUM communication determination unit 119, which is typified by the DF selection of EVPN. That is, in the border device that determines that the BUM traffic in the NW#1→NW#2 direction is suppressed by the NW#1→NW#2 direction BUM communication determination unit 119, an instruction is given to the forwarding suppression enabling unit 11a to suppress the BUM traffic in the NW#2→NW#1 direction as well. As already described, the forwarding suppression enabling unit 11a issues an instruction to the NW#2→NW#1 direction forwarding suppression unit 114 to suppress frame forwarding in the NW#2→NW#1 direction. As a result, it is possible to suppress the BUM frame in the NW#2→NW#1 direction that does not exchange information about the border device straddling NW#1 and NW#2.

[0040] On the other hand, unicast frames are not subject to forwarding suppression. Therefore, frame forwarding is possible from NW#1 to NW#2 and from NW#2 to NW#1 at any of the border devices between NW#1 and NW#2.

[0041] As described above, this embodiment combines a DF selection function (NW#1 → NW#2 direction BUM communication feasibility determination unit 119) with a filter function (NW#2 → NW#1 direction forwarding suppression unit 114), and for non-DF devices, discards BUM traffic (broadcast, unknown unicast, multicast) in the NW#2 → NW#1 direction.

[0042] A frame received by the NW#2 side port frame receiver 113 is judged as being BUM traffic or not, and if it is judged as being BUM, the forwarding is suppressed by the NW#2 → NW#1 direction forwarding suppression unit 114. This function is initially enabled by the NW#2 → NW#1 direction forwarding suppression enabling unit 11a. In other words, this function is enabled in all devices, and this function is disabled only in the device selected as the DF.

[0043] [Second embodiment] In the first embodiment, the NW#1→NW#2 direction BUM communication availability determination unit 119 and the forwarding inhibition validation unit 11a may be implemented in different devices. Fig. 4 shows an example of a system configuration of this embodiment.

[0044] In the communication system of this embodiment, the network 30 and the network 40 are connected by the border device 31 and the border device 41, and the border device 32 and the border device 42. The border devices 31 and 32 function as first network devices, and the border devices 41 and 42 function as second network devices. The communication system of this embodiment exchanges information about the border devices that straddle the network 30 and other networks via the network 30, and suppresses forwarding in the NW#2→NW#1 direction at the border device 41.

[0045] 5 shows an example of the configuration of the boundary device 31. The boundary device 31 according to this embodiment is a boundary device having a NW#2 side physical port 311, a NW#1 side physical port 312, a NW#2 side port frame receiver 313, a NW#1 side port frame transmitter 315, a NW#1 side port frame receiver 316, a NW#1→NW#2 direction transfer inhibition unit 317, a NW#2 side port frame transmitter 318, a NW#1→NW#2 direction BUM communication availability determination unit 319, a transfer inhibition activation unit 31a, a boundary device information DB 31b, and a transfer inhibition instruction transmitter 31c. The boundary device 32 also has the same configuration as the boundary device 31.

[0046] 6 shows an example of the configuration of the boundary device 41. The boundary device 41 according to this embodiment is a boundary device having a NW#2 side physical port 411, a NW#1 side physical port 412, a NW#2 side port frame receiver 413, a NW#2→NW#1 direction forwarding suppression unit 414, a NW#1 side port frame transmitter 415, a NW#1 side port frame receiver 416, a NW#2 side port frame transmitter 418, a forwarding suppression activation unit 41a, and a forwarding suppression instruction receiver 41d. The boundary device 42 also has a similar configuration to the boundary device 41.

[0047] The NW#2 side port frame receivers 313 and 413 have the same function as the NW#2 side port frame receiver 113, the NW#2 → NW#1 direction transfer inhibition unit 414 has the same function as the NW#2 → NW#1 direction transfer inhibition unit 114, the NW#1 side port frame transmitters 315 and 415 have the same function as the NW#1 side port frame transmitter 115, and the NW#1 side port frame receivers 316 and 416 have the same function as the NW#1 side port frame receiver 116. the NW#1 → NW#2 direction forwarding inhibition unit 317 has functions similar to the NW#1 → NW#2 direction forwarding inhibition unit 117, the NW#2 side port frame transmitters 318 and 418 have functions similar to the NW#2 side port frame transmitter 118, the NW#1 → NW#2 direction BUM communication feasibility determination unit 319 has functions similar to the NW#1 → NW#2 direction BUM communication feasibility determination unit 119, and the border device information DB31b has functions similar to the border device information DB11b.

[0048] The border device 31 does not include the NW#2→NW#1 direction forwarding inhibition unit 114, and instead includes a forwarding inhibition instruction transmission unit 31c. The border device 41 does not include the NW#1→NW#2 direction forwarding inhibition unit 117 and the border device information DB 11b, and instead includes a forwarding inhibition instruction reception unit 41d. The forwarding inhibition activation unit 31a of the border device 31 activates / inactivates the NW#1→NW#2 direction forwarding inhibition unit 317. The forwarding inhibition activation unit 41a of the border device 41 activates / inactivates the NW#2→NW#1 direction forwarding inhibition unit 414.

[0049] In this embodiment, information from the NW#1→NW#2 direction BUM communication availability determination unit 319 included in the border device 31 capable of exchanging information about border devices spanning the network 30 and other networks is transmitted to an adjacent device via the transfer inhibition instruction transmission unit 31c. In the border device 41, which is the adjacent device, information from the NW#1→NW#2 direction BUM communication availability determination unit 319 is provided to the transfer inhibition activation unit 41a via the transfer inhibition instruction reception unit 41d. Based on the provided information, the transfer inhibition activation unit 41a instructs the NW#2→NW#1 transfer inhibition unit 414 to transfer or inhibit BUM traffic.

[0050] For example, when the border device 31 is a non-DF, the NW#1→NW#2 direction BUM communication availability determination unit 319 of the border device 31 determines not to forward BUM traffic. The forwarding suppression instruction transmission unit 31c of the border device 31 transmits a non-DF notification to the border device 41. When the forwarding suppression instruction reception unit 41d of the border device 41 receives the non-DF notification, it transmits the notification to the forwarding suppression activation unit 41a. The forwarding suppression activation unit 41a of the border device 41 activates the NW#2→NW#1 forwarding suppression unit 414. As a result, as shown in FIG. 7, forwarding in the NW#2→NW#1 direction can be suppressed in the border device 41.

[0051] When the border device 32 is a DF, the NW#1→NW#2 direction BUM communication availability determination unit 319 of the border device 32 determines that the BUM traffic can be forwarded. The forwarding suppression instruction transmission unit 31c of the border device 32 transmits a DF notification to the border device 42. When the forwarding suppression instruction reception unit 41d of the border device 42 receives the DF notification, it transmits the notification to the forwarding suppression activation unit 41a. The forwarding suppression activation unit 41a of the border device 42 disables the NW#2→NW#1 forwarding suppression unit 414. As a result, the border device 42 can perform forwarding in the NW#2→NW#1 direction, as shown in FIG. 7.

[0052] As described above, this embodiment combines a DF selection function (NW#1 → NW#2 direction BUM communication feasibility determination unit 319) with a filter function (NW#2 → NW#1 direction forwarding suppression unit 414), and for non-DF border devices, the forwarding of BUM traffic (broadcast, unknown unicast, multicast) in the NW#2 → NW#1 direction is suppressed.

[0053] In this embodiment, the border device 31 that performs the DF judgment is separated from the border device 41 that actually discards frames. The border device 31 notifies the adjacent device of DF or non-DF. The adjacent border device 41 discards frames based on the notified information. In the case of Figure 4, the border devices 31 and 32 are devices that judge DF or non-DF, and the border devices 41 and 42 correspond to the adjacent devices that discard frames.

[0054] Since it is not possible to determine whether the border device 41 or 42 should communicate with the BUM, this can be achieved by passing DF selection information. The border devices 31, 32, 41, and 42 can also be realized by a computer and a program, and the program can be recorded on a recording medium or provided via a network.

[0055] It should be noted that the present disclosure is not limited to the embodiments. The embodiments are merely illustrative, and the present disclosure can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art. [Industrial Applicability]

[0056] The present disclosure can be applied to the information and communications industry. [Explanation of symbols]

[0057] 10, 20, 30, 40: Network 11, 12, 31, 32, 41, 42: Boundary device 13, 23, 33, 43: User device 111, 311, 411: Physical ports on NW#2 side 112, 312, 412: Physical ports on NW#1 side 113, 313, 413: NW#2 side port frame receiver 114, 414: NW#2 → NW#1 direction transfer suppression unit 115, 315, 415: NW#1 side port frame transmitter 116, 316, 416: NW#1 side port frame receiver 117, 317: NW#1 → NW#2 direction transfer suppression section 118, 318, 418: NW#2 side port frame sending section 119, 319: NW#1 → NW#2 direction BUM communication availability determination section 11a, 31a, 41a: forwarding suppression enabling section 11b, 31b: Boundary device information DB 31c: Forwarding suppression instruction transmission unit 41d: Transfer suppression instruction receiving unit

Claims

1. A communication system in which a first network, which is an EVPN (Ethernet Virtual Private Network), and a second network, which is an L2 network, are connected by a plurality of paths, the plurality of paths include a forwarding suppression unit configured to suppress forwarding of only a frame determined to be any one of a broadcast frame, an unknown unicast frame, and a multicast frame from the second network to the first network, among a unicast frame, a broadcast frame, an unknown unicast frame, and a multicast frame; only a specific route among the plurality of routes disables the forwarding inhibition unit, and forwards a unicast frame, a broadcast frame, an unknown unicast frame, and a multicast frame from the second network to the first network; A network device provided on the plurality of paths includes: a BUM communication availability determination unit that obtains, via the first network, identification information of a network device installed at a boundary between the first network and the second network, and determines whether the forwarding inhibition unit is enabled using the obtained information; a transfer inhibition enabling unit that enables the transfer inhibition unit according to a determination made by the BUM communication availability determining unit; Equipped with The BUM communication determination unit determines whether the forwarding inhibition unit is enabled by using a designated forwarder (DF) function provided in the EVPN. Communication systems.

2. At least one of the multiple routes is a first network device connected to the first network, and a second network device connected to the second network; is connected, the first network device includes the BUM communication determination unit, and the second network device includes the forwarding inhibition activation unit and the forwarding inhibition unit; The communication system according to claim 1 .

3. A communication method executed by a communication system in which a first network, which is an EVPN (Ethernet Virtual Private Network), and a second network, which is an L2 network, are connected by a plurality of paths, comprising: the plurality of paths include a forwarding suppression unit configured to suppress forwarding of only a frame determined to be any one of a broadcast frame, an unknown unicast frame, and a multicast frame from the second network to the first network, among a unicast frame, a broadcast frame, an unknown unicast frame, and a multicast frame; only a specific route among the plurality of routes disables the forwarding inhibition unit, and forwards a unicast frame, a broadcast frame, an unknown unicast frame, and a multicast frame from the second network to the first network; A network device provided on the plurality of paths, a BUM communication availability determination step of acquiring, via the first network, identification information of a network device installed at a boundary between the first network and the second network, and determining whether the forwarding inhibition unit is enabled using the acquired information; a transfer inhibition enabling step of enabling the transfer inhibition unit according to the determination in the BUM communication possibility determining step; Run In the BUM communication determination step, a DF (Designated forwarder) function provided in the EVPN is used to determine whether the forwarding inhibition unit is enabled. Communication methods.

4. A network device connected to a boundary between a first network, which is an EVPN (Ethernet Virtual Private Network), and a second network, which is an L2 network, comprising: a forwarding inhibition unit that inhibits forwarding of only a frame determined to be any one of a broadcast frame, an unknown unicast frame, and a multicast frame from the second network to the first network, among a unicast frame, a broadcast frame, an unknown unicast frame, and a multicast frame; a BUM communication availability determination unit that obtains, via the first network, identification information of a network device installed at a boundary between the first network and the second network, and determines whether the forwarding inhibition unit is enabled using the obtained information; a transfer inhibition enabling unit that enables the transfer inhibition unit according to a determination made by the BUM communication availability determining unit; Equipped with The BUM communication determination unit determines whether the forwarding inhibition unit is enabled by using a designated forwarder (DF) function provided in the EVPN, When the forwarding inhibition unit is disabled, a unicast frame, a broadcast frame, an unknown unicast frame, and a multicast frame are forwarded from the second network to the first network. Network device.

5. A program for causing a computer to realize each of the functional units of the network device according to claim 4.

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