JP5333290B2 - Network evaluation apparatus, network evaluation system, and network evaluation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently and accurately measure the time required for changing a communication path, in both the directions of communication for a ring-type redundant network. <P>SOLUTION: For a network 2 having redundancy by an STP, a network evaluation device 1 is used to accurately measure the time required for changing a redundant path in link-down. The evaluation device 1 transmits frames 18, 20 for learning frame by frame from the respective ports 4a, 4b by a measuring instrument 4. Respective switching hubs 8, 10, 12, 14 learn (store) the respective transmission source MAC addresses A, B of the frames 18, 20 for learning for registering in an FDB. Furthermore, the measuring instrument 4 continuously transmits frames 22, 24 for measurement indicating the transmission source MAC address differing from that of the frames 18, 20 for learning from the respective ports 4a, 4b. A link-down is generated within the network 2 in the transmission process, and change time is measured from the number of frame transmission and reception times in the respective ports 4a, 4b of the measuring instrument 4. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a network evaluation apparatus, a network evaluation system, and a network evaluation method that contribute to network evaluation by accurately measuring a time required until a communication path is switched when a failure occurs in a redundant network. .

  Conventionally, regarding a ring topology network configured by connecting multiple switching hubs (relay devices) that operate using the spanning tree protocol, if a loop occurs in the network due to a special failure, A prior art that detects the occurrence of the loop in a short time and automatically cancels the loop is known (for example, see Patent Document 1).

  Usually, in a network made redundant using a spanning tree protocol, occurrence of a loop is prevented by logically blocking one of the ports. However, for example, when a special failure occurs in the relay device in the network (BPDU: Bridge Protocol Data Unit frame transmission / reception function or relay function failure), the logical block of the port is released by switching the redundant path. Loops may occur unintentionally in later networks.

  For this reason, in the above-described prior art (Patent Document 1), a test frame for loop detection is constantly transmitted from one relay apparatus in a redundant network, and the test frame circulates in the network to return to the original. When it is detected that the network has returned to the relay device, it is determined that an unintended loop has occurred in the network. In this case, the loop can be automatically canceled by forcibly disconnecting the port that received the test frame in the original relay device.

JP 2004-222106 A

  In general, as one index for evaluating the performance of a redundant network, the time required for the redundant path switching operation when a failure occurs can be cited. The above-described prior art (Patent Document 1) is useful in that the occurrence of a loop triggered by a communication failure in the network is detected within a short time, and the subsequent countermeasures are automated to improve the network performance. is there. However, the prior art does not detect how long a redundant path switching operation is performed when a failure occurs, and does not have a method for evaluating the performance of the network itself.

  Also, as in the prior art (Patent Document 1), when a loop detection test frame is transmitted from only one port of the relay device by unicast communication, in order to detect the occurrence of a loop in both directions of communication, It is not possible to ignore the fact that test frames need to be transmitted for each direction, and that much work is required. If this point is applied to the network performance evaluation, it is necessary to verify individually in both directions of communication how long the redundant path switching operation in unicast communication is completed in the event of a failure. Therefore, it cannot be denied that it takes a lot of work man-hours.

  Accordingly, an object of the present invention is to provide a technique for efficiently performing accurate evaluation of bidirectional communication using a redundant network.

  The present invention is a network evaluation apparatus that evaluates a network that forms a logically redundant communication path by connecting a plurality of switching hubs that perform a relay operation using a predetermined redundancy protocol. This network evaluation apparatus includes a measuring instrument, various learning frame transmitting means, a measuring frame transmitting means, and a measuring means that function using the measuring instrument. Among these, the measuring instrument has one of the plurality of switching hubs in the network as each node, the first port connected to one of the nodes, and the other switching hub to the first port is the MAC (Media Access Control) A second port with a different address is connected.

  The learning frame transmitting means transmits a learning frame whose destination is the MAC address of each port from the first and second ports of the measuring device to the second and first ports facing each other. In the process in which the learning frame is transferred facing each node in the network, each of the plurality of switching hubs learns communication path information based on the redundancy protocol.

  The measurement frame transmitting means is for measuring contents that do not match the communication path information learned by a plurality of switching hubs, with the MAC addresses of the first and second ports as destinations after transmission of the learning frame is completed. Frames are continuously transmitted from the first and second ports of the measuring instrument toward the opposing second and first ports, respectively.

  When the communication path switching operation based on the redundant protocol is performed in the network during the transmission of the measurement frame, the measuring means transmits and receives between the first and second ports by the measuring device at least during the switching operation. The time required for the switching operation is measured based on the number of transmission / reception of measurement frames.

  According to the network evaluation apparatus of the present invention, the learning frame information transmitted bidirectionally between the nodes is learned by each switching hub, so that (1) A bidirectional communication path for communication from the first port of the measuring instrument to the second port and (2) communication from the second port of the measuring instrument to the first port is established based on the redundancy protocol. Is done. At this time, if a communication failure occurs in the network (for example, transmission line) during the continuous transmission of measurement frames, each switching hub performs a switching operation of the communication path based on the redundancy protocol. During the measurement, the measurement frame transmitted from the measuring instrument is discarded by the switching hub that has received it. After that, when a new communication path after switching is established based on the redundancy protocol, measurement frames can be transferred at last, so the number of measurement frames transmitted from the measuring device during this period and the receiving by the measuring device There is a difference between the number of measured frames. Based on this difference, the time required for switching the communication path can be accurately calculated.

  However, the time until the switching operation of the communication path is completed in the network differs depending on the directions (1) and (2). Note that the switching time varies depending on the direction, for example, due to the difference in the physical configuration of the network and the processing speed of each switching hub. In any case, when the communication path is switched first in any one of the above-mentioned (1) and (2), the communication path of each switching hub is transferred by transferring the measurement frame on the new communication path. Although the information is rewritten, if this rewrite affects the communication path in the other direction, the transmission of the measurement frame is started before the normal switching operation in the other direction is completed, and the exact switching operation time It may be difficult to measure.

  Therefore, in the present invention, the evaluation frame transmitted from the measuring device is divided into a learning frame and a measurement frame, thereby enabling accurate time measurement. In other words, even if the measurement frame transmitted after the learning frame is received by the switching hub during the communication path switching operation, the content thereof is the existing (before switching) communication path information (FDB: For the Forwarding DataBase), a device that does not affect the rewriting is adopted. Accordingly, it is possible to accurately measure the switching operation time for each communication direction without interfering with communication in the other direction by communication in any one direction. Needless to say, the measurement frame is transmitted in both directions from each port of the measuring instrument, so it is possible to accurately measure the time required for the bidirectional switching operation efficiently without performing the measurement work in each direction. can do.

  The learning frame transmitting means described above uses the second MAC address corresponding to the second port as the destination and the learning frame having the first MAC address corresponding to the first port as the transmission source. The first frame is transmitted from the first port to the second port, and the learning frame having the first MAC address as the destination and the second MAC address as the transmission source is transmitted from the second port of the measuring device to the first port. By transmitting toward, each switching hub is made to learn communication path information including the first and second MAC addresses. In addition, the measurement frame transmission means sends the measurement frame having the third MAC address different from both the first and second MAC addresses as the transmission source to the first MAC address of the measuring device while setting the second MAC address as the destination. Transmitting from the port to the second port, and for measurement with the first MAC address as the destination and the fourth MAC address different from any of the first, second, and third MAC addresses as the source Preferably, the frame is transmitted from the second port of the measuring instrument toward the first port.

  In the above aspect, the first and second MAC addresses assigned to each port of the measuring instrument are reflected as they are for the learning frame. However, for the measurement frame, the source MAC address is virtually ( (Or pseudo) content (for example, logical third and fourth MAC addresses different from physical first and second MAC addresses), and inadvertently existing communication path information This prevents the rewriting from occurring.

  That is, for example, when a failure occurs on a communication path in a network, a switching hub (referred to as switching hub (1)) that detects this failure is simultaneously transmitted to other switching hubs (referred to as switching hub (2)). The link down information is notified, and the communication path information stored so far is deleted (for example, FDB is flushed). The switching hub (1) then floods the received measurement frame, for example, in order to construct new communication path information. At this time, before the link down information is received by the other switching hub (2), for example, the measurement flooded in the communication direction (communication direction (1)) from the first port to the second port. Since the MAC address of the transmission source does not match the existing communication path information (information learned by the learning frame) even if the transmission frame (transmission source is the third MAC address) is received, the communication direction (1) This measurement frame does not affect the communication path information in the other direction (communication direction (2)) by overwriting. Therefore, the other switching hub (2) still holds the opposite measurement frame (measurement frame transmitted from the second port to the first port) transferred in the communication direction (2). Since it is transferred based on the communication path information, it is discarded by the switching hub that detects link down.

  After that, when the other switching hub (2) finally receives the link down information and the communication path information is deleted, the measurement frame transmitted in the communication direction (2) is flooded toward the new communication path. Is done. As a result, new communication path information is reconstructed for the communication path (2) in each switching hub, and is transferred from the second port to the first port. Thereby, it is possible to accurately measure each switching time in parallel for bidirectional communication via the network.

  Further, in the present invention, the learning frame transmitting means has the second MAC address corresponding to the second port as the destination, the first MAC address corresponding to the first port as the transmission source, and The learning frame with the first network identification information added is transmitted from the first port of the measuring device to the second port, and the second MAC address is transmitted while the first MAC address is the destination. Each switching is performed by transmitting a learning frame based on the second network identification information different from the first network identification information to the first port from the second port of the measuring device. The hub may be made to learn communication path information including the first and second network identification information. In addition, the measurement frame transmission means uses the first MAC address as the transmission source and the measurement frame to which the second network identification information is added while setting the second MAC address as the destination. Transmits from the port to the second port, and measures the measurement frame to which the first MAC address is added and the first MAC identification information is added while the first MAC address is the destination It is possible to transmit from the second port of the device to the first port.

  In the case of the above aspect, for example, when a plurality of communication paths (for example, VLAN: Virtual Local Area Network) are constructed in the network, or for a wide area network that transfers MAC frames using an encapsulation technique ( 1) a communication direction for transferring frames from the first port to the second port via the wide area network; and (2) a communication direction for transferring frames from the second port to the first port via the wide area network. For both directions, it is possible to accurately measure the time required for the switching operation when a failure occurs.

  That is, in the above aspect, when the encapsulation technology is applied to the network, even if the content of the MAC address of the transmission source is processed by the measuring device (measurement frame transmission means), the switching hub that finally becomes the edge switch This is because the measurement frame is encapsulated and the processing of the source MAC address is not reflected in the communication path information. For this reason, in the above aspect, the network identification information is divided according to the direction of communication, thereby preventing invalidation of processing due to encapsulation. Specifically, for both the learning frame and the measurement frame, the first and second MAC addresses assigned to the respective ports of the measuring instrument are reflected as they are. Different contents (VLAN ID) are set for each direction. This prevents inadvertent rewriting of existing communication path information due to measurement frames transferred from the opposite direction during the switching operation at the time of failure, and ensures accurate communication in both directions. The switching operation time can be measured.

The present invention also provides a network evaluation system. The network evaluation system of the present invention includes a network that forms a communication path, and an evaluation device that evaluates the performance of the network while connected to the network.
The network of the evaluation system has a plurality of switching hubs that are connected to each other via a transmission line and logically redundantly configure communication paths by performing relay operations individually using a predetermined redundancy protocol. is there. Similarly to the network evaluation apparatus described above, the evaluation apparatus has a configuration of a measuring device, a learning frame transmission unit, a measurement frame transmission unit, and a measurement unit.

  The measuring device of the evaluation apparatus has a first port connected to one of a plurality of switching hubs in a network and one of the switching hubs as a node, and the first port is connected to the other switching hub. A second port with a different MAC address is connected. The learning frame transmission means of the evaluation device transmits a learning frame whose destination is the MAC address of each port from the first and second ports of the measuring device to the opposing second and first ports, respectively. As a result, in the process in which the learning frame is transferred between the nodes in the network, each of the plurality of switching hubs learns the communication path information based on the redundancy protocol. The measurement frame transmission means of the evaluation device has contents that do not match the communication path information learned by a plurality of switching hubs, with each MAC address of the first and second ports as the destination after transmission of the learning frame is completed. Are continuously transmitted from the first and second ports of the measuring device to the opposing second and first ports, respectively. Then, the measuring means of the evaluation apparatus, when the communication path switching operation based on the redundancy protocol is performed in the network during the transmission of the measurement frame, at least during the switching operation, the measuring device includes the first and second ports. The time required for the switching operation is measured based on the number of transmission / reception of measurement frames transmitted / received between them.

  As described above, the network evaluation system of the present invention includes the network infrastructure as a communication path and the evaluation device for evaluating the performance thereof, so that the “network” and the “evaluation device” each have utility value as a single unit. In addition to having the added value, the system as a whole has added value. Further, the network evaluation system of the present invention can exhibit the same usefulness as the above-described “network evaluation apparatus” by the configuration of the “evaluation apparatus”. It is possible to accurately and efficiently measure the time required for the switching operation of the communication path.

  Similarly for the “network evaluation system”, the learning frame transmission means of the “evaluation device” is directed to the second MAC address corresponding to the second port and the first MAC address corresponding to the first port. A learning frame with the first MAC address as the destination and the second MAC address as the transmission source, while transmitting the learning frame from the first port of the measuring device to the second port Is transmitted from the second port of the measuring instrument to the first port, whereby each switching hub can learn communication path information including the first and second MAC addresses. In addition, the measurement frame transmission means sends the measurement frame having the third MAC address different from both the first and second MAC addresses as the transmission source to the first MAC address of the measuring device while setting the second MAC address as the destination. Transmitting from the port to the second port, and for measurement with the first MAC address as the destination and the fourth MAC address different from any of the first, second, and third MAC addresses as the source Preferably, the frame is transmitted from the second port of the measuring instrument toward the first port.

  As a result, as in the case of the network evaluation apparatus described above, the first and second MAC addresses assigned to the respective ports of the measuring instrument are reflected as they are for the learning frame, while the transmission source for the measurement frame. By changing the MAC address of the network to virtual (or pseudo) content (for example, logical third and fourth MAC addresses different from the physical first and second MAC addresses). Inadvertent rewriting of the route information can be prevented. For this reason, as in the case of the network evaluation apparatus, each switching time can be accurately measured in parallel for bidirectional communication via the network.

  Alternatively, in the network evaluation system of the present invention, a plurality of switching hubs constituting a network can construct a plurality of virtual communication paths (for example, VLANs) that are mutually identified based on predetermined network identification information in the network. There may be. In this case, the learning frame transmitting means of the evaluation device uses the first MAC address corresponding to the first port as the transmission source while the second MAC address corresponding to the second port is the destination, and the first The learning frame to which the network identification information of 1 is added is transmitted from the first port of the measuring device to the second port, and the second MAC address is the transmission source while the first MAC address is the destination. And the learning frame to which the second network identification information different from the first network identification information is added is transmitted from the second port of the measuring device to the first port, thereby switching each switching hub. It is preferable to perform learning of communication path information including the first and second network identification information. In addition, the measurement frame transmission means uses the first MAC address as the transmission source and the measurement frame to which the second network identification information is added while setting the second MAC address as the destination. Transmits from the port to the second port, and measures the measurement frame to which the first MAC address is added and the first MAC identification information is added while the first MAC address is the destination It is preferable to transmit from the second port of the device toward the first port.

  In the case of the above aspect, for example, when a plurality of communication paths (for example, VLAN) are constructed in the network, or in the case of the network evaluation apparatus when the encapsulation technology is applied, each of the two directions of communication is accurate. The switching operation time can be measured.

  The present invention also provides a network evaluation method. The network evaluation method of the present invention is a network evaluation that evaluates a network that forms a logically redundant communication path by connecting a plurality of switching hubs that perform relay operations using a predetermined redundancy protocol. The method includes the following steps [1] to [3].

[1] Learning frame transmission process In this process, one of the plurality of switching hubs is used as each node, the first port is connected to one of the nodes, and the other switching hub is connected to the first port. Using a measuring instrument connected to a second port with a different MAC address, learning with the MAC address of each port as the destination from the first and second ports toward the opposing second and first ports, respectively By transmitting the communication frame, each of the plurality of switching hubs is made to learn the communication path information based on the redundancy protocol in the process in which the learning frame is transferred between the nodes in the network.

[2] Measurement frame transmission step In this step, after the transmission of the learning frame in the learning frame transmission step is completed, the MAC addresses of the first and second ports are set as destinations, and a plurality of switching hubs are transmitted. Then, measurement frames that do not match the learned communication path information are continuously transmitted from the first and second ports of the measuring device to the opposing second and first ports, respectively.

[3] Measurement process In this process, when a communication path switching operation based on the redundant protocol is performed in the network during the transmission of the measurement frame in the measurement frame transmission process, at least during the switching operation, The time required for the switching operation is measured based on the number of transmission / reception of measurement frames transmitted / received between the first and second ports.

  According to the network evaluation method of the present invention, in the learning frame transmitting step of [1], learning frame information transmitted bi-directionally between nodes is learned by each switching hub. (1) communication from the first port of the measuring device to the second port, and (2) communication from the second port of the measuring device to the first port. A bidirectional communication path is established based on the redundancy protocol. In the measurement frame transmission step [2], the measurement frame is transmitted bidirectionally using the communication path that has already been established.

  In the measurement step [3] above, when a communication failure occurs in the network (for example, transmission line) during the continuous transmission of measurement frames, each switching hub performs a communication path switching operation based on the redundancy protocol. However, while this switching operation is being performed, the measurement frame transmitted from the measuring instrument is discarded by the switching hub that has received it. After that, when a new communication path after switching is established based on the redundancy protocol, measurement frames can be transferred at last, so the number of measurement frames transmitted from the measuring device during this period and the receiving by the measuring device There is a difference between the number of measured frames. Based on this difference, the time required for switching the communication path can be accurately calculated.

  Also in the network evaluation method of the present invention, as in the network evaluation apparatus and the network evaluation system described above, regarding the evaluation frame transmitted from the measuring device, the learning frame transmitted in the step [1], and the above-described [2] It is possible to accurately measure time by configuring the measurement frame to be transmitted separately in the process. Similarly, measurement frames are transmitted in both directions from each port of the measuring instrument, so that the time required for efficient bidirectional switching can be accurately measured without performing measurement in each direction. can do.

  In the learning frame transmission step of [1], a learning frame is measured with the second MAC address corresponding to the second port as the destination and the first MAC address corresponding to the first port as the transmission source. Transmitting from the first port of the measuring device to the second port, and sending a learning frame from the second port of the measuring device to the second port of the measuring device with the first MAC address as the destination and the second MAC address as the transmission source. By transmitting to one port, it is assumed that each switching hub learns communication path information including the first and second MAC addresses.

  Further, in the measurement frame transmission step of [2], the measurement frame having the second MAC address as the destination and the third MAC address different from any of the first and second MAC addresses is measured. The first MAC address is transmitted from the first port to the second port, and the fourth MAC address different from any of the first, second, and third MAC addresses is transmitted while the first MAC address is the destination. Assume that the original measurement frame is transmitted from the second port of the measuring device to the first port.

  If it is said aspect, like the case of the network evaluation apparatus and network evaluation system which were mentioned above, about the learning frame, reflecting the 1st and 2nd MAC addresses assigned to each port of the measuring instrument as it is, For the measurement frame, the source MAC address is set to virtual (or pseudo) content (for example, logical third and fourth MAC addresses different from the physical first and second MAC addresses). By changing, it is possible to prevent inadvertent rewriting of existing communication path information. For this reason, as in the case of the network evaluation apparatus and the network evaluation system, the switching times of the two-way communication via the network can be accurately measured in parallel.

  Alternatively, in the learning frame transmission step of [1], the second MAC address corresponding to the second port is the destination, the first MAC address corresponding to the first port is the transmission source, and The learning frame with the first network identification information added is transmitted from the first port of the measuring device to the second port, and the second MAC address is transmitted while the first MAC address is the destination. Each switching is performed by transmitting a learning frame based on the second network identification information different from the first network identification information to the first port from the second port of the measuring device. The hub may be made to learn communication path information including the first and second network identification information.

  In the measurement frame transmission step of [2], the measurement frame is measured with the first MAC address as the transmission source and the second network identification information added, while the second MAC address is the destination. The first MAC port to the second port, the first MAC address as the destination, the second MAC address as the source, and the first network identification information added The measurement frame may be transmitted from the second port of the measuring device toward the first port.

  In the case of the above aspect, for example, in the case where a plurality of communication paths (for example, VLAN) are constructed in the network, or in the same manner as the network evaluation apparatus and the network evaluation system when the encapsulation technology is applied, both communication The switching operation time can be accurately measured for each direction.

  As described above, according to the network evaluation device, the network evaluation system, and the network evaluation method of the present invention, the network performance can be efficiently and accurately evaluated for bidirectional communication via the network.

It is the figure which showed schematically the example of a structure of the network evaluation apparatus of 1st Embodiment. It is a figure which shows roughly the structure of the frame for a learning, and the frame for a measurement. It is the figure which showed roughly the transfer path | route of the frame for a learning transmitted through each network from each port of a measuring device. It is a figure which shows roughly the structure of the FDB table registered (learned) in each switching hub with transmission of the learning frame. It is a figure which shows roughly the structure of the FDB table registered (updated) in each switching hub with transmission of the flame | frame for measurement. It is the schematic which shows the state in which the switching operation | movement of the communication path based on the redundancy protocol was performed in the network. It is a flowchart which shows the process in the switching hub at the time of link down generation | occurrence | production. It is a flowchart which shows the process in the switching hub at the time of link down generation | occurrence | production. It is a flowchart which shows the process during the frame transfer in a switching hub. It is a figure which shows roughly the FDB table of each switching hub reconfigure | reconstructed after link-down occurrence. It is a figure which shows roughly the structure of the frame for a learning used in 2nd Embodiment, and the frame for a measurement. It is the figure which showed schematically the transfer path | route of the frame for a learning transmitted through the network from each port of a measuring device in 2nd Embodiment. It is a figure which shows roughly the structure of the FDB table registered (learned) in each switching hub with transmission of the learning frame. It is a figure which shows roughly the structure of the FDB table registered (updated) in each switching hub with transmission of the frame for a measurement from a measuring device. It is the schematic which shows the state in which the switching operation | movement of the communication path based on the redundancy protocol was performed in the network in 2nd Embodiment. It is a figure which shows roughly the structure of the FDB table of the switching hub after link down generation | occurrence | production.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following, the network evaluation apparatus and the embodiment of the network evaluation method implemented using the network evaluation apparatus will be mainly described. However, a combination of the network evaluation apparatus and the network is an embodiment as a “network evaluation system”. Become.

[First Embodiment]
FIG. 1 is a diagram schematically illustrating a configuration example of a network evaluation device 1 according to the first embodiment. The network evaluation device 1 according to the first embodiment can evaluate the network 2 in a state where it is connected to the ring network 2 using, for example, a redundancy protocol. The redundant network 2 is evaluated by, for example, accurately measuring the time required for the redundant path switching operation that is executed when link down occurs. That is, the measured required time indicates that the shorter the result (the faster the switching), the higher the performance of the network 2.

  The network evaluation apparatus 1 mainly includes a measuring instrument 4 and a PC 6 (personal computer). Among these, the measuring device 4 is a communication device having a network communication function, and the network communication operation by the measuring device 4 can be operated using, for example, the PC 6. The measuring device 4 has a first port 4a connected to the port 8a of one switching hub 8 and a transmission line 3 (network cable), and a second port 4b connected to the port 14c of the switching hub 14 and the transmission line 5 By connecting these two, the network 2 can be accessed with these two switching hubs 8 and 14 as nodes. The measuring instrument 4 transmits and receives frames at the ports 4a and 4b, and also has a function of counting the number of transmitted and received frames and storing the number.

  The network 2 to be evaluated forms a ring (loop) topology by connecting a plurality of switching hubs 8, 10, 12, and 14 through transmission lines 9, 11, 13, and 15. That is, in the network 2, for example, the switching hub 8 and the switching hub 10 are connected between the respective ports 8b and 10a by the transmission line 9, and the switching hub 10 and the switching hub 14 are connected between the respective ports 10b and 14b. They are connected by a transmission line 11. The switching hub 14 and the switching hub 12 are connected to each other between the ports 14a and 12b by a transmission line 15, and the switching hub 12 and the switching hub 8 are connected to each other between the ports 12a and 8c. Connected with.

  Each of the switching hubs 8, 10, 12, and 14 is implemented with a redundancy protocol such as STP (Spanning Tree Protocol) or RSTP (Rapid Spanning Tree Protocol). As a result, the root bridge, the root port, and the blocking port are determined for each switching hub 8, 10, 12, and 14 in the network 2 based on the redundancy protocol, and the redundant path in the network 2 is determined.

  In the network 2 described above, for example, one port 12b of the switching hub 12 is logically put into a blocking state, and frame transfer and reception are not performed at the blocking port 12b. The other ports 8b and 8c of the switching hub 8, the ports 10a and 10b of the switching hub 10, and the ports 14a and 14b of the switching hub 14 are all set to the forwarding state, and these ports 8b, 8c, 10a, 10b, Frames 14b and 14c can transfer and receive frames.

  FIG. 2 is a diagram schematically showing the configuration of the learning frames 18 and 20 and the measurement frames 22 and 24 used in the network 2 evaluation method. These learning frames 18 and 20 and measurement frame 22 are shown by extracting only a part of the header of the MAC frame for convenience, and all of them are destination MAC addresses 18a, 20a, 22a, 24a and The source MAC addresses 18b, 20b, 22b, and 24b are included in a part of the header of the MAC frame. The network evaluation device 1 transmits the learning frames 18 and 20 and the measurement frames 22 and 24 separately from the ports 4a and 4b of the measuring instrument 4, thereby accurately determining the time required for switching the redundant path by the network 2. Can be measured.

[Learning frame]
In FIG. 2, (A): First, the learning frame 18 shown in the upper part has a configuration in which, for example, the destination MAC address 18a is “B” and the source MAC address 18b is “A”. On the other hand, the learning frame 20 shown in the lower row has a configuration in which the destination MAC address 20a is “A” and the source MAC address 22a is “B”. At this time, “A” is assigned as a physical MAC address in advance to the first port 4a of the measuring instrument 4, and “B” is assigned as a physical MAC address to the second port 4b. It shall be. The MAC addresses “A” and “B” may be logically assigned to the ports 4a and 4b.

[Measurement frame]
In FIG. 2, (B): Next, in the measurement frame 22 shown in the upper part, for example, the destination MAC address 22a is set to “B” corresponding to the port 4b, and the source MAC address 22b is set to any of the ports 4a and 4b. The configuration is “D” which does not correspond to the above. On the other hand, in the measurement frame 24 shown in the lower part, the destination MAC address 24a is set to “A” corresponding to the port 4a, and the source MAC address 22a is set to “C” which does not correspond to any of the ports 4a and 4b. It has a configuration. These source MAC addresses “D” and “C” are logical MAC addresses virtually (pseudo) assigned to the ports 4 a and 4 b of the measuring device 4.

  Next, a method for evaluating the network 2 using the learning frames 18 and 20 and the measurement frames 22 and 24 will be described.

[Learning frame transmission process]
FIG. 3 is a diagram schematically showing transfer paths of learning frames 18 and 20 transmitted from the ports 4a and 4b of the measuring device 4 through the network 2. As shown in FIG. In the drawings and the following description, the abbreviations “DA (Destination Address)” and “SA (Source Address)” are used for the learning frames 18 and 20 or the measurement frames 22 and 24.

  First, the measuring instrument 4 is operated using the PC 6, and only one learning frame 18 (DA: B, SA: A) is transmitted from the first port 4a to the second port 4b. On the other hand, only one frame for learning 20 (DA: A, SA: B) is transmitted from the second port 4b of the measuring instrument 4 to the first port 4a. As used herein, “DA” is an abbreviation for “destination MAC address”, and “SA” is an abbreviation for “source MAC address”. Therefore, when the learning frame 18 is represented as “DA: B, SA: A”, it indicates that the destination MAC address 18a of the MAC frame portion is “B” and the source MAC address 18b is “A”. It means that there is. Similarly, when the learning frame 20 is expressed as “DA: A, SA: B”, the destination MAC address 20a of the MAC frame portion is “A”, and the source MAC address 20b is “B”. (The same applies to the following.)

  As shown in FIG. 3, one of the learning frames 18 (denoted by “DA: B, SA: A”) is transmitted from the first port 4a of the measuring instrument 4 that is the transmission source to the network 2. Are sequentially transferred via the switching hubs 8, 10, and 14, and finally transferred to the destination port 4b. Another learning frame 20 (denoted by “DA: A, SA: B”) passes through the switching hubs 14, 10, and 8 within the network 2 from the second port 4 b of the measuring device 4 that is the transmission source. Are sequentially transferred, and finally transferred to the destination port 4a.

  At this time, when each of the switching hubs 8, 10, 14 receives the learning frame 18 described by “DA: B, SA: A”, the source MAC address “A” and the ports 8 a, 10 a that have received the source MAC address “A”. , 14b in association with each other, and the result is registered in the FDB. Similarly, for the learning frame 20 described by “DA: A, SA: B”, each switching hub 14, 10, 8 has its source MAC address “B” and the port 14c, 10b and 8b are associated and learned, and the result is registered in the FDB.

[Learning with learning frame for DA: B, SA: A]
For example, if the switching hub 8 as one node has not yet received the opposite learning frame 20, the MAC address “B” corresponding to the port 4b of the measuring instrument 4 is not registered in the FDB. As for the learning frame 18 representing the destination MAC address “B”, the port to which this frame is to be transferred is not uniquely determined. Therefore, when the switching hub 8 receives the learning frame 18 from the measuring device 4, the learning frame 18 is flooded from the ports 8b and 8c other than the port 8a that has received the learning frame 18. Similarly, when the switching hubs 10 and 14 receive the learning frame 18 indicating the destination MAC address “B” that is not registered in the FDB, the ports 10 b, 14 a, and 14 c other than the ports 10 a and 14 b that have received these frames. The learning frame 18 is flooded and the source MAC address “A” is registered in the FDB in association with each of the ports 10a and 14b.

[Learning with learning frame for DA: A, SA: B]
Alternatively, if the switching hub 14 serving as the other node has not yet received the learning frame 18, the MAC address “A” corresponding to the port 4a of the measuring instrument 4 is not registered in the FDB. Also for the learning frame 20 representing the MAC address “A”, the port to which this frame is to be transferred is not uniquely determined. Therefore, when the switching hub 14 receives the opposite learning frame 20 from the measuring device 4, the learning frame 20 is flooded from the ports 14a and 14b other than the port 14c that has received the learning frame 20. Similarly, when the switching hubs 10 and 8 receive the learning frame 20 indicating the destination MAC address “A” that is not registered in the FDB, the ports 10a, 8a, and 8c other than the ports 10b and 8b that have received them are received. The learning frame 20 is flooded and the source MAC address “B” is registered in the FDB in association with each port 10b, 8b.

  When the above learning is performed, the first path 4b from the second port 4b to the second port 4b via the network 2 from the first port 4a of the measuring instrument 4 and the first port via the network 2 will be described later. A communication path toward the port 4a is established in both directions.

  FIG. 4 is a diagram schematically showing the configuration of the FDB table registered (learned) in each switching hub 8, 10, 14 with the transmission of the learning frames 18, 20 from the measuring device 4. In addition, since the learning frames 18 and 20 are not transferred in the switching hub 12 in which the blocking port is logically set in the network 2, the FDB related to the switching hub 12 is not shown here.

  4A: In the FDB of the switching hub 8 connected to the first port 4a of the measuring device 4, the MAC address “A” of the first port 4a is received in the port 8a that has received the learning frame 18. Is learned, and the MAC address “B” of the second port 4b is learned at the port 8b that has received the learning frame 20 opposite thereto.

  4B: Next, in the FDB of the switching hub 10, the MAC address “A” of the first port 4 a is learned in the port 10 a that has received the learning frame 18, and is opposite to this. The MAC address “B” of the second port 4b is learned at the port 10b that has received the learning frame 20.

  4C: In the FDB of the switching hub 14 connected to the second port 4b of the measuring instrument 4, the MAC address “B” of the second port 4b is received in the port 14c that has received the learning frame 20. And the MAC address “A” of the first port 4a is learned at the port 14b that has received the learning frame 18 opposite thereto.

[Measurement frame transmission process]
The network evaluation apparatus 1 transmits the learning frames 18 and 20 from the ports 4a and 4b of the measuring device 4 one frame at a time, and then transmits the measurement frames 22 and 24 at an arbitrary rate (for example, 10,000 frames). / Sec) continuously from each port 4a, 4b. At this stage, since FDB registration (learning) has already been completed for the MAC addresses “A” and “B”, each of the switching hubs 8, 10, and 14 has a destination MAC indicated in the measurement frames 22 and 24. The addresses “B” and “A” are compared with the MAC addresses registered in the respective FDBs, and the measurement frames 22 and 24 are transferred from the corresponding ports.

  On the other hand, since the source MAC addresses “D” and “C” shown in the measurement frames 22 and 24 do not exist in the FDB entry at the present time, the switching hubs 8, 10, and 14 Along with the transfer of 22 and 24, MAC addresses “D” and “C” are newly added to the FDB.

  As described above, when the measurement frames 22 and 24 are continuously transmitted from the respective ports 4a and 4b of the measuring instrument 4, the measurement frames 22 and 24 are moved along the path indicated by the white arrow in FIG. It is transferred in the opposite direction. Although not shown in particular, the learning frame 18 shown in FIG. 3 is replaced with the measurement frame 22 (DA: B, SA: D) during transmission of the measurement frames 22 and 24, and the learning frame opposite to the measurement frame 22 (DA: B, SA: D). 20 is replaced with the measurement frame 24 (DA: A, SA: C). That is, the measurement frame 22 is transmitted from the first port 4a of the measuring instrument 4 and is received by the second port 4b via the switching hubs 8, 10, and 14 in the network 2 in order. On the other hand, the measurement frame 24 is transmitted from the first port 4 b of the measuring instrument 4 and is received by the first port 4 a via the switching hubs 14, 10, 8 in the network 2 in order.

  FIG. 5 is a diagram schematically showing the configuration of the FDB table registered (updated) in each of the switching hubs 8, 10, 14 with the transmission of the measurement frames 22, 24 from the measuring device 4. Similarly, since the measurement frames 22 and 24 are not transferred in the switching hub 12 in which the blocking port is logically set in the network 2, the FDB related to the switching hub 12 is not shown.

  In FIG. 5, (D): As described above, the measurement frames 22 and 24 have MAC addresses “D” and “C” that do not exist in the learned FDB entry (communication path information). For this reason, the FDB of the switching hub 8 is learned by adding the MAC address “D” to the port 8a that has received the measurement frame 22, and the port 8b that has received the opposite measurement frame 24 has been learned. Is learned by adding the MAC address “C”.

  In FIG. 5E, the FDB of the switching hub 10 is learned by adding the MAC address “D” to the port 10a that has received the measurement frame 22, and the measurement frame 24 opposite thereto. The MAC address “C” is additionally learned in the port 10b that has received.

  (F) in FIG. 5: In the FDB of the switching hub 14, the MAC address “C” is additionally learned by the port 14c that has received the measurement frame 24, and the measurement frame opposite to this is learned. The MAC address “D” is additionally learned in the port 14 b that has received 22.

[Measurement process]
With the start of transmission of the measurement frames 22 and 24, the number of transmission / reception of the measurement frames 22 and 24 by the measuring device 4 is counted, and the number of frame transmissions and the number of receptions for each port 4a and 4b is measured by the measuring device 4 (PC6 may be used). ).

  In the process of continuously transmitting the measurement frames 22 and 24, a link down (communication failure) occurs in the network 2. In this case, the network 2 performs an operation of switching the communication path so far based on the redundancy protocol. Specifically, an operation of switching from a communication path that passes through the switching hubs 8, 10, and 14 before the link down to a new communication path that passes through the switching hubs 8, 12, and 14 is performed. Until the communication path is switched, the measurement frames 22 and 24 transmitted from the measuring device 4 are continuously discarded by the switching hub (not specifying the code) that detects link-down. When the switching operation of the communication path is completed, the measurement frames 22 and 24 are transferred through the network 2 through the new communication path. During this time, the measuring instrument 4 performs the measurement frames 22 and 24 respectively. Therefore, there is a difference between the number of transmitted frames and the number of received frames. Therefore, the time required for switching the communication path can be accurately calculated from a value obtained by dividing this difference by a rate (for example, 10,000 frames / sec). For example, if the difference between the number of transmitted frames and the number of received frames is 1,000 frames, the time required for switching can be calculated as 1,000 / 10,000 = 0.1 seconds.

  FIG. 6 is a schematic diagram showing a state in which a communication path switching operation based on the redundancy protocol is performed in the network 2. Below, for example, the flow of the switching operation will be described assuming that a failure occurs in the transmission line 9 between the switching hubs 8 and 10.

  When the port 8b of the switching hub 8 is linked down, the MAC address “B” learned at the port 8b is flushed (“flush” means “erase registered contents”. ). Then, the measurement frame 22 having the destination MAC address “B” is flooded by the switching hub 8 and transmitted to the switching hub 12 from another port 8 c. In addition, the switching hubs 8 and 10 that have detected the occurrence of link down together transmit link down information to the other switching hubs 12 and 14 in the network 2.

  Further, when the switching hub 14 receives the link down information from the switching hub 10 (or the switching hub 8) that detects the occurrence of the link down, the switching hub 14 flushes its own FDB table. As a result, the MAC address “A” that has been learned at the port 14 b until then is cleared, so the measurement frame 24 with the destination MAC address “A” is also flooded by the switching hub 14 and switched from another port 14 a. It will be transmitted to the hub 12.

  On the other hand, when the switching hub 12 in which the port 12b has been in the blocking state until then receives the link down information from the switching hub 8, for example, the switching hub 12 releases the blocking state of the port 12b and changes it to the forwarding state. As a result, the measurement frames 22 and 24 are transferred bidirectionally via the switching hub 12 thereafter.

[Switching operation time]
The switching operation described above includes (1) communication from the first port 4a of the measuring instrument 4 to the second port 4b, and (2) communication from the second port 4b of the measuring instrument 4 to the first port 4a. Since the switching mechanism is different in each direction, the time required for the switching operation differs depending on the direction. When a failure occurs in the transmission line 9 due to the physical configuration of the network 2 shown in FIG. 6, the FDB flush occurs first from the switching hub 8 near this, and then the link hub information is received and then the switching hub 14 causes an FDB flush. Therefore, it is considered that the communication of (2) usually takes a longer time for the switching operation than the above (1).

  That is, (1) For communication from the first port 4a of the measuring instrument 4 to the second port 4b, at least FDB flushing by the switching hub 8 and from the blocking state of the port 12b by the switching hub 12 to the forwarding state. The switching operation is performed by performing the transition. For this reason, the FDB flush by the switching hub 14 is not directly related there. However, since the measurement frames 22 received by the switching hub 12 are discarded until the port 12b transitions from the blocking state to the forwarding state, the total number of measurement frames 22 discarded during this time is required for the switching operation. Will accurately represent the time spent. Note that the number of discarded frames is represented by the difference between the number of transmitted frames and the number of received frames as described above.

  On the other hand, for (2) communication from the second port 4b of the measuring instrument 4 to the first port 4a, at least FDB flushing by the switching hub 14 and the blocking state of the port 12b by the switching hub 12 are changed to the forwarding state. The switching operation is performed by performing the transition. For this reason, the FDB flush by the switching hub 8 is not directly related there. However, the switching hub 14 continues to transfer the measurement frame 24 from the port 14b to the switching hub 10 that is physically linked down until the FDB is flushed by the switching hub 14. The transferred measurement frame 24 is discarded by the switching hub 10. Therefore, for the communication (2), the total number of measurement frames 24 discarded during this time accurately represents the time required for the switching operation. Similarly, the number of discarded frames is represented by the difference between the number of transmission frames and the number of reception frames as described above.

[Comparative example]
However, for example, regarding communication (2) from the second port 4b of the measuring device 4 to the first port 4a, before the FDB is flushed by the switching hub 14, the port 14a is associated with the MAC address “A”. Is overwritten and updated, the measurement frame 24 is transferred from the port 14 a of the switching hub 14 toward the switching hub 12. In this case, even if the switching operation is not completed according to the original mechanism, the measuring device 4 is ready to receive the measurement frame 24, and the switching operation time is accurately calculated from the difference in the number of frames transmitted and received. Can not do.

  The comparative example as described above may occur when the source MAC address “A” is indicated in the opposite measurement frame 22. That is, when the port 12b of the switching hub 12 transitions to the forwarding state before FDB flushing is performed at the switching hub 14, the opposite measurement frame 22 passes through the switching hubs 8 and 10 at the port 14a of the switching hub 14. Received. In this case, in the switching hub 14, the learning of the transmission source MAC address “A” causes a problem that the FDB overwrite update is performed in a state where the MAC address “A” is associated with the port 14 a.

  Therefore, in the first embodiment, by setting the source MAC address “D” that does not exist in the FDB entry that has already been learned in the switching hub 14 in the measurement frame 22, the occurrence of the above-described problem can be prevented, It enables accurate switching operation time measurement. Alternatively, when a failure occurs in another transmission line 11, it is expected that the communication of (1) above will be switched with a delay, but this also applies to the FDB already learned in the switching hub 8. By setting the source MAC address “C” that does not exist in the entry to the measurement frame 24, the occurrence of the same problem is prevented.

  In order to make the understanding of the network evaluation method used in the first embodiment more reliable, a specific example is given below for the processing executed by each switching hub 8, 12, 14 as part of the switching operation by the network 2. explain.

  FIG. 7 is a flowchart showing processing in the switching hub 8 when a link down occurs. Here, as described above, it is assumed that a failure occurs in the transmission line 9 between the switching hub 8 and the switching hub 10. In the switching hub 8, for example, when link down is detected at the port 8b, the processing of FIG. 7 is started using this as a trigger.

  Step S102: First, the switching hub 8 transmits a link down message simultaneously from the ports 8a and 8c that have not detected the link down.

  Step S104: Next, when the measurement hub 22 is received, the switching hub 8 discards the received measurement frame 22 because the transfer from the port 8b that has detected link down cannot be executed. On the other hand, the measurement frame 24 received at the port 8b immediately before the occurrence of the link down is transferred from the port 8a to the port 4a of the measuring instrument 4 based on the FDB. After the link down is detected, the measurement frame 24 is not transferred to the switching hub 8 until the switching hub 14 executes FDB flushing as described above.

  Step S106: The switching hub 8 executes FDB flush (erase) as described above. As a result, all the MAC addresses associated with the port 8b registered in the FDB are deleted. When the FDB flush is not executed, the procedure of step S104 and step S106 is repeated until the flush is executed.

  Step S108: The switching hub 8 starts learning the MAC address newly received by the port 8c in the flushed FDB.

  Step S110: The measuring frame 22 is continuously transmitted from the measuring device 4 to the port 8a even while the link down is continued. At this time, since the destination MAC address “B” of the measurement frame 22 does not exist in the FDB of the switching hub 8, the transfer destination port is not uniquely determined. Therefore, the switching hub 8 floods the measurement frame 22 from the port 8c. However, the above flooding is not executed from the port 8a that has received the measurement frame 22 and the port 8b that has detected link-down.

  When the opposite measurement frame 24 is transferred from the switching hub 12 while the link down is continuing, the switching hub 8 learns the source MAC address “D” in association with the port 8c, and registers this in the FDB. (Step S108). Then, the switching hub 8 floods the transferred measurement frame 24 from the port 8a (step S110).

When the above procedure is executed, the switching hub 8 ends (END) this flow.
In this way, the switching hub 8 continues to discard the measurement frame 22 from when the link down is detected until the FDB is refreshed. When the FDB is flushed, the measurement frame 22 can be transferred from the port 8c to the switched communication path.

  Next, FIG. 8 is a flowchart showing processing in the switching hub 12 when link down occurs. Since the switching hub 12 has the blocking port (port 12b) as described above, the measurement frames 22 and 24 are not transferred until the link down occurs in the network 2, but if the link down occurs, the communication is performed. The measurement frames 22 and 24 are transferred in place of the switching hub 10 as a path switching destination. That is, the switching hub 12 starts the following process triggered by the reception of the link down message from the switching hub 8 at the port 12a.

  Step S202: First, the switching hub 12 cancels the setting of the port 12b in the blocking state, and shifts the port 12b to the forwarding state as described above.

  Step S204: Next, when the switching hub 12 receives the flooded measurement frame 22 from the switching hub 8 (Yes), the switching hub 12 learns the source MAC address “D” of the measurement frame 22 in association with the port 12a, This is registered in the FDB (step S206). Further, the measurement frame 22 is flooded from the port 12b in the forwarding state (step S208). If the measurement frame 22 has not been received (No), the switching hub 12 bypasses steps S206 and S208 and proceeds to step S210.

  Step S210: The switching hub 12 transfers the link-down message from the port 12b other than the port 12a that has received the link-down message.

  Step S212: When the switching hub 12 receives the measurement frame 24 from the switching hub 14 at the port 12b as described above (Yes), the process proceeds to the next step S214. If the measurement frame 24 has not been received (No), the procedure of step S212 is repeated until it is received. Note that the measurement frame 24 is actually received from the switching hub 14 after the FDB flush occurs in the switching hub 14 as described above.

  Step S214: The switching hub 12 learns the transmission source MAC address “C” of the measurement frame 24 in association with the port 12b, and registers this in the FDB.

  Step S216: At this time, since the transfer destination port for the destination MAC address “A” of the received measurement frame 24 is not registered in the FDB, the switching hub 12 floods the measurement frame 24 from the port 12a other than the port 12b. To do. After that, when the measurement frame 22 is received from the switching hub 8, the switching hub 12 floods the measurement frame 22 from the port 12b in the forwarding state as in the previous step S208.

  When the above procedure is executed, the switching hub 12 ends (END) this flow.

  Next, FIG. 9 is a flowchart showing processing during frame transfer in the switching hub 14. Due to the occurrence of link down, a link down message is transferred from the switching hub 10 or the switching hub 12 to the switching hub 14. However, the processing flow executed by the switching hub 14 varies depending on the timing at which the measurement frame 22 is transferred from the switching hub 12 to the switching hub 14.

  Step S300: When the switching hub 14 receives a link down message from either the switching hub 12 or the switching hub 10 during frame transfer (Yes), the switching hub 14 transmits a link down message from a port other than the port that received the link down message. (Step S302). When the link down message has not been received yet (No), the switching hub 14 executes the next step S306.

[Before receiving link down message]
Step S306: When the switching hub 14 receives the measurement frame 22 from the switching hub 12 (judgment result = A), the port 14b associated with the MAC address “D” in the FDB is overwritten on the port 14a to the FDB. Register (step S308). Further, the destination MAC address “B” of the measurement frame 22 is checked against the FDB, and this is transferred from the port 14c to the measuring device 4 (step S310).

  On the other hand, when the measurement frame 24 transmitted from the measuring instrument 4 is received at the port 14c (judgment result = B), the switching hub 14 transfers the measurement frame 24 from the port 14b based on the FDB (step S312). As for the processing of the measurement frame 22 and the measurement frame 24, the above steps S300 and steps S306 to S312 are repeated until a link down message is received. Note that the measurement frame 24 transferred from the port 14 b is discarded by the switching hub 10.

[After receiving the link down message]
Step S304: After receiving the link down message, when the switching hub 14 performs FDB flush (Yes), the switching hub 14 erases all the MAC addresses registered in association with the ports 14a and 14b, and Step S314 is executed.

  Step S314: When the FDB is flushed, the switching hub 14 receives the measurement frame 24 transmitted from the measuring instrument 4 at the port 14c, or the measurement frame 22 flooded from the switching hub 12 at the port 14a. Receive.

  Step S324: The switching hub 14 updates the FDB based on the received measurement frames 22 and 24. That is, the transmission source MAC address “D” of the measurement frame 22 is registered in the FDB in association with the port 14a, and the transmission source MAC address “C” of the measurement frame 24 is registered in the FDB in association with the port 14c.

  Step S326: However, since the MAC addresses “A” and “B” are not registered in the FDB after flushing, the switching hub 14 floods the measurement frame 24 from the ports 14a and 14b and also measures the measurement frame 22 Are flooded from the ports 14b, 14c. Both the measurement frames 22 and 24 flooded from the port 14b are discarded by the switching hub 10. The measurement frame 22 flooded from the port 14 c is received by the port 4 b of the measuring device 4. The measurement frame 24 flooded from the port 14 a is transferred to the port 4 a of the measuring instrument 4 via the switching hub 12 and the switching hub 8.

  In the previous step S304, if the FDB flush has not been executed yet due to the time lag after receiving the link down message (No), the switching hub 14 executes step S316.

  Step S316: When the measurement frame 22 is received before executing the FDB flush (judgment result = A), the switching hub 14 changes the association of the source MAC address “D” from the port 14b to the port 14a and changes the FDB. Is overwritten (step S318). Further, based on the FDB, the measurement frame 22 is transferred from the port 14c to the measuring instrument 4 (step S320).

  On the other hand, when the measurement frame 24 is received at the port 14c (judgment result = B), the switching hub 14 transfers this from the port 14b based on the FDB (step S322). For the transfer of the measurement frames 22 and 24, the procedure from step S304 and step S316 to step S322 is repeated until the FDB flush is executed. Note that the measurement frame 24 transferred from the port 14 b is discarded by the switching hub 10.

  When the above procedure is executed, the switching hub 14 ends (END) this flow.

  As described above, in order to transfer the measurement frame 24 from the switching hub 14 which is the communication path after switching to the port 4a of the measuring instrument 4 via the switching hub 12 and the switching hub 8, the switching hub 14 It can be seen that the FDB needs to be flushed.

  FIG. 10 is a diagram schematically showing the FDB table of each of the switching hubs 8, 12, and 14 reconstructed after the link down occurs.

  In FIG. 10, (A): In the FDB of the switching hub 8, the MAC address “D” is registered in association with the port 8a. Further, the MAC address “C” is registered in the FDB in association with the port 8c.

  FIG. 10B: In the FDB of the switching hub 12, the source MAC address “D” is registered in association with the port 12a by learning the flooded learning frame 22. In addition, the source MAC address “C” is registered in association with the port 12b by learning the measurement frame 24 flooded on the opposite side.

  (C) in FIG. 10: In the FDB of the switching hub 14, the source MAC address “D” is registered in association with the port 14 a by the measurement frame 22 flooded from the switching hub 12. Further, all the MAC addresses registered in association with the port 14b are deleted, and learning of the MAC address is performed again. As a result, the MAC address “C” is registered in association with the port 14c.

  (D) in FIG. 10: This shows the state of the FDB learned when the switching hub 14 receives the measurement frame 22 from the switching hub 12 before the FDB flush is executed. That is, when the measurement frame 22 is received before receiving the link down message in step S306 in FIG. 9, the source MAC address “D” is changed from the port 14b to the port 14a and overwritten in the FDB in the subsequent step S308. The At this time, the transfer destination MAC address “A” of the measurement frame 24 is registered in the FDB in association with the port 14b. For this reason, even if the measurement frame 24 is transferred from the port 14b, it is discarded by the switching hub 10 thereafter.

  As described above, in the network evaluation method executed by the network evaluation apparatus 1, after the learning frames 18 and 20 are transmitted, the measurement frames 22 and 24 that do not match the FDB entries learned by these are transmitted to perform the switching operation. Therefore, even when the measurement is performed while transmitting the measurement frames 22 and 24 in both directions, it is possible to measure the exact switching operation time in each direction.

  In addition, it is not necessary to separately measure the switching operation time for each direction, and the time required for each switching operation can be accurately calculated in parallel with bi-directional communication. Can be suppressed.

[Second Embodiment]
Next, a second embodiment of the network evaluation device 1 will be described. In the second embodiment, the physical configuration of the network 2 (FIG. 1) is the same as that of the first embodiment, but it is assumed that there are a plurality of virtual networks (VLANs) having different identification information in the network 2. Yes.

  FIG. 11 is a diagram schematically showing the configuration of the learning frames 180 and 200 and the measurement frames 220 and 240 used in the second embodiment. That is, in the second embodiment, a VLAN TAG is included in a part of the MAC frame header of the learning frames 180 and 200 and the measurement frames 220 and 240, and a VLAN ID (hereinafter referred to as VID) in the VLAN TAG is communicated. This is different from the first embodiment in that each direction is changed.

  In this case, it is assumed that different “VID1” and “VID2” are set in the ports 4a and 4b of the measuring instrument 4, respectively. Since other physical configurations are the same as those in the first embodiment, the same reference numerals as those in the first embodiment are assigned to these components, and redundant description thereof is omitted. Hereinafter, the difference from the first embodiment will be mainly described.

  FIG. 11 schematically shows configurations of learning frames 180 and 200 and measurement frames 220 and 240 used in the second embodiment.

[Learning frame]
In FIG. 11, (A): As shown in the upper part, the learning frame 180 used in the second embodiment includes a destination MAC address 180a, a source MAC address 180b, and a VLAN TAG 180c in a part of the header of the MAC frame. It is assumed that “VID1” is included in the VLAN TAG 180c.
Also, as shown in the lower row, the destination learning MAC address 200a, the source MAC address 200b, and the VLAN TAG 200c are also included in a part of the header of the MAC frame in the learning frame 200 on the opposite side. “VID2” is included in the TAG 200c.

[Measurement frame]
(B) in FIG. 11: As shown in the upper part, the measurement frame 220 used in the second embodiment is the same as that described above with respect to the destination MAC address 220a and the source MAC address 220b for a part of the header of the MAC frame. Although the MAC addresses “B” and “A” are the same as those of the learning frame 180, different “VID2” is included in the VLAN TAG 220c.

  Further, as shown in the lower row, the measurement frame 240 on the opposite side has the same MAC address as the learning frame 24 with respect to the destination MAC address 240a and the source MAC address 240b with respect to a part of the header of the MAC frame. Each has “A” and “B”, but the VLAN TAG 240c includes different “VID1”.

  In the second embodiment, each switching hub 8, 10, 12, 14 transfers a frame for each VLAN based on the VID. Therefore, the VIDs in the VLAN TAGs 180c and 220c are switched between the learning frame 180 and the measurement frame 220 for each communication direction, and the VIDs in the VLAN TAGs 200c and 240c are switched between the learning frame 200 and the measurement frame 240. As a result, even if the FDB is overwritten before the FDB is flushed by the switching hubs 8, 10, 12, and 14 when a link down occurs, these measurement frames 220 and 240 are flushed until the FDB is flushed. It does not go through the switching destination communication path. More specific description will be given below.

[Learning frame transmission process]
FIG. 12 is a diagram schematically showing transfer paths of learning frames 180 and 200 transmitted through the network 2 from the ports 4a and 4b of the measuring device 4 in the second embodiment.

  As in the first embodiment, the measuring instrument 4 is operated using, for example, the PC 6, and the learning frame 180 (DA: B, SA: A, VID1) is directed from the first port 4a to the second port 4b. Send only one frame. On the other hand, only one frame for learning 200 (DA: A, SA: B, VID2) is transmitted from the second port 4b of the measuring instrument 4 to the first port 4a. The port 12b of the switching hub 12 is logically blocked as in the first embodiment.

  Of these, the learning frame 180 (indicated by “DA: B, SA: A, VID1”) is connected to the switching hubs 8, 10, and 14 within the network 2 from the first port 4 a of the measuring device 4 that is the transmission source. The data is sequentially transferred via the network, and finally transferred to the destination port 4b. Another learning frame 200 (denoted by “DA: A, SA: B, VID2”) is sent from the second port 4b of the measuring device 4 that is the transmission source within the network 2 to the switching hubs 14, 10, 8 Are sequentially transferred to the destination port 4a.

  In the second embodiment, when each switching hub 8, 10, 14 receives the learning frame 180 described by “DA: B, SA: A, VID 1”, its source MAC addresses “A” and “VID 1”. Are associated with the received ports 8a, 10a, and 14b, and the results are registered in the FDB. Similarly, for the learning frame 200 described by “DA: A, SA: B, VID2”, each switching hub 14, 10, 8 receives the source MAC address “B” and “VID2”. The learning is performed in association with the ports 14c, 10b, and 8b, and the result is registered in the FDB.

  FIG. 13 is a diagram schematically showing the configuration of the FDB table registered (learned) in each switching hub 8, 10, and 14 with the transmission of the learning frames 180 and 200. As shown in FIG. That is, the second embodiment differs from the first embodiment in that VID information is further added to the FDB.

  13A: In the FDB of the switching hub 8, the MAC addresses “A” and “VID1” are registered in association with the port 8a that has received the learning frame 180. For the port 8b, MAC addresses “B” and “VID2” are associated and registered.

  In FIG. 13B, the MAC address “A” and “VID1” are registered in the FDB of the switching hub 10 in association with the port 10a. For the other port 10b, MAC addresses “B” and “VID2” are associated and registered.

  In FIG. 13, (C): In the FDB of the switching hub 14, the MAC addresses “A” and “VID1” are registered in association with the port 14b. Further, the MAC address “B” and “VID2” are registered in association with the port 14c.

  When the above learning is performed, the communication path of “VID1” from the first port 4a of the measuring instrument 4 to the second port 4b via the network 2 and the second port 4b via the network 2 are thereafter performed. Thus, a “VID2” communication path toward the first port 4a is established in both directions. At this time, in the network 2, two VLANs identified by “VID1” and “VID2” are constructed.

[Measurement frame transmission process]
The network evaluation apparatus 1 according to the second embodiment transmits the learning frames 180 and 200 from the ports 4a and 4b of the measuring device 4 one frame at a time, and subsequently transmits the measurement frames 220 and 240 at an arbitrary rate. It transmits continuously from each port 4a, 4b at (for example, 10,000 frames / sec). However, for each “VID2” and “VID1” in the VLAN TAGs 220c and 240c shown in the measurement frames 220 and 240, the association with the MAC addresses “A” and “B” matches the learned FDB entry at the present time. I have not done it. Therefore, the switching hubs 8, 10, and 14 newly add associations of the MAC addresses “A” and “B” with “VID1” and “VID2” to the FDB along with the transfer of the measurement frames 220 and 240. .

  As described above, when the measurement frames 220 and 240 are continuously transmitted from the ports 4a and 4b of the measuring device 4, the measurement frames 220 and 240 are transmitted along the path indicated by the white arrow in FIG. It is transferred in the opposite direction. Although not shown in particular, during transmission of the measurement frames 220 and 240, the learning frame 180 shown in FIG. 12 is replaced with the measurement frame 220 (DA: B, SA: A, VID2), and learning that opposes this. The measurement frame 200 is replaced with the measurement frame 240 (DA: A, SA: B, VID1). That is, the measurement frame 220 is transmitted from the first port 4a of the measuring instrument 4 and is received by the second port 4b via the switching hubs 8, 10, and 14 in the network 2 in order. On the other hand, the measurement frame 240 is transmitted from the first port 4 b of the measuring instrument 4 and is received by the first port 4 a via the switching hubs 14, 10, 8 in the network 2 in order.

  FIG. 14 is a diagram schematically showing the configuration of the FDB table registered (updated) in each switching hub 8, 10, and 14 with the transmission of the measurement frames 220 and 240 from the measuring device 4. As shown in FIG.

  In FIG. 14, (D): As described above, the measurement frames 220 and 240 have different VLAN IDs in the VLAN TAGs 220c and 240c as compared with the learning frames 180 and 200 transmitted one frame at a time. As a whole, the content does not match the learned FDB entry (communication path information). For this reason, in the FDB of the switching hub 8, the MAC addresses “A” and “VID2” are newly registered and added (added) to the port 8a that has received the measurement frame 220. For the port 8b, the MAC addresses “B” and “VID1” of the measurement frame 240 are newly associated and registered (added).

  14E: Similarly, in the FDB of the switching hub 10, the MAC addresses “A” and “VID2” of the measurement frame 220 are newly associated (registered) with the port 10a. For the port 10b, the MAC addresses “B” and “VID1” of the measurement frame 240 are newly registered and added (added).

  In FIG. 14, (F): In the FDB of the switching hub 14, the MAC addresses “B” and “VID1” of the measurement frame 240 are newly associated with the port 14c and registered (added). Further, the MAC addresses “A” and “VID2” of the measurement frame 220 are newly registered and added (added) to the port 14b.

  Based on each VID registered in addition to the FDB as described above, the measurement frames 220 and 240 are transferred through the network 2 by the switching hubs 8, 10, and 14.

  FIG. 15 is a schematic diagram illustrating a state in which a communication path switching operation based on the redundancy protocol is performed in the network 2 in the second embodiment. Below, for example, the flow of the switching operation will be described assuming that a failure occurs in the transmission line 9 between the switching hubs 8 and 10.

  When the port 8b of the switching hub 8 is linked down, the MAC address “B” learned at the port 8b is flushed. Then, the measurement frame 220 whose destination MAC address is “B” is flooded by the switching hub 8 and transmitted to the switching hub 120 from another port 8 c. In addition, the switching hubs 8 and 10 that have detected the occurrence of link down together transmit link down information to the other switching hubs 12 and 14 in the network 2.

  Further, when the switching hub 14 receives the link down information from the switching hub 10 (or the switching hub 8) that detects the occurrence of the link down, the switching hub 14 flushes its FDB table. As a result, the MAC address “A” that has been learned in the port 14 b until then is cleared, and therefore the measurement frame 240 whose destination MAC address is “A” is also flooded by the switching hub 14 and switched from another port 14 a. It will be transmitted to the hub 12.

  On the other hand, when the switching hub 12 in which the port 12b has been in the blocking state until then receives the link down information from the switching hub 8, for example, the switching hub 12 releases the blocking state of the port 12b and changes it to the forwarding state. As a result, the measurement frames 220 and 240 are transferred bidirectionally via the switching hub 12 thereafter.

[Switching operation time]
Also in the second embodiment, the above switching operation is performed by (1) communication from the first port 4a of the measuring instrument 4 to the second port 4b, and (2) first from the second port 4b of the measuring instrument 4. Since communication is performed in both directions toward the port 4a, and the mechanism of the switching operation is different in each direction, the time required for the switching operation is also different for each direction. Note that the mechanism of the switching operation for each direction and the measurement principle of the time required for the switching operation are the same as those in the first embodiment, and therefore, redundant description is omitted here.

  FIG. 16 is a diagram schematically showing the configuration of the FDB table of the switching hub 8, 12, 14 after the occurrence of link down.

  In FIG. 16, (A): When the switching hub 8 detects a link down at the port 8b, all the MAC addresses associated with the ports 8a, 8b and 8c are erased from the FDB by flushing. The measurement frame 240 is flooded from the switching hub 12 and transferred to the port 8c. Therefore, in the FDB, the source MAC addresses “B” and “VID1” indicated in the measurement frame 240 are registered in association with the port 8c.

  In FIG. 16, (B): The switching hub 12 receives the measurement frames 220 and 240 flooded from the other switching hubs 8 and 14, respectively, and registers each information in the FDB. As a result, the source MAC addresses “A” and “VID2” indicated in the measurement frame 220 are registered in association with the port 12a. In the FDB, the source MAC addresses “B” and “VID1” indicated in the measurement frame 240 are registered in association with the port 12b.

[After FDB flush execution]
In FIG. 16, (C): The switching hub 14 that has received the link down message flushes the FDB and erases all the MAC addresses associated with the ports 14a, 14b, and 14c. Then, the source MAC addresses “A” and “VID2” indicated in the measurement frame 220 flooded from the switching hub 12 are newly added to the FDB in association with the port 14a.

[Before executing FDB flush]
In FIG. 16, (D): When the measurement frame 220 is received at the port 14a from the switching hub 12 after the link down occurs and before the FDB flush of the switching hub 14 is executed, the MAC addresses “A” and “VID2” are newly added. "Is learned at the port 14a, but does not match the existing FDB entry, so the correspondence between the MAC addresses" A "and" VID1 "is maintained on the port 14b on the FDB.

  Further, even if the measurement frame 240 is received at the port 14c of the switching hub 14 before the FDB flash, the information included in the VLAN TAG 240c is “VID1”, and therefore represents the MAC addresses “A” and “VID1”. Measurement frame 240 currently does not match the FDB entry for port 14a. Therefore, the switching hub 14 still transfers the received measurement frame 240 from the port 14b to the switching hub 10. Note that the measurement frame 240 transferred from the port 14 b is discarded by the switching hub 10.

  As described above, also in the second embodiment assuming a plurality of VLANs, the measurement frames 220 and 240 are not transferred to the communication path after switching until the FDB is flushed by the switching hub 14. . Therefore, the network evaluation apparatus 1 determines the communication path based on the difference between the number of frames of the measurement frames 220 and 240 transmitted from the measuring device 4 and the number of frames of the received measurement frames 220 and 240 during this period. The time required for the switching operation can be accurately measured in both directions.

  The above-described evaluation method according to the second embodiment is suitable when, for example, a protocol that performs encapsulation such as EoE (Ethernet over Ethernet (Ethernet is a registered trademark)) or IEEE 802.1ah is used. Can be implemented. That is, when the above-described encapsulation technique is used, even if the source MAC address is divided between the learning frames 18 and 20 and the measurement frames 22 and 24 as in the first embodiment, the edge device is finally used. Since each frame is encapsulated, the source MAC address becomes the source MAC address of the edge device, and cannot deal with the problems described in the “comparative case”. On the other hand, in the second embodiment, the source MAC address is not divided, but the VLAN ID is divided according to the direction of communication. Therefore, even when the encapsulation technique is used, the number of test steps is not increased and the unicast communication can be performed. The switching time can be measured accurately.

  The present invention can be implemented with various modifications without being limited to the above-described embodiments. For example, in each embodiment, the measuring device 4 may be connected to a switching hub connected thereto via a network (for example, an IP-VPN network) different from the network 2. Further, the topology of the network 2 may be more complicated than the illustrated example.

  Alternatively, even if the network does not constitute a ring topology (bus type or the like), for example, if the FDB flash is generated in a device other than the device in which the failure has occurred, and the communication path is switched, the implementation is performed. A form evaluation method can be applied.

  In each embodiment, the learning frames 18, 20, 180, and 200 are transmitted one frame at a time. However, the transmission of the learning frames 18, 20, 180, and 200 is stopped after two or more frames are transmitted. Then, the continuous transmission of the measurement frames 22, 24, 220, 240 may be started from there. In any case, by generating a link down during transmission of the measurement frames 22, 24, 220, and 240, the time required for the redundant path switching operation can be accurately measured in both directions.

  Further, in each embodiment, in order to actively generate a link down, the cable may be directly removed, or the setting of the port that detects the link down may be deleted by logical control.

DESCRIPTION OF SYMBOLS 1 Network evaluation apparatus 2 Ring type network 4 Measuring instrument 4a 1st port 4b 2nd port 6 PC
8, 10, 12, 14 Switching hub 18, 20 Learning frame 22, 24 Measuring frame 180, 200 Learning frame 220, 240 Measuring frame

Claims (9)

A network evaluation device that evaluates a network that forms a logically redundant communication path by connecting a plurality of switching hubs that perform a relay operation using a predetermined redundancy protocol,
Among the plurality of switching hubs, any two switching hubs are used as nodes, and a first port is connected to one of the nodes, and a second port having a MAC address different from that of the first port is connected to the other switching hub. Connected measuring instrument,
The learning frame is transmitted by transmitting a learning frame whose destination is the MAC address of each port from the first and second ports of the measuring device to the second and first ports facing each other. Learning frame transmitting means for causing each of the plurality of switching hubs to learn communication path information based on the redundancy protocol in a process in which the nodes in the network are transferred facing each other.
After the transmission of the learning frame, the measurement frames having contents that do not match the communication path information learned by the plurality of switching hubs, with the MAC addresses of the first and second ports as destinations, are measured. Measurement frame transmitting means for continuously transmitting from the first and second ports of the device toward the second and first ports facing each other;
When a communication path switching operation based on the redundant protocol is performed in the network during the transmission of the measurement frame, the measurement device transmits and receives between the first and second ports at least during the switching operation. A network evaluation apparatus comprising: a measuring unit that measures a time required for the switching operation based on the number of transmission / reception of the measurement frames. The network evaluation device according to claim 1,
The learning frame transmitting means includes:
The learning frame having the second MAC address corresponding to the second port as the destination and the first MAC address corresponding to the first port as the transmission source is transmitted from the first port of the measuring device. The learning frame is transmitted from the second port of the measuring device to the second port, and the learning frame is sent from the second port of the measuring device to the first MAC address as a destination and the second MAC address as a transmission source. Transmitting to one port, causing each switching hub to learn the communication path information including the first and second MAC addresses,
The measurement frame transmitting means includes
While the second MAC address is the destination, the measurement frame having a third MAC address different from any of the first and second MAC addresses as a transmission source is transmitted from the first port of the measuring device. The measurement that is transmitted toward the second port and that has the first MAC address as the destination and the fourth MAC address that is different from any of the first, second, and third MAC addresses. A network evaluation apparatus, wherein a network frame is transmitted from the second port of the measuring device toward the first port. The network evaluation device according to claim 1,
The learning frame transmitting means includes:
The learning in which the second MAC address corresponding to the second port is a destination, the first MAC address corresponding to the first port is a transmission source, and the first network identification information is added A frame for transmission from the first port of the measuring device to the second port, the first MAC address as a destination, the second MAC address as a transmission source, and the By transmitting the learning frame to which the second network identification information different from the first network identification information is added toward the first port from the second port of the measuring device, A hub is made to execute learning of the communication path information including the first and second network identification information,
The measurement frame transmitting means includes
The measurement frame to which the second MAC identification information is added from the first port of the measuring device is sent from the first MAC address while the second MAC address is the destination. The measurement is transmitted to the second port, the first MAC address is a destination, the second MAC address is a transmission source, and the first network identification information is added. A network evaluation apparatus, wherein the frame is transmitted from the second port of the measuring device to the first port. A network evaluation system comprising a network that forms a communication path, and an evaluation device that evaluates the performance of the network while connected to the network,
The network is
A plurality of switching hubs connected to each other via a transmission line and configured to logically redundantly configure the communication path by performing a relay operation individually using a predetermined redundancy protocol;
The evaluation device is
Among the plurality of switching hubs of the network, any two switching hubs are used as nodes, a first port is connected to one of them, and the other switching hub has a MAC address different from that of the first port. A measuring instrument connected to two ports;
The learning frame is transmitted by transmitting a learning frame whose destination is the MAC address of each port from the first and second ports of the measuring device to the second and first ports facing each other. Learning frame transmitting means for causing each of the plurality of switching hubs to learn communication path information based on the redundancy protocol in a process in which the nodes in the network are transferred facing each other.
After the transmission of the learning frame, the measurement frames having contents that do not match the communication path information learned by the plurality of switching hubs, with the MAC addresses of the first and second ports as destinations, are measured. Measurement frame transmitting means for continuously transmitting from the first and second ports of the device toward the second and first ports facing each other;
When a communication path switching operation based on the redundant protocol is performed in the network during the transmission of the measurement frame, the measurement device transmits and receives between the first and second ports at least during the switching operation. And a measuring means for measuring the time required for the switching operation based on the number of transmission / reception of the measurement frames. The network evaluation system according to claim 4,
The learning frame transmitting means includes:
The learning frame having the second MAC address corresponding to the second port as the destination and the first MAC address corresponding to the first port as the transmission source is transmitted from the first port of the measuring device. The learning frame is transmitted from the second port of the measuring device to the second port, and the learning frame is sent from the second port of the measuring device to the first MAC address as a destination and the second MAC address as a transmission source. Transmitting to one port, causing each switching hub to learn the communication path information including the first and second MAC addresses,
The measurement frame transmitting means includes
While the second MAC address is the destination, the measurement frame having a third MAC address different from any of the first and second MAC addresses as a transmission source is transmitted from the first port of the measuring device. The measurement that is transmitted toward the second port and that has the first MAC address as the destination and the fourth MAC address that is different from any of the first, second, and third MAC addresses. A network evaluation system, wherein a network frame is transmitted from the second port of the measuring device to the first port. The network evaluation system according to claim 4,
The plurality of switching hubs are:
A plurality of virtual communication paths that are mutually identified based on predetermined network identification information can be constructed in the network,
The learning frame transmitting means includes:
The learning in which the second MAC address corresponding to the second port is a destination, the first MAC address corresponding to the first port is a transmission source, and the first network identification information is added A frame for transmission from the first port of the measuring device to the second port, the first MAC address as a destination, the second MAC address as a transmission source, and the By transmitting the learning frame to which the second network identification information different from the first network identification information is added toward the first port from the second port of the measuring device, A hub is made to execute learning of the communication path information including the first and second network identification information,
The measurement frame transmitting means includes
The measurement frame to which the second MAC identification information is added from the first port of the measuring device is sent from the first MAC address while the second MAC address is the destination. The measurement is transmitted to the second port, the first MAC address is a destination, the second MAC address is a transmission source, and the first network identification information is added. A network evaluation system, wherein a frame is transmitted from the second port of the measuring device toward the first port. A network evaluation method for evaluating a network that forms a logically redundant communication path by connecting a plurality of switching hubs that perform a relay operation using a predetermined redundancy protocol,
Among the plurality of switching hubs, any two switching hubs are used as nodes, and a first port is connected to one of the nodes, and a second port having a MAC address different from that of the first port is connected to the other switching hub. By using a connected measuring instrument, by transmitting learning frames destined for the MAC address of each port from the first and second ports to the opposing second and first ports, respectively. A learning frame transmitting step of causing each of the plurality of switching hubs to learn communication path information based on the redundancy protocol in a process in which the learning frame is transferred oppositely between the nodes in the network; ,
The communication path information learned by the plurality of switching hubs with the MAC addresses of the first and second ports as destinations after finishing the transmission of the learning frame in the learning frame transmission step A measurement frame transmission step of continuously transmitting measurement frames that do not match the above-mentioned measurement from the first and second ports of the measuring device to the opposing second and first ports, respectively.
When a communication path switching operation based on the redundancy protocol is performed in the network during transmission of the measurement frame in the measurement frame transmission step, at least during the switching operation, the first and And a measurement step of measuring a time required for the switching operation based on the number of transmission / reception of the measurement frames transmitted / received between the second ports. The network evaluation method according to claim 7,
In the learning frame transmission step,
The learning frame having the second MAC address corresponding to the second port as the destination and the first MAC address corresponding to the first port as the transmission source is transmitted from the first port of the measuring device. The learning frame is transmitted from the second port of the measuring device to the second port, and the learning frame is sent from the second port of the measuring device to the first MAC address as a destination and the second MAC address as a transmission source. Transmitting to one port, causing each switching hub to learn the communication path information including the first and second MAC addresses,
In the measurement frame transmission step,
While the second MAC address is the destination, the measurement frame having a third MAC address different from any of the first and second MAC addresses as a transmission source is transmitted from the first port of the measuring device. The measurement that is transmitted toward the second port and that has the first MAC address as the destination and the fourth MAC address that is different from any of the first, second, and third MAC addresses. A network evaluation method, comprising: transmitting a communication frame from the second port of the measuring device toward the first port. The network evaluation method according to claim 7,
In the learning frame transmission step,
The learning in which the second MAC address corresponding to the second port is a destination, the first MAC address corresponding to the first port is a transmission source, and the first network identification information is added A frame for transmission from the first port of the measuring device to the second port, the first MAC address as a destination, the second MAC address as a transmission source, and the By transmitting the learning frame to which the second network identification information different from the first network identification information is added toward the first port from the second port of the measuring device, Causing the hub to learn the communication path information including the first and second network identification information;
In the measurement frame transmission step,
The measurement frame to which the second MAC identification information is added from the first port of the measuring device is sent from the first MAC address while the second MAC address is the destination. The measurement is transmitted to the second port, the first MAC address is a destination, the second MAC address is a transmission source, and the first network identification information is added. A network evaluation method, comprising: transmitting a frame from the second port of the measuring device toward the first port.

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