JP5635029B2 - Communication network, relay node, and communication path switching method - Google Patents

Description

  The present invention relates to a communication path switching method for maintaining communication as much as possible even when multiple failures occur by controlling a switching operation between a ring protocol and a link aggregation in a ring network using link aggregation.

  Currently, the relay network used for the wide area Ethernet (registered trademark) service and the like is ITU-T recommendation G.264. 8032 / Y. By using a ring protocol such as 1344 Ethernet (registered trademark) ring protection, it is possible to economically construct a redundant path (Non-Patent Document 1). In a relay network using the ring protocol, it is possible to construct a redundant path with node failure tolerance throughout the relay network by connecting each ring redundantly, and when any node in the relay network fails In addition, the path is switched to ensure the normality of communication.

  In addition, in a relay network, two or more physical links can be connected for the purpose of expanding the transmission bandwidth per link and avoiding communication interruption in the remaining physical links even if a failure occurs in a part of the physical link. There is a line integration technique called link aggregation that is bundled into one logical link (Non-patent Document 2). Normally, link aggregation operates by setting line integration to a plurality of physical ports of a relay node to form one logical port. When line aggregation is performed using link aggregation, when all physical links are normal, Ethernet (registered trademark) frames flowing into one logical link are distributed and transferred to each physical link based on VLAN and MAC address By doing so, it is possible to expand the transmission band of one logical link. In addition, when a failure occurs in one physical link among multiple physical links, communication is maintained by switching the communication path of the traffic that was used as the communication path to another physical link of the same logical link. It has a failure recovery function. In a network of a telecommunications carrier, a broadband and highly redundant network is constructed by combining the link aggregation and the ring protocol.

  FIG. 1 shows a ring network using link aggregation. As shown in the figure, in this network, the relay nodes 101 to 108 are connected by two physical links 301-1, 301-2,... 308-1, 308-2, and the physical port of each relay node. The logical ports 201 to 208 and 211 to 218 are configured by performing line integration setting using a link aggregation technique in 201-1, 201-2, 211-1, 211-2,. A ring network using link aggregation is configured by using a logical link connecting the logical ports as a ring network link.

  As shown in Fig. 1, in order to combine link protection with other protection technologies, the link aggregation can set whether or not to operate the fault recovery function when a fault occurs in a physical section integrated with a line. it can. When “no failure recovery operation” is set, if communication disconnection occurs in one section of the physical link, the logical link including the physical link is disconnected. When "failure recovery operation is enabled" is set, if one section of the physical link is disconnected, path switching is performed by the above-described link aggregation technology failure recovery function to maintain communication of the logical link. . Normally, when link aggregation and other protection technologies are combined, setting "with failure recovery operation" will cause a loss of user data due to a reduction in link bandwidth when a communication loss occurs on a physical link. , “No failure recovery operation” is set, and when communication disconnection occurs, it is operated so that the route is switched by another protection technology.

  Here, the operation when a failure occurs in the network of FIG. 1 will be described with reference to FIG. FIG. 2A shows a ring network before a failure occurs, and an arrow shows a communication path between the relay node 108 and the relay node 105. FIG. 2B shows a situation where a failure has occurred in one of the physical links between the relay node 106 and the relay node 107. As described above, if the failure recovery function of link aggregation is set to “no failure recovery operation”, a logical link including the physical link is disconnected due to a failure of one physical link. As a result, protection based on the ring protocol operates, the logical port is blocked, and the path is switched based on the ring protocol.

  Here, FIG. 2C shows the operation at the time of multiple failure in which a failure further occurs in the physical link at another location. Since the failure recovery function of link aggregation is set to “no failure recovery operation”, the logical link including the physical link is disconnected due to a failure of one physical link, as in the case of FIG. 2B. Thus, the logical port is blocked. Then, as shown in FIG. 2C, it can be seen that the communication between the relay node 108 and the relay node 105 that has been secured so far is interrupted. However, referring to FIG. 2C, since a part of the physical link between the relay node 108 and the relay node 104 is still communicable, it is desirable that communication can be maintained using the remaining physical link.

  In order to secure a communication path as much as possible even in the case of multiple failures as described above, a method of setting the failure recovery function of link aggregation as “with failure recovery operation” as an operation at the time of failure can be considered. The operation in such a case will be described with reference to FIG. FIG. 3A shows a ring network before a failure occurs, and an arrow shows a communication path between the relay node 108 and the relay node 105. FIG. 3B shows a situation where a failure has occurred in one of the physical links between the relay node 106 and the relay node 107. Here, because the failure recovery function of link aggregation technology is set to "with failure recovery operation", the link aggregation failure recovery function operates to switch the route, and the same communication route as before the failure Will pass. However, in this case, since the bandwidth of the logical link between the relay node 106 and the relay node 107 is reduced, there is a problem that congestion may occur in the logical link and frame loss may occur. .

Recommendation ITU-T G. 8032 / Y. 1344 “Ethernet (R) Ring Protection Switching (2010/03)” IEEE Std 802.1 AX-2008 IEEE Standard for Local and Metropolitan Area Networks-Link Aggregation

  As shown in Fig. 2 (c), in a ring network configured using link aggregation, when the link aggregation failure recovery function is set to "no failure recovery operation", if multiple failures occur simultaneously, However, there is a problem that a redundant path cannot be constructed even though a physical link that can be used remains. In addition, when the failure recovery function of link aggregation is set to “with failure recovery operation”, the bandwidth of the logical link is reduced when a failure occurs, so congestion may occur and frame loss may occur. There was a problem that there was.

  Therefore, in order to solve the above-mentioned problem, it is possible to switch the path when there is a single failure and maintain communication even when there are multiple failures by switching the link aggregation failure recovery operation according to the state of the ring network. An object is to provide a communication network, a relay node, and a communication path switching method.

The communication network of the present invention is a ring network in which a plurality of relay nodes are connected in a ring shape through a relay section, and at least one of the plurality of relay nodes has a failure in its own node In this case, a failure level defined by the number of physical links in the section where the logical link is formed in the ring network and a ratio of the physical links occupied by the failure link is calculated, and the highest failure level is calculated. Reference is made to a ring state record table that holds a ring state level defined by a level value. When the failure level in the own node is higher than the ring state level, the logical port including the failure section in the own node is blocked. , if the fault level at the own node is smaller than the ring status level put on the local node And performing the opening of the logical port including a faulted segment.
As a result, the path can be switched when there is a single failure, and communication can be maintained even when there are multiple failures.

In the communication network according to the present invention, when the failure level of the one relay node is higher than the ring state level , the one relay node sets the ring state level held in the ring state record table according to the failure level. The ring state level after the update may be notified to other relay nodes .

The relay node according to the present invention detects the state of two ring ports, which are logical ports obtained by integrating a plurality of physical ports, and the physical port that constitutes the logical port by integrating the lines, and performs link aggregation. A physical port control unit that controls the operation of line integration, a port status recording table that records port status information indicating whether each physical port notified from the physical port control unit is normal or abnormal, and the port status information wherein the ring port failure state detection unit that the physical port by being notified from the physical port control unit detects a normal or abnormal, the number of physical links of the section are formed of logical links definitive in the ring network physical It is defined at the highest level value among disabled level defined as a percentage by failed link of the links The ring port and the ring status notification receiving unit for transmitting and receiving a message notifying a ring-state level, the ring status record table for holding the ring status level for receiving the ring status notification receiving unit, from the ring port failure state detection unit The failure level of the own node is calculated using the port state information recorded in the port state recording table, and the failure level is higher than the ring state level of the ring state recording table. A ring control unit that closes a logical port including a faulty section in its own node when it is large, and opens a logical port including a faulty section in its own node when the fault level in its own node is lower than the ring state level and, equipped with a.

In the relay node according to the present invention, the ring control unit updates the ring state level of the ring state record table according to the failure level when the failure level in the node is higher than the ring state level, The ring state notification transmission / reception unit may transmit a message notifying the updated ring state level .

In the communication path switching method according to the present invention, a part or all of a ring network in which a plurality of relay nodes are connected in a ring shape via a relay section is multiplexed by link integration by link aggregation. If a failure that occur in the section of the communication network, a relay node with disabilities, as a percentage by failed link of the number and the physical links of the physical links of the section is formed of a logical link in the ring network A failure level to be defined is calculated, and a ring state recording table holding a ring state level defined by the highest level value among the failure levels is referred to. closing the logical ports including faulted segment in its own node when is large, contact to the own node That said if fault level is less than the ring-state level perform opening of the logical port including a faulted segment in its own node.

  The present invention can provide a communication network, a relay node, and a communication path switching method capable of switching paths when there is a single failure and maintaining communication even when there are multiple failures.

An example of the ring network using link aggregation is shown. An example of a ring network before a failure occurs is shown. A situation in which a failure has occurred in one of the physical links in a conventional ring network is shown. A situation in which a failure has occurred in two physical links in a conventional ring network is shown. An example of a ring network before a failure occurs is shown. A situation in which a failure has occurred in one of the physical links in a conventional ring network is shown. It is a figure which shows the component of the relay node in this invention. An example of a ring state recording table is shown. An example of a line integrated setting information storage table is shown. An example of a port status recording table is shown. An example of the operation | movement flow of the communication path switching operation | movement in Embodiment 1 is shown. This shows the situation where all sections are operating normally. Indicates a situation where a failure has occurred in one of the physical links of the ring network. A situation where a failure has occurred in two physical links of the ring network is shown. It is a figure which shows the example of the communication network which concerns on Embodiment 2. FIG. An example of the operation | movement flow of the communication path switching operation | movement in Embodiment 2 is shown. An example of the operation | movement flow of the communication path switching operation | movement at the time of receiving the notification of a ring state in Embodiment 2 is shown. An example of the ring state recording table in Embodiment 2 is shown. It is the 1st explanatory view of a ring state level. It is the 2nd explanatory view of a ring state level.

  Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are examples of the present invention, and the present invention is not limited to the following embodiments. In the present specification and drawings, the same reference numerals denote the same components.

(Embodiment 1)
FIG. 1 is a diagram illustrating an example of a communication network according to the present embodiment. 1 includes relay nodes 101 to 108, physical ports 201-1, 201-2, 211-1, 211-2, 202-1, 202-2, 212-1, 212-2,. 208-1, 208-2, 218-1, 218-2, logical ports 201, 211, 202, 212,... 208, 218 integrated with a plurality of physical ports, physical link sections 301-1, 301- 2, 302-1, 302-2,... 308-1, 308-2.

  The relay nodes 101 to 108 are configured like the relay node 100 shown in FIG. The relay nodes 101 to 108 are connected by physical link sections 301-1 to 308-2 connected to the physical ports 201-1 to 218-2, and the physical link sections 301-1 and 301-2 to 308-1. , 308-2, line integration using link aggregation as defined in IEEE 802.3ad is performed. As a result, the physical ports are integrated to form logical ports 201-218.

  The relay nodes 101 to 108 are connected to the ITU-T recommendation G.264 by the logical ports 201 to 218. 8032 / Y. Route redundancy using ring protection as defined in 1344 Ethernet (registered trademark) ring protection is performed.

  Note that the shape of the communication network in the present embodiment is not limited to the shape as shown in FIG. 1. In a network in which relay nodes are connected in a ring shape and path redundancy is ensured by a ring protocol, Any form may be used as long as a plurality of physical link sections are integrated by a link aggregation technique at least one of the links between the relay nodes. The relay node according to the present embodiment is applied to a relay node that is integrated with a line by link aggregation technology.

  FIG. 4 is a diagram showing components of the relay node in the present invention. The relay node 100 includes physical ports 200-1, 200-2, 210-1, 210-2, logical ports 200, 210, a ring control unit 401, ring state notification transmission / reception units 402-1 and 402-2, and physical port control. Sections 403-1 and 403-2, a ring port failure state detection unit 404, a ring state recording table 405, a line integrated setting information storage table 406, and a port state recording table 407. The physical ports 200-1, 200-2, 210-1, 210-2 are interfaces connected to physical ports of other relay nodes. At this time, the physical ports 200-1, 200-2, 210-1, 210-2 have been subjected to line integration using link aggregation as defined in IEEE 802.3ad, and line integration setting information Based on the line integration setting information stored in the storage table 406, it is controlled by the physical port control units 403-1 and 403-2. Further, the physical ports 200-1, 200-2, 210-1, 210-2 form logical ports 200, 210 by line integration.

  The ring control unit 401 controls the ring protection operation when line integration using link aggregation described later is performed. Further, the ring control unit 401 determines the ring state from the ring state information recorded in the ring state notification message received by the ring state notification transmission / reception units 402-1 and 402-2, and the state of the physical port and logical port of the own node. And the ring state recorded in the ring state recording table 405 is updated.

  The ring state notification transmission / reception units 402-1 and 402-2 receive ring state notification messages transmitted from other nodes via the logical ports 200 and 210. In addition, a ring state notification message is transmitted from the own node via the logical ports 200 and 210. The ring status notification message contains ring status information used for ring control, and records whether there is a protection status in which a failure has occurred in some sections or an idle status in which all sections of the ring are operating normally. Has been.

  The physical port control units 403-1 and 403-2 monitor, manage, and control each physical port. For example, the physical port controllers 403-1 and 403-2 detect a failure in the physical ports 200-1, 200-2, 210-1, and 210-2 and detect a ring port failure state. To the unit 404 and the port status recording table 407. Also, based on an instruction from the ring control unit 401, control is performed to stop frame transmission / reception. Further, line integration control using link aggregation technology is performed based on the line integration setting information held in the line integration setting information storage table 406.

  The ring port failure state detection unit 404 receives the failure state of the physical ports 200-1, 200-2, 210-1, 210-2 notified from the physical port control units 403-1 and 403-2, and performs ring control. This is notified to the unit 401.

  In the ring state recording table 405, the ring state is updated and recorded in accordance with an instruction from the ring control unit 401. As shown in FIG. 5A, the ring state recording table 405 is in a protection state in which a failure has occurred in some sections or in an idle state in which all the sections of the ring are operating normally. Is recorded and held as the state of each ring.

  The line integration setting information storage table 406 stores the line integration setting information in the physical port. As shown in FIG. 5B, the line integration setting information storage table 406 corresponds to physical port IDs, presence / absence of line integration setting of each physical port, and IDs of physical ports targeted for line integration. I remember it.

  The port status recording table 407 records the physical port status notified from the physical port control units 403-1 and 403-2. As shown in FIG. 5C, the port status record table records and holds the physical port ID and whether each physical port is in a normal state where communication is possible or in a failure state where communication is not possible. .

  FIG. 6 shows an operation flow of the communication path switching operation when line integration using the link aggregation technique in the present embodiment is used. The communication path switching method according to the present embodiment includes a failure detection procedure and a failure recovery procedure in order. In the failure detection procedure, step S402 is executed. In the failure recovery procedure, steps S403 to S410 are executed.

  When a failure occurs in any node or section in the ring (step S401), the port failure state detection unit 404 detects the failure in the relay node that constitutes the section (step S402), and the ring control unit 401 Be notified.

  The ring control unit 401 refers to the line integrated setting information storage table 406 to determine whether there is physical port redundancy in the link in the logical port where the failure is detected (step S403). For example, the ring control unit 401 determines from the line integration setting information storage table 406 whether there is a physical port ID that is a line integration target of the faulty physical port ID. If port redundancy does not exist, the ring control unit 401 blocks the logical port including the failed section by blocking the logical port including the failed physical port (step S406), and switches the communication path by ring protection. (Step S407) and the fact that it is in the protection state is registered in the ring state recording table 405. Then, the failure recovery process is terminated (step S410).

If port redundancy exists in step S403, the ring control unit 401 refers to the ring state recording table 405 (step S404), and checks whether the ring state is in the protection state or the idle state (step S405). .
If the ring state is not the protection state, the ring control unit 401 operates in steps S406, S407, and S410.
When the ring state is the protection state, the ring control unit 401 confirms whether there is a communicable physical port in the logical port including the physical port in which the failure is detected with reference to the port state record table 407 (step) S408). If there is no physical port capable of communication, the process proceeds to step S406 and subsequent steps. If there is a communicable physical port, the ring control unit 401 executes a failure recovery operation by the link aggregation technique (step S409), and ends the failure recovery process (step S410).

Next, this route switching method will be described using the communication network shown in FIG. FIG. 7A shows a situation where all the sections are operating normally. FIG. 7B shows a situation in which a failure has occurred in one of the physical links connecting the relay node 106 and the relay node 107.
In this case, in the failure recovery process shown in FIG. 6, there is port redundancy in the logical link connecting the relay node 106 and the relay node 107 (step S403), and the ring state is the idle state (step S405). 106 and the relay node 107 block the logical port including the failure section (step S406), and perform redundancy control by ring protection (step S407).

  Next, as shown in FIG. 7C, it is assumed that a failure occurs in one of the physical links connecting the relay node 103 and the relay node 104 following the situation of FIG. 7B. In this case, in the failure recovery process shown in FIG. 6, port redundancy exists in the logical link (step S403), the ring state is the protection state (step S405), and there is a physical port that can communicate with the logical port. Therefore, the ring control unit 401 in the relay node 103 and the relay node 104 performs failure recovery by link aggregation on the logical link in which the failure has occurred (step S409).

(Embodiment 2)
FIG. 8 is a diagram illustrating an example of a communication network according to the present embodiment. The communication network illustrated in FIG. 8 includes relay nodes 101 to 108. As shown in the figure, the number of physical links between the relay nodes is different, and one 100G physical path is connected between the relay node 106 and the relay node 107, and four 10G physical paths are integrated between the other relay nodes. It is assumed that they are connected in the form of

Also, in the configuration as shown in the figure, a failure level and a ring state level are newly defined.
The failure level is defined by the number of physical links in the section where the logical link is formed and the ratio of the physical link in the section occupied by the failed link. For example, when a failure occurs in one logical link of a 100G physical link such as the logical link of the relay node 106 and the relay node 107 and the LAG (Link AggrGate) is in a 100% degenerate state, the failure level is 4. In the case of a logical link in which four 10G path physical links are integrated, such as the logical link of the relay node 105 and the relay node 106, if there is no failure in any of the physical links, the failure level is 0 and one physical link is present. If a failure occurs in the failure link and the ratio of the failure link is LAG 25%, the failure level is 1, and if the failure occurs in two physical links and the failure link is in the LAG 50% degradation state, the failure level is 2. Failure level 3 when the failure occurs in 3 links and the ratio occupied by the failed link is 75% degraded, and failure level 4 occurs when the failure occurs in 4 physical links and the proportion occupied by the failed link is LAG 100% degraded. Become. The number of links and the numerical value of the failure level in the figure are merely examples, and are not limited to the number of links and the numerical value of the failure level in the present embodiment.

  The ring status level is defined by the number of logical links in the ring network and the proportion of the logical links occupied by the failed links. If all of the logical links are normal, the ring status level is 0, and two of the eight logical links. If the logical link fails and the LAG 25% degeneration protection state, ring state level 1; if four of the eight logical links fail and the LAG 50% degeneration protection state, ring state levels 2 and 8 If a failure occurs in six of the logical links and the protection state is LAG 75% degeneration, the ring state level 3 is obtained. Note that the numbers of logical links and ring state level values in the figure are merely examples, and are not limited to the numbers of logical links and ring state levels in this embodiment.

  FIG. 9 and FIG. 10 show the operation flow of the communication path switching operation when the line integration using the link aggregation technique in this embodiment is used. The communication path switching method according to the present embodiment includes a failure detection procedure and a failure recovery procedure in order. In the failure detection procedure, step S502 is executed. In the failure recovery procedure, steps S503 to S514 are executed.

  When a failure occurs in any node or section in the ring (step S501), the failure is detected by the ring port failure state detection unit 404 and notified to the ring control unit 401 (step S502).

  Next, when the failure recovery operation by link aggregation exists in the physical port, the ring control unit 401 executes the failure recovery operation by link aggregation (step S503). Thereafter, the ring control unit 401 refers to the line integration setting information storage table 406 and the port state recording table 407 to determine the failure level in the section. The failure level in the present embodiment is the one defined in FIG. 8, and is determined according to the number of physical link failures (step S504).

  For example, the ring control unit 401 extracts from the line integration setting information storage table 406 all physical port IDs that are subject to line integration of the failed physical port ID, and all the extracted physical port IDs. The port status is extracted from the port status record table 407. Then, the ring control unit 401 uses the port status extracted from the port status recording table 407 to calculate the ratio of the physical link occupied by the failed link. Thereby, the ring control unit 401 can determine the failure level.

  Next, the ring control unit 401 refers to the ring state recording table 405 (step S505), and compares the ring state level notified as the ring state with the failure level of the section (step S506). As a result of the comparison, if the failure level is smaller than the ring state level, the ring control unit 401 ends the failure recovery process (step S510).

  If the failure level is higher than the ring state level in step S506, the ring control unit 401 closes the logical port including the failure section (step S507), and performs communication path switching by ring protection (step S508). ). Thereafter, the ring control unit 401 updates the ring state level recorded in the ring state recording table 405 shown in FIG. 11 to a level equivalent to the failure level of the logical port, and notifies the ring state (step S509).

  The ring state level is defined as the highest level value among the failure levels of logical links in the ring network. For example, in FIG. 12, when a failure occurs in two physical links in the logical link between the relay node 101 and the relay node 102, the failure level in the section becomes 2. Further, in the logical link between the relay node 105 and the relay node 106, when a failure occurs in one of the physical links, the failure level becomes 1. Here, since the maximum failure level in the ring is 2, 2 is recorded in each relay node as the ring state level. Further, as shown in FIG. 13, when a failure occurs in the physical link between the relay node 106 and the relay node 107 from this state, the failure level of the section becomes 4, so the ring state level is updated as 4 and notified. And recorded in each relay node.

When the notification of the ring state is received (step S511), the received ring state level is compared with the failure level of the own node, and the failure level of the own node is smaller than the received ring state level. Opens the logical port including the failure section (step S513) and ends. If more failure level of the node is greater than the received ring status level is terminated without performing step S513.

  The present invention can be applied to the information communication industry.

100, 101-108: Relay nodes 200-1, 200-2, 210-1, 210-2, 201-1, 201-2, 211-1, 211-2, 202-1, 202-2, 212- 1, 212-2,... 208-1, 208-2, 218-1, 218-2: physical ports 200, 210, 201, 211, 202, 212,... 208, 218: logical port 301- 1, 301-2, 302-1, 302-2,... 308-1, 308-2: Physical link section 401: Ring control unit 402-1, 402-2: Ring state notification transmission / reception unit 403-1, 403-2: Physical port control unit 404: Ring port failure state detection unit 405: Ring state recording table 406: Line integrated setting information storage table 407: Port state recording table

Claims (5)

A ring network in which a plurality of relay nodes are connected in a ring shape via a relay section,
At least one relay node of the plurality of relay nodes is
If there is a failure in the local node ,
Calculate the failure level defined by the number of physical links in the section where the logical link in the ring network is formed and the proportion of the physical links occupied by the failed links,
Referring to a ring state record table that holds a ring state level defined by the highest level value of the failure levels;
When the failure level in the own node is higher than the ring state level, the logical port including the failure section in the own node is blocked ,
A communication network comprising: opening a logical port including a failure section in a local node when the failure level in the local node is lower than the ring state level . The one relay node updates the ring state level held in the ring state record table according to the failure level when the failure level in the node is higher than the ring state level, and The communication network according to claim 1, wherein the ring state level is notified to another relay node . Two ring ports, which are logical ports obtained by integrating multiple physical ports,
A physical port control unit that detects the state of the physical port that configures the logical port by circuit integration and controls the operation of circuit integration by link aggregation;
A port status recording table for recording port status information indicating whether each physical port notified from the physical port control unit is normal or abnormal;
A ring port failure state detection unit that detects whether each physical port is normal or abnormal by notifying the port state information from the physical port control unit;
The number and the highest level of ring state defined by the value in the fault level defined as a percentage by failed link of said physical links of the physical links of the section are formed of logical links definitive in the ring network A ring state notification transmission / reception unit for transmitting / receiving a message notifying the level ;
A ring status record table that holds the ring status level received by the ring status notification transceiver;
The ring port failure state detection unit receives a notification of an abnormality of the ring port, calculates the failure level of the own node using the port state information recorded in the port state recording table, and the failure level is When the ring state record table is larger than the ring state level, the logical port including the failure section in the own node is blocked, and when the failure level in the own node is smaller than the ring state level, the failure section in the own node. and ring control unit that performs the opening of the logical port including,
Relay node, characterized in that it comprises a. The relay node according to claim 3, wherein
The ring control unit updates the ring state level of the ring state record table according to the failure level when the failure level in the node is higher than the ring state level,
The ring state notification transmission / reception unit transmits a message notifying the updated ring state level . A failure occurs in the section of the communication network in which a part or all of the ring network in which a plurality of relay nodes are connected in a ring shape through the relay section is multiplexed by link aggregation by link aggregation If you that,
The faulty relay node
Calculate the failure level defined by the number of physical links in the section where the logical link in the ring network is formed and the proportion of the physical links occupied by the failed links,
Referring to a ring state record table that holds a ring state level defined by the highest level value of the failure levels;
When the failure level in the own node is higher than the ring state level, the logical port including the failure section in the own node is blocked,
When the failure level in the own node is smaller than the ring state level, the logical port including the failure section in the own node is opened.
Communication path switching method.

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