JP5592172B2 - Communication network, ring connection node and communication network control method - Google Patents

Description

  The present invention relates to a communication network, a ring connection node, and a communication network control method that can flexibly eliminate ring segmentation according to a failure occurrence condition.

  In an L2 (Layer 2) network, ring protection is used as one technique for setting a redundant path in order to prevent communication disconnection when a failure occurs. In ring protection, a blocking location is set as a ring path in order to prevent a loop failure. When the failure location of the ring path is a single location, a redundant route can be secured. When there are multiple fault locations on the ring path, depending on the block location setting position, a physical bypass path exists, but a logical bypass path does not exist, so a redundant path is secured. This is sometimes called ring segmentation. In Non-Patent Document 1, in order to eliminate ring segmentation, a redundant route is secured by moving the set position of the blockage location.

  FIG. 1 is a diagram illustrating a communication path when a communication network in the prior art is not faulty. The communication network N includes an upper ring R and a lower segment S. In the upper ring R, ring connection node 1-1, nodes 2-1, 2-2, 2-3, 2-4, 2-5, ring connection node 1-2, and node 2-6 are in this order. Connected. In the lower segment S, the ring connection node 1-1, the nodes 3-1, 3-2, 3-3, 3-4, 3-5 and the ring connection node 1-2 are connected in a line in this order. . The upper ring R and the lower segment S are connected at ring connection nodes 1-1 and 1-2.

  In FIG. 1, no failure has occurred in the communication network N. The block location of the upper ring R is set between the nodes 2-4 and 2-5, and the block location of the lower segment S is set between the nodes 3-4 and 3-5. When transmitting a frame from the node 2-2 to the node 3-5, the node 2-2, 2-1, the ring connection node 1-1, the node 2-6, the ring connection node 1-2, and the node 3-5 Frames can be transmitted in the following order.

  FIG. 2 is a diagram showing a redundant path at the time of failure of the communication network in the prior art. In FIG. 2, the prior art described in Non-Patent Document 1 is not applied. A failure has occurred between the nodes 2-3 and 2-4, and a failure has occurred between the ring connection node 1-2 and the node 2-6. Since a failure has occurred in the upper ring R, the blocked portion of the upper ring R is opened between the nodes 2-4 and 2-5, and the lower segment S is between the nodes 3-4 and 3-5. The blockage location is set. That is, the set position of the blockage location is not moved between the nodes 3-4 and 3-5 before and after the occurrence of the failure. When transmitting a frame from the node 2-2 to the node 3-5, the node 2-2, 2-1, the ring connection node 1-1, and the nodes 3-1, 3-2, 3-3, 3-4 In this order, the frame can be transmitted from the node 2-2 to the node 3-4, but the frame cannot be transmitted from the node 3-4 to the node 3-5, and the ring segmentation can be eliminated. Absent.

  FIG. 3 is a diagram showing a redundant path when a communication network failure occurs in the prior art. In FIG. 3, the prior art described in Non-Patent Document 1 is applied. A failure has occurred between the nodes 2-3 and 2-4, and a failure has occurred between the ring connection node 1-2 and the node 2-6. Since a failure has occurred in the upper ring R, the blocking location of the upper ring R is opened between the nodes 2-4 and 2-5, and the lower ring is connected between the node 3-5 and the ring connection node 1-2. The block location of segment S is set. That is, before and after the occurrence of the failure, the setting position of the blockage location is moved from between the nodes 3-4 and 3-5 to between the node 3-5 and the ring connection node 1-2. When transmitting a frame from the node 2-2 to the node 3-5, the node 2-2, 2-1, the ring connection node 1-1, and the nodes 3-1, 3-2, 3-3, 3-4 , 3-5, frames can be transmitted, and ring segmentation can be eliminated.

ITU-T Q9 / 15 Working Document, WD43 in Shenzhen interim meeting (2010/02), “The initial draft of appending interconnecting ensembles”.

  In Non-Patent Document 1, regardless of the location where a failure occurs in the ring path, the set position of the blocked location is moved by a single method. For this reason, ring segmentation may not be eliminated depending on the location of failure in the ring path, which may further promote ring segmentation.

  FIG. 4 is a diagram showing a redundant path at the time of failure of the communication network in the prior art. In FIG. 4, the prior art described in Non-Patent Document 1 is applied. A failure has occurred between the ring connection node 1-1 and the node 2-1, and a failure has occurred between the node 2-6 and the ring connection node 1-1. Since a failure has occurred in the upper ring R, the blocking location of the upper ring R is opened between the nodes 2-4 and 2-5, and the lower ring is connected between the node 3-5 and the ring connection node 1-2. The block location of segment S is set. That is, in FIG. 4 as well as in FIG. 3, before and after the occurrence of the failure, the set position of the blockage point is moved from between the nodes 3-4 and 3-5 to between the node 3-5 and the ring connection node 1-2. ing. The connection between the upper ring R and the lower segment S is completely broken, which further facilitates ring segmentation rather than being able to eliminate ring segmentation.

Therefore, in order to solve the above problems, the present invention is, depending on the point of failure of the ring path, the setting position of the occlusion be to move, without further promote ring segmentation between predetermined nodes mutually and to provide can be Ru communication network to secure a communication path, the control method for a ring connection node and the communication network in.

  In order to achieve the above object, when a failure occurs in a plurality of locations of the upper ring and at least one of the upper ring ports of the ring connection node fails, the lower segment port of the ring connection node is blocked. I made it. Alternatively, the lower segment port of the ring connection node is blocked when a failure has occurred in a plurality of locations of the upper ring and no failure has occurred in any of the upper ring ports of the ring connection node.

Specifically, the present invention provides:
An upper ring in which a plurality of nodes are connected in a ring shape, and a lower segment in which a plurality of nodes are connected in a line, and the upper ring and the lower segment are included in the upper ring and the lower segment A communication network connected by two ring connection nodes located at both ends of
The two ring connection nodes are:
Two upper ring ports that are interfaces to two nodes that are adjacent to each other and that are included in the upper ring;
One lower segment port that is an interface with one node adjacent to itself and included in the lower segment;
The two conductive state information indicating the conduction state between the nodes in the two paths of the upper ring that connects the ring connection node, wherein the two paths, the two or we respectively obtain higher Ringupo DOO, the conducting A connection state monitoring unit between ring connection nodes that detects that a failure has occurred in the two paths based on state information;
An upper ring port state monitoring unit that monitors the state of the two upper ring ports possessed by itself and detects that a failure has occurred in at least one of the two upper ring ports possessed by itself;
When a failure occurs in the two paths and a failure occurs in any of the two upper ring ports, a lower segment port blocking unit that blocks the lower segment port according to a predetermined setting table;
With
The setting table is
If a failure occurs in the two paths of the upper ring and a failure occurs in both of the two upper ring ports for one of the two ring connection nodes, the two upper The communication network is configured to block the lower segment port provided in a ring connection node in which a failure has occurred in both of the ring ports.

  According to this configuration, since the ring connection node in which a failure has occurred can be separated from the communication network, the influence of ring segmentation can be minimized.

The present invention also provides:
An upper ring in which a plurality of nodes are connected in a ring shape, and a lower segment in which a plurality of nodes are connected in a line, and the upper ring and the lower segment are included in the upper ring and the lower segment A communication network connected by two ring connection nodes located at both ends of
The two ring connection nodes are:
Two upper ring ports that are interfaces to two nodes that are adjacent to each other and that are included in the upper ring;
One lower segment port that is an interface with one node adjacent to itself and included in the lower segment;
The two conductive state information indicating the conduction state between the nodes in the two paths of the upper ring that connects the ring connection node, wherein the two paths, the two or we respectively obtain higher Ringupo DOO, the conducting A connection state monitoring unit between ring connection nodes that detects that a failure has occurred in the two paths based on state information;
An upper ring port state monitoring unit that monitors the state of the two upper ring ports possessed by itself and detects that a failure has occurred in at least one of the two upper ring ports possessed by itself;
When a failure occurs in the two paths and a failure occurs in any of the two upper ring ports, a lower segment port blocking unit that blocks the lower segment port according to a predetermined setting table;
With
The setting table is
A failure occurs in the two routes, and a failure occurs in an upper ring port connected to one of the two routes for at least one of the two ring connection nodes. But the upper ring port connected to the other route has not failed.
The lower segment port provided in one ring connection node where a failure has occurred in the upper ring port of the two ring connection nodes is set to be blocked, or
Set to block the lower segment port provided in the low priority ring connection node of the two ring connection nodes, or
The communication network is configured to block the lower segment port provided in a ring connection node in which no failure has occurred in both of the two upper ring ports of the two ring connection nodes. .

  According to this configuration, when the priority of communication related to one ring connection node is lower than the priority of communication related to another ring connection node, the port of one ring connection node can be blocked. The influence of ring segmentation can be minimized.

The present invention also provides:
A ring connection node that connects the upper ring and the lower segment by including a plurality of nodes in an upper ring connected in a ring shape and being positioned at one end of a lower segment connected in a line shape. There,
Two upper ring ports that are interfaces to two nodes that are adjacent to each other and that are included in the upper ring;
One lower segment port that is an interface with one node adjacent to itself and included in the lower segment;
The two conductive state information indicating the conduction state between the nodes in the two paths of the upper ring that connects the ring connection node, wherein the two paths, the two or we respectively obtain higher Ringupo DOO, the conducting A connection state monitoring unit between ring connection nodes that detects that a failure has occurred in the two paths based on state information;
An upper ring port state monitoring unit that monitors the state of the two upper ring ports possessed by itself and detects that a failure has occurred in at least one of the two upper ring ports possessed by itself;
When a failure occurs in the two paths and a failure occurs in any of the two upper ring ports, a lower segment port blocking unit that blocks the lower segment port according to a predetermined setting table;
With
The setting table is
If a failure occurs in the two paths of the upper ring and a failure occurs in both of the two upper ring ports for one of the two ring connection nodes, the two upper The ring connection node is configured to block the lower segment port provided in the ring connection node in which a failure has occurred in both of the ring ports.

  According to this configuration, since the ring connection node in which a failure has occurred can be separated from the communication network, the influence of ring segmentation can be minimized.

The present invention also provides:
A ring connection node that connects the upper ring and the lower segment by including a plurality of nodes in an upper ring connected in a ring shape and being positioned at one end of a lower segment connected in a line shape. There,
Two upper ring ports that are interfaces to two nodes that are adjacent to each other and that are included in the upper ring;
One lower segment port that is an interface with one node adjacent to itself and included in the lower segment;
The two conductive state information indicating the conduction state between the nodes in the two paths of the upper ring that connects the ring connection node, wherein the two paths, the two or we respectively obtain higher Ringupo DOO, the conducting A connection state monitoring unit between ring connection nodes that detects that a failure has occurred in the two paths based on state information;
An upper ring port state monitoring unit that monitors the state of the two upper ring ports possessed by itself and detects that a failure has occurred in at least one of the two upper ring ports possessed by itself;
When a failure occurs in the two paths and a failure occurs in any of the two upper ring ports, a lower segment port blocking unit that blocks the lower segment port according to a predetermined setting table;
With
The setting table is
A failure occurs in the two routes, and a failure occurs in an upper ring port connected to one of the two routes for at least one of the two ring connection nodes. But the upper ring port connected to the other route has not failed.
The lower segment port provided in one ring connection node where a failure has occurred in the upper ring port of the two ring connection nodes is set to be blocked, or
Set to block the lower segment port provided in the low priority ring connection node of the two ring connection nodes, or
A ring connection node configured to block the lower segment port provided in a ring connection node in which no failure has occurred in both of the two upper ring ports of the two ring connection nodes. is there.

  According to this configuration, when the priority of communication related to the ring connection node is lower than the priority of communication related to another ring connection node, the port of the ring connection node can be blocked. Can be minimized.

The present invention also provides:
An upper ring in which a plurality of nodes are connected in a ring shape, and a lower segment in which a plurality of nodes are connected in a line, and the upper ring and the lower segment are included in the upper ring and the lower segment A communication network control method connected in two ring connection nodes located at both ends of
In the two ring connection nodes, a failure occurs in two paths of an upper ring connecting the two ring connection nodes, and the two ring connection nodes are connected to one of the two ring connection nodes. When a failure occurs in both of the upper ring ports, a setting table is set in advance so as to set the lower segment port included in the ring connection node in which both of the two upper ring ports have failed,
At least one of the two ring connection nodes is
The conduction state information indicating the conduction state between the nodes in the two paths, the the two paths, the two upper Ringupo bets or we respectively obtain, is a failure in the two paths on the basis of the conductive state information Detect what happened, and
The status of two upper ring ports that are adjacent to each other and are interfaces with two nodes included in the upper ring are monitored, and a failure occurs in at least one of the two upper ring ports that the self has When we detect that
The communication network control method is characterized in that, according to the setting table, the lower segment port provided in a ring connection node in which a failure has occurred in both of the two upper ring ports is blocked.

  According to this configuration, since the ring connection node in which a failure has occurred can be separated from the communication network, the influence of ring segmentation can be minimized.

The present invention also provides:
An upper ring in which a plurality of nodes are connected in a ring shape, and a lower segment in which a plurality of nodes are connected in a line, and the upper ring and the lower segment are included in the upper ring and the lower segment A communication network control method connected in two ring connection nodes located at both ends of
In the two ring connection nodes, a failure occurs in two paths of an upper ring connecting the two ring connection nodes, and the two paths are connected to one of the two ring connection nodes. If a failure has occurred in the upper ring port connected to one of the paths, but no failure has occurred in the upper ring port connected to the other route, the two ring connection nodes Hold in advance a setting table that sets to block the lower segment port of any ring connection node,
At least one of the two ring connection nodes is
The two conductive state information indicating the conduction state between the nodes in the two paths of the upper ring that connects the ring connection node, wherein the two paths, the two or we respectively obtain higher Ringupo DOO, the conducting Detecting that a failure has occurred in the two routes based on the state information; and
The status of two upper ring ports that are adjacent to each other and are interfaces with two nodes included in the upper ring are monitored, and a failure occurs in at least one of the two upper ring ports that the self has When we detect that
According to the setting table,
Blocking the lower segment port provided in one ring connection node in which the upper ring port of the two ring connection nodes has failed, or
Blocking the lower segment port provided in the ring connection node having a low priority of the two ring connection nodes, or
The communication network control method is characterized in that the lower segment port provided in a ring connection node in which no failure has occurred in both of the two upper ring ports of the two ring connection nodes is blocked. .

  According to this configuration, when the priority of communication related to one ring connection node is lower than the priority of communication related to another ring connection node, the port of one ring connection node can be blocked. The influence of ring segmentation can be minimized.

The present invention is, depending on the point of failure of the ring path, the setting position of the occlusion be to move, without further promote ring segmentation, as possible out to secure a communication path between the predetermined node mutual A communication network, a ring connection node, and a communication network control method can be provided.

It is a figure which shows the communication path | route at the time of the non-failure of a communication network. It is a figure which shows the redundant path at the time of the failure of the communication network in a prior art. It is a figure which shows the redundant path at the time of the failure of the communication network in a prior art. It is a figure which shows the redundant path at the time of the failure of the communication network in a prior art. It is a figure which shows the component of the ring connection node in this invention. It is a figure which shows the setting content of the ring connection node in this invention. It is a figure which shows the processing content of the ring connection node in this invention. It is a figure which shows the setting content of the ring connection node in Embodiment 1. FIG. It is a figure which shows the movement method of the obstruction | occlusion location in Embodiment 1. FIG. It is a figure which shows the movement method of the obstruction | occlusion location in Embodiment 1. FIG. It is a figure which shows the setting content of the ring connection node in Embodiment 2. FIG. It is a figure which shows the movement method of the obstruction | occlusion location in Embodiment 2. FIG. It is a figure which shows the movement method of the obstruction | occlusion location in Embodiment 2. FIG. It is a figure which shows the setting content of the ring connection node in Embodiment 3. It is a figure which shows the movement method of the obstruction | occlusion location in Embodiment 3. FIG. It is a figure which shows the movement method of the obstruction | occlusion location in Embodiment 3. FIG.

  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.

(Outline of the present invention)
FIG. 1 is a diagram showing a communication path when a communication network is not faulty in the present invention. The communication path when the communication network N is not faulty is the same in the present invention and the prior art. The communication network N is a network such as an L2 network where a loop failure may occur.

  FIG. 5 is a diagram showing components of the ring connection node in the present invention. Ring connection node 1 includes upper ring ports 11 and 12, lower segment port 13, frame transmission / reception unit 14, conduction state monitoring unit 15 between ring connection nodes, upper ring port state monitoring unit 16, ring segmentation avoidance process setting table 17, ring It comprises a segmentation avoidance process control unit 18 and a lower segment port control unit 19.

  The upper ring ports 11 and 12 are interfaces with two nodes 2 adjacent to the ring connection node 1 and included in the upper ring R. In the ring connection node 1-1, the upper ring ports 11 and 12 are interfaces with the nodes 2-1 and 2-6, respectively. In the ring connection node 1-2, the upper ring ports 11 and 12 are interfaces with the nodes 2-5 and 2-6, respectively. The lower segment port 13 is an interface with one node 3 adjacent to the ring connection node 1 and included in the lower segment S. In the ring connection node 1-1, the lower segment port 13 is an interface with the node 3-1. In the ring connection node 1-2, the lower segment port 13 is an interface with the node 3-5. The frame transmission / reception unit 14 relays frame transmission / reception between the upper ring ports 11 and 12 and the lower segment port 13.

  When the ring connection node conduction state monitoring unit 15 monitors the conduction state between the ring connection node 1 and the other ring connection node 1 and detects that a failure has occurred in a plurality of locations of the upper ring R, , The upper ring failure information to that effect is output. For example, Ethernet (registered trademark) OAM (Operations, Administration and Maintenance) can be used as the connection state monitoring unit 15 between the ring connection nodes. The upper ring port state monitoring unit 16 monitors the state of the upper ring ports 11 and 12 included in the ring connection node 1. When the upper ring port state monitoring unit 16 detects that a failure has occurred in at least one of the upper ring ports 11 and 12 of the ring connection node 1, it outputs higher ring port failure information to that effect. When the upper ring port state monitoring unit 16 detects that no failure has occurred in any of the upper ring ports 11 and 12 of the ring connection node 1, the upper ring port state monitoring unit 16 outputs the upper ring port non-failure information to that effect. To do.

  The ring segmentation avoidance process setting table 17 includes a lower segment port control unit 19 when the ring connection node conduction state monitoring unit 15 and the upper ring port state monitoring unit 16 output upper ring failure information and upper ring port failure information, respectively. Sets whether to move the set position of the blockage. The ring segmentation avoidance process setting table 17 includes a lower segment port control unit when the ring connection node conduction state monitoring unit 15 and the upper ring port state monitoring unit 16 output upper ring failure information and upper ring port non-failure information, respectively. 19 sets whether or not to move the set position of the blockage location. The ring segmentation avoidance process setting table 17 is created by the administrator of the communication network N according to the circumstances of the communication network N.

  The ring segmentation avoidance process control unit 18 receives the ring segmentation avoidance process when the upper ring failure information and the upper ring port failure information are input, or when the upper ring failure information and the upper ring port non-failure information are input. Refer to the setting table 17. When the ring segmentation avoidance process setting table 17 is set so that the lower segment port control unit 19 moves the set position of the blockage point, the ring segmentation avoidance process control unit 18 instructs the lower segment port control unit 19 to Then, the lower segment port control unit 19 closes the lower segment port 13 of the ring connection node 1. The ring segmentation avoidance process control unit 18 and the lower segment port control unit 19 function as a lower segment port blocking unit.

  FIG. 6 is a diagram showing the setting contents of the ring connection node in the present invention. The setting items of the ring segmentation avoidance process setting table 17 include “ring segmentation avoidance process execution setting”, “lower segment switching execution setting when both upper ring ports fail”, “lower segment switching execution setting when upper ring one port fails”, “ “Lower segment switching execution setting when no upper ring port failure occurs”, “execution standby time setting A”, “execution standby time setting B”, “execution standby time setting C”, and “execution standby time setting D” may be set. it can.

  When “ring segmentation avoidance process execution setting” is set to “ON”, the ring segmentation avoidance process is executed. When set to “OFF”, the ring segmentation avoidance process is not executed.

  When “Upper Ring Port Failure Lower Segment Switch Execution Setting” is set to “ON”, if both the upper ring ports 11 and 12 have failed, the lower segment port 13 is blocked. When “OFF” is set, the lower segment port 13 is not blocked even if a failure has occurred in either the upper ring port 11 or 12.

  When “Upper ring one port failure lower segment switching execution setting” is set to “Primary” or “Secondary”, if any of the upper ring ports 11 and 12 has failed, the lower segment port 13 Blocked. When set to “OFF”, the lower segment port 13 is not blocked even if a failure occurs in either the upper ring port 11 or 12. When set to “Primary”, the lower segment port 13 is closed more quickly than when set to “Secondary”.

  When "Upper Ring Port Failure No Lower Segment Switching Execution Setting" is set to "ON", if no failure has occurred in either upper ring port 11 or 12, lower segment port 13 is blocked. . When set to “OFF”, the lower segment port 13 is not blocked even if a failure has not occurred in any of the upper ring ports 11 and 12.

  "Execution waiting time setting A", "Execution waiting time setting B", "Execution waiting time setting C", and "Execution waiting time setting D" indicate that the ring connection node continuity monitoring unit 15 has a plurality of locations on the upper ring R. 7 is a setting item for preventing the lower segment port control unit 19 from closing the lower segment port 13 of the ring connection node 1 immediately after detecting that a failure has occurred. Will be described later.

  FIG. 7 is a diagram showing the processing contents of the ring connection node in the present invention. When the ring connection node conduction state monitoring unit 15 monitors the conduction state between the ring connection node 1 and the other ring connection node 1 and detects that a failure has occurred in a plurality of locations of the upper ring R, The upper ring failure information to that effect is output (step S101). The ring segmentation avoidance process control unit 18 refers to the ring segmentation avoidance process setting table 17 when the upper ring failure information is input (step S102). When “ring segmentation avoidance process execution setting” is set to “ON” (YES in step S102), ring segmentation avoidance process control unit 18 waits for the time set in “execution waiting time setting A”. (Step S103) and Step S104 are executed. When “ring segmentation avoidance process execution setting” is set to “OFF” (NO in step S102), ring segmentation avoidance process control unit 18 ends the ring segmentation avoidance process.

  The upper ring port state monitoring unit 16 monitors the state of the upper ring ports 11 and 12 included in the ring connection node 1. When the upper ring port state monitoring unit 16 detects that a failure has occurred in both the upper ring ports 11 and 12 of the ring connection node 1, the upper ring port state monitoring unit 16 outputs higher ring port failure information to that effect.

The ring segmentation avoidance process control unit 18 refers to the ring segmentation avoidance process setting table 17 when the upper ring port failure information is input (YES in step S104) (step S105). When “upper ring both-port failure lower segment switching execution setting” is set to “ON” (YES in step S105), ring segmentation avoidance process control unit 18 executes step S114 described later. When “upper ring ring port failure lower segment switching execution setting” is set to “OFF” (NO in step S105), ring segmentation avoidance process control unit 18 is set in “execution waiting time setting B”. (Step S106), and the ring segmentation avoidance process is terminated. The ring segmentation avoidance process control unit 18 waits for the time set in the “execution standby time setting B” when the upper ring port failure information is not input (NO in step S104) (step S106). Execute.

  The upper ring port state monitoring unit 16 monitors the state of the upper ring ports 11 and 12 included in the ring connection node 1. When the upper ring port state monitoring unit 16 detects that a failure has occurred in either the upper ring port 11 or 12 of the ring connection node 1, the upper ring port state monitoring unit 16 outputs higher ring port failure information to that effect.

  The ring segmentation avoidance process control unit 18 refers to the ring segmentation avoidance process setting table 17 when the upper ring port failure information is input (YES in step S107) (step S108). When “upper ring one-port failure lower segment switching execution setting” is set to “Primary” (YES in step S108), ring segmentation avoidance process control unit 18 executes step S114 described later. When “upper ring one port failure lower segment switching execution setting” is not set to “Primary” (NO in step S108), ring segmentation avoidance process control unit 18 is set in “execution waiting time setting C”. For a predetermined time (step S109), and executes step S111. The ring segmentation avoidance process control unit 18 waits for the time set in the “execution standby time setting C” when the upper ring port failure information is not input (NO in step S107) (step S110). The system waits for the time set in “Standby time setting D” (step S112), and executes step S113.

When “upper ring one-port failure lower segment switching execution setting” is set to “Secondary” (YES in step S111), ring segmentation avoidance process control unit 18 executes step S114 described later. When “Upper ring one port failure lower segment switching execution setting” is not set to “Secondary” (NO in step S111), the ring segmentation avoidance process control unit 18 is set in “Execution waiting time setting D”. (Step S112), and the ring segmentation avoidance process is terminated.

  The upper ring port state monitoring unit 16 monitors the state of the upper ring ports 11 and 12 included in the ring connection node 1. When the upper ring port state monitoring unit 16 detects that no failure has occurred in any of the upper ring ports 11 and 12 of the ring connection node 1, the upper ring port state monitoring unit 16 outputs the upper ring port non-failure information to that effect. To do.

  The ring segmentation avoidance process control unit 18 refers to the ring segmentation avoidance process setting table 17 when the upper ring port non-failure information is input (step S113). When “lower segment switching execution setting when no upper ring port failure has occurred” is set to “ON” (YES in step S113), ring segmentation avoidance process control unit 18 executes step S114 described later. When “lower segment switching execution setting when no upper ring port failure has occurred” is set to “OFF” (NO in step S113), ring segmentation avoidance process control unit 18 ends the ring segmentation avoidance process.

  Step S114 described above will be described. In the normal state in which the closed portion of the lower segment S is set between the nodes 3-4 and 3-5 (YES in step S114), the ring segmentation avoidance process control unit 18 instructs the lower segment port control unit 19 to The lower segment port control unit 19 closes the lower segment port 13 of the ring connection node 1 (step S115), and ends the ring segmentation avoidance process. In the switching state in which the closed portion of the lower segment S is not set between the nodes 3-4 and 3-5 (NO in step S114), the ring segmentation avoidance process control unit 18 ends the ring segmentation avoidance process.

  The ring connection node 1 moves the blocking position of the lower segment S from between the nodes 3-4 and 3-5 to the lower segment port 13 when a failure occurs in at least one of the upper ring ports 11 and 12. be able to. The ring connection node 1 in which the failure has occurred can be separated from the communication network N, and the influence of ring segmentation can be suppressed to the communication involving the ring connection node 1 in which the failure has occurred.

  The ring connection node 1 moves the blocking position of the lower segment S from between the nodes 3-4 and 3-5 to the lower segment port 13 when neither of the upper ring ports 11 and 12 has a failure. Can be made. When the priority of communication related to one ring connection node 1 is lower than the priority of communication related to another ring connection node 1, the influence of ring segmentation is suppressed to the communication related to one ring connection node 1. it can.

(Embodiment 1)
FIG. 8 is a diagram illustrating the setting contents of the ring connection node in the first embodiment. In the ring segmentation avoidance process setting table 17 in the ring connection nodes 1-1 and 1-2 shown in FIG. 8, “ring segmentation avoidance process execution setting” is “ON”, and “lower segment switching execution setting when both upper ring ports fail” "" Is ON, "" Upper ring one port failure lower segment switching execution setting "is" OFF "," Upper ring port failure no lower segment switching execution setting "is" OFF "," Execution waiting time setting A " “30 seconds”, “execution standby time setting B” is set to “30 seconds”, “execution standby time setting C” is set to “30 seconds”, and “execution standby time setting D” is set to “30 seconds”.

  FIG. 9 is a diagram illustrating a moving method of the closed portion in the first case of the first embodiment. A failure has occurred between the node 2-5 and the ring connection node 1-2, and a failure has occurred between the ring connection node 1-2 and the node 2-6. Since a failure has occurred in the upper ring R, the blocked portion of the upper ring R is opened between the nodes 2-4 and 2-5. Before the ring segmentation avoidance process, a blockage location of the lower segment S is set between the nodes 3-4 and 3-5.

  In ring connection node 1-1, YES in step S102, waits 30 seconds in step S103, NO in step S104, waits 30 seconds in step S106, NO in step S107, and 30 in step S110. Wait for 2 seconds, wait for 30 seconds in step S112, and NO in step S113. In the ring connection node 1-1, “lower segment switching execution setting when both upper ring ports fail” is set to “ON”, but no failure has occurred in either upper ring port 11 or 12. The lower segment port 13 is not blocked.

  The ring connection node 1-2 is YES in step S102, waits for 30 seconds in step S103, YES in step S104, YES in step S105, and YES in step S114. In the ring connection node 1-2, the “lower segment switching execution setting when both upper ring ports fail” is set to “ON”, and a failure has occurred in both the upper ring ports 11 and 12. The lower segment port 13 is blocked after a waiting time of 30 seconds.

  In the block location moving method shown in FIG. 9, the ring connection node 1-2 in which the failure has occurred can be separated from the communication network N, and the influence of the ring segmentation involves the ring connection node 1-2 in which the failure has occurred. It can be suppressed only to communication.

  FIG. 10 is a diagram illustrating a moving method of the closed portion in the second case of the first embodiment. A failure has occurred between the nodes 2-3 and 2-4, and a failure has occurred between the node 2-6 and the ring connection node 1-1. Since a failure has occurred in the upper ring R, the blocked portion of the upper ring R is opened between the nodes 2-4 and 2-5. Before the ring segmentation avoidance process, a blockage location of the lower segment S is set between the nodes 3-4 and 3-5.

  In ring connection node 1-1, YES in step S102, waits for 30 seconds in step S103, NO in step S104, waits for 30 seconds in step S106, YES in step S107, NO in step S108 It waits for 30 seconds in step S109, NO in step S111, waits for 30 seconds in step S112, and NO in step S113. In the ring connection node 1-1, “lower segment switching execution setting when both upper ring ports fail” is set to “ON”, but since only the upper ring port 12 has failed, the lower segment port 13 is not blocked.

  The ring connection node 1-2 is YES in step S102, waits for 30 seconds in step S103, NO in step S104, waits for 30 seconds in step S106, NO in step S107, and 30 in step S110. Wait for 2 seconds, wait for 30 seconds in step S112, and NO in step S113. In ring connection node 1-2, “lower segment switching execution setting when both upper ring ports fail” is set to “ON”, but no failure has occurred in either upper ring port 11 or 12. The lower segment port 13 is not blocked.

  In the block location moving method shown in FIG. 10, it is possible to prevent communication between the nodes 2-4 and 2-5, the ring connection node 1-2, and the node 3-5 from being disconnected. When the communication between the ring connection node 1-2 and the nodes 2-5, 2-6, and 3-5 adjacent to the ring connection node 1-2 has a higher priority than other communication, the blocking illustrated in FIG. The method of moving the location is effective.

(Embodiment 2)
FIG. 11 is a diagram illustrating the setting contents of the ring connection node in the second embodiment. In the ring segmentation avoidance process setting table 17 in the ring connection node 1-1 shown in FIG. 11A, “ring segmentation avoidance process execution setting” is “ON”, and “lower segment switching execution setting when both upper ring ports fail” "OFF", "Upper ring one port failure lower segment switching execution setting" is "Secondary", "Upper ring port failure no lower segment switching execution setting" is "OFF", "Execution waiting time setting A" is “15 seconds”, “execution standby time setting B” are set to “45 seconds”, “execution standby time setting C” is set to “60 seconds”, and “execution standby time setting D” is set to “60 seconds”. In the ring segmentation avoidance process setting table 17 in the ring connection node 1-2 shown in FIG. 11B, “ring segmentation avoidance process execution setting” is “ON”, and “lower segment switching execution setting when both upper ring ports fail” Is "OFF", "Upper ring one port failure lower segment switching execution setting" is "Primary", "Upper ring port failure no lower segment switching execution setting" is "OFF", "Execution waiting time setting A" is “15 seconds”, “execution standby time setting B” are set to “45 seconds”, “execution standby time setting C” is set to “60 seconds”, and “execution standby time setting D” is set to “60 seconds”.

  FIG. 12 is a diagram illustrating a moving method of the closed portion in the first case of the second embodiment. A failure has occurred between the nodes 2-3 and 2-4, and a failure has occurred between the node 2-6 and the ring connection node 1-2. Since a failure has occurred in the upper ring R, the blocked portion of the upper ring R is opened between the nodes 2-4 and 2-5. Before the ring segmentation avoidance process, a blockage location of the lower segment S is set between the nodes 3-4 and 3-5.

  In ring connection node 1-1, YES in step S102, waits for 15 seconds in step S103, NO in step S104, waits for 45 seconds in step S106, NO in step S107, and 60 in step S110. Wait for 2 seconds, wait for 60 seconds in step S112, and NO in step S113. In the ring connection node 1-1, “lower segment switching execution setting when upper ring one port fails” is set to “Secondary”, but no failure has occurred in either upper ring port 11 or 12. The lower segment port 13 is not blocked.

  The ring connection node 1-2 is YES in step S102, waits for 15 seconds in step S103, NO in step S104, waits for 45 seconds in step S106, YES in step S107, and YES in step S108. And YES in step S114. In ring connection node 1-2, “Upper ring one port failure lower segment switching execution setting” is set to “Primary”, and only upper ring port 11 has failed, so 60 seconds standby The lower segment port 13 is blocked over time.

  In the block location moving method shown in FIG. 12, the failed ring connection node 1-2 and connection nodes 2-4 and 2-5 can be separated from the communication network N, and the influence of ring segmentation can be reduced. It is possible to suppress the communication involving the ring connection node 1-2 and the connection nodes 2-4 and 2-5 that have occurred. Communication between the nodes 2-2 and 2-1, the ring connection node 1-1, and the nodes 3-1 and 3-2 can be ensured. Therefore, a vertical communication path between the upper ring R and the lower segment S can be secured. This is because the communication paths between the nodes 2-2 and 2-1, the ring connection node 1-1 and the nodes 3-1 and 3-2 are used as the active system, and the nodes 2-4, 2-5 and the ring This is effective when the communication path between the connection node 1-2 and the nodes 3-5 and 3-4 is used as a backup system.

  FIG. 13 is a diagram illustrating a moving method of the closed portion in the second case of the second embodiment. A failure has occurred between the nodes 2-2 and 2-3, and a failure has occurred between the node 2-6 and the ring connection node 1-1. Since a failure has occurred in the upper ring R, the blocked portion of the upper ring R is opened between the nodes 2-4 and 2-5. Before the ring segmentation avoidance process, a blockage location of the lower segment S is set between the nodes 3-4 and 3-5.

  In ring connection node 1-1, YES in step S102, waits for 15 seconds in step S103, NO in step S104, waits for 45 seconds in step S106, YES in step S107, NO in step S108 It waits for 60 seconds in step S109, YES in step S111, and YES in step S114. In the ring connection node 1-1, the “upper ring one port failure lower segment switching execution setting” is set to “Secondary”, and the upper ring port 12 has failed, so a waiting time of 120 seconds After that, the lower segment port 13 is closed.

  In the ring connection node 1-2, YES in step S102, waits for 15 seconds in step S103, NO in step S104, waits for 45 seconds in step S106, NO in step S107, and 60 in step S110. Wait for 2 seconds, wait for 60 seconds in step S112, and NO in step S113. In the ring connection node 1-2, “lower segment switching execution setting at the time of upper ring one port failure” is set to “Primary”, but no failure has occurred in either of the upper ring ports 11 and 12. The lower segment port 13 is not blocked.

  In the block location moving method shown in FIG. 13, the ring connection node 1-1 and the nodes 2-1 and 2-2 in which the failure has occurred can be separated from the communication network N, and the failure is caused by the influence of ring segmentation. It is possible to suppress communication involving the ring connection node 1-1 and the nodes 2-1, 2-2. Communication between the nodes 2-4 and 2-5, the ring connection node 1-2 and the nodes 3-5 and 3-4 can be ensured. Therefore, a vertical communication path between the upper ring R and the lower segment S can be secured. This is because the communication paths between the nodes 2-4 and 2-5, the ring connection node 1-2 and the nodes 3-5 and 3-4 are used as the active system, and the nodes 2-2, 2-1, This is effective when the communication path between the connection node 1-1 and the nodes 3-1, 3-2 is used as a backup system.

(Embodiment 3)
FIG. 14 is a diagram illustrating the setting contents of the ring connection node according to the third embodiment. In the ring segmentation avoidance process setting table 17 in the ring connection node 1-1 shown in FIG. 14 (a), “ring segmentation avoidance process execution setting” is “ON”, and “lower segment switching execution setting when both upper ring ports fail” Is "OFF", "Upper ring one port failure lower segment switching execution setting" is "OFF", "Upper ring port failure no lower segment switching execution setting" is "OFF", "Execution waiting time setting A" is “10 seconds”, “execution standby time setting B” are set to “10 seconds”, “execution standby time setting C” is set to “10 seconds”, and “execution standby time setting D” is set to “10 seconds”. In the ring segmentation avoidance process setting table 17 in the ring connection node 1-2 shown in FIG. 14B, “ring segmentation avoidance process execution setting” is “ON”, and “lower segment switching execution setting when both upper ring ports fail” Is "OFF", "Upper ring one port failure lower segment switching execution setting" is "OFF", "Upper ring port failure no lower segment switching execution setting" is "ON", "Execution waiting time setting A" is “10 seconds”, “execution standby time setting B” are set to “10 seconds”, “execution standby time setting C” is set to “10 seconds”, and “execution standby time setting D” is set to “10 seconds”.

  FIG. 15 is a diagram illustrating a moving method of the closed portion in the first case of the third embodiment. A failure has occurred between the nodes 2-3 and 2-4, and a failure has occurred between the node 2-6 and the ring connection node 1-1. Since a failure has occurred in the upper ring R, the blocked portion of the upper ring R is opened between the nodes 2-4 and 2-5. Before the ring segmentation avoidance process, a blockage location of the lower segment S is set between the nodes 3-4 and 3-5.

  In ring connection node 1-1, YES in step S102, waits for 10 seconds in step S103, NO in step S104, waits for 10 seconds in step S106, YES in step S107, NO in step S108 It waits for 10 seconds in step S109, NO in step S111, waits for 10 seconds in step S112, and NO in step S113. In the ring connection node 1-1, “lower segment switching execution setting when both upper ring ports fail”, “lower segment switching execution setting when one upper ring port fails” and “lower segment switching execution setting when no upper ring port failure occurs” "Is set to" OFF ", and the lower segment port 13 is not blocked.

  In the ring connection node 1-2, YES in step S102, waits for 10 seconds in step S103, NO in step S104, waits for 10 seconds in step S106, NO in step S107, and 10 in step S110. Wait for 2 seconds, wait for 10 seconds in step S112, YES in step S113, and YES in step S114. In the ring connection node 1-2, the “lower segment switching execution setting when no upper ring port failure has occurred” is set to “ON”, and no failure has occurred in either the upper ring port 11 or 12. The lower segment port 13 is blocked after a waiting time of 40 seconds.

  In the blocking location moving method shown in FIG. 15, when the priority of communication involving the ring connection node 1-2 is lower than the priority of communication involving the ring connection node 1-1, the influence of ring segmentation is ring connected. It is possible to suppress communication involving the node 1-2.

  FIG. 16 is a diagram illustrating a moving method of the closed portion in the second case of the third embodiment. A failure has occurred between the nodes 2-2 and 2-3, and a failure has occurred between the node 2-6 and the ring connection node 1-2. Since a failure has occurred in the upper ring R, the blocked portion of the upper ring R is opened between the nodes 2-4 and 2-5. Before the ring segmentation avoidance process, a blockage location of the lower segment S is set between the nodes 3-4 and 3-5.

  In ring connection node 1-1, YES in step S102, waits for 10 seconds in step S103, NO in step S104, waits for 10 seconds in step S106, NO in step S107, and 10 in step S110. Wait for 2 seconds, wait for 10 seconds in step S112, and NO in step S113. In the ring connection node 1-1, “lower segment switching execution setting when both upper ring ports fail”, “lower segment switching execution setting when one upper ring port fails” and “lower segment switching execution setting when no upper ring port failure occurs” "Is set to" OFF ", and the lower segment port 13 is not blocked.

In the ring connection node 1-2, YES in step S102, waits for 10 seconds in step S103, NO in step S104, waits for 10 seconds in step S106, YES in step S107, NO in step S108 It waits for 10 seconds in step S109, NO in step S111, waits for 10 seconds in step S112, YES in step S113, and YES in step S114. In the ring connection node 1-2, when a failure has occurred in the upper ring port 11, the “lower segment switching execution setting at the time of upper ring one port failure” is set to “OFF”. “Lower segment switching execution setting when no failure occurs” is set to “ON”. Therefore, instead of using “upper ring one port failure lower segment switching execution setting”, by using “lower ring port failure no lower segment switching execution setting” , after waiting for 40 seconds, End the ring segmentation avoidance process.

  In the block location moving method shown in FIG. 16, when the priority of communication involving the ring connection node 1-2 is lower than the priority of communication involving the ring connection node 1-1, the influence of ring segmentation is connected to the ring. It is possible to suppress communication involving the node 1-2.

  The communication network, ring connection node, and communication network control method according to the present invention can be applied to a network such as an L2 network that uses ring protection and can cause a loop failure.

N: Communication network R: Upper ring S: Lower segment 1: Ring connection node 2, 3: Node 11, 12: Upper ring port 13: Lower segment port 14: Frame transmission / reception unit 15: Inter-ring connection node conduction state monitoring unit 16 : Upper ring port state monitoring unit 17: Ring segmentation avoidance process setting table 18: Ring segmentation avoidance process control unit 19: Lower segment port control unit

Claims (6)

An upper ring in which a plurality of nodes are connected in a ring shape, and a lower segment in which a plurality of nodes are connected in a line, and the upper ring and the lower segment are included in the upper ring and the lower segment A communication network connected by two ring connection nodes located at both ends of
The two ring connection nodes are:
Two upper ring ports that are interfaces to two nodes that are adjacent to each other and that are included in the upper ring;
One lower segment port that is an interface with one node adjacent to itself and included in the lower segment;
The two conductive state information indicating the conduction state between the nodes in the two paths of the upper ring that connects the ring connection node, wherein the two paths, the two or we respectively obtain higher Ringupo DOO, the conducting A connection state monitoring unit between ring connection nodes that detects that a failure has occurred in the two paths based on state information;
An upper ring port state monitoring unit that monitors the state of the two upper ring ports possessed by itself and detects that a failure has occurred in at least one of the two upper ring ports possessed by itself;
When a failure occurs in the two paths and a failure occurs in any of the two upper ring ports, a lower segment port blocking unit that blocks the lower segment port according to a predetermined setting table;
With
The setting table is
If a failure occurs in the two paths of the upper ring and a failure occurs in both of the two upper ring ports for one of the two ring connection nodes, the two upper A communication network, wherein the lower segment port of a ring connection node in which a failure has occurred in both ring ports is set to be blocked. An upper ring in which a plurality of nodes are connected in a ring shape, and a lower segment in which a plurality of nodes are connected in a line, and the upper ring and the lower segment are included in the upper ring and the lower segment A communication network connected by two ring connection nodes located at both ends of
The two ring connection nodes are:
Two upper ring ports that are interfaces to two nodes that are adjacent to each other and that are included in the upper ring;
One lower segment port that is an interface with one node adjacent to itself and included in the lower segment;
The two conductive state information indicating the conduction state between the nodes in the two paths of the upper ring that connects the ring connection node, wherein the two paths, the two or we respectively obtain higher Ringupo DOO, the conducting A connection state monitoring unit between ring connection nodes that detects that a failure has occurred in the two paths based on state information;
An upper ring port state monitoring unit that monitors the state of the two upper ring ports possessed by itself and detects that a failure has occurred in at least one of the two upper ring ports possessed by itself;
When a failure occurs in the two paths and a failure occurs in any of the two upper ring ports, a lower segment port blocking unit that blocks the lower segment port according to a predetermined setting table;
With
The setting table is
A failure occurs in the two routes, and a failure occurs in an upper ring port connected to one of the two routes for at least one of the two ring connection nodes. But the upper ring port connected to the other route has not failed.
The lower segment port provided in one ring connection node where a failure has occurred in the upper ring port of the two ring connection nodes is set to be blocked, or
Set to block the lower segment port provided in the low priority ring connection node of the two ring connection nodes, or
The communication network is configured to block the lower segment port provided in a ring connection node in which no failure has occurred in both of the two upper ring ports of the two ring connection nodes. A ring connection node that connects the upper ring and the lower segment by including a plurality of nodes in an upper ring connected in a ring shape and being positioned at one end of a lower segment connected in a line shape. There,
Two upper ring ports that are interfaces to two nodes that are adjacent to each other and that are included in the upper ring;
One lower segment port that is an interface with one node adjacent to itself and included in the lower segment;
The two conductive state information indicating the conduction state between the nodes in the two paths of the upper ring that connects the ring connection node, wherein the two paths, the two or we respectively obtain higher Ringupo DOO, the conducting A connection state monitoring unit between ring connection nodes that detects that a failure has occurred in the two paths based on state information;
An upper ring port state monitoring unit that monitors the state of the two upper ring ports possessed by itself and detects that a failure has occurred in at least one of the two upper ring ports possessed by itself;
When a failure occurs in the two paths and a failure occurs in any of the two upper ring ports, a lower segment port blocking unit that blocks the lower segment port according to a predetermined setting table;
With
The setting table is
If a failure occurs in the two paths of the upper ring and a failure occurs in both of the two upper ring ports for one of the two ring connection nodes, the two upper A ring connection node configured to block the lower segment port provided in a ring connection node in which a failure has occurred in both of the ring ports. A ring connection node that connects the upper ring and the lower segment by including a plurality of nodes in an upper ring connected in a ring shape and being positioned at one end of a lower segment connected in a line shape. There,
Two upper ring ports that are interfaces to two nodes that are adjacent to each other and that are included in the upper ring;
One lower segment port that is an interface with one node adjacent to itself and included in the lower segment;
The two conductive state information indicating the conduction state between the nodes in the two paths of the upper ring that connects the ring connection node, wherein the two paths, the two or we respectively obtain higher Ringupo DOO, the conducting A connection state monitoring unit between ring connection nodes that detects that a failure has occurred in the two paths based on state information;
An upper ring port state monitoring unit that monitors the state of the two upper ring ports possessed by itself and detects that a failure has occurred in at least one of the two upper ring ports possessed by itself;
When a failure occurs in the two paths and a failure occurs in any of the two upper ring ports, a lower segment port blocking unit that blocks the lower segment port according to a predetermined setting table;
With
The setting table is
A failure occurs in the two routes, and a failure occurs in an upper ring port connected to one of the two routes for at least one of the two ring connection nodes. But the upper ring port connected to the other route has not failed.
The lower segment port provided in one ring connection node where a failure has occurred in the upper ring port of the two ring connection nodes is set to be blocked, or
Set to block the lower segment port provided in the low priority ring connection node of the two ring connection nodes, or
A ring connection node configured to block the lower segment port provided in a ring connection node in which no failure has occurred in both of the two upper ring ports of the two ring connection nodes. An upper ring in which a plurality of nodes are connected in a ring shape, and a lower segment in which a plurality of nodes are connected in a line, and the upper ring and the lower segment are included in the upper ring and the lower segment A communication network control method connected in two ring connection nodes located at both ends of
In the two ring connection nodes, a failure occurs in two paths of an upper ring connecting the two ring connection nodes, and the two ring connection nodes are connected to one of the two ring connection nodes. When a failure occurs in both of the upper ring ports, a setting table is set in advance so as to set the lower segment port included in the ring connection node in which both of the two upper ring ports have failed,
At least one of the two ring connection nodes is
The conduction state information indicating the conduction state between the nodes in the two paths, the the two paths, the two upper Ringupo bets or we respectively obtain, is a failure in the two paths on the basis of the conductive state information Detect what happened, and
The status of two upper ring ports that are adjacent to each other and are interfaces with two nodes included in the upper ring are monitored, and a failure occurs in at least one of the two upper ring ports that the self has When we detect that
A communication network control method comprising: blocking the lower segment port provided in a ring connection node in which a failure has occurred in both of the two upper ring ports according to the setting table. An upper ring in which a plurality of nodes are connected in a ring shape, and a lower segment in which a plurality of nodes are connected in a line, and the upper ring and the lower segment are included in the upper ring and the lower segment A communication network control method connected in two ring connection nodes located at both ends of
In the two ring connection nodes, a failure occurs in two paths of an upper ring connecting the two ring connection nodes, and the two paths are connected to one of the two ring connection nodes. If a failure has occurred in the upper ring port connected to one of the paths, but no failure has occurred in the upper ring port connected to the other route, the two ring connection nodes Hold in advance a setting table that sets to block the lower segment port of any ring connection node,
At least one of the two ring connection nodes is
The two conductive state information indicating the conduction state between the nodes in the two paths of the upper ring that connects the ring connection node, wherein the two paths, the two or we respectively obtain higher Ringupo DOO, the conducting Detecting that a failure has occurred in the two routes based on the state information; and
The status of two upper ring ports that are adjacent to each other and are interfaces with two nodes included in the upper ring are monitored, and a failure occurs in at least one of the two upper ring ports that the self has When we detect that
According to the setting table,
Blocking the lower segment port provided in one ring connection node in which the upper ring port of the two ring connection nodes has failed, or
Blocking the lower segment port provided in the ring connection node having a low priority of the two ring connection nodes, or
A method for controlling a communication network, comprising: blocking the lower segment port provided in a ring connection node in which a failure has not occurred in both of the two upper ring ports of the two ring connection nodes.

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