WO2017148093A1

WO2017148093A1 - Node device and ring network switching method

Info

Publication number: WO2017148093A1
Application number: PCT/CN2016/092372
Authority: WO
Inventors: 游莉萍; 吴克巍
Original assignee: 中兴通讯股份有限公司
Priority date: 2016-03-03
Filing date: 2016-07-29
Publication date: 2017-09-08
Also published as: CN107154886A

Abstract

A ring network switching method, comprising: during the switching process of a ring network, each ring network node configuring an unknown package of a system to have no speed limit, and until the switching of the ring network is completed, each ring network node recovering a speed limit function of the unknown package of the system. Also disclosed is a node device. In the technical solution, during the switching of a ring network, an unknown package of a system is automatically set to have no speed limit, and after the switching is completed, a speed limit function of the system is recovered. In this way, the switching performance of a ring network is improved, without affecting the security of a system.

Description

Node device and ring network switching method

Technical field

The present application relates to, but is not limited to, the field of network communications, and in particular, to a handover scheme of a ring protection network.

Background technique

The ring network protection protocol (the ERPS (Ethernet Ring Protection Switching) protocol described in G.8032 is used as an example.) The RPL (Ring Protection Link ring protection link) is blocked when the network is normal, and the link fault is detected. After the faulty link is blocked, the RPL link is opened to implement service protection and fast switching. The ring network switching mainly occurs in the following scenarios (here, the ERPS ring network works in the return mode as an example): the ring network detects the link fault; the ring network link fails to recover; manually or forcibly switches the ring network node; Or force the ring node to switch. During the ring network switching process, link fault detection, ring network protocol state machine processing, protocol packet transmission, port shutdown and opening, and MAC (Media Access Control) address forwarding table cleaning and re-learning are involved. Etc., therefore, the ring network service is interrupted. The most intuitive performance for the user is that packet loss occurs when the ring network is switched.

According to the current requirements of G.8032, the switching time of the ring network must be less than 50 milliseconds, and the switching time should be as short as possible. However, in a real-world networking environment where ring network protection is used, the rate limit of unknown packets is usually enabled. This is a security measure for attack defense and a guarantee for the bandwidth of packet forwarding. When the ring network is switched, each network node needs to clear the Layer 2 forwarding table because of changes in the network topology. This causes the service packets originally on the ring network to become unknown packets, and the packets are unknown by the system. The rate limit of the packet rate limit is severe, which causes serious packet loss. In particular, when the packet rate before the ring network is switched, the packet loss is more obvious, and the switching performance of the ring network becomes worse (the switching time becomes longer). Meet the performance requirements of 50 milliseconds.

Summary of the invention

The following is an overview of the topics detailed in this document. This Summary is not intended to limit the scope of the claims.

The present invention provides a node device and a ring network switching method, which can solve the problem of poor handover performance caused by the unknown packet rate limiting function in the related ring network switching process.

The present application discloses a ring network switching method, which includes:

During the switching of the ring network, each ring network node configures the unknown packets of the system to an unlimited speed. After the ring network is switched, each ring network node recovers the unknown packet rate limit function of the system.

Optionally, in the foregoing method, in the process of switching the ring network, each ring network node configures the unknown packet of the system to an unlimited speed, and after the ring network is switched, each ring network node recovers the unknown packet rate limit. The functional process includes:

When the ring network detects a link fault, the faulty node notifies other ring network nodes that the link is faulty, and the ring network switches.

The faulty node and all ring network nodes that receive the link failure notification configure the unknown packet of the system to an unlimited speed;

When the ring network is switched and the ring network is in a stable fault state, each ring network node recovers the unknown packet rate limit function of the system.

When the ring network recovers, the fault recovery node notifies the other ring network nodes that the link is faulty and the ring network switches.

The fault recovery node and all ring network nodes that receive the link failure recovery notification configure the unknown packet of the system to an unlimited speed;

The ring network protection link (RPL) autonomous node receives the link failure recovery notification, and notifies all ring network nodes to restore the system's unknown packet rate limiting function after the timer event ends.

Optionally, in the foregoing method, the process that the RPL autonomous node notifies all ring network nodes to recover the unknown packet rate limiting function after the timer event ends includes:

The RPL autonomous node first sends a ring protection switch to restore the R-APS (NR, RB) message when the timer expires, the timer event ends, and the R-APS (NR, RB) message is sent again to notify each ring. The network node recovers the system's unknown packet rate limit function.

When manually switching the node port of the ring network, the R-APS (Ring-Automatic Protection Switching) message indicating the manual switching (MS) is sent to the other ring network node and the ring network is switched.

The manually switched node and all the ring network nodes that receive the R-APS message configure the unknown packet of the system to an unlimited speed;

When the ring network is manually switched, all ring nodes restore the system's unknown packet rate limit function.

When the manual switching is cleared, the node that is manually switched off sends an R-APS (NR) message to other ring network nodes, and the ring network switches.

Clearing the manually switched node and all ring nodes receiving the R-APS (NR) message set the unknown packet of the system to an unlimited speed;

The RPL autonomous node receives the R-APS (NR) message, and sends an R-APS (NR, RB) message to all ring network nodes and blocks the PRL link when the timer expires;

The ring network node that receives the R-APS (NR, RB) message releases the blocking caused by the manual switching command;

After the ring network node is unblocked, the RPL autonomous node notifies the node that clears the manual switch and all the ring network nodes to recover the unknown packet rate limit function of the system.

Optionally, in the foregoing method, the process for the RPL autonomous node to notify the node that clears the manual handover and all the ring network nodes to recover the unknown packet rate limit function of the system includes:

The RPL autonomous node notifies the clearing of the manually switched node and all ring network nodes to recover the unknown packet rate limiting function by resending the R-APS (NR, RB) message.

Optionally, in the foregoing method, in the process of switching the ring network, each ring network node configures the unknown packet of the system to an unlimited speed, and after the ring network is switched, each ring network node recovers the unknown packet limit. The speed function process includes:

When forcibly switching the ring network node port, the node that is forcibly switched sends an R-APS message indicating the forced switching (FS) to all ring network nodes, and the ring network switches.

The node that is forcibly switched and all the ring network nodes that receive the R-APS message configure the unknown packet of the system to an unlimited speed;

After the ring network forced switchover is completed, all ring network nodes recover the system's unknown packet rate limit function.

When the forced switchover is cleared, the node that is cleared forcibly switches sends an R-APS (NR) message to all ring network nodes, and the ring network switches.

Clearing the node that is forcibly switched or all ring nodes that receive the R-APS (NR) message configure the unknown packet of the system to an unlimited speed;

Receiving, by the RPL autonomous node, the R-APS (NR) message, after the timer event expires, sending an R-APS (NR, RB) message and blocking the PRL link;

The ring network node that receives the R-APS (NR, RB) message releases the blocking caused by the forced switching command;

After the congestion is released, the RPL autonomous node notifies the node that clears the forced handover and all the ring network nodes to recover the unknown packet rate limiting function of the system.

Optionally, in the foregoing method, the process for the RPL autonomous node to notify the node that clears the forced handover and all the ring network nodes to recover the unknown packet rate limiting function of the system includes:

The RPL autonomous node notifies the node that has forcibly switched and all the ring network nodes to recover the unknown packet rate limiting function by resending the R-APS (NR, RB) message.

The application also discloses a node device, which includes:

The first unit is configured to configure the unknown packet of the system to be an unlimited speed during the switching of the ring network;

The second unit is configured to restore the system's unknown packet rate limiting function after the ring network is switched.

Optionally, in the foregoing node device, the process of switching the ring network includes one or more of the following:

Ring network switching when the ring network detects a link fault;

Ring network switching when the ring network recovers;

Ring network switching when manually switching the ring node port;

Clearing the ring network switching performed during manual switching;

Ring network switching when the ring network node port is forcibly switched;

Clear the ring switch performed during forced switching.

The present application also provides a computer readable storage medium storing computer executable instructions that, when executed, implement the ring switching method described above.

In the technical solution of the present application, when the ring network is switched, the system unknown packet is automatically set to an unlimited speed, and the speed limit function of the system is restored after the handover is completed. In this way, the switching performance of the ring network can be improved without affecting the security of the system, and the implementation of the solution is extremely simple, and does not bring additional overhead to the system, and is easily implemented in related network devices.

Other aspects will be apparent upon reading and understanding the drawings and detailed description.

BRIEF abstract

1 is a flowchart of a ring network switching method according to an embodiment of the present invention;

2 is a schematic diagram of networking in a normal working state according to an embodiment of the present invention;

3 is a schematic diagram of networking of a link failure in a ring network according to an embodiment of the present invention;

4 is a schematic diagram of a format of a R-APS PDU (Protocol Data Unit) packet according to an embodiment of the present disclosure;

5 is a schematic diagram of a format of R-APS specific information in the R-APS PDU packet shown in FIG. 4;

FIG. 6 is a schematic diagram of a node device according to an embodiment of the present invention.

Embodiments of the invention

The technical solutions of the present application will be further described in detail below with reference to the accompanying drawings. It should be noted, The features of the embodiments and the embodiments of the present application may be combined with each other arbitrarily without conflict.

Embodiment 1

As shown in FIG. 1 , this embodiment provides a ring network switching method, including the following operations:

The ring network switching involved in this embodiment includes ring network switching triggered by various conditions, for example, the following types:

1. The ring network is switched when the ring network detects a link fault.

When the ring network detects a link failure, the faulty node sends an R-APS (SF) message to notify other ring network nodes of the link failure (that is, the ring network switch is considered to start), the failed node and all the messages received. The ring network node sets the system's unknown packet rate limit value to an unlimited speed;

When the ring network is in a stable fault state (that is, the ring network switching is completed), the unknown packet speed limit value of the system is restored (that is, the speed limit function of the unknown packet of the recovery system is restored, and the unknown packet speed limit value of the recovery system in the following is Restore the system's unknown packet speed limit function).

2. Ring network switching during ring network recovery.

When the ring network recovers, the fault recovery node sends an R-APS (NR) message to notify other ring network nodes of link failure recovery (ie, it can be considered to start ring network switching), the fault recovery node and all rings that receive the message. The node sets the system's unknown packet rate limit value to an unlimited speed;

The RPL owner node receives the R-APS (NR) message and notifies all ring nodes to recover the system's unknown packet rate limit value after a timer event ends. Optionally, the timer of the RPL owner node is a periodic timer, for example, a WTR (Wait to Restore) timer, that is, the WTR timer expires, and the RPL owner node starts to periodically send the R-APS (NR, RB). The message, after receiving the R-APS (NR, RB) message, each node starts to process the forwarding table clearing. After the timer event ends, the RPL owner node can periodically send an R-APS (NR, RB) message to notify. Each ring network node recovers the system's unknown packet rate limit value. Thus, when each ring network node receives the R-APS (NR, RB) message for the second time, the RPL owner node receives the R-APS again (NR, All ring nodes of the RB) message recover the unknown packet rate limit value of the system.

3. Ring network switching when manually switching the ring network node port.

When manually switching the ring node port, the node that is manually switched will send an R-APS message indicating the manual handover (MS) (ie, it can be considered to start the ring network handover), the manually switched node and all the rings that receive the message. The node sets the system's unknown packet rate limit value to an unlimited speed;

After the manual switching of the ring network is completed, the system's unknown packet rate limit value is restored.

4. Clear the ring network switching performed during manual switching.

When the manual switch is cleared, the node that is manually cleared will send an R-APS (NR) message (that is, start ring network switch), and the node that is manually switched or all ring nodes that receive the message will be unknown. The packet speed limit value is set to an unlimited speed;

The RPL owner node receives the R-APS (NR) message, and after a timer event expires, it sends an R-APS (NR, RB) message and blocks the PRL link, thus receiving the R-APS (NR, RB). The ring node of the message will cancel the blocking caused by the manual switching command, and then the RPL owner node notifies all ring nodes to restore the system's unknown packet rate limit value. Optionally, the RPL owner node may notify each ring network node to recover the unknown packet rate limit value by sending an R-APS (NR, RB) message again, and each ring network node receives the R-APS for the second time. (NR, RB) message can restore the system's unknown packet speed limit value.

5. Ring network switching when the switch of the ring network node port is forcibly switched.

When forcibly switching the ring network node port, the node that is forcibly switched will send an R-APS message indicating forced switching (FS) (that is, it can be considered to start ring network switching), the node that is forced to switch, and all rings that receive the message. The node sets the system's unknown packet rate limit value to an unlimited speed;

After the ring network forced switchover is completed, the system's unknown packet rate limit value is restored.

6. Clear the ring network switching when forced switching.

When the forced switchover is cleared, the node that is cleared for forced handover will send an R-APS (NR) message (that is, it can be considered to start the ring network handover), and the node that is forcibly switched or all ring nodes that receive the message will be unknown. The packet speed limit value is set to an unlimited speed;

The RPL owner node receives the R-APS (NR) message, sends an R-APS (NR, RB) message and blocks the PRL link after a timer event times out; receives the R-APS (NR, RB) message. The ring network node cancels the blocking caused by the forced switching command. At this point, the clearing of the forced switching is completed, and the RPL owner node notifies each ring network node to restore the system's unknown packet rate limit value. Optionally, RPL The owner node can notify each ring node to recover the unknown packet rate limiting function of the system by sending an R-APS (NR, RB) message again.

In addition, each node in the ring network needs to record the current unknown rate limit value of the system. If the user changes the speed limit value, the ring network node also needs to update the rate limit value. When the ring network switch is completed, the ring network node follows the ring network node. The updated speed limit value restores the system's unknown packet speed limit function.

The implementation of the technical solution is further described in detail below with reference to the accompanying drawings. Here, only the most common link failure detection and recovery is used to describe the processing of the unknown packet rate limit during the ring network switching, and the switching processing of other scenarios is similar. Not specified). The present application is not described or described in detail by those skilled in the art, and the various operations will be described in a plurality of separate steps in sequence.

The general networking of the embodiment of the present invention is as shown in FIG. 2. A plurality of devices form a ring network and run an ERPS ring network protection protocol. The RPL link can be configured as a link between any two devices in the ring network. The port on the RPL link is blocked during normal operation. In the networking, nodes 1, node 2, node 3, and node 4 form a ring network. The RPL link is the link between node 3 and node 4. The port on node 4 is the owner node. DUT1 and DUT2 simulate two network element devices that need to communicate in the live network. The ports are respectively connected to the two ports of the tester, and the tester simulates the transceiver package. In the general application, the system sets the speed limit of the unknown packet, and the message between the tester ports A and B is a known packet, and is not subject to the speed limit control of the unknown packet. The nodes in each ring record the current unknown packet rate limit of the system.

Under normal circumstances, the tester's ports A and B communicate through DUT1—node4—node1—node2—node3—DUT2, as shown in Figure 2; when the non-RPL link in the ring network fails, the tester's Ports A and B communicate through DUT1—node4—node3—DUT2, as shown in Figure 3.

The processing flow when the ring link detects a fault is as follows:

After detecting a link fault, node1 and node2 set the device's unknown packet rate limit to an unlimited speed; block the faulty port and clear the MAC address forwarding table; periodically send an R-APS (SF) message to notify other ring network nodes of the link fault. .

Node3 and node4 receive the R-APS (SF) message for the first time, set the device's unknown packet rate limit to unlimited speed; clear the MAC address forwarding table; node4 is the RPL-owner node, and the node4 node port is blocked.

Node3 and node4 receive the R-APS (SF) message for the second time, and trigger the logic to clear the MAC address forwarding table according to the rules defined in G.8032.

Node3 and node4 receive the R-APS (SF) message for the third time, and restore the unknown packet rate limit of the device. At this point, the network is already in a stable state of protection.

The RPL-owner node node4 sends a message to notify the faulty node to recover the unknown packet rate limit value of the device.

After receiving the message, node1 and node2 restore the unknown packet rate limit of the device.

It should be noted that, here, a new message can be designed to notify the failed node, and the unknown packet rate limit value is restored. Since some reserved fields in the specific information field in the R-APS PDU field are unused, As shown in FIG. 4, these fields can be used to represent the message. For example, the status reserved bit in the status field in the R-APS specific information format in FIG. 5 can be used, and the status reserved bit is set to 00001 to indicate recovery. Unknown packet speed limit value message.

The processing flow when the ring link fault recovery (link failure recovery between the ring node node1 and node2) is as follows:

After detecting the link fault recovery, node1 and node2 set the device's unknown packet rate limit to an unlimited speed; periodically send an R-APS (NR) message to notify other ring network nodes of link fault recovery.

Node3 and node4 receive the R-APS (NR) message, and set the device's unknown packet rate limit to an unlimited speed; the RPL-owner node node4 turns on the WTR timer.

Node2 receives the R-APS (NR) message from node1 and opens the port where the link failed before (according to the G.8032 protocol, the node ID of node2 is assumed to be greater than the node ID of node1).

The WTR timer of the RPL-owner node node4 expires, the RPL-owner port is closed, the R-APS (NR, RB) message is sent, and the MAC address forwarding table is cleared.

Each node receives an R-APS (NR, RB) message, and clears the MAC address forwarding table according to the rules defined in G.8032;

Node1 receives the R-APS (NR, RB) message, starts the port with the link failure before, and stops sending the R-APS (NR) message.

Subsequently, each node receives the R-APS (NR, RB) message a second time, and the second received R-APS (NR, RB) message is used to notify each ring network node to recover each node. Unknown packet speed limit value.

Embodiment 2

As shown in FIG. 6, the embodiment provides a node device, which can implement the method in the foregoing Embodiment 1, where the node device includes at least a first unit and a second unit.

The process of ring network switching involved in this embodiment includes one or more of the following:

Ring network switching when the ring network detects a link fault;

Ring network switching when the ring network recovers;

Ring network switching when manually switching the ring node port;

Clearing the ring network switching performed during manual switching;

Ring network switching when the ring network node port is forcibly switched;

Clear the ring switch performed during forced switching.

The node device provided in this embodiment can implement the method in the foregoing embodiment. Therefore, for the other operations of the node device, refer to the corresponding content in the first embodiment, and details are not described herein again.

The embodiment of the invention further provides a computer readable storage medium, which stores computer executable instructions, and when the computer executable instructions are executed, implements the ring network switching method according to the first embodiment.

One of ordinary skill in the art will appreciate that all or a portion of the above steps may be performed by a program to instruct related hardware, such as a processor, which may be stored in a computer readable storage medium, such as a read only memory, disk or optical disk. Wait. Alternatively, all or part of the steps of the above embodiments may also be implemented using one or more integrated circuits. Correspondingly, the module/unit (processor) in the foregoing embodiment may be implemented in the form of hardware, for example, by implementing an integrated circuit to implement its corresponding function, or may be implemented in the form of a software function module, for example, being stored in the memory by a processor. The program/instruction in it to implement its corresponding function. This application is not limited to any specific combination of hardware and software.

The above descriptions are only preferred examples of the present application and are not intended to limit the scope of the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of this application, All should be included in the scope of protection of this application.

Industrial applicability

The embodiment of the present application provides a ring network switching method and a node device, which can improve the switching performance of the ring network without affecting the security of the system, and the implementation of the solution is extremely simple, and does not bring additional overhead to the system. It is easy to implement in related network devices.

Claims

A ring network switching method includes:

During the switching of the ring network, each ring network node configures the unknown packets of the system to an unlimited speed. After the ring network is switched, each ring network node recovers the unknown packet rate limit function of the system.
The method according to claim 1, wherein in the process of switching the ring network, each ring network node configures an unknown packet of the system to an unlimited speed until after the ring network is switched, each ring network node The process of recovering the unknown packet speed limit function includes:

When the ring network detects a link fault, the faulty node notifies other ring network nodes that the link is faulty, and the ring network switches.

The faulty node and all ring network nodes that receive the link failure notification configure the unknown packet of the system to an unlimited speed;

When the ring network is switched and the ring network is in a stable fault state, each ring network node recovers the unknown packet rate limit function of the system.
The method according to claim 1 or 2, wherein in the process of switching the ring network, each ring network node configures an unknown packet of the system to an unlimited speed until after the ring network is switched, each ring The process of recovering the unknown packet rate limit function by the network node includes:

When the ring network recovers, the fault recovery node notifies the other ring network nodes that the link is faulty and the ring network switches.

The fault recovery node and all ring network nodes that receive the link failure recovery notification configure the unknown packet of the system to an unlimited speed;

The ring network protection link RPL autonomous node receives the link failure recovery notification, and notifies all ring network nodes to restore the system's unknown packet rate limiting function after the timer event ends.
The method of claim 3, wherein the process by which the RPL autonomous node notifies all ring network nodes to recover the system's unknown packet rate limiting function after the timer event ends includes:

The RPL autonomous node first sends a ring network protection switching to recover the R-APS (NR, RB) message when the timer timing time arrives, the timer event ends, and the R-APS (NR, RB) message is sent again to notify each ring. The network node recovers the system's unknown packet rate limit function.
The method of claim 3, wherein during the switching of the ring network, each The ring network node configures the unknown packet of the system to an unlimited speed. After the ring network is switched, the process of restoring the unknown packet rate limit function of each ring network node includes:

When manually switching the node port of the ring network, the node that is manually switched sends a ring network automatic protection switching R-APS message indicating that the MS is manually switched to the other ring network node, and the ring network switches.

The manually switched node and all the ring network nodes that receive the R-APS message configure the unknown packet of the system to an unlimited speed;

When the ring network is manually switched, all ring nodes restore the system's unknown packet rate limit function.
The method according to claim 5, wherein in the process of switching the ring network, each ring network node configures an unknown packet of the system to an unlimited speed until after the ring network is switched, each ring network node The process of recovering the unknown packet speed limit function includes:

When the manual switching is cleared, the node that is manually switched off sends a ring protection switch to restore the R-APS (NR) message to other ring network nodes, and the ring network switches.

Clearing the manually switched node and all ring nodes receiving the R-APS (NR) message set the unknown packet of the system to an unlimited speed;

The RPL autonomous node receives the R-APS (NR) message, and sends an R-APS (NR, RB) message to all ring network nodes and blocks the PRL link when the timer expires;

The ring network node that receives the R-APS (NR, RB) message releases the blocking caused by the manual switching command;

After the ring network node is unblocked, the RPL autonomous node notifies the node that clears the manual switch and all the ring network nodes to recover the unknown packet rate limit function of the system.
The method of claim 6, wherein the RPL autonomous node notifies the clearing of the manually switched node and all ring network nodes to recover the unknown packet rate limiting function of the system includes:

The RPL autonomous node notifies the clearing of the manually switched node and all ring network nodes to recover the unknown packet rate limiting function by resending the R-APS (NR, RB) message.
The method according to claim 3, wherein in the process of switching the ring network, each ring network node configures an unknown packet of the system to an unlimited speed until after the ring network is switched, each ring network node The process of recovering the unknown packet speed limit function includes:

When forcibly switching the ring network node port, the node that is forcibly switched sends a ring network automatic protection switching R-APS message indicating that the FS is forcibly switched to all ring network nodes, and the ring network switches.

The node that is forcibly switched and all the ring network nodes that receive the R-APS message configure the unknown packet of the system to an unlimited speed;

After the ring network forced switchover is completed, all ring network nodes recover the system's unknown packet rate limit function.
The method according to claim 3, wherein in the process of switching the ring network, each ring network node configures the unknown packet of the system to an unlimited speed, and after the ring network switching is completed, each ring network node recovers the unknown. The process of the packet speed limit function includes:

When the forced switchover is cleared, the node that is cleared forcibly switches sends a ring protection switch to restore the R-APS (NR) message to all ring nodes, and the ring network switches.

Clearing the node that is forcibly switched or all ring nodes that receive the R-APS (NR) message configure the unknown packet of the system to an unlimited speed;

Receiving, by the RPL autonomous node, the R-APS (NR) message, after the timer event expires, sending an R-APS (NR, RB) message and blocking the PRL link;

The ring network node that receives the R-APS (NR, RB) message releases the blocking caused by the forced switching command;

After the congestion is released, the RPL autonomous node notifies the node that clears the forced handover and all the ring network nodes to recover the unknown packet rate limiting function of the system.
The method of claim 9, wherein the RPL autonomous node notifies the clearing of the forcibly switched node and all of the ring network nodes to recover the system's unknown packet rate limiting function includes:

The RPL autonomous node notifies the node that has forcibly switched and all the ring network nodes to recover the unknown packet rate limiting function by resending the R-APS (NR, RB) message.
A node device, comprising:

The first unit is configured to configure the unknown packet of the system to be an unlimited speed during the switching of the ring network;

The second unit is configured to restore the system's unknown packet rate limiting function after the ring network is switched.
The node device according to claim 11, wherein the process of switching the ring network includes one or more of the following:

Ring network switching when the ring network detects a link fault;

Ring network switching when the ring network recovers;

Ring network switching when manually switching the ring node port;

Clearing the ring network switching performed during manual switching;

Ring network switching when the ring network node port is forcibly switched;

Clear the ring switch performed during forced switching.