A small-particle dual-homing protection switching method and system based on full-path APS

Abstract

The application belongs to the technical field of communication service protection and switching, and provides a small-granularity dual-homing protection switching method and system based on full-path APS, which is used for a master / standby switching architecture, the architecture includes a westward domain and / or an eastward domain, each domain includes multiple access nodes and multiple groups of dual-homing nodes, the method includes: sending and receiving APS-W codes between adjacent two nodes on a master working path, and sending and receiving APS-P codes between adjacent two nodes on a standby working path; sending and receiving DN I codes between dual-homing master / standby nodes in the same group through a DN I link; when protection switching is needed, nodes perform protection switching based on protection switching information received from a non-faulty path, the protection switching information including APS-W codes, APS-P codes and DN I codes. The method can reduce the announcement process of protection switching and the involved nodes, reduce the time consumption of protection switching, and improve the performance of protection switching.

Description

Technical Field

[0001] This invention belongs to the field of communication service protection and switching technology, and particularly relates to a small-granularity dual-homing protection switching method and system based on full-path APS. Background Technology

[0002] Regarding the technical fields of MTN (Metro Transport Network) and FGU (Fine Granularity Unit), the G.83 series of standard recommendations were released in 2020, among which the protection standard is G.8331-202202, which defines a 1+1 end-to-end protection model and applies the metropolitan area network protection model G.8331 to cross-domain scenarios.

[0003] To address the issue of low fault diagnosis efficiency in 1+1 end-to-end protection models applied in cross-domain scenarios, where a fault at any point necessitates switching at both ends, a patent with publication number CN117544485A proposes a small-granularity dual-homing protection switching method and system based on three-way APS code negotiation. The patent specification includes... Figure 6 The protection switching logic for two fault scenarios within and between domains is as follows: (1) Faults at two points: NE2 and NE3, NE4: NE4 fault detection takes time t1. (2) NE4 running its state machine and transmitting information to NE5 takes time t2. (3) NE5 running its state machine and transmitting information to NE3 takes time t3. (4) NE3 running its state machine and transmitting information to NE1 takes time t4. (5) NE1 running its state machine and performing service switching takes time t5.

[0004] As can be seen from the above protection switching logic, the two fault scenarios mentioned above involve a large number of sites, a long information transmission path, and inter-vendor communication. Therefore, there is a problem of poor protection switching performance in such two fault scenarios. Summary of the Invention

[0005] This invention provides a small-particle dual-homing protection switching method and system based on full-path APS, aiming to solve the problem of poor protection switching performance in two-point fault scenarios in the prior art.

[0006] The technical solution of the present invention to solve the above-mentioned technical problems is as follows:

[0007] A small-granularity dual-homed protection switching method based on full-path APS is disclosed. This method is used in a primary / backup switching architecture, which includes a westward domain and / or an eastward domain. Each domain includes multiple access nodes and multiple groups of dual-homed nodes. Each group of dual-homed nodes includes a dual-homed primary node and a dual-homed backup node. One access node is connected to another access node via each dual-homed primary node to form a primary working path. One access node is connected to another access node via each dual-homed backup node to form a backup protection path. A DNI link is established between the dual-homed primary and backup nodes in the same group.

[0008] The method includes the following steps:

[0009] Each node located on the primary working path sends and receives traffic through the primary working path;

[0010] Each node located on the backup working path sends and receives traffic through the backup protection path;

[0011] The primary working path automatic protection switching (APS-W) code is sent and received between two adjacent nodes on the primary working path; the APS-W code includes the dual-node interconnection DNI link status field of the primary node.

[0012] The automatic protection switching (APS-P) code for backup protection path is sent and received between two adjacent nodes on the backup working path; the APS-P code includes the DNI link status field of the backup node.

[0013] The dual-homed primary and backup nodes in the same group send and receive DNI codes through the DNI link. When protection switching is required, the DNI link is also used to send and receive traffic. The DNI code includes the following information switching fields: west-bound domain signal fault field, west-bound domain signal degradation field, west-bound domain switching field, east-bound domain signal fault field, east-bound domain signal degradation field, and east-bound domain switching field.

[0014] When any node needs protection switching, it sends protection switching information related to the reason for protection switching to neighboring nodes. Protection switching is performed based on the protection switching information received from the non-faulty path. The protection switching information includes: APS-W code, APS-P code and DNI code.

[0015] Furthermore, the westbound domain signal fault field is defined as wF, where 0 indicates normal and 1 indicates signal fault; the westbound domain signal degradation field is defined as wD, where 0 indicates normal and 1 indicates signal degradation; the westbound domain switching field is defined as wS, where 0 indicates no switching and 1 indicates switching; the eastbound domain signal fault field is defined as eF, where 0 indicates normal and 1 indicates signal fault; the eastbound domain signal degradation field is defined as eD, where 0 indicates normal and 1 indicates signal degradation; the eastbound domain switching field is defined as eS, where 0 indicates no switching and 1 indicates switching; the DNI link status field is a newly added field in the Requested signal field of the standard APS code, where 0 indicates DNI normal and 1 indicates DNI fault.

[0016] Define NE1 as the access point, NE2 as the dual-homed primary node, and NE3 as the dual-homed backup node in the same group as NE2. The adjacent nodes of NE1 are NE2 and NE3, and NE1 to NE3 form the westward domain. Define NE4 as the dual-homed primary node, NE5 as the dual-homed backup node in the same group as NE4, and NE6 as another access point. The adjacent nodes of NE6 are NE4 and NE5. Define the traffic sent from the primary working path NE1 to NE6 as eastward primary traffic, and the traffic sent from NE6 to NE1 as westward primary traffic. Define the traffic sent from the backup protection path NE1 to NE6 as eastward backup traffic, and the traffic sent from NE6 to NE1 as westward backup traffic.

[0017] Furthermore, in the scenario of a single-point path failure in the westward domain, the primary working path between NE1 and NE2 fails.

[0018] The protection switching method for eastbound traffic is as follows: When NE2 detects a westbound fault, N2 first switches to select the eastbound backup traffic to send to NE4, and sends a DNI code with wF=1 to NE3, and sends an APS-W code indicating a primary fault SF-W to NE1; after receiving wF=1, NE3 switches to send the eastbound backup traffic to both NE2 and NE5.

[0019] Westbound traffic: NE2 switches to sending the primary westbound traffic from NE4 to both NE1 and NE3; NE3 receives wF=1 from NE2, switches to selecting the primary westbound traffic from NE2 for forwarding to NE1, and replies to NE2 with a DNI code of wS=1, and sends an APS-P code indicating primary failure SF-W to NE1; NE1 sends APS-W and APS-P codes indicating primary failure SF-W to NE2 and NE3, and switches to selecting the primary westbound traffic for continued westward forwarding.

[0020] Furthermore, in the scenario of a single-point path failure in the eastward domain, the primary working path between NE2 and NE4 fails.

[0021] Protection switching method for eastbound traffic: When NE2 detects a westbound fault, it first switches to sending eastbound primary traffic to both NE3 and NE4, sending a DNI code with eF=1 to NE3 and an APS-W code indicating a primary fault SF-W to NE4; NE3 receives eF=1 from NE2, switches to sending the eastbound primary traffic from NE2 to NE5, and replies with a DNI code with eS=1 to NE2; the switching logic for NE4 is the same as for NE2, but due to the fault, it selects the eastbound primary traffic from NE5 to send to NE6, sends a DNI code with wF=1 to NE5, and sends an APS-W code indicating a primary fault SF-W to NE2; the switching logic for NE5 is the same as for NE3, sending the eastbound primary traffic from NE3 to both NE4 and NE6, and NE6 selects the eastbound primary traffic from NE4 for forwarding;

[0022] Protection switching method for westbound traffic: NE4 detects a westbound fault and first switches to sending westbound primary traffic to both NE2 and NE5, sending a DNI code with wF=1 to NE5 and an APS-W code indicating a primary fault (SF-W) to NE2; after receiving wF=1 from NE4, NE5 switches to sending the westbound primary traffic from NE4 to NE3; it also replies to NE4 with a DNI code with wS=1 and sends an APS-P code indicating a primary fault (SF-W) to NE3; after receiving eF=1 from NE2, NE3 sends the westbound primary traffic from NE5 to both NE1 and NE2, replies to NE2 with a DNI code with eS=1, and sends an APS-P code indicating a primary fault (SF-W) to NE5; NE2 first switches to sending the westbound primary traffic from NE3 to NE1, and NE1 then forwards the westbound primary traffic from NE2.

[0023] Furthermore, in the two-point fault scenario of the west-bound and east-bound domains, NE1 and NE2 fail, and NE2 and NE4 fail.

[0024] Protection switching method for eastbound traffic: NE2 sends a DNI code with wF=1 and eF=1 to NE3, and sends an APS-W code indicating a primary fault SF-W to NE1 and NE4; NE3 switches to send the eastbound backup traffic from NE1 to NE5, and replies to NE2 with a DNI code with wS=1 and eS=1, and sends an APS-P code indicating a primary fault SF-W to NE1 and NE5; NE4 switches to send the eastbound backup traffic selected from NE5 to NE6, and sends wF=1 to NE5, and sends an APS-W code indicating a primary fault SF-W to NE2; NE5 receives wF=1 from NE4, and sends the eastbound backup traffic from NE3 to both NE4 and NE6, and replies to NE4 with wS=1, and sends an APS-P code indicating SF-W to NE3; NE6 selects the eastbound backup traffic from NE4 for forwarding;

[0025] Protection switching method for westbound traffic: NE4 switches to sending westbound primary traffic to both NE2 and NE5, sending a DNI code with wF=1 to NE5 and an APS-W code indicating a primary fault SF-W to NE2; after receiving wF=1 from NE4, NE5 switches to sending westbound primary traffic from NE4 to NE3, replies with a DNI code with wS=1 to NE4, and sends an APS-P code indicating a primary fault SF-W to NE3; after receiving the DNI code with wF=1 and eF=1 from NE2, NE3 sends westbound primary traffic from NE5 to both NE1 and NE2, and sends an APS-P code indicating a primary fault SF-W to both NE1 and NE5 respectively; NE1 switches to receiving westbound primary traffic and continues forwarding it westward.

[0026] Furthermore, in the two-point fault scenario of DNI and the eastward domain, NE2 and NE3 fail, and NE2 and NE4 fail.

[0027] Protection switching method for eastbound traffic: NE2 sends an APS-W code indicating a remote primary fault to NE1, and sends a DNI code with eF=1 to NE3, and sends an APS-W code indicating a DNI fault to NE4; NE3 sends an APS-P code indicating a DNI fault to NE1 and NE5 respectively.

[0028] Protection switching method for westbound traffic: When NE1 receives the APS-W code from NE2 indicating a switchover notice of remote primary failure and the DNI fault APS-P code from NE3, protection switching is triggered, and westbound primary traffic from NE3 is selected for forwarding.

[0029] Furthermore, in the scenario of two-point faults in DNI and the westward domain, there are faults between NE1 and NE2, and between NE2 and NE3; protection switching of NE1, NE4 and NE5;

[0030] Protection switching method for eastbound traffic: NE1 switches to NE3, sending an APS-W code indicating a primary fault to NE2 and an APS-P code indicating a primary fault to NE3. NE2 sends an APS-W code indicating a remote primary fault to NE4 and a DNI code with wF=1 to NE3, and an APS-W code indicating a DNI fault to NE1. NE3 sends an APS-P code indicating a DNI fault to both NE1 and NE5. Upon receiving the APS-W code from NE2 announcing the remote primary fault switchover, NE4 triggers protection switching, selects the eastbound backup traffic from NE5 to send to NE6, and sends a DNI code with wF=1 to NE5. Upon receiving the DNI code with wF=1 from NE4, NE5 triggers protection switching and replies with a DNI code with wS=1 to NE4. NE6 then selects the eastbound backup traffic from NE4 for forwarding.

[0031] Protection switching method for westbound traffic: NE6 transmits traffic twice. After NE4 receives the APS-W code indicating a remote primary path failure, it first switches to transmitting westbound primary traffic to both NE2 and NE5, sending a DNI code with wF=1 to NE5. After receiving the DNI code with wF=1 from NE4, NE5 switches to sending the westbound primary traffic from NE4 to NE3, replies with a DNI code with wS=1 to NE4, and sends an APS-P code with SF-W to NE3. NE2 sends an APS-W code indicating a DNI failure to NE1, sends wF=1 to NE3, and sends an APS-W code to NE4. NE3 sends the westbound primary traffic to NE1, and sends an APS-P code indicating a DNI failure to both NE1 and NE5. NE1 then switches to forwarding the westbound primary traffic from NE3 westward.

[0032] Furthermore, in the node power failure scenario: NE2 node loses power; protection switching occurs for NE1, NE4, and NE5.

[0033] Eastbound traffic protection switching: NE1 switches to NE3, sending an APS-W code indicating a primary path failure to NE2 and an APS-P code indicating a primary path failure to NE3; NE3 sends an APS-P code indicating a DNI failure to NE1 and NE5 respectively; NE4 triggers protection switching and sends a DNI code with wF=1 to NE5; after receiving the DNI code with wF=1 from NE4, NE5 triggers protection switching and replies with a DNI code with wS=1 to NE4; NE6 selects the eastbound backup traffic from NE4 for forwarding;

[0034] Westbound traffic protection switching: NE6 sends dual traffic to NE4 and NE5. NE4 first switches to sending dual westbound primary traffic to NE2 and NE5, and sends a DNI code with wF=1 to NE5. After receiving the DNI code with wF=1 from NE4, NE5 switches to send the westbound primary traffic from NE4 to NE3, replies with a DNI code with wS=1 to NE4, and sends an APS-P code with SF-W to NE3. NE3's switching status remains unchanged, and it sends the westbound primary traffic to NE1, sending an APS-P code indicating a DNI failure to both NE1 and NE5. NE1 switches to continue forwarding the westbound primary traffic from NE3 westward.

[0035] Furthermore, in the three-point fault scenario, there are faults between NE2 and NE3, NE2 and NE4, and NE4 and NE5, and NE1 and NE6 are switched over;

[0036] Protection switching method for westbound traffic: NE2 sends an APS-W code for remote primary fault to NE1, and sends a DNI code for master node eastbound domain fault to NE3, and an APS-W code for DNI fault to NE4; NE3 sends an APS-P code for DNI fault to NE1 and NE5 respectively; NE1 receives the APS-W code for remote primary fault switching notification from NE2 and the APS-P code for DNI fault from NE3, triggers protection switching, and selects to forward the westbound backup traffic from NE3.

[0037] Protection switching method for eastbound traffic: NE4 sends an APS-W code indicating a remote primary fault to NE6, and sends a DNI code indicating a westbound domain fault to NE5, and sends an APS-W code indicating a DNI fault to NE2; NE5 sends APS-P codes indicating a DNI fault to NE3 and NE6 respectively; NE6 receives the APS-W code of the remote primary fault switching notification from NE4 and the DNI fault APS-P code of NE5, triggers protection switching, and selects and forwards the eastbound backup traffic from NE5.

[0038] On the other hand, a small-granularity dual-homing protection switching system based on full-path APS is proposed. The system has a primary-backup switching architecture, which includes a westward domain and / or an eastward domain. Each domain includes multiple access nodes and multiple groups of dual-homing nodes. Each group of dual-homing nodes includes a dual-homing primary node and a dual-homing backup node. An access node is connected to another access node through each dual-homing primary node to form a primary working path. An access node is connected to another access node through each dual-homing backup node to form a backup protection path. A DNI link is established between the dual-homing primary and backup nodes in the same group.

[0039] Each node located on the primary working path is used to send and receive traffic through the primary working path; send and receive primary working path automatic protection switching (APS-W) codes with adjacent nodes on the primary working path; and when protection switching is required, send protection switching information related to the reason for protection switching to adjacent nodes, and perform protection switching based on the protection switching information received from the non-faulty path. The protection switching information includes: APS-W code, APS-P code, and DNI code. The APS-W code includes the dual-node interconnection DNI link status field of the primary node.

[0040] Each node located on the backup working path is used to send and receive traffic through the backup protection path; send and receive backup protection path automatic protection switching APS-P codes with adjacent nodes on the backup working path; and when protection switching is required, send protection switching information related to the reason for protection switching to adjacent nodes, and perform protection switching based on the protection switching information received from the non-faulty path, wherein the APS-P code includes the backup node's DNI link status field;

[0041] Each dual-homed primary node located on the primary working path is also used to send and receive DNI codes with dual-homed backup nodes in the same group via the DNI link. When protection switching is required, the DNI link is also used to send and receive traffic. The DNI code includes the following information switching fields: westbound domain signal fault field, westbound domain signal degradation field, westbound domain switching field, eastbound domain signal fault field, eastbound domain signal degradation field, and eastbound domain switching field.

[0042] Each dual-homed backup node located on the primary working path is also used to send and receive DNI codes with the dual-homed primary node in the same group via the DNI link.

[0043] Compared with the prior art, the present invention has the following advantages:

[0044] 1. The design of the DNI message format between dual-homed primary and backup nodes has been simplified and optimized. The naming has been optimized from intra-domain and inter-domain to westbound and eastbound domain, reducing message complexity and improving processing efficiency.

[0045] 2. The APS code, originally used only on the backup protection path, has been expanded to be used on both the primary working path and the backup protection path. At the same time, the content of the APS code has been expanded to include a field representing the DNI link status, which allows nodes to obtain more information for protection switching more conveniently and in greater quantities. Therefore, the notification process for protection switching and the number of nodes involved can be reduced, the protection switching time can be reduced, and the protection switching performance can be improved.

[0046] 3. Supports protection switching for three-point fault scenarios, adding system functionality and improving network resilience.

[0047] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 A schematic diagram illustrating the principle of the small-particle dual-homing protection switching method based on full-path APS in a normal scenario according to Embodiment 1 of the present invention is shown.

[0050] Figure 2A schematic diagram of the principle of the small-particle dual-homing protection switching method based on full-path APS in a single-point fault scenario in the westward domain according to Embodiment 2 of the present invention is shown.

[0051] Figure 3 A schematic diagram of the principle of the small-particle dual-homing protection switching method based on full-path APS in the eastward domain single-point fault scenario according to Embodiment 3 of the present invention is shown.

[0052] Figure 4 A schematic diagram of the principle of the small-particle dual-homing protection switching method based on full-path APS in a two-point fault scenario in the west-to-east domain according to Embodiment 4 of the present invention is shown.

[0053] Figure 5 A schematic diagram of the principle of the small-particle dual-homing protection switching method based on full-path APS in the two-point fault scenario of DNI and eastward domain according to Embodiment 5 of the present invention is shown.

[0054] Figure 6 A schematic diagram of the principle of the small-particle dual-homing protection switching method based on full-path APS in the two-point fault scenario of DNI and westward domain according to Embodiment 6 of the present invention is shown.

[0055] Figure 7 A schematic diagram of the principle of the small-particle dual-homing protection switching method based on full-path APS in a node power failure scenario according to Embodiment 7 of the present invention is shown.

[0056] Figure 8 A schematic diagram of the principle of the small-particle dual-homing protection switching method based on full-path APS in a three-point fault scenario according to Embodiment 8 of the present invention is shown. Detailed Implementation

[0057] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0058] To address the technical problem of poor switchover performance in the patent with publication number CN117544485A, the inventors first performed the following work:

[0059] 1. The design of the full-path APS code is divided into the following three categories:

[0060] (1) Working path APS design: APS-W (Automatic Protection Switching for Working) is used to transmit APS switching information in the primary working path;

[0061] (2) Protection path APS design: APS-P (Automatic Protection Switching for Protection) is used to transmit APS switching information in the backup protection path;

[0062] (3) Design of DNI code block field: As shown in Table 1 below, the DNI field is optimized from 7 bits in the patent CN117544485A to 6 bits; the naming is optimized from intra-domain and inter-domain to west-to-east-to-east domain, which is applicable to both domains and one domain.

[0063] After receiving the APS-W code and APS-P code, the node makes the following decision rules for protection switching:

[0064] (1) Generally, the APS-P code is still used as the basis for switching decisions;

[0065] (2) Ignore the APS code received by the faulty path;

[0066] (3) Both the primary and backup paths are normal and the APS-W and APS-P codes are inconsistent. Based on comprehensive decision-making, the final protection switchover will generate a complete path from the access point to another access point via the primary and backup dual-homing nodes.

[0067] The APS-W code mentioned above is the name used when the APS code is used on the primary working path, while the APS-W code is the name used when the APS code is used on the backup working path.

[0068] Table 1. Design Specifications of DNI Code Block Fields

[0069]

[0070] Specifically, Table 1 adds a DNI code block with Type = 0x3 after the APS code block with Type = 0x2 in the existing standard small-granularity service signaling code block. The DNI code block data content contains 4 data areas, named DNI_data[B0], DNI_data[B1], DNI_data[B2], and DNI_data[B3] in sequence. DNI_data[B0] stores westbound domain information, using 3 bits of data, with the other bits reserved. Bit 2 is named Westbound Domain Signal Fail (internal domain signal failure), abbreviated as wF, where 0 indicates normal and 1 indicates signal failure (SF). Bit 1 is named Westbound Domain Signal Degrade (internal domain signal degrade), abbreviated as wD, where 0 indicates normal and 1 indicates signal degrade (SD). Bit 0 indicates Westbound Domain Switching (internal domain switching), abbreviated as iS, where 0 indicates no switching and 1 indicates switching. DNI_data[B1] stores the Eastbound domain information, using 3 bits of data. The other bits are reserved. Bit 2 is named Eastbound Domain Signal Fail (eF), where 0 indicates normal and 1 indicates signal failure (SF). Bit 1 is named Eastbound Domain Signal Degrade (eD), where 0 indicates normal and 1 indicates signal degrade (SD). Bit 0 indicates Eastbound Domain Switching (eS), where 0 indicates no switching and 1 indicates switching. DNI_data[B2] and DNI_data[B3] are reserved.

[0071] 2. Expand the content of APS code

[0072] Enable bit[2] in the Requested signal field of the G.8331 standard APS code. 1 indicates DNI fault, that is, in an interrupted fault state, and 0 indicates DNI normal.

[0073] (1) The dual-homed master node uses the newly started bit to interact with the master node’s DNI fault status via the APS-W code.

[0074] (2) The dual-backup node uses the newly started bit to interact with the backup node's DNI fault status via the APS-P code.

[0075] The technical solution of the present invention will be described below:

[0076] An embodiment of the present invention provides a small-particle dual-homing protection switching method based on full-path APS, the method comprising the following steps:

[0077] This method is used for a primary / backup failover architecture, which includes a westward domain and / or an eastward domain. Each domain includes multiple access nodes and multiple sets of dual-homed nodes. Each set of dual-homed nodes includes a dual-homed primary node and a dual-homed backup node. One access node connects to another access node via each dual-homed primary node to form a primary working path. One access node connects to another access node via each dual-homed backup node to form a backup protection path. A DNI link is established between the dual-homed primary and backup nodes in the same group.

[0078] The method includes the following steps:

[0079] Each node located on the primary working path sends and receives traffic through the primary working path;

[0080] Each node located on the backup working path sends and receives traffic through the backup protection path;

[0081] The primary working path automatic protection switching (APS-W) code is sent and received between two adjacent nodes on the primary working path; the APS-W code includes the dual-node interconnection DNI link status field of the primary node.

[0082] The automatic protection switching (APS-P) code for backup protection path is sent and received between two adjacent nodes on the backup working path; the APS-P code includes the DNI link status field of the backup node.

[0083] The dual-homed primary and backup nodes in the same group send and receive DNI codes through the DNI link. When protection switching is required, the DNI link is also used to send and receive traffic. The DNI code includes the following information switching fields: west-bound domain signal fault field, west-bound domain signal degradation field, west-bound domain switching field, east-bound domain signal fault field, east-bound domain signal degradation field, and east-bound domain switching field.

[0084] When any node needs protection switching, it sends protection switching information related to the reason for protection switching to neighboring nodes. Protection switching is performed based on the protection switching information received from the non-faulty path. The protection switching information includes: APS-W code, APS-P code and DNI code.

[0085] In this invention, the fault detection method is the small-particle OAM method, which is used to monitor, diagnose, and manage network traffic.

[0086] In this embodiment, NE1 is defined as an access point, NE2 represents a dual-homed primary node, NE3 represents a dual-homed backup node in the same group as NE2, and the adjacent nodes of NE1 are NE2 and NE3. NE1 to NE3 form the westward domain. NE4 is defined as a dual-homed primary node, NE5 represents a dual-homed backup node in the same group as NE4, and NE6 is another access point. The adjacent nodes of NE6 are NE4 and NE5.

[0087] Deploy FGU1+1 dual-transmitter selective source protection (based on G.8331 standard) on NE1 and NE6. For example, if the source is NE1, the primary working path is to NE2, and the backup protection path is to NE3.

[0088] FGU dual-homed primary and backup protection is deployed in NE2 and NE3, and NE4 and NE5 respectively.

[0089] Traffic sent from the primary path NE1 to NE6 is defined as eastward primary traffic, represented by a solid line with an arrow pointing eastward. Traffic in each segment of the path is also called eastward primary traffic.

[0090] Traffic sent from the primary path NE6 to NE1 is called westward primary traffic, represented by a solid line with a westward arrow. The traffic in each segment of the path is also called westward primary traffic.

[0091] Traffic sent from the backup protection path NE1 to NE6 is called eastward backup traffic, which is represented by a dashed line with an arrow pointing eastward. The traffic in each segment of the path is also called eastward backup traffic.

[0092] Traffic sent from the backup protection path NE6 to NE1 is called westward backup traffic, represented by a dashed line with a westward arrow. The traffic in each segment of the path is also called westward primary traffic.

[0093] For ease of description, the network diagrams in each embodiment are simplified, with only three network devices listed in each domain. However, the deployment of four or more devices in one domain is also within the scope of protection of this invention.

[0094] The technical solution of the invention will be described in more detail below through various specific application scenarios shown in the embodiments.

[0095] Example 1

[0096] like Figure 1 The image shows a scenario where the path, nodes, and DNI are all functioning correctly:

[0097] (1) The business trend is as follows:

[0098] Eastbound traffic: NE2 receives the eastbound primary traffic (solid line traffic) from NE1 and forwards it to NE4; NE3 receives the eastbound backup traffic (dashed line traffic) from NE1 and forwards it to NE5.

[0099] Westbound traffic: NE2 receives westbound primary traffic (solid line traffic) from NE4 and sends it to NE1. NE3 receives westbound backup traffic (dashed line traffic) from NE5 and sends it to NE1.

[0100] (2) Full-path APS code deployment instructions:

[0101] Enable the transmission and reception of APS-W codes between segments NE1-NE2-NE4-NE6;

[0102] Enable the transmission and reception of APS-P codes between segments NE1-NE3-NE5-NE6;

[0103] The transmission and reception of DNI codes are enabled between NE2 and NE3, and between NE4 and NE5.

[0104] (3) Explanation of the full path APS code content:

[0105] This explanation uses the APS codes received and transmitted by NE2 and NE3 as examples. The DNI transmission and reception of NE2 is equivalent to the reception and transmission of NE3, so only the DNI reception and transmission are displayed on NE2. The primary reception of NE1 is equivalent to the APS-W transmission of NE2, and the reception of the backup path of NE1 is equivalent to the APS-P transmission of NE3. The APS-W code received by NE4 from the west is equivalent to the APS-W transmission of NE2 from the east, and the APS-P code received by NE5 from the west is equivalent to the APS-W transmission of NE3 from the east.

[0106] The following tables, Tables 2 and 3, describe the APS code content received and transmitted in the three directions of NE2 and NE3 in this scenario:

[0107] Table 2 Codes for the NE2 master node in three directions under normal scenarios

[0108]

[0109] Table 3 Codes for the three directions of the NE3 backup node under normal scenarios

[0110]

[0111] In this normal scenario, the difference from the patent with publication number CN117544485A is that the DNI link does not initially transmit service traffic. Both the primary and backup nodes directly forward the traffic. That is, traffic coming from the west is directly forwarded and flows out from the east; traffic coming from the east is directly forwarded and flows out from the west; no traffic is sent in the DNI direction.

[0112] Example 2

[0113] Westbound domain single point of failure scenario: such as Figure 2As shown, in this embodiment, there is a path fault between NE1 and NE2. NE1, NE2, and NE3 undergo protection switching.

[0114] Protection switching for eastbound traffic: NE1 transmits traffic twice; NE2 (due to a westbound domain failure) first switches to select the eastbound backup traffic (dashed line traffic) to send to NE4, and sends a DNI code with wF=1 to NE3, and sends an APS-W code with SF-W to NE1; after receiving wF=1, NE3 switches to transmit the eastbound backup traffic (dashed line traffic) twice to NE2 and NE5; NE4, NE5 and NE6 do not switch.

[0115] Protection switching for westbound traffic: NE6 transmits traffic twice; NE5 transmits traffic to NE3 once; NE4 transmits traffic to NE2 once; NE2 (due to a westbound domain failure) switches to transmitting the primary westbound traffic (solid line traffic) from NE4 twice to NE1 (unreachable) and NE3; NE3 receives wF=1 from NE2, switches to selecting the primary westbound traffic (solid line traffic) from NE2 for forwarding to NE1, and replies to NE2 with a DNI code of wS=1, and sends an SF-W APS-P code to NE1; NE1 (due to a primary failure) sends an SF-W APS-W code and an APS-P code to NE2 and NE3, and switches to receiving the primary westbound traffic (solid line traffic) for continued westward forwarding.

[0116] In the single-point-of-failure scenario of this westward domain, the APS codes received and transmitted by the NE2 master node in three directions are shown in Table 4, and the APS codes received and transmitted by the NE3 backup node in three directions are shown in Table 5.

[0117] Table 4 Codes of the NE2 master node in a single-point-of-failure scenario in the westbound domain

[0118]

[0119] Table 5 Codes of NE3 Backup Nodes in Single-Point-of-Failure Scenario in the Westbound Domain

[0120]

[0121] In this westbound single-point fault scenario, the difference from the patent with publication number CN117544485A is that (1) since the fault is detected in the westbound domain of NE2, the APS-W code received in the westbound domain is ignored; (2) when the westbound fault of NE2 is detected, NE2 immediately performs protection switching, instead of the scheme in CN117544485A: NE2 first sends DNI information with iF=1 to NE3, and only performs switching after NE2 receives DNI information with iS=1 from NE3. Therefore, the protection switching performance is improved in this scenario.

[0122] Example 3

[0123] Eastbound domain single point of failure scenario: such as Figure 3As shown, in this embodiment, there is a path fault between NE2 and NE4. NE2, NE3, NE4, and NE5 undergo protection switching.

[0124] Eastbound traffic protection switching: NE1 transmits traffic twice; NE2 (due to an eastbound domain failure) first switches to transmitting eastbound primary traffic (solid line traffic) twice to NE3 and NE4 (unreachable), and sends a DNI code with eF=1 to NE3 and an APS-W code with SF-W to NE4; NE3 receives eF=1 from NE2, switches to sending the eastbound primary traffic (solid line traffic) from NE2 to NE5, and replies with a DNI code with eS=1 to NE2; NE4 switching logic is the same as NE2, but due to the failure, it selects the eastbound primary traffic (solid line traffic) from NE5 to NE6, sends a DNI code with wF=1 to NE5, and sends an APS-W code with SF-W to NE2; NE5 switching logic is the same as NE3, and sends the eastbound primary traffic (solid line traffic) from NE3 twice to NE4 and NE6, and NE6 still selects the eastbound primary traffic (solid line traffic) from NE4 for forwarding.

[0125] Westbound traffic protection switching: NE6 transmits traffic twice; NE4 (due to a westbound fault) first switches to transmitting westbound primary traffic (solid line traffic) to both NE2 (unreachable) and NE5, sending a DNI code with wF=1 to NE5 and an APS-W code with SF-W to NE2; after receiving wF=1 from NE4, NE5 switches to sending the westbound primary traffic (solid line traffic) from NE4 to NE3; and replies with a DNI code with wS=1 to NE4, and sends to NE3... SF-W APS-P code; After NE3 receives eF=1 from NE2, it will send the westward primary traffic (solid line traffic) from NE5 to both NE1 and NE2, and reply to NE2 with eS=1 DNI code, and send the SF-W APS-P code to NE5; NE2 (due to eastward failure) first switches to send the westward primary traffic (solid line traffic) from NE3 to NE1, and NE1 still selects the westward primary traffic (solid line traffic) from NE2 for forwarding.

[0126] In the single-point-of-failure scenario of this eastward domain, the APS codes received and transmitted by the NE2 master node in three directions are shown in Table 6, and the APS codes received and transmitted by the NE3 backup node in three directions are shown in Table 7.

[0127] The difference between this eastbound domain single-point fault scenario and the patent with publication number CN117544485A is as follows: (1) Since the fault is detected in the eastbound direction of NE2, the APS-W code received in the eastbound direction is ignored; (2) When the eastbound fault of NE2 is detected, NE2 immediately performs protection switching, instead of the scheme in CN117544485A: NE2 first sends eF=1 DNI information to NE3, and only performs switching after NE2 receives eS=1 DNI information from NE3. Therefore, the protection switching performance is improved in this eastbound domain single-point fault scenario.

[0128] Table 6 Codes of NE2 Master Nodes in Eastbound Domain Single Point of Failure Scenario

[0129]

[0130] Table 7 Codes of NE3 Backup Nodes in Eastbound Domain Single-Point Failure Scenario

[0131]

[0132] Example 4

[0133] Two-point fault scenarios in the westbound and eastbound domains: such as Figure 4 As shown, in this embodiment, when NE1 and NE2 fail, and NE2 and NE4 fail, the protection switches of NE1, NE2, NE3, NE4 and NE5 are switched.

[0134] Eastbound traffic protection switching: NE1 transmits traffic twice; NE2 (due to two faults) sends a DNI code with wF=1 and eF=1 to NE3, and sends an SF-W APS-W code to NE1 and NE4; NE3 switches to send the eastbound backup traffic (dashed line traffic) from NE1 to NE5, and replies to NE2 with a DNI code with wS=1 and eS=1, and sends an SF-W APS-P code to NE1 and NE5; NE4 (due to a westbound domain fault) switches to send the dashed line traffic selected from NE5 to NE6, and sends wF=1 to NE5, and sends an SF-W APS-W code to NE2; NE5 receives wF=1 from NE4, and transmits the eastbound backup traffic (dashed line traffic) from NE3 twice to NE4 and NE6, and replies to NE4 with wS=1, and sends an SF-W APS-P code to NE3; NE6 still selects the eastbound backup traffic (dashed line traffic) from NE4 for forwarding.

[0135] Westbound traffic protection switching: NE6 transmits traffic twice. NE4 (due to a westbound failure) switches to transmitting westbound primary traffic (solid line traffic) twice to NE2 (unreachable) and NE5, sending a DNI code with wF=1 to NE5 and an APS-W code with SF-W to NE2. After receiving wF=1 from NE4, NE5 switches to sending the westbound primary traffic (solid line traffic) from NE4 to NE3, replies with a DNI code with wS=1 to NE4, and sends an APS-P code with SF-W to NE3. After receiving the DNI codes with wF=1 and eF=1 from NE2, NE3 transmits the westbound primary traffic (solid line traffic) from NE5 twice to NE1 and NE2, and sends an APS-P code with SF-W to NE1 and NE5 respectively. NE1 (due to a primary failure) switches to receiving the westbound primary traffic (solid line traffic) and continues to forward it westward.

[0136] In the scenario of a two-point failure in the westbound and eastbound domains, the APS codes received and transmitted by the NE2 master node in the three directions are shown in Table 8, and the APS codes received and transmitted by the NE3 backup node in the three directions are shown in Table 9.

[0137] Table 8 Codes of the NE2 master node in a two-point failure scenario in the westbound and eastbound domains.

[0138]

[0139] Table 9 Codes of NE3 Backup Nodes in Two-Point Failure Scenarios in Westbound and Eastbound Domains

[0140]

[0141] The difference between this two-point fault scenario in the westbound and eastbound domains and that in publication number CN117544485A is that since faults are detected in both the eastbound and westbound domains of NE2, the APS-W codes received in the eastbound and westbound domains are ignored.

[0142] Example 5

[0143] Two-point fault scenarios in DNI and eastbound domain, such as Figure 5 As shown, in this embodiment 5, NE2 and NE3 fail, NE2 and NE4 fail, and the protection switches for NE1, NE4, and NE5 are switched. The workflow in this scenario is as follows:

[0144] The workflow for eastbound traffic is as follows: NE1 sends dual traffic; NE2 (due to DNI and eastbound failure), with its switchover status unchanged, sends an APS-W code indicating a remote primary failure to NE1, and a DNI code indicating a primary node eastbound domain failure to NE3; it also sends an APS-W code indicating a DNI failure to NE4; NE3 (due to a DNI failure), with its switchover status unchanged, sends the dashed traffic to NE5, and sends an APS-P code indicating a DNI failure to both NE1 and NE5; the switchover logic for NE4 is to select traffic from NE5. The dashed traffic is sent to NE6. NE5 sends a DNI code with wF=1 to indicate a westbound domain failure and an APS-W code with SF-W to indicate a primary path failure. After receiving the DNI code with wF=1 from NE4, NE5 sends the dashed traffic from NE3 to both NE4 and NE6. NE5 replies to NE4 with a DNI code with wS=1 to indicate a switchover has been performed and sends an APS-P code with SF-W to indicate a primary path failure. NE6 then forwards the dashed traffic from NE4.

[0145] The workflow for westbound traffic: NE6 sends traffic to both NE4 and NE5 simultaneously. NE4 processes this (due to an eastbound domain failure). Upon detecting the eastbound domain failure, NE4 first switches to sending solid line traffic to both NE2 (unreachable) and NE5. It sends a DNI code with wF=1 to NE5 to indicate a westbound domain failure and an APS-W code with SF-W to NE2 to indicate a primary path failure. After receiving the DNI code with wF=1 from NE4, NE5 switches to sending solid line traffic from NE4 to NE3 and sends a response to NE4. A DNI code with wS=1 indicates a switchover has occurred. An SF-W APS-P code is sent to NE3 to indicate a primary path failure. NE2's switchover status remains unchanged. It sends an SF-W APS-W code indicating a remote primary path failure to NE1, a DNI code (eF=1) indicating a primary node eastbound domain failure to NE3, and an SF-W APS-W code indicating a DNI failure to NE4. NE3's switchover status remains unchanged. It sends solid line traffic to NE1 and sends APS-P codes indicating a DNI failure to both NE1 and NE5. NE1's switchover selects solid line traffic from NE3 for continued westward forwarding.

[0146] In the scenario of two-point failure in this DNI and the eastward domain, the APS codes received and transmitted in the three directions of the NE2 master node are shown in Table 10, and the APS codes received and transmitted in the three directions of the NE3 backup node are shown in Table 11.

[0147] Table 10 Codes of the NE2 master node under two-point failure scenarios in DNI and eastbound domain

[0148]

[0149] Table 11 Codes of NE3 Backup Nodes under Two-Point Failure Scenarios in DNI and Eastbound Domain

[0150]

[0151] The difference between this DNI and the two-point fault scenario in the eastbound domain and the patent with publication number CN117544485A is that the notification process of the CN117544485A patent is: through the process of NE4-NE5-NE3-NE1, the present invention directly notifies the APS-W code from NE2 to NE1, which improves the switching performance.

[0152] Example 6

[0153] Two-point fault scenarios in DNI and westbound domain: such as Figure 6 As shown in Example 6, in the event of a fault between NE1 and NE2, or between NE2 and NE3, the protection switches of NE1, NE4, and NE5 are switched. The workflow in this scenario is as follows:

[0154] Protection switching for eastbound traffic: NE1 (due to primary path failure), NE1 simultaneously sends traffic to NE2 and NE3, sending an APS-W code indicating primary path failure to NE2 and an APS-P code indicating primary path failure to NE3; NE2's switching status remains unchanged, sending an APS-W code indicating DNI failure to NE1, a DNI code indicating westbound domain failure of the primary node (wF=1) to NE3, and an APS-W code indicating remote primary path failure to NE4; NE3's switching status remains unchanged, sending APS-P codes indicating DNI failure to NE1 and NE5 respectively; NE4 performs protection switching, selecting dashed traffic from NE5 to send to NE6, sending a DNI code with wF=1 to NE5 to indicate westbound domain failure; after receiving the DNI code with wF=1 from NE4, NE5 replies with a DNI code with wS=1 to NE4, indicating that switching has been performed; NE6 selects dashed traffic from NE4 for forwarding.

[0155] Protection switching for westbound traffic: NE6 transmits traffic twice. After NE4 receives the APS-W code indicating a remote primary path failure, it first switches to transmitting solid line traffic to both NE2 (unreachable) and NE5, sending a DNI code with wF=1 to NE5 to indicate a westbound domain failure. After NE5 receives the DNI code with wF=1 from NE4, it switches to sending solid line traffic from NE4 to NE3, replies to NE4 with a DNI code with wS=1 to indicate that the switching has been performed, and sends an APS-P code with SF-W to NE3 to indicate a primary path failure. NE2's switching status remains unchanged. It sends an APS-W code indicating a DNI failure to NE1, a DNI code (wF=1) indicating a westbound domain failure of the primary node to NE3, and an APS-W code indicating a remote primary path failure to NE4. NE3's switching status remains unchanged. It sends solid line traffic to NE1 and sends APS-P codes indicating a DNI failure to both NE1 and NE5. NE1 switched to forwarding the solid traffic from NE3 westward.

[0156] In the scenario of two-point failure in this DNI and the westward domain, the APS codes received and transmitted in the three directions of the NE2 master node are shown in Table 12, and the APS codes received and transmitted in the three directions of the NE3 backup node are shown in Table 13.

[0157] Table 12 Codes of the NE2 master node under two-point failure scenarios in DNI and westbound domain

[0158]

[0159] Table 13 Codes of NE3 Backup Nodes under Two-Point Failure Scenarios in DNI and Westbound Domain

[0160]

[0161] Compared to the patent with publication number CN117544485A, the notification process for NE4 switching in the patent CN117544485A is: through the process of NE1-NE3-NE5-NE4. In this invention, the solution directly notifies the APS-W code from NE2 to NE4 in the two-point fault scenario of DNI and westward domain, thereby improving the switching performance.

[0162] Example 7

[0163] Node power failure scenarios: such as Figure 7 As shown, in this embodiment 7, the NE2 node loses power; the protection switches for NE1, NE4, and NE5. The workflow in this scenario is as follows:

[0164] Eastbound traffic protection switching: NE1 (due to primary path failure) sends traffic to both NE2 and NE3 simultaneously, sending an APS-W code indicating primary path failure to NE2 and an APS-P code indicating primary path failure to NE3; NE3 (due to DNI failure) maintains its switching status and sends dashed traffic to NE5, sending an APS-P code indicating DNI failure to both NE1 and NE5; NE4 (due to westbound failure) performs protection switching, selecting dashed traffic from NE5 to send to NE6, sending a DNI code with wF=1 to NE5 to indicate a westbound domain failure; after receiving the DNI code with wF=1 from NE4, NE5 sends dashed traffic from NE3 to both NE4 and NE6, replying to NE4 with a DNI code with wS=1 to indicate that switching has been performed; NE6 selects dashed traffic from NE4 for forwarding.

[0165] Westbound Traffic Protection Switching: NE6 sends traffic to both NE4 and NE5. NE4 (due to a westbound fault) first switches to sending solid line traffic to both NE2 (unreachable) and NE5, sending a DNI code with wF=1 to NE5 to indicate a westbound domain fault. After receiving the wF=1 DNI code from NE4, NE5 switches to sending solid line traffic from NE4 to NE3, replies with a wS=1 DNI code to NE4 to indicate that the switch has been performed, and sends an SF-W APS-P code to NE3 to indicate a primary path fault. NE3's switchover status remains unchanged, sending solid line traffic to NE1, and sending APS-P codes indicating a DNI fault to both NE1 and NE5 respectively. NE1 then switches to forwarding solid line traffic from NE3 westward.

[0166] In the event of a power outage at this node, the NE2 master node is unable to send the DNI code to the NE3 backup node due to the power failure. Therefore, the NE3 backup node receives and sends the APS code in both directions. The APS codes received and sent by the NE3 backup node in both directions are shown in Table 14.

[0167] Table 14 Codes for the NE3 standby node in two directions under node power failure scenario

[0168]

[0169] Example 8

[0170] Three fault scenarios: such as Figure 8 As shown, in this embodiment 8, NE2 and NE3, NE2 and NE4, and NE4 and NE5 are all faulty. In this scenario, NE1 and NE6 are switched over, and the workflow is as follows:

[0171] Protection switching for westbound traffic: NE2 (due to DNI and eastbound faults) maintains its switching status, sends an APS-W code for remote primary fault to NE1, a DNI code for master node eastbound domain fault to NE3, and an APS-W code for DNI fault to NE4; NE3 (due to DNI faults) maintains its switching status, sends an APS-P code for DNI fault to both NE1 and NE5. Upon receiving the APS-W code for remote primary fault switching from NE2 and the APS-P code for DNI fault from NE3, NE1 triggers protection switching and selectively forwards traffic from the dotted line of NE3.

[0172] Protection switching for eastbound traffic: NE4 (due to DNI and westbound faults) maintains its switching status, sends an APS-W code for a remote primary fault to NE6, a DNI code for a westbound domain fault to NE5, and an APS-W code for a DNI fault to NE2. NE5 (due to a DNI fault) maintains its switching status, sending APS-P codes for a DNI fault to both NE3 and NE6. Upon receiving the APS-W code from NE4's remote primary fault switching notification and the APS-P code from NE5's DNI fault notification, NE6 triggers protection switching, selectively forwarding the dashed line traffic from NE5.

[0173] In this three-point failure scenario, the APS codes received and transmitted in three directions by the NE2 master node and the NE3 backup node are shown in Tables 15 and 16:

[0174] Table 15 Codes of the NE2 master node under three-point failure scenarios

[0175]

[0176] Table 16 Codes of NE3 Backup Nodes under Three-Point Fault Scenarios

[0177]

[0178] Compared to the appendix of patent publication number CN117544485A Figure 6 In a further fault scenario, if NE4 and NE5 fail, NE1 will be unable to switch over. In this case, the above-mentioned patented solution becomes invalid, meaning it cannot support this three-point fault scenario. The solution of this invention solves the protection switching problem in a three-point fault scenario.

[0179] Based on the same inventive concept as the above method, this invention also provides a small-granularity dual-homing protection switching system based on full-path APS. The system has a primary / backup switching architecture, which includes a westward domain and / or an eastward domain. Each domain includes multiple access nodes and multiple groups of dual-homing nodes. Each group of dual-homing nodes includes a dual-homing primary node and a dual-homing backup node. One access node is connected to another access node via each dual-homing primary node to form a primary working path. One access node is connected to another access node via each dual-homing backup node to form a backup protection path. A DNI link is established between the dual-homing primary and backup nodes in the same group.

[0180] Each node located on the primary working path is used to send and receive traffic through the primary working path; send and receive primary working path automatic protection switching (APS-W) codes with adjacent nodes on the primary working path; and when protection switching is required, send protection switching information related to the reason for protection switching to adjacent nodes, and perform protection switching based on the protection switching information received from the non-faulty path. The protection switching information includes: APS-W code, APS-P code, and DNI code. The APS-W code includes the dual-node interconnection DNI link status field of the primary node.

[0181] Each node located on the backup working path is used to send and receive traffic through the backup protection path; send and receive backup protection path automatic protection switching APS-P codes with adjacent nodes on the backup working path; and when protection switching is required, send protection switching information related to the reason for protection switching to adjacent nodes, and perform protection switching based on the protection switching information received from the non-faulty path, wherein the APS-P code includes the backup node's DNI link status field;

[0182] Each dual-homed master node located on the primary working path is also used to send and receive DNI codes with the dual-homed backup nodes in the same group via the DNI link. When protection switching is required, the DNI link is also used to send and receive traffic. The DNI code includes the following information switching fields: westbound domain signal fault field, westbound domain signal degradation field, westbound domain switching field, eastbound domain signal fault field, eastbound domain signal degradation field, and eastbound domain switching field.

[0183] Each dual-homed backup node located on the primary working path is also used to send and receive DNI codes with the dual-homed primary node in the same group via the DNI link.

[0184] The above description is merely a preferred embodiment of the present invention and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of disclosure in this invention is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this invention.

Claims

1. A small-particle dual-homing protection switching method based on full-path APS, characterized in that, This method is used for a primary / backup failover architecture, which includes a westward domain and / or an eastward domain. Each domain includes multiple access nodes and multiple sets of dual-homed nodes. Each set of dual-homed nodes includes a dual-homed primary node and a dual-homed backup node. One access node connects to another access node via each dual-homed primary node to form a primary working path. One access node connects to another access node via each dual-homed backup node to form a backup protection path. A DNI link is established between the dual-homed primary and backup nodes in the same group. The method includes the following steps: Each node located on the primary working path sends and receives traffic through the primary working path; Each node located on the backup working path sends and receives traffic through the backup protection path; The primary working path automatic protection switching (APS-W) code is sent and received between two adjacent nodes on the primary working path; the APS-W code includes the dual-node interconnection DNI link status field of the primary node. The automatic protection switching (APS-P) code for backup protection path is sent and received between two adjacent nodes on the backup working path; the APS-P code includes the DNI link status field of the backup node. The dual-homed primary and backup nodes in the same group send and receive DNI codes through the DNI link. When protection switching is required, the DNI link is also used to send and receive traffic. The DNI code includes the following information switching fields: west-bound domain signal fault field, west-bound domain signal degradation field, west-bound domain switching field, east-bound domain signal fault field, east-bound domain signal degradation field, and east-bound domain switching field. When any node needs protection switching, it sends protection switching information related to the reason for protection switching to neighboring nodes. Protection switching is performed based on the protection switching information received from the non-faulty path. The protection switching information includes: APS-W code, APS-P code and DNI code.

2. The method according to claim 1, characterized in that, The following fields are defined: Westbound domain signal fault field: wF (0 indicates normal, 1 indicates signal fault); Westbound domain signal degradation field: wD (0 indicates normal, 1 indicates signal degradation); Westbound domain switching field: wS (0 indicates no switching, 1 indicates switching); Eastbound domain signal fault field: eF (0 indicates normal, 1 indicates signal fault); Eastbound domain signal degradation field: eD (0 indicates normal, 1 indicates signal degradation); Eastbound domain switching field: eS (0 indicates no switching, 1 indicates switching); The DNI link status field is a newly added field in the Requestedsignal field of the standard APS code, where 0 indicates DNI normal and 1 indicates DNI fault. Define NE1 as the access point, NE2 as the dual-homed primary node, and NE3 as the dual-homed backup node in the same group as NE2. The adjacent nodes of NE1 are NE2 and NE3, and NE1 to NE3 constitute the westward domain. Define NE4 as the dual-homed primary node, NE5 as the dual-homed backup node in the same group as NE4, and NE6 as another access point. The adjacent nodes of NE6 are NE4 and NE5. Define the traffic sent from the primary working path NE1 to NE6 as eastward primary traffic, and the traffic sent from NE6 to NE1 as westward primary traffic. Traffic sent from NE1 to NE6 via the backup protection path is eastbound backup traffic, and traffic sent from NE6 to NE1 is westbound backup traffic.

3. The method according to claim 2, characterized in that, In the scenario of a single-point path failure in the westbound domain, the primary working path between NE1 and NE2 fails. The protection switching method for eastbound traffic is as follows: When NE2 detects a westbound fault, N2 first switches to select the eastbound backup traffic to send to NE4, and sends a DNI code with wF=1 to NE3, and sends an APS-W code indicating a primary fault SF-W to NE1; after receiving wF=1, NE3 switches to send the eastbound backup traffic to both NE2 and NE5. Westbound traffic: NE2 switches to sending the primary westbound traffic from NE4 to both NE1 and NE3; NE3 receives wF=1 from NE2, switches to selecting the primary westbound traffic from NE2 for forwarding to NE1, and replies to NE2 with a DNI code of wS=1, and sends an APS-P code indicating primary failure SF-W to NE1; NE1 sends APS-W and APS-P codes indicating primary failure SF-W to NE2 and NE3, and switches to selecting the primary westbound traffic for continued westward forwarding.

4. The method according to claim 2, characterized in that, In the scenario of a single-point path failure in the eastbound domain, the primary working path between NE2 and NE4 fails. Protection switching method for eastbound traffic: When NE2 detects a westbound fault, it first switches to sending eastbound primary traffic to both NE3 and NE4, and sends a DNI code with eF=1 to NE3, and an APS-W code indicating a primary fault SF-W to NE4; NE3 receives eF=1 from NE2, switches to sending the eastbound primary traffic from NE2 to NE5, and replies with a DNI code with eS=1 to NE2; the switching logic for NE4 is the same as for NE2, but due to the fault, it selects the eastbound primary traffic from NE5 to send to NE6, sends a DNI code with wF=1 to NE5, and sends an APS-W code indicating a primary fault SF-W to NE2; The switching logic for NE5 is the same as that for NE3. The eastbound primary traffic from NE3 is sent to both NE4 and NE6, and NE6 selects the eastbound primary traffic from NE4 for forwarding. Protection switching method for westbound traffic: NE4 detects a westbound fault and first switches to sending westbound primary traffic to both NE2 and NE5, sending a DNI code with wF=1 to NE5 and an APS-W code indicating a primary fault (SF-W) to NE2; after receiving wF=1 from NE4, NE5 switches to sending the westbound primary traffic from NE4 to NE3; it also replies to NE4 with a DNI code with wS=1 and sends an APS-P code indicating a primary fault (SF-W) to NE3; after receiving eF=1 from NE2, NE3 sends the westbound primary traffic from NE5 to both NE1 and NE2, replies to NE2 with a DNI code with eS=1, and sends an APS-P code indicating a primary fault (SF-W) to NE5; NE2 first switches to sending the westbound primary traffic from NE3 to NE1, and NE1 then forwards the westbound primary traffic from NE2.

5. The method according to claim 2, characterized in that, In a two-point fault scenario in the west-to-east domain, NE1 and NE2 fail, and NE2 and NE4 fail. Protection switching method for eastbound traffic: NE2 sends a DNI code with wF=1 and eF=1 to NE3, and sends an APS-W code indicating a primary fault SF-W to NE1 and NE4; NE3 switches to send the eastbound backup traffic from NE1 to NE5, and replies to NE2 with a DNI code with wS=1 and eS=1, and sends an APS-P code indicating a primary fault SF-W to NE1 and NE5; NE4 switches to send the eastbound backup traffic selected from NE5 to NE6, and sends wF=1 to NE5, and sends an APS-W code indicating a primary fault SF-W to NE2; NE5 receives wF=1 from NE4, and sends the eastbound backup traffic from NE3 to both NE4 and NE6, and replies to NE4 with wS=1, and sends an APS-P code indicating SF-W to NE3; NE6 selects the eastbound backup traffic from NE4 for forwarding; Protection switching method for westbound traffic: NE4 switches to sending westbound primary traffic to both NE2 and NE5, sending a DNI code with wF=1 to NE5 and an APS-W code indicating a primary fault SF-W to NE2; after receiving wF=1 from NE4, NE5 switches to sending westbound primary traffic from NE4 to NE3, replies with a DNI code with wS=1 to NE4, and sends an APS-P code indicating a primary fault SF-W to NE3; after receiving the DNI code with wF=1 and eF=1 from NE2, NE3 sends westbound primary traffic from NE5 to both NE1 and NE2, and sends an APS-P code indicating a primary fault SF-W to both NE1 and NE5 respectively; NE1 switches to receiving westbound primary traffic and continues forwarding it westward.

6. The method according to claim 2, characterized in that, In the two-point failure scenario of DNI and Eastbound Domain, NE2 and NE3 fail, and NE2 and NE4 fail. Protection switching method for eastbound traffic: NE2 sends an APS-W code indicating a remote primary fault to NE1, and sends a DNI code with eF=1 to NE3, and sends an APS-W code indicating a DNI fault to NE4; NE3 sends an APS-P code indicating a DNI fault to NE1 and NE5 respectively. Protection switching method for westbound traffic: When NE1 receives the APS-W code from NE2 indicating a switchover notice of remote primary failure and the DNI fault APS-P code from NE3, protection switching is triggered, and westbound primary traffic from NE3 is selected for forwarding.

7. The method according to claim 2, characterized in that, In the scenario of two-point faults in DNI and westward domain, there are faults between NE1 and NE2, and between NE2 and NE3; protection switching of NE1, NE4 and NE5; Protection switching method for eastbound traffic: NE1 switches to NE3, sending an APS-W code indicating a primary fault to NE2 and an APS-P code indicating a primary fault to NE3. NE2 sends an APS-W code indicating a remote primary fault to NE4 and a DNI code with wF=1 to NE3, and an APS-W code indicating a DNI fault to NE1. NE3 sends an APS-P code indicating a DNI fault to both NE1 and NE5. Upon receiving the APS-W code from NE2 announcing the remote primary fault switchover, NE4 triggers protection switching, selects the eastbound backup traffic from NE5 to send to NE6, and sends a DNI code with wF=1 to NE5. Upon receiving the DNI code with wF=1 from NE4, NE5 triggers protection switching and replies with a DNI code with wS=1 to NE4. NE6 then selects the eastbound backup traffic from NE4 for forwarding. Protection switching method for westbound traffic: NE6 transmits traffic in pairs. After NE4 receives the APS-W code indicating a remote primary path failure, it first switches to transmitting westbound primary traffic to both NE2 and NE5, sending a DNI code with wF=1 to NE5. After NE5 receives the DNI code with wF=1 from NE4, it switches to sending the westbound primary traffic from NE4 to NE3, replies with a DNI code with wS=1 to NE4, and sends an APS-P code with SF-W to NE3. NE2 sends an APS-W code indicating a DNI failure to NE1, sends wF=1 to NE3, and sends an APS-W code to NE4; NE3 sends westward primary traffic to NE1, and sends APS-P codes indicating a DNI failure to NE1 and NE5 respectively. NE1 then switches to forwarding westward primary traffic from NE3.

8. The method according to claim 1 or 2, characterized in that, Node power failure scenario: NE2 node power failure; NE1, NE4 and NE5 protection switching; Eastbound traffic protection switching: NE1 switches to NE3, sending APS-W code for primary path failure to NE2 and APS-P code for primary path failure to NE3 respectively; NE3 sends APS-P codes indicating DNI failure to NE1 and NE5 respectively; NE4 triggers protection switching and sends a DNI code with wF=1 to NE5; after receiving the DNI code with wF=1 from NE4, NE5 triggers protection switching and replies with a DNI code with wS=1 to NE4; NE6 selects the eastbound backup traffic from NE4 for forwarding. Westbound traffic protection switching: NE6 sends dual traffic to NE4 and NE5. NE4 first switches to sending dual westbound primary traffic to NE2 and NE5, and sends a DNI code with wF=1 to NE5. After receiving the DNI code with wF=1 from NE4, NE5 switches to send the westbound primary traffic from NE4 to NE3, replies with a DNI code with wS=1 to NE4, and sends an APS-P code with SF-W to NE3. NE3's switching status remains unchanged, and it sends the westbound primary traffic to NE1, sending an APS-P code indicating a DNI failure to both NE1 and NE5. NE1 switches to continue forwarding the westbound primary traffic from NE3 westward.

9. The method according to claim 2, characterized in that, In a three-point fault scenario, there are faults between NE2 and NE3, NE2 and NE4, and NE4 and NE5, and NE1 and NE6 are switched over. Protection switching method for westbound traffic: NE2 sends the APS-W code of remote primary fault to NE1, and sends the DNI code of primary node eastbound domain fault to NE3, and sends the APS-W code of DNI fault to NE4; NE3 sends the APS-P code of DNI fault to NE1 and NE5 respectively. When NE1 receives the APS-W code of the remote primary fault switching notification from NE2 and the DNI fault APS-P code from NE3, it triggers protection switching and selects to forward the westward backup traffic from NE3. Protection switching method for eastbound traffic: NE4 sends an APS-W code indicating a remote primary fault to NE6, and sends a DNI code indicating a westbound domain fault to NE5, and sends an APS-W code indicating a DNI fault to NE2; NE5 sends APS-P codes indicating a DNI fault to NE3 and NE6 respectively; NE6 receives the APS-W code of the remote primary fault switching notification from NE4 and the DNI fault APS-P code of NE5, triggers protection switching, and selects and forwards the eastbound backup traffic from NE5.

10. A small-particle dual-homing protection switching system based on full-path APS, characterized in that, The system is a primary / backup failover architecture, which includes a westward domain and / or an eastward domain. Each domain includes multiple access nodes and multiple sets of dual-homed nodes. Each set of dual-homed nodes includes a dual-homed primary node and a dual-homed backup node. One access node connects to another access node via each dual-homed primary node to form a primary working path. One access node connects to another access node via each dual-homed backup node to form a backup protection path. DNI links are established between dual-homed primary and backup nodes in the same group. Each node located on the primary working path is used to send and receive traffic through the primary working path; Sending and receiving APS-W codes for automatic protection switching of the primary working path between adjacent nodes on the primary working path; When protection switching is required, protection switching information related to the reason for protection switching is sent to adjacent nodes. Protection switching is performed based on the protection switching information received from the non-faulty path. The protection switching information includes: APS-W code, APS-P code and DNI code. The APS-W code includes the dual-node interconnection DNI link status field of the master node. Each node located on the backup working path is used to send and receive traffic through the backup protection path; send and receive backup protection path automatic protection switching APS-P codes with adjacent nodes on the backup working path; and when protection switching is required, send protection switching information related to the reason for protection switching to adjacent nodes, and perform protection switching based on the protection switching information received from the non-faulty path, wherein the APS-P code includes the backup node's DNI link status field; Each dual-homed primary node located on the primary working path is also used to send and receive DNI codes with dual-homed backup nodes in the same group via the DNI link. When protection switching is required, the DNI link is also used to send and receive traffic. The DNI code includes the following information switching fields: westbound domain signal fault field, westbound domain signal degradation field, westbound domain switching field, eastbound domain signal fault field, eastbound domain signal degradation field, and eastbound domain switching field. Each dual-homed backup node located on the primary working path is also used to send and receive DNI codes with the dual-homed primary node in the same group via the DNI link.

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