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

Abstract

The invention belongs to the technical field of communication service protection and switching, and provides a small-particle dual-homing protection switching method and system based on a full-path APS, which are used for a main and standby switching architecture, the architecture comprises a west domain and / or an east domain, each domain comprises a plurality of access nodes and a plurality of groups of dual-homing nodes, the method comprises the following steps: sending and receiving an APS-W code between two adjacent nodes on a main working path, and sending and receiving an APS-P code between two adjacent nodes on a standby working path; dN I codes are sent and received between the dual-homing main nodes and the dual-homing standby nodes in the same group through DN I links, and when protection switching is needed, the nodes carry out protection switching based on protection switching information which is received from a non-fault path and comprises APS-W codes, APS-P codes and DN I codes. The notification process of protection switching and related nodes can be reduced, the time consumption of protection switching is reduced, and the protection switching performance is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of communication service protection and switching, and in particular relates to a small-granularity dual-homing protection switching method and system based on full-path APS. Background Art

[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. 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] In order to solve the problem that when a 1+1 end-to-end protection model fails at any point in a cross-domain scenario, both ends need to be switched and the troubleshooting efficiency is low, the patent with publication number CN117544485A proposes a small-granular dual-homing protection switching method and system based on three-way APS code negotiation. Figure 6 The protection switching logic for the scenario of two faults in the middle domain and between domains is as follows: (1) Faults between NE2, NE3, and NE4: NE4 fault detection takes t1. (2) NE4 runs the state machine and transmits information to NE5 takes t2. (3) NE5 runs the state machine and transmits information to NE3 takes t3. (4) NE3 runs the state machine and transmits information to NE1 takes t4. (5) NE1 runs the state machine and executes service switching takes t5.

[0004] It can be seen from the above protection switching logic that the above two-point fault scenario involves more sites, a longer information transmission path and involves intercommunication between different manufacturers. Therefore, there is a problem of poor protection switching performance in such two-point fault scenarios. Summary of the invention

[0005] The present invention provides a small-granularity 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 existing in the above-mentioned prior art.

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

[0007] A small-granular dual-homing protection switching method based on full-path APS, the method is used for a master-slave 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, each group of dual-homing nodes includes a dual-homing master node and a dual-homing backup node; an access node is connected to another access node via each dual-homing master node to form a master working path; an 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 master and backup nodes in the same group;

[0008] The method comprises the following steps:

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

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

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

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

[0013] The dual-homing active and standby 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 domain signal failure field, west domain signal degradation field, west domain switching field, east domain signal failure field, east domain signal degradation field, and east domain switching field.

[0014] When any node needs protection switching, it sends protection switching information related to the protection switching reason to the adjacent node, and performs protection switching based on the protection switching information received from the non-fault path, wherein the protection switching information includes: APS-W code, APS-P code and DNI code.

[0015] Further, the west domain signal failure field is defined as wF, 0 indicates normal, 1 indicates signal failure; the west domain signal degradation field is defined as wD, 0 indicates normal, 1 indicates signal degradation; the west domain switching field is defined as wS, 0 indicates no switching, 1 indicates switching; the east domain signal failure is defined as eF, 0 indicates normal, 1 indicates signal failure; the east domain signal degradation field is defined as eD, 0 indicates normal, 1 indicates signal degradation; the east domain switching field is defined as eS, 0 indicates no switching, 1 indicates switching; the DNI link status field is a newly added field in the request signal Requested signal field of the standard APS code, 0 indicates DNI normal, 1 indicates DNI failure;

[0016] Define NE1 as an access point, NE2 as a dual-home master node, NE3 as a dual-home backup node in the same group as NE2, NE1's adjacent nodes are NE2 and NE3, and NE1 to NE3 are the westbound domain; define NE4 as a dual-home master node, NE5 as a dual-home backup node in the same group as NE4, NE6 as another access point, and NE6's adjacent nodes are NE4 and NE5; define the traffic sent from NE1 to NE6 through the primary working path as eastbound primary traffic, and the traffic sent from NE6 to NE1 as westbound primary traffic; define the traffic sent from NE1 to NE6 through the backup protection path as eastbound backup traffic, and the traffic sent from NE6 to NE1 as westbound backup traffic.

[0017] Furthermore, in the single-point path failure scenario in the west-bound 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 sending eastbound backup traffic 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 NE3 receives wF=1, it switches to sending eastbound backup traffic to both NE2 and NE5;

[0019] Westbound traffic: NE2 switches to sending the westbound main traffic from NE4 to both NE1 and NE3; NE3 receives wF=1 from NE2, switches to forwarding the westbound main traffic from NE2 to NE1, replies with the DNI code of wS=1 to NE3, and sends the APS-P code indicating the main fault SF-W to NE1; NE1 sends the APS-W code and APS-P code indicating the main fault SF-W to NE2 and NE3, switches to receiving the westbound main traffic and continues to forward it to the west.

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

[0021] Protection switching method for eastbound traffic: NE2 detects a westbound fault and first switches to sending eastbound active traffic to both NE3 and NE4, and sends a DNI code with eF=1 to NE3, and sends an APS-W code indicating an active failure SF-W to NE4; NE3 receives eF=1 from NE2, switches to sending the eastbound active traffic from NE2 to NE5, and replies to NE2 with a DNI code with eS=1; NE4 has the same switching logic as NE2. Due to the fault, it selects the eastbound active traffic from NE5 to be sent to NE6, and sends a DNI code with wF=1 to NE5, and sends an APS-W code indicating an active failure SF-W to NE2; NE5 has the same switching logic as NE3. It sends the eastbound active traffic from NE3 to both NE4 and NE6, and NE6 selects the eastbound active traffic from NE4 to forward;

[0022] Protection switching method for westbound traffic: When NE4 detects a westbound fault, it first switches to sending westbound primary traffic to both NE2 and NE5, sends a DNI code with wF=1 to NE5, and sends an APS-W code indicating a primary fault SF-W to NE2; after NE5 receives wF=1 from NE4, it switches to sending the westbound primary traffic from NE4 to NE3; and 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 NE3 receives eF=1 from NE2, it sends the westbound primary traffic from NE5 to both NE1 and NE2, replies with a DNI code with eS=1 to NE2, 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 alone, and NE1 selects the westbound primary traffic from NE2 to forward.

[0023] Furthermore, in the two-point failure scenario of the west-bound domain and the east-bound domain, NE1 and NE2 fail, and NE2 and NE4 fail;

[0024] Protection switching method for eastbound traffic: NE2 sends DNI code of wF=1 and eF=1 to NE3, and sends APS-W code indicating active fault SF-W to NE1 and NE4; NE3 switches to select eastbound standby traffic from NE1 and sends it to NE5, and replies DNI code of wS=1 and eS=1 to NE2, and sends APS-P code indicating active fault SF-W to NE1 and NE5; NE4 switches to select eastbound standby traffic from NE5 and sends it to NE6, and sends wF=1 to NE5, and sends APS-W code indicating active fault SF-W to NE4; NE5 receives wF=1 from NE4, sends eastbound standby traffic from NE3 to both NE4 and NE6, replies wS=1 to NE4, and sends APS-P code of SF-W to NE3; NE6 selects eastbound standby traffic from NE4 and forwards it;

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

[0026] Furthermore, in the two-point failure scenario of DNI and the eastbound domain, NE2 and NE3 failed, and NE2 and NE4 failed;

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

[0028] Protection switching method for westbound traffic: NE1 receives the APS-W code of the switching notification indicating the remote master failure from NE2 and the APS-P code of the DNI failure from NE3, triggering protection switching and selecting the westbound master traffic from NE3 for forwarding.

[0029] Furthermore, in the two-point fault scenario of DNI and westbound domain, faults occur between NE1 and NE2, and between NE2 and NE3; protection switching of NE1, NE4, and NE5 occurs;

[0030] Protection switching method for eastbound traffic: NE1 switches to NE3, and sends APS-W code indicating active failure to NE2 and APS-P code indicating active failure to NE3 respectively; NE2 sends APS-W code indicating remote active failure to NE4, and sends DNI code with wF=1 to NE3, and sends APS-W code indicating DNI failure to NE1; NE3 sends APS-P code indicating DNI failure to NE1 and NE5 respectively; NE4 receives APS-W code of remote active failure switching notification from NE2, triggers protection switching, selects eastbound standby traffic from NE5 and sends it to NE6, and sends DNI code with wF=1 to NE5; NE5 receives DNI code with wF=1 from NE4, triggers protection switching, and replies DNI code with wS=1 to NE4; NE6 selects eastbound standby traffic from NE4 for forwarding;

[0031] Protection switching method for westbound traffic: NE6 sends traffic in both directions. After NE4 receives the APS-W code indicating a remote primary path failure, it first switches to sending westbound primary traffic in both directions to NE2 and NE5, and sends 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 the DNI code with wS=1 to NE4, and sends the APS-P code with SF-W to NE3. NE2 sends the APS-W code indicating a DNI failure to NE1, sends wF=1 to NE3, and sends the APS-W code to NE4. NE3 sends the westbound primary traffic to NE1, and sends the APS-P code indicating a DNI failure to NE1 and NE5 respectively. NE1 switches to selecting the westbound primary traffic from NE3 and continues to forward it westward.

[0032] Furthermore, the node power failure scenario: NE2 node power failure; NE1, NE4 and NE5 protection switching;

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

[0034] Westward traffic protection switching: NE6 sends traffic to NE4 and NE5 in both directions. NE4 first switches to sending westward main traffic to NE2 and NE5 in both directions, and sends a DNI code of wF=1 to NE5. After NE5 receives the DNI code of wF=1 from NE4, it switches to sending the westward main traffic from NE4 to NE3, replies with the DNI code of wS=1 to NE4, and sends the APS-P code of SF-W to NE3. NE3's switching status remains unchanged, and the westward main traffic is sent to NE1, and the APS-P code indicating a DNI failure is sent to NE1 and NE5 respectively. NE1 switches to sending the westward main traffic from NE3 to continue forwarding it westward.

[0035] Furthermore, in a three-point failure scenario, failures occur between NE2 and NE3, NE2 and NE4, and NE4 and NE5, and NE1 and NE6 switch;

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

[0037] Protection switching method for eastbound traffic: NE4 sends the APS-W code of remote master failure to NE6, sends the DNI code of master node westbound domain failure to NE5, and sends the APS-W code indicating DNI failure to NE2; NE5 sends the APS-P code indicating DNI failure to NE3 and NE6 respectively; NE6 receives the APS-W code of NE4's remote master failure switching notification and NE5's DNI failure APS-P code, triggers protection switching, and selects the eastbound backup traffic from NE5 for forwarding.

[0038] On the other hand, a small-granular dual-homing protection switching system based on full-path APS is proposed. The system has a primary-standby switching architecture, which includes a westbound domain and / or an eastbound domain. Each domain includes multiple access nodes and multiple groups of dual-homing nodes. Each group of dual-homing nodes includes a dual-homing master node and a dual-homing backup node. An access node is connected to another access node via each dual-homing master node to form a primary working path. An 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 master and backup nodes in the same group.

[0039] Each node located on the main working path is used to send and receive traffic through the main working path; send and receive the main working path automatic protection switching APS-W code between adjacent nodes on the main working path; and when protection switching is required, send protection switching information related to the protection switching reason to the adjacent node, and perform protection switching based on the protection switching information received from the non-fault path, wherein the protection switching information includes: APS-W code, APS-P code and DNI code, wherein the APS-W code includes the dual-node interconnection DNI link status field of the main node;

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

[0041] Each dual-home master node located on the active working path is also used to send and receive DNI codes with the dual-home backup nodes in the same group through the DNI link, wherein the DNI link is also used to send and receive traffic when protection switching is required, and the DNI code includes the following information switching fields: west domain signal failure field, west domain signal degradation field, west domain switching field, east domain signal failure field, east domain signal degradation field and east domain switching field;

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

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

[0044] 1. Simplified and optimized the DNI message format design between dual-homing active and standby nodes, and optimized the naming from intra-domain and inter-domain to west-domain and east-domain, reducing the complexity of messages and improving processing efficiency.

[0045] 2. The APS code, which was originally used only on the backup protection path, is expanded to be used on both the main working path and the backup protection path. At the same time, the content of the APS code is expanded, and a new field representing the DNI link status is added, so that nodes can obtain more information for protection switching more conveniently. Therefore, the notification process of protection switching and the nodes involved can be reduced, the time consumption of protection switching can be reduced, and the protection switching performance can be improved.

[0046] 3. Supports protection switching in three-point fault scenarios, adds new system functions, and improves network survivability.

[0047] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0049] Figure 1 A schematic diagram showing the principle of a small-granular dual-homing protection switching method based on an all-path APS in a normal scenario according to Embodiment 1 of the present invention is shown;

[0050] Figure 2A schematic diagram showing the principle of a small-granularity dual-homing protection switching method based on the full-path APS in a west-bound domain single-point failure scenario according to Embodiment 2 of the present invention is shown;

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

[0052] Figure 4 A schematic diagram showing the principle of a small-granularity 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 showing the principle of a small-granularity dual-homing protection switching method based on the full-path APS in a two-point failure scenario of the DNI and the eastbound domain according to Embodiment 5 of the present invention is shown;

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

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

[0056] Figure 8 A schematic diagram showing the principles of a small-granularity dual-homing protection switching method based on an all-path APS in a three-point fault scenario according to Embodiment 8 of the present invention is shown. DETAILED DESCRIPTION

[0057] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0058] In order to solve the technical problem of poor switching performance in the patent with publication number CN117544485A, the inventor first did the following work:

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

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

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

[0062] (3) DNI code block field design: 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 westbound domain and eastbound domain, which is applicable to both two domains and one domain.

[0063] After a node receives the APS-W code and the APS-P code, the decision rules for protection switching are as follows:

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

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

[0066] (3) Both the primary and backup paths are normal and the APS-W and APS-P codes are inconsistent. Comprehensive decision-making and judgment enable the final protection switching to produce a complete path from the access point to another access point via the primary and backup dual-homing nodes.

[0067] The above-mentioned APS-W code is the name of the APS code when it is used on the main working path, and the APS-W code is the name of the APS code when it is used on the backup working path.

[0068] Table 1 DNI code block field design description

[0069]

[0070] Specifically, Table 1 adds a DNI code block of Type = 0x3 after the APS code block of Type = 0x2 in the existing standard small-granularity service signaling code block. The DNI code block data content includes 4 data areas, which are named DNI_data[B0], DNI_data[B1], DNI_data[B2], and DNI_data[B3] in sequence. DNI_data[B0] stores the westbound domain information, using 3 bits of data, and the other bits are reserved. Bit2 is named as internal domain signal failure (wF), 0 for normal, 1 for signal failure SF (Signal Fail); Bit1 is named as internal domain signal degrade (wD), 0 for normal, 1 for signal degrade SD (Signal Degrade); Bit0 indicates internal domain switching (iS), 0 for no switching, 1 for switching. DNI_data[B1] stores the eastbound domain information, using 3 bits of data. The other bits are reserved. Bit2 is named as the eastbound domain signal failure (External Domain Signal Fail), abbreviated as eF, 0 indicates normal, 1 indicates signal failure SF (Signal Fail); Bit1 is named as the eastbound domain signal degrade (External Domain Signal Degrade), abbreviated as eD, 0 indicates normal, 1 indicates signal degrade SD (Signal Degrade); Bit0 indicates the eastbound domain switching (External Domain Switching), abbreviated as eS, 0 indicates no switching, 1 indicates switching. DNI_data[B2] and DNI_data[B3] are reserved.

[0071] 2. Expand the APS code content

[0072] In the Requested signal field of the G.8331 standard APS code, bit [2] is enabled. 1 indicates a DNI failure, that is, a faulty state of interruption, and 0 indicates that the DNI is normal.

[0073] (1) The dual-homing master node uses the newly started bit to communicate the DNI fault status of the master node through the APS-W code.

[0074] (2) The dual-homing standby node uses the new bit to communicate the standby node's DNI fault status through the APS-P code.

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

[0076] A small-granular dual-homing protection switching method based on full-path APS in an embodiment of the present invention includes the following steps:

[0077] The method is used for a master-slave switchover architecture, which includes a westbound domain and / or an eastbound domain, each domain includes multiple access nodes and multiple groups of dual-home nodes, each group of dual-home nodes includes a dual-home master node and a dual-home backup node; an access node is connected to another access node via each dual-home master node to form a master working path; an access node is connected to another access node via each dual-home backup node to form a backup protection path; a DNI link is established between the dual-home master and backup nodes in the same group;

[0078] The method comprises the following steps:

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

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

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

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

[0083] The dual-homing active and standby 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 domain signal failure field, west domain signal degradation field, west domain switching field, east domain signal failure field, east domain signal degradation field, and east domain switching field.

[0084] When any node needs protection switching, it sends protection switching information related to the protection switching reason to the adjacent node, and performs protection switching based on the protection switching information received from the non-fault path, wherein the protection switching information includes: APS-W code, APS-P code and DNI code.

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

[0086] In this embodiment, NE1 is defined as an access point, NE2 represents a dual-homing master node, NE3 represents a dual-homing backup node in the same group as NE2, NE1's adjacent nodes are NE2 and NE3, and NE1 to NE3 are westbound domains; NE4 is defined as a dual-homing master node, NE5 represents a dual-homing backup node in the same group as NE4, NE6 is another access point, and NE6's adjacent nodes are NE4 and NE5;

[0087] FGU1+1 dual-transmitter and selective receiver with same-source but different-destination protection is deployed on NE1 and NE6 (based on the G.8331 standard). For example, the source is NE1, the main working path is to NE2, and the backup protection path is to NE3.

[0088] FGU dual-homing active-standby protection is deployed on NE2 and NE3, and NE4 and NE5 respectively.

[0089] Define the traffic sent from NE1 to NE6 through the primary path as eastbound primary traffic, which is represented by a solid line with an arrow pointing eastward. Each segment of traffic in the path is also called eastbound primary traffic.

[0090] Traffic sent from NE6 to NE1 through the primary path is westbound primary traffic, which is represented by a solid line with an arrow pointing westward. Each segment of traffic in the path is also called westbound primary traffic.

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

[0092] The traffic sent to NE1 through the backup protection path NE6 is westbound backup traffic, which is represented by a dotted line with an arrow pointing westward. Each segment of traffic in the path is also called westbound primary traffic.

[0093] For the convenience of description, the engineering networking diagram is simplified in each embodiment, and only three network devices are listed in each domain. The deployment of four or more devices in one domain is also within the protection scope of the present invention.

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

[0095] Example 1

[0096] like Figure 1 The following figure shows a scenario where the paths, nodes, and DNI are all normal:

[0097] (1) The business trends are as follows:

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

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

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

[0101] Enable sending and receiving APS-W codes between NE1-NE2-NE4-NE6;

[0102] Enable sending and receiving APS-P codes between NE1-NE3-NE5-NE6;

[0103] The sending and receiving of DNI codes are enabled between NE2 and NE3 and between NE4 and NE5.

[0104] (3) Full path APS code content description:

[0105] Here, the APS codes received and sent by NE2 and NE3 are used as an example for explanation. The DNI sending and receiving of NE2 is equivalent to the receiving and sending of NE3, so the DNI receiving and sending are only displayed on NE2; the reception of NE1 as the main path is equivalent to the APS-W sending of NE2, and the reception of NE1 as the backup path is equivalent to the APS-P sending of NE3; the APS-W code received by NE4 from the west is equivalent to the APS-W sending of NE2 to the east, and the APS-P code received by NE5 from the west is equivalent to the APS-W sending of NE3 to the east.

[0106] The following table 2 and table 3 respectively illustrate the contents of APS codes received and sent in three directions by NE2 and NE3 in this scenario:

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

[0108]

[0109]

[0110] Table 3 Codes of three directions of NE3 standby node in normal scenario

[0111]

[0112] The difference between this normal scenario and the patent with publication number CN117544485A is that the DNI link does not initially transmit business traffic, and both the dual-home master and backup nodes directly forward it, that is, the traffic coming from the west is directly forwarded and flows out from the east; the traffic coming from the east is directly forwarded and flows out from the west; it is not sent in the DNI direction.

[0113] Example 2

[0114] Single point failure scenario in the west domain: Figure 2 As shown, in this embodiment, the path between NE1 and NE2 fails. NE1, NE2, and NE3 perform protection switching.

[0115] Protection switching of eastbound traffic: NE1 sends traffic in both directions; NE2 (due to a westbound domain failure) first switches to sending eastbound standby traffic (dashed line traffic) to NE4, and sends a DNI code with wF=1 to NE3, and an APS-W code with SF-W to NE1; after receiving wF=1, NE3 switches to sending the eastbound standby traffic (dashed line traffic) in both directions to NE2 and NE5; NE4, NE5, and NE6 do not switch;

[0116] Protection switching of westbound traffic: NE6 sends traffic in both directions; NE5 sends traffic in a single direction to NE3; NE4 sends traffic in a single direction to NE2; NE2 (due to a westbound domain failure) switches to sending the westbound main traffic (solid line traffic) from NE4 in both directions to NE1 (unreachable) and NE3; NE3 receives wF=1 from NE2, switches to selecting the westbound main traffic (solid line traffic) from NE2 and forwarding it to NE1, and replies the DNI code of wS=1 to NE2, and sends the APS-P code of SF-W to NE1; NE1 (due to a main failure) sends the APS-W code and APS-P code of SF-W to NE2 and NE3, switches to selecting the westbound main traffic (solid line traffic) and continues to forward it westward.

[0117] In the single-point failure scenario in the westbound domain, the APS codes received and sent by the NE2 master node in three directions are shown in Table 4, and the APS codes received and sent by the NE3 standby node in three directions are shown in Table 5:

[0118] Table 4 Codes of the NE2 master node in the westbound domain single point failure scenario

[0119]

[0120] Table 5 Codes of the standby node NE3 in the westbound domain single point failure scenario

[0121]

[0122] The difference between this westbound single-point failure scenario and the patent with publication number CN117544485A is that (1) since NE2 detects a fault in the westbound direction, the APS-W code received in the westbound direction is ignored; (2) upon detecting a westbound fault of NE2, NE2 immediately performs protection switching, instead of the solution of CN117544485A: NE2 first sends DNI information with iF=1 to NE3, and then performs switching after NE2 receives DNI information with iS=1 from NE3. Therefore, the protection switching performance is improved in this scenario.

[0123] Example 3

[0124] Single point failure scenario in the east domain: Figure 3 As shown, in this embodiment, the path between NE2 and NE4 fails. NE2, NE3, NE4 and NE5 perform protection switching.

[0125] Eastbound traffic protection switching: NE1 sends traffic in both directions; NE2 (due to eastbound domain failure) first switches to sending eastbound main traffic (solid line traffic) in both directions to NE3 and NE4 (unreachable), and sends a DNI code of eF=1 to NE3, and sends an APS-W code of SF-W to NE4; NE3 receives eF=1 from NE2, switches to sending the eastbound main traffic (solid line traffic) from NE2 to NE5, and replies with a DNI code of eS=1 to NE2; NE4 has the same switching logic as NE2, and due to a failure, selects the eastbound main traffic (solid line traffic) from NE5 to be sent to NE6, and sends a DNI code of wF=1 to NE5, and sends an APS-W code of SF-W to NE2; NE5 has the same switching logic as NE3, and sends the eastbound main traffic (solid line traffic) from NE3 in both directions to NE4 and NE6, and NE6 still selects the eastbound main traffic (solid line traffic) from NE4 to forward.

[0126] Westward traffic protection switching: NE6 sends traffic in both directions; NE4 (due to a westward failure) first switches to sending the westward main traffic (solid line traffic) in both directions to NE2 (unreachable) and NE5, and sends the DNI code of wF=1 to NE5, and sends the APS-W code of SF-W to NE2; after NE5 receives wF=1 from NE4, it switches to sending the westward main traffic (solid line traffic) from NE4 to NE3; and replies to NE4 with the DNI code of wS=1, and sends to NE3 SF-W's APS-P code; after NE3 receives eF=1 from NE2, it sends the westbound main traffic (solid line traffic) from NE5 to both NE1 and NE2, replies with the DNI code of eS=1 to NE2, and sends SF-W's APS-P code to NE5; NE2 (due to an eastbound failure) first switches to send the westbound main traffic (solid line traffic) from NE3 to NE1 alone, and NE1 still selects the westbound main traffic (solid line traffic) from NE2 for forwarding.

[0127] In the single-point failure scenario of the eastbound domain, the APS codes received and sent by the NE2 master node in three directions are shown in Table 6, and the APS codes received and sent by the NE3 standby node in three directions are shown in Table 7:

[0128] The difference between this eastbound domain single-point failure scenario and the patent with publication number CN117544485A is that: (1) because NE2 detects a fault in the eastbound direction, the APS-W code received in the eastbound direction is ignored; (2) when the NE2 eastbound fault is detected, NE2 immediately performs protection switching, instead of the solution of CN117544485A: NE2 first sends DNI information with eF=1 to NE3, and then performs switching after NE2 receives DNI information with eS=1 from NE3. Therefore, the protection switching performance is improved in this eastbound domain single-point failure scenario.

[0129] Table 6 Codes of the NE2 master node in the scenario of a single point failure in the east domain

[0130]

[0131] Table 7 Codes of the NE3 standby node in the scenario of a single point failure in the east domain

[0132]

[0133] Example 4

[0134] Two-point failure scenario in the west-bound domain and the east-bound domain: Figure 4 As shown, in this embodiment, NE1 and NE2 fail, NE2 and NE4 fail, and NE1, NE2, NE3, NE4 and NE5 perform protection switching.

[0135] Eastbound traffic protection switching: NE1 sends traffic in both directions; NE2 (due to two failures) sends DNI codes of wF=1 and eF=1 to NE3, and sends APS-W code of SF-W to NE1 and NE4; NE3 switches to select the eastbound standby traffic (dashed line traffic) from NE1 and sends it to NE5, and replies DNI codes of wS=1 and eS=1 to NE2, and sends APS-P code of SF-W to NE1 and NE5; NE4 (due to a westbound domain failure) switches to select the dotted line traffic from NE5 and sends it to NE6 alone, and sends wF=1 to NE5, and sends APS-W code of SF-W to NE4; NE5 receives wF=1 from NE4, and sends the eastbound standby traffic (dashed line traffic) from NE3 in both directions to NE4 and NE6, replies wS=1 to NE4, and sends APS-P code of SF-W to NE3; NE6 still selects the eastbound standby traffic (dashed line traffic) from NE4 for forwarding.

[0136] Westward traffic protection switching: NE6 sends traffic in both directions, and NE4 (due to a westward failure) switches to sending the westward main traffic (solid line traffic) in both directions to NE2 (unreachable) and NE5, and sends the DNI code of wF=1 to NE5, and sends the APS-W code of SF-W to NE2; after receiving wF=1 from NE4, NE5 switches to select the westward main traffic (solid line traffic) from NE4 and sends it to NE3, and replies with the DNI code of wS=1 to NE4, and sends the APS-P code of SF-W to NE3; NE3 receives the DNI code of wF=1 and eF=1 from NE2, and sends the westward main traffic (solid line traffic) from NE5 in both directions to NE1 and NE2, and sends the APS-P code of SF-W to NE1 and NE5 respectively; NE1 (due to a main failure) switches to receive the westward main traffic (solid line traffic) and continues to forward it westward.

[0137] In the two-point failure scenario of the west-bound and east-bound domains, the APS codes received and sent by the NE2 master node in three directions are shown in Table 8, and the APS codes received and sent by the NE3 standby node in three directions are shown in Table 9:

[0138] Table 8 Codes of the NE2 master node in the two-point failure scenario in the west-bound domain and the east-bound domain

[0139]

[0140] Table 9 Codes of the standby node NE3 in the two-point failure scenario in the west-bound domain and the east-bound domain

[0141]

[0142]

[0143] The two-point fault scenario in the west-bound domain and the east-bound domain is different from that in the publication number CN117544485A in that: since faults are detected in both the east and west directions of NE2, the APS-W codes received in the east and west directions are ignored.

[0144] Example 5

[0145] The DNI and eastbound domain have two faults, such as Figure 5 As shown, in this embodiment 5, NE2 and NE3 fail, NE2 and NE4 fail, and NE1, NE4 and NE5 perform protection switching. The workflow in this scenario is:

[0146] The workflow of eastbound traffic: NE1 sends traffic in both directions. NE2 (due to DNI and eastbound failures) does not change its switching status. It sends the APS-W code of the remote master failure to NE1, and sends the DNI code of the master node eastbound domain failure to NE3. It sends the APS-W code of the DNI failure to NE4. NE3 (due to DNI failure) does not change its switching status. It sends the dotted traffic to NE5 and sends the APS-P code indicating the DNI failure to NE1 and NE5 respectively. The switching logic of NE4 is to select the APS-P code from NE5. The dotted line traffic is sent unidirectionally to NE6, and the DNI code of wF=1 is sent to NE5, indicating a westbound domain failure. The APS-W code of SF-W is sent to NE2, indicating a primary path failure. After NE5 receives the DNI code of wF=1 from NE4, it sends the dotted line traffic from NE3 to NE4 and NE6, replies with the DNI code of wS=1 to NE4, indicating that the switch has been made, and sends the APS-P code of SF-W to NE3, indicating a primary path failure. NE6 selects the dotted line traffic from NE4 to forward.

[0147] The workflow of westbound traffic: NE6 sends traffic to both NE4 and NE5. NE4 processes the traffic (due to a failure in the eastbound domain). After NE4 detects the failure in the eastbound domain, it switches to sending solid line traffic to both NE2 (unreachable) and NE5. It sends the DNI code wF=1 to NE5, indicating a failure in the westbound domain, and the APS-W code SF-W to NE2, indicating a failure in the primary path. After NE5 receives the DNI code wF=1 from NE4, it switches to sending the solid line traffic from NE4 to NE3, and sends the traffic back to NE4. The DNI code of wS=1 is repeated, indicating that the switch has been carried out, and the APS-P code of SF-W is sent to NE3, indicating that the main path is faulty; NE2's switching state remains unchanged, and the APS-W code of SF-W indicating the remote main path fault is sent to NE1, and the DNI code (eF=1) of the master node eastward domain fault is sent to NE3, and the APS-W code of SF-W indicating DNI fault is sent to NE4; NE3's switching state remains unchanged, and the solid line traffic is sent to NE1, and the APS-P code indicating DNI fault is sent to NE1 and NE5 respectively. NE1 switches and selects the solid line traffic from NE3 to continue forwarding to the west.

[0148] In the DNI and eastbound domain two-point failure scenario, the APS codes received and sent by the NE2 master node in three directions are shown in Table 10, and the APS codes received and sent by the NE3 standby node in three directions are shown in Table 11:

[0149] Table 10 Codes of the NE2 master node in the scenario of two-point failure in the DNI and east domain

[0150]

[0151] Table 11 Codes of NE3 standby node in the scenario of two-point failure in DNI and east domain

[0152]

[0153] The present DNI and eastbound domain two-point failure scenario is different from the patent with publication number CN117544485A in that the notification process of switching in the CN117544485A patent is: through the process of NE4-NE5-NE3-NE1, the solution of the present invention directly notifies the APS-W code from NE2 to NE1, thereby improving the switching performance.

[0154] Example 6

[0155] DNI and westbound domain two-point failure scenario: Figure 6 As shown, in this embodiment 6, there is a fault between NE1 and NE2, and between NE2 and NE3, and NE1, NE4 and NE5 are protected and switched. The workflow in this scenario is as follows:

[0156] Protection switching of eastbound traffic: NE1 (due to a primary failure), NE1 sends traffic to NE2 and NE3 at the same time, and sends the APS-W code of the primary path failure to NE2 and the APS-P code of the primary path failure to NE3 respectively; NE2's switching state remains unchanged, and it sends the APS-W code of DNI failure to NE1, sends the DNI code of the master node westbound domain failure to NE3 (wF=1), and sends the APS-W code indicating the remote primary path failure to NE4; NE3's switching state remains unchanged, and it sends the APS-P code indicating the DNI failure to NE1 and NE5 respectively. NE4 performs protection switching, selects the dotted line traffic from NE5 to send to NE6, and sends the DNI code of wF=1 to NE5, indicating the westbound domain failure; after NE5 receives the DNI code of wF=1 from NE4, it replies with the DNI code of wS=1 to NE4, indicating that the switching has been performed; NE6 selects the dotted line traffic from NE4 to forward.

[0157] Protection switching of westbound traffic: NE6 sends traffic in both directions. After NE4 receives the APS-W code indicating a remote primary path failure, it first switches to sending real-line traffic in both directions to NE2 (unreachable) and NE5, and sends a DNI code of wF=1 to NE5, indicating a westbound domain failure. After NE5 receives the DNI code of wF=1 from NE4, it switches to sending the real-line traffic from NE4 to NE3, replies with a DNI code of wS=1 to NE4, indicating that the switch has been made, and sends an APS-P code of SF-W to NE3, indicating a primary path failure. NE2's switching state remains unchanged, and it sends an APS-W code of DNI failure to NE1, sends a DNI code of the master node westbound domain failure (wF=1) to NE3, and sends an APS-W code indicating a remote primary path failure to NE4. NE3's switching state remains unchanged, and it sends real-line traffic to NE1, and sends APS-P codes indicating DNI failure to NE1 and NE5, respectively. NE1 switches and selects the solid line traffic from NE3 to continue forwarding westward.

[0158] In the DNI and westbound domain two-point failure scenario, the APS codes received and sent by the NE2 master node in three directions are shown in Table 12, and the APS codes received and sent by the NE3 standby node in three directions are shown in Table 13:

[0159] Table 12 Codes of the NE2 master node in the scenario of two-point failure in the DNI and west domain

[0160]

[0161]

[0162] Table 13 Codes of NE3 standby node in the scenario of two-point failure in DNI and west domain

[0163]

[0164] Compared with the patent with publication number CN117544485A, the notification process of NE4 switching in CN117544485A is: through the process of NE1-NE3-NE5-NE4. The solution of the present invention directly notifies the APS-W code from NE2 to NE4 in this DNI and west domain two-point failure scenario, thereby improving the switching performance.

[0165] Example 7

[0166] Node power failure scenario: Figure 7 As shown, in this embodiment 7, the NE2 node loses power; NE1, NE4 and NE5 perform protection switching. The workflow in this scenario is as follows:

[0167] Eastbound traffic protection switching: NE1 (due to a primary failure) sends traffic to NE2 and NE3 at the same time, and sends the APS-W code of the primary path failure to NE2 and the APS-P code of the primary path failure to NE3 respectively; NE3 (due to a DNI failure) the switching state remains unchanged, and sends the dotted line traffic to NE5, and sends the APS-P code indicating the DNI failure to NE1 and NE5 respectively; NE4 (due to a westbound failure) performs protection switching, selects the dotted line traffic from NE5 to send to NE6, and sends the DNI code of wF=1 to NE5, indicating a westbound domain failure; after NE5 receives the DNI code of wF=1 from NE4, it sends the dotted line traffic from NE3 to both NE4 and NE6, and replies with the DNI code of wS=1 to NE4, indicating that the switching has been performed; NE6 selects the dotted line traffic from NE4 to forward.

[0168] Westward traffic protection switching: NE6 sends traffic to NE4 and NE5 in both directions. NE4 (due to a westward fault) first switches to sending solid line traffic to NE2 (unreachable) and NE5 in both directions, and sends a DNI code of wF=1 to NE5, indicating a westward domain fault. After NE5 receives the DNI code of wF=1 from NE4, it switches to sending the solid line traffic from NE4 to NE3, replies to NE4 with a DNI code of wS=1, indicating that the switch has been made, and sends an APS-P code of SF-W to NE3, indicating a primary path fault. NE3's switching state remains unchanged, and the solid line traffic is sent to NE1, and an APS-P code indicating a DNI fault is sent to NE1 and NE5 respectively. NE1 switches to selecting the solid line traffic from NE3 and continues to forward it westward.

[0169] In the power-off scenario of this node, the NE2 master node cannot send the DNI code to the NE3 standby node because of the power-off. Therefore, the NE3 standby node receives and sends the APS code in two directions. The APS codes received and sent by the NE3 standby node in two directions are shown in Table 14:

[0170] Table 14 Codes of two directions of NE3 standby node in the node power failure scenario

[0171]

[0172] Example 8

[0173] Three-point failure scenario: Figure 8 As shown, in this embodiment 8, NE2 and NE3, NE2 and NE4, NE4 and NE5 are all faulty. In this scenario, NE1 and NE6 are switched, and the working process is as follows:

[0174] Protection switching of westbound traffic: NE2 (due to DNI and eastbound failures), the switching state remains unchanged, and sends the APS-W code of the remote master failure to NE1, and sends the DNI code of the master node eastbound domain failure to NE3, and sends the APS-W code of the DNI failure to NE4; NE3 (due to DNI failure), the switching state remains unchanged, and sends the APS-P code of the DNI failure to NE1 and NE5 respectively. NE1 receives the APS-W code of the remote master failure switching notification of NE2 and the APS-P code of the DNI failure of NE3, triggering the protection switching, and selects the dotted line traffic from NE3 for forwarding.

[0175] Protection switching of eastbound traffic: NE4 (due to DNI and westbound failures), the switching state remains unchanged, and sends the APS-W code of the remote master failure to NE6, and sends the DNI code of the master node westbound domain failure to NE5, and sends the APS-W code of the DNI failure to NE2. NE5 (due to DNI failure), the switching state remains unchanged, and sends the APS-P code of the DNI failure to NE3 and NE6 respectively. NE6 receives the APS-W code of the remote master failure switching notification of NE4 and the APS-P code of the DNI failure of NE5, triggering protection switching, and selects the dotted line traffic from NE5 for forwarding.

[0176] In this three-point fault scenario, the APS codes received and sent in three directions by the NE2 master node and the NE3 standby node are shown in Table 15 and Table 16:

[0177] Table 15 Codes of the NE2 master node in the three-point failure scenario

[0178]

[0179] Table 16 Codes of NE3 standby node in three-point failure scenario

[0180]

[0181] Compared with the patent publication number CN117544485A Figure 6 Fault scenario: further, if NE4 and NE5 fail, NE1 will not be able to switch. At this time, the above patent solution becomes invalid, that is, it cannot support this three-point fault scenario. The solution of the present invention solves the protection switching problem of the three-point fault scenario.

[0182] Based on the same inventive concept as the above method, the present invention also provides a small-granular dual-home protection switching system based on full-path APS, wherein the system is a master-slave switching architecture, which includes a westward domain and / or an eastward domain, each domain includes multiple access nodes and multiple groups of dual-home nodes, each group of dual-home nodes includes a dual-home master node and a dual-home backup node; an access node is connected to another access node via each dual-home master node to form a primary working path; an access node is connected to another access node via each dual-home backup node to form a backup protection path; a DNI link is established between the dual-home master and backup nodes in the same group;

[0183] Each node located on the main working path is used to send and receive traffic through the main working path; send and receive the main working path automatic protection switching APS-W code between adjacent nodes on the main working path; and when protection switching is required, send protection switching information related to the protection switching reason to the adjacent node, and perform protection switching based on the protection switching information received from the non-fault path, wherein the protection switching information includes: APS-W code, APS-P code and DNI code, wherein the APS-W code includes the dual-node interconnection DNI link status field of the main node;

[0184] Each node on the standby working path is configured to send and receive traffic through the standby protection path; send and receive the standby protection path automatic protection switching APS-P code with the adjacent node on the standby working path; and when protection switching is required, send protection switching information related to the protection switching reason to the adjacent node, and perform protection switching based on the protection switching information received from the non-faulty path, wherein the APS-P code includes the DNI link status field of the standby node;

[0185] Each dual-home master node located on the active working path is also used to send and receive DNI codes with the dual-home backup nodes in the same group through the DNI link, wherein the DNI link is also used to send and receive traffic when protection switching is required, and the DNI code includes the following information switching fields: west domain signal failure field, west domain signal degradation field, west domain switching field, east domain signal failure field, east domain signal degradation field and east domain switching field;

[0186] Each dual-homing backup node located on the active working path is also used to send and receive DNI codes with the dual-homing active node in the same group through the DNI link.

[0187] The above description is only a preferred embodiment of the present invention and an explanation of the technical principles used. Those skilled in the art should understand that the disclosure scope involved in the present invention is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above disclosed concept. For example, the above features are replaced with the technical features with similar functions disclosed in the present invention (but not limited to) by each other.

Claims

1. A small-granular dual-homing protection switching method based on full-path APS, characterized in that: The method is used for a master-slave switchover architecture, which includes a westbound domain and / or an eastbound domain, each domain includes multiple access nodes and multiple groups of dual-home nodes, each group of dual-home nodes includes a dual-home master node and a dual-home backup node; an access node is connected to another access node via each dual-home master node to form a master working path; an access node is connected to another access node via each dual-home backup node to form a backup protection path; a DNI link is established between the dual-home master and backup nodes in the same group; The method comprises the following steps: Each node on the primary working path sends and receives traffic through the primary working path; Each node on the backup working path sends and receives traffic through the backup protection path; The APS-W code for automatic protection switching of the primary working path is sent and received between two adjacent nodes on the primary working path; wherein the APS-W code includes a dual-node interconnection DNI link status field of the primary node; The APS-P code of automatic protection switching of the standby protection path is sent and received between two adjacent nodes on the standby working path; wherein the APS-P code includes the DNI link status field of the standby node; The dual-homing active and standby 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 domain signal failure field, west domain signal degradation field, west domain switching field, east domain signal failure field, east domain signal degradation field, and east domain switching field. When any node needs protection switching, it sends protection switching information related to the protection switching reason to the adjacent node, and performs protection switching based on the protection switching information received from the non-fault path, wherein 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 west domain signal fault field is defined as wF, 0 indicates normal, 1 indicates signal fault; the west domain signal degradation field is defined as wD, 0 indicates normal, 1 indicates signal degradation; the west domain switching field is defined as wS, 0 indicates no switching, 1 indicates switching; the east domain signal fault is defined as eF, 0 indicates normal, 1 indicates signal fault; the east domain signal degradation field is defined as eD, 0 indicates normal, 1 indicates signal degradation; the east domain switching field is defined as eS, 0 indicates no switching, 1 indicates switching; the DNI link status field is a newly added field in the request signal Requestedsignal field of the standard APS code, 0 indicates DNI normal, 1 indicates DNI fault; Define NE1 as an access point, NE2 as a dual-homing master node, NE3 as a dual-homing backup node in the same group as NE2, NE1's adjacent nodes as NE2 and NE3, and NE1 to NE3 as the westbound domain; define NE4 as a dual-homing master node, NE5 as a dual-homing backup node in the same group as NE4, NE6 as another access point, and NE6's adjacent nodes as NE4 and NE5; define the traffic sent from NE1 to NE6 through the primary working path as eastbound primary traffic, and the traffic sent from NE6 to NE1 as westbound primary traffic; The traffic sent from NE1 to NE6 through the backup protection path is eastbound backup traffic, and the traffic sent from NE6 to NE1 is westbound backup traffic.

3. The method according to claim 2, characterized in that In the single-point path failure scenario in the west 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 sending eastbound backup traffic 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 NE3 receives wF=1, it switches to sending eastbound backup traffic to both NE2 and NE5; Westbound traffic: NE2 switches to sending the westbound main traffic from NE4 to both NE1 and NE3; NE3 receives wF=1 from NE2, switches to forwarding the westbound main traffic from NE2 to NE1, replies with the DNI code of wS=1 to NE3, and sends the APS-P code indicating the main fault SF-W to NE1; NE1 sends the APS-W code and APS-P code indicating the main fault SF-W to NE2 and NE3, switches to receiving the westbound main traffic and continues to forward it to the west.

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

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

6. The method according to claim 2, characterized in that In the two-point failure scenario of DNI and the 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 master failure to NE1, sends a DNI code with eF=1 to NE3, and sends an APS-W code indicating a DNI failure to NE4; NE3 sends an APS-P code indicating a DNI failure to NE1 and NE5 respectively; Protection switching method for westbound traffic: NE1 receives the APS-W code of the switching notification indicating the remote master failure from NE2 and the APS-P code of the DNI failure from NE3, triggering protection switching and selecting the westbound master traffic from NE3 for forwarding.

7. The method according to claim 2, characterized in that In the DNI and westbound domain two-point fault scenario, faults occur 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, and sends APS-W code indicating active failure to NE2 and APS-P code indicating active failure to NE3 respectively; NE2 sends APS-W code indicating remote active failure to NE4, and sends DNI code with wF=1 to NE3, and sends APS-W code indicating DNI failure to NE1; NE3 sends APS-P code indicating DNI failure to NE1 and NE5 respectively; NE4 receives APS-W code of remote active failure switching notification from NE2, triggers protection switching, selects eastbound standby traffic from NE5 and sends it to NE6, and sends DNI code with wF=1 to NE5; NE5 receives DNI code with wF=1 from NE4, triggers protection switching, and replies DNI code with wS=1 to NE4; NE6 selects eastbound standby traffic from NE4 for forwarding; Protection switching method for westbound traffic: NE6 sends traffic in both directions. After NE4 receives the APS-W code indicating the failure of the remote primary path, it first switches to sending westbound primary traffic in both directions to NE2 and NE5, and sends the DNI code of wF=1 to NE5. After NE5 receives the DNI code of wF=1 from NE4, it switches to sending the westbound primary traffic from NE4 to NE3, replies the DNI code of wS=1 to NE4, and sends the APS-P code of SF-W to NE3. NE2 sends the APS-W code indicating DNI failure to NE1, sends wF=1 to NE3, and sends the APS-W code to NE4. NE3 sends the westbound active traffic to NE1, and sends the APS-P code indicating DNI failure to NE1 and NE5 respectively. NE1 switches and selects the westbound active traffic from NE3 to continue forwarding it westward.

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

9. The method according to claim 2, characterized in that: In the three-point fault scenario, NE2 and NE3, NE2 and NE4, and NE4 and NE5 all fail, and NE1 and NE6 switch; Protection switching method for westbound traffic: NE2 sends the APS-W code of remote master failure to NE1, sends the DNI code of master node eastbound domain failure to NE3, and sends the APS-W code of DNI failure to NE4; NE3 sends the APS-P code of DNI failure to NE1 and NE5 respectively; NE1 receives the APS-W code of NE2's remote active fault switching notification and the APS-P code of NE3's DNI fault, triggering protection switching and selecting the westbound backup traffic from NE3 for forwarding; Protection switching method for eastbound traffic: NE4 sends the APS-W code of remote master failure to NE6, sends the DNI code of master node westbound domain failure to NE5, and sends the APS-W code indicating DNI failure to NE2; NE5 sends the APS-P code indicating DNI failure to NE3 and NE6 respectively; NE6 receives the APS-W code of NE4's remote master failure switching notification and NE5's DNI failure APS-P code, triggers protection switching, and selects the eastbound backup traffic from NE5 for forwarding.

10. A small-granular dual-homing protection switching system based on full-path APS, characterized in that: The system has a primary-standby switching architecture, which includes a westbound domain and / or an eastbound domain, each domain includes multiple access nodes and multiple groups of dual-home nodes, each group of dual-home nodes includes a dual-home master node and a dual-home backup node; an access node is connected to another access node via each dual-home master node to form a primary working path; an access node is connected to another access node via each dual-home backup node to form a backup protection path; a DNI link is established between the dual-home master 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; Send and receive the APS-W code for automatic protection switching of the main working path between adjacent nodes on the main working path; When protection switching is required, protection switching information related to the protection switching reason is sent to the adjacent node, and protection switching is performed based on the protection switching information received from the non-fault path, wherein the protection switching information includes: APS-W code, APS-P code and DNI code, wherein the APS-W code includes a dual-node interconnection DNI link status field of the master node; Each node on the standby working path is configured to send and receive traffic through the standby protection path; send and receive the standby protection path automatic protection switching APS-P code with the adjacent node on the standby working path; and when protection switching is required, send protection switching information related to the protection switching reason to the adjacent node, and perform protection switching based on the protection switching information received from the non-faulty path, wherein the APS-P code includes the DNI link status field of the standby node; Each dual-home master node located on the active working path is also used to send and receive DNI codes with the dual-home backup nodes in the same group through the DNI link, wherein the DNI link is also used to send and receive traffic when protection switching is required, and the DNI code includes the following information switching fields: west domain signal failure field, west domain signal degradation field, west domain switching field, east domain signal failure field, east domain signal degradation field and east domain switching field; Each dual-homing backup node located on the active working path is also used to send and receive DNI codes with the dual-homing active node in the same group through the DNI link.

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