CN102740171B - A kind of EPON loop detecting method and system - Google Patents

Abstract

The present invention relates to a passive optical network loop detection method. The passive optical network adopts a full protection mode. The method includes: the first OLT sends a loop communication message to the active ONU, and the active ONU receives the After the loop communication message, the loop communication message is sent to the standby ONU; after the second OLT receives the loop communication message sent by the standby ONU, the loop communication message is forwarded to the first OLT; After receiving the loop communication message, the first OLT judges that the passive optical network is a loop network. The invention also provides a passive optical network loop detection system. With the present invention, the OLT judges the loop communication with the ONU, and when the main optical fiber or the branch optical fiber is disconnected, the standby OLT notifies the ONU to perform protection switching, which shortens the time for ONU protection switching and enables the ONU and the OLT to recover quickly communication, which improves the service quality of the PON system.

Description

A passive optical network loop detection method and system

technical field

The present invention relates to the communication field, in particular to a passive optical network (Passive Optical Network, PON for short) loop detection method and system.

Background technique

Gigabit-Capable Passive Optical Network (GPON, Gigabit-Capable Passive Optical Network) and Ethernet Passive Optical Network (EPON, Ethernet Passive Optical Network) are two important technical branches in the PON family, similar to other PON technologies, GPON and EPON is also a passive optical access technology using a point-to-multipoint topology.

As shown in Figure 1, it is a topological structure diagram of a PON system. PON consists of an optical line terminal (OLT, Optical Line Terminal) on the office side, an optical network unit (ONU, Optical Network Unit) Distribution Network), usually using a point-to-multipoint network structure. ODN consists of passive optical components such as single-mode fiber, optical splitter, and optical connector. ODN provides an optical transmission medium for the physical connection between OLT and ONU.

In the PON system, the data transmission in the downlink direction (from the OLT to the ONU) adopts the broadcast method, and each ONU receives all frames separately, and then according to the ONU identification (ONU-ID), GPON encapsulation mode port identification (GEM-Port ID, GPON Encapsulation Mode-Port Identity), and allocation identification (Alloc-ID, Allocation-Identity), medium access control address (MAC ID, Medium Access Control ID) or logical link identification (LLID, Logical Link Identity) to obtain their own frame. For data transmission in the upstream direction (from ONU to OLT), since each ONU needs to share the transmission medium, each ONU should transmit upstream data in the time slot assigned to it by the OLT. The distance between each ONU and the OLT is different. In order to prevent the uplink data sent by each ONU from reaching the OLT at the same time, the OLT needs to measure the distance of the ONUs in the registration and activation phase to achieve synchronization of uplink transmission.

In the deployment and application of passive optical networks, some users need higher security. It is hoped that operators can provide a guarantee mechanism to ensure that their service channels are not interrupted, or the secondary requirement is to be able to Quick recovery afterwards. This puts forward requirements for protection paths and fast switching paths for passive optical networks carrying user services.

Fig. 2(a) is a first topological structure diagram of a passive optical network in a full protection mode, and Fig. 2(b) is a second topological structure diagram of a passive optical network in a full protection mode. As shown in Figure 2(a) and (b), OLT1 and OLT2 are respectively connected to two 1:N ODNs, each ODN is connected to each ONU through optical fiber in the downlink direction, and each ONU has two ONUs, respectively The active ONU and the standby ONU, OLT1 is connected to each active ONU through ODN1, and OLT2 is connected to each standby ONU through ODN2; OLT1 and OLT2 can be two OLTs connected through a network management node, as shown in Figure 2a; it can also be The two PON ports of the OLT are shown in Figure 2b. In the initial state, OLT1 communicates with all active ONUs. When OLT1 fails or the optical fiber between OLT1 and optical splitter 1 is interrupted, OLT2 communicates with all standby ONUs. If the OLT under optical splitter 1 If a branch fiber is interrupted, or a master ONU fails, the OLT2 will communicate with the interrupted branch fiber or the backup ONU corresponding to the faulty ONU. The full protection of the OLT, ONU and each section of optical fiber in the PON system is realized through the above method. In the above-mentioned full protection mode, when the optical fiber between OLT1 and optical splitter 1 is interrupted, or a branch optical fiber under optical splitter 1 is interrupted, each active ONU detects that the downlink signal is interrupted, and then performs protection switching to switch itself The upstream service of the backup ONU is switched to the standby ONU, and the service communication is carried out between the standby ONU and OLT2. During the above protection switching process, the active ONU detects a line failure and performs protection switching. The switching process takes a long time and cannot meet the time-sensitive service interruption. Due to the need for quick recovery, the prior art does not provide a method for the OLT to determine whether the loop between the OLT and the ONU can communicate.

Contents of the invention

The technical problem to be solved by the present invention is to provide a passive optical network loop detection method. By using the method, the communication between the OLT and the ONU can be quickly restored after the passive optical network fails in the full protection mode. The invention also provides a passive optical network loop detection system.

In order to solve the above problems, the present invention provides a method for detecting loops in a passive optical network, the passive optical network adopts a full protection mode, and the method includes:

The first OLT sends a loop communication message to the active ONU, and after the active ONU receives the loop communication message, it sends the loop communication message to the standby ONU;

After receiving the loop communication message sent by the standby ONU, the second OLT forwards the loop communication message to the first OLT;

After receiving the loop communication message, the first OLT judges that the passive optical network is a loop network.

In the above method, wherein the first OLT determines that the passive optical network is a loop network, specifically,

The first OLT determines that the loop communication message is consistent with the loop communication message sent by it, and then determines that the passive network is a loop network.

The above method, wherein, after receiving the loop communication message, the active ONU, standby ONU, and second OLT add their identity information to the loop communication message and send it.

In the above method, wherein the first OLT determines that the passive optical network is a loop network, specifically,

The first OLT judges that the passive network is a loop network according to the identity information of all or some nodes on the loop in the loop communication message.

In the above method, after the second OLT receives the loop communication message sent by the standby ONU, it forwards the loop communication message to the first OLT through a network management node.

The above method, wherein, the loop communication message is a PLOAM message;

The above method, wherein, the loop communication message includes ONU ID, message structure type and identity information.

The above-mentioned method, wherein, the method also includes,

If the first OLT detects that the trunk optical fiber or the branch optical fiber fails, it sends an instruction to the second OLT, ordering the second OLT to notify all or part of the ONUs to perform active/standby protection switching.

The above method, wherein,

The main ONU and the standby ONU are two logical ONUs located inside the same ONU, or belong to two PON ports of the same ONU, and the two logical ONUs or the two PON ports of the same ONU have their own optical modules respectively and media access control chip, and managed by a common CPU.

The present invention also provides a passive optical network loop detection system, which includes:

The first OLT is configured to send a loop communication message to the active ONU, and after receiving the loop communication message, determine that the passive optical network is a loop network;

The active ONU is used to send the loop communication message to the standby ONU after receiving the loop communication message;

The backup ONU is used to send the loop communication message to the second OLT after receiving the loop communication message;

The second OLT is configured to forward the loop communication message to the first OLT after receiving the loop communication message sent by the backup ONU.

In the above system, wherein the first OLT is used to determine that the passive optical network is a loop network, specifically,

The first OLT is used to determine that the loop communication message is consistent with the loop communication message sent by it, and then determine that the passive network is a loop network.

In the above system, after receiving the loop communication message, the active ONU, standby ONU, and second OLT add their identity information to the loop communication message and send it.

In the above system, wherein the first OLT is used to determine that the passive optical network is a loop network, specifically,

The first OLT is configured to judge that the passive network is a loop network according to the identity information of all or some nodes on the loop in the loop communication message.

In the above system, wherein the first OLT is further configured to send an instruction to the second OLT to instruct all or part of the ONUs to perform active-standby protection switching when detecting a failure of the main optical fiber or the branch optical fiber.

With the method and system of the present invention, the OLT judges the loop communication with the ONU, and when the trunk optical fiber or branch optical fiber is disconnected, the standby OLT notifies the ONU to perform protection switching, which shortens the time for ONU protection switching and protects the PON The timely transmission of time-sensitive services in the system enables the ONU and OLT to quickly resume communication and improves the service quality of the PON system.

Description of drawings

The accompanying drawings described here are used to provide a further understanding of the present invention, and constitute a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention, and do not constitute improper limitations to the present invention. In the attached picture:

Fig. 1 is a topological structure diagram of a PON system;

Fig. 2 (a) is the first topological structure diagram of the passive optical network of full protection mode;

Fig. 2 (b) is the second topological structure diagram of the full protection mode passive optical network;

Fig. 3 is a flowchart of Embodiment 1 of the present invention;

Fig. 4 is a flow chart of Embodiment 2 of the present invention;

Fig. 5 is a structural diagram of a passive optical network loop detection system.

Detailed ways

In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer and clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

Embodiment one:

In Fig. 2 (a), (b), OLT1 is connected with all active ONUs through optical splitter 1. OLT1 and the main ONU are based on GPON or the next-generation PON based on GPON technology to perform registration activation of ONU and transmission of service data between OLT and ONU. As shown in Figure 3, it is a flow chart of the embodiment of the present invention, as shown in Figure 3, OLT1 adopts the following steps to judge whether the loop formed by OLT1, active ONU, standby ONU and OLT2 can communicate:

Step S301, OLT1 sends the ring communication Round_Trip_Correspondence message to the active ONU, the message adopts the PLOAM (Physical Layer Operations, Administration and Maintenance, physical layer operation, management and maintenance) mechanism, and PLOAM is suitable for fast and timely management between the OLT and the ONU Maintenance information interaction and processing. The format of the loop communication message is shown in Table 1:

Table 1 Structure of the Round_Trip_Correspondence message

As shown in Table 1, the first byte of the Round_Trip_Correspondence message is the value of the ONU-ID, indicating that the message is sent to an ONU whose ONU-ID value is ONU-ID1, or that the message is an ONU whose ONU-ID value is ONU-ID1 Sent by the ONU; the content of the second byte indicates that the type of the PLOAM message is the structure information type of the Round_Trip_Correspondence message; the content of the third to twelfth bytes is reserved, or the node that receives the message fills in its own The identity information value (does not cover the identity information filled in by other nodes), or the node that receives the message fills in its own identity information value (covers the identity information filled in by other nodes);

Step S302, after receiving the loop communication Round_Trip_Correspondence message sent by OLT1, the active ONU forwards the Round_Trip_Correspondence message directly to the standby ONU;

Step S303, after receiving the Round_Trip_Correspondence message sent by the active ONU, the standby ONU forwards the Round_Trip_Correspondence message directly to OLT2;

Step S304, OLT2 forwards the Round_Trip_Correspondence message directly to OLT1 after receiving the Round_Trip_Correspondence message sent by the standby ONU;

Step S305, after OLT1 receives the Round_Trip_Correspondence message sent by OLT2, if the Round_Trip_Correspondence message is the same as the Round_Trip_Correspondence message sent by itself, then OLT1 judges that the ring formed by OLT1, active ONU, standby ONU and OLT2 is communicable.

In this embodiment, OLT1 judges that the loop formed by OLT1, active ONU, standby ONU, and OLT2 is communicable. In other embodiments, OLT1 can use the same method to determine the active OLT, active ONU, standby ONU, standby OLT, and network management node can finally communicate with the main OLT loop, then when OLT1 detects that the optical fiber between itself and optical splitter 1 is disconnected, if OLT1 judges that OLT1, main ONU, and standby ONU , OLT2, and the network management node cannot communicate, then OLT1 instructs OLT2 to notify all ONUs to perform protection switching through the network management node; OLT1 judges that the ring composed of OLT1, active ONU, standby ONU, OLT2 and network management node cannot communicate, then OLT1 instructs OLT2 through the network management node to notify all or ONUs on the branch fiber that has failed to perform protection switching.

In this embodiment, the delivery sequence of the Round_Trip_Correspondence message sent by OLT1 is OLT1, active ONU, backup ONU, OLT2 and finally OLT1. In other embodiments, the delivery order of the Round_Trip_Correspondence message sent by OLT1 can also be active OLT, The standby OLT, standby ONU, and active ONU finally reach the active OLT; when the ring is composed of the active OLT, the active ONU, the standby ONU, the standby OLT, and the network management node, the delivery order of the Round_Trip_Correspondence message sent by OLT1 is the active one. OLT, active ONU, standby ONU, standby OLT, network management node finally to the active OLT; the delivery order of the Round_Trip_Correspondence message sent by OLT1 can also be the active OLT, network management node, standby OLT, standby ONU, active ONU to the active Use OLT.

The standby ONU and the active ONU described in this embodiment are two logical ONUs located inside the same ONU, or two PON ports belonging to the same ONU, and the two logical ONUs or the two PON ports of the same ONU Each has its own optical module and medium access control chip, and is managed by a common CPU.

This embodiment is applicable to GPON systems, EPON systems, and next-generation PON systems based on GPON technology or EPON technology, such as XG PON systems and 10G EPON systems.

Embodiment two:

In Fig. 2 (a), (b), OLT1 is connected with all active ONUs through optical splitter 1. OLT1 and the main ONU are based on GPON or the next-generation PON based on GPON technology to perform registration activation of ONU and transmission of service data between OLT and ONU. As shown in Figure 4, OLT1 uses the following steps to determine whether the ring composed of OLT1, active ONU, standby ONU, and OLT2 can communicate:

Step S401, OLT1 sends a loop communication Round_Trip_Correspondence message to the active ONU, using the PLOAM mechanism, and the format of the loop communication message is as shown in Table 1:

Table 2 Structure of the Round_Trip_Correspondence message

As shown in Table 2, the first byte of the Round_Trip_Correspondence message is the value of the ONU-ID, indicating that the message is sent to an ONU whose ONU-ID value is ONU-ID1, or that the message is an ONU-ID value of ONU- Sent by the ONU of ID1; the content of the second byte indicates that the type of the PLOAM message is the structure information type of the Round_Trip_Correspondence message; the content of the third to twelfth bytes is reserved, or filled in by the node receiving the message Its own identity information value (does not cover the identity information filled in by other nodes), or the node that receives the message fills in its own identity information value (covers the identity information filled in by other nodes).

Step S402, after the main ONU receives the Round_Trip_Correspondence message sent by OLT1, its ONU-ID value (or its own logical link identification LLID value) is written into the first non-zero Data field of the Round_Trip_Correspondence message, and then the The Round_Trip_Correspondence message is directly forwarded to the standby ONU;

Step S403, after the standby ONU receives the Round_Trip_Correspondence message sent by the active ONU, write its ONU-ID value (or its own logical link identification LLID value) into the first non-zero Data field of the Round_Trip_Correspondence message, and then The Round_Trip_Correspondence message is directly forwarded to OLT2;

Step S404, after OLT2 receives the Round_Trip_Correspondence message that standby ONU sends, writes own identity information value (such as PON identification value) to the first non-zero Data domain of Round_Trip_Correspondence message, then directly forwards described Round_Trip_Correspondence message to OLT1;

Step S405, after OLT1 receives the Round_Trip_Correspondence message sent by OLT2, it judges that the ring composed of OLT1, active ONU, standby ONU and OLT2 is communicable according to the identity information values filled in by all nodes or department nodes in the Round_Trip_Correspondence message .

In this embodiment, after each node receives the Round_Trip_Correspondence message sent by the previous node, it writes its identity information value into the first non-zero Data field of the Round_Trip_Correspondence message, and then sends it to the next node. In the embodiment of , it is also possible to use each node to write its own identity information value into the Data field of the Round_Trip_Correspondence message after receiving the Round_Trip_Correspondence message sent by the previous node, that is, to cover the identity information value written by the previous node, and then send To the next node, after OLT1 receives the Round_Trip_Correspondence message sent by OLT2, it judges that the loop formed by OLT1, active ONU, standby ONU and OLT2 is communicable according to the identity information value filled in by OLT2 in the Round_Trip_Correspondence message.

In this embodiment, OLT1 judges that the loop formed by OLT1, active ONU, standby ONU, and OLT2 is communicable. In other embodiments, OLT1 can use the same method to determine the active OLT, active ONU, standby ONU, standby OLT, and network management node can finally communicate with the main OLT loop, then when OLT1 detects that the optical fiber between itself and optical splitter 1 is disconnected, if OLT1 judges that OLT1, main ONU, and standby ONU , OLT2, and the network management node cannot communicate, then OLT1 instructs OLT2 to notify all ONUs to perform protection switching through the network management node; when OLT1 detects that some or all of the optical fibers between If the ring composed of OLT1, main ONU, standby ONU, OLT2 and network management node cannot communicate, OLT1 instructs OLT2 through the network management node to notify all or ONUs on the failed branch fiber to perform protection switching.

In this embodiment, the delivery sequence of the Round_Trip_Correspondence message sent by OLT1 is OLT1, active ONU, backup ONU, OLT2 and finally OLT1. In other embodiments, the delivery order of the Round_Trip_Correspondence message sent by OLT1 can also be active OLT, The standby OLT, standby ONU, and active ONU finally reach the active OLT; when the ring is composed of the active OLT, the active ONU, the standby ONU, the standby OLT, and the network management node, the delivery order of the Round_Trip_Correspondence message sent by OLT1 is the active one. OLT, active ONU, standby ONU, standby OLT, network management node finally to the active OLT; the delivery order of the Round_Trip_Correspondence message sent by OLT1 can also be the active OLT, network management node, standby OLT, standby ONU, active ONU to the active Use OLT.

The standby ONU and the active ONU described in this embodiment are two logical ONUs located inside the same ONU, or two PON ports belonging to the same ONU, and the two logical ONUs or the two PON ports of the same ONU Each has its own optical module and medium access control chip, and is managed by a common CPU.

This embodiment is applicable to GPON systems, EPON systems, and next-generation PON systems based on GPON technology or EPON technology, such as XG PON systems and 10G EPON systems.

Embodiment three

As shown in Figure 5, it is a structural diagram of a passive optical network loop detection system, and the system includes,

The first OLT is configured to send a loop communication message to the active ONU, and after receiving the loop communication message, determine that the passive optical network is a loop network;

The active ONU is used to send the loop communication message to the standby ONU after receiving the loop communication message;

The backup ONU is used to send the loop communication message to the second OLT after receiving the loop communication message;

The second OLT is configured to forward the loop communication message to the first OLT after receiving the loop communication message sent by the backup ONU.

The first OLT is used to determine that the passive optical network is a loop network, specifically,

The first OLT is used to determine that the loop communication message is consistent with the loop communication message sent by it, and then determine that the passive network is a loop network.

After receiving the loop communication message, the active ONU, standby ONU, and second OLT add their identity information to the loop communication message and send it.

The first OLT is used to determine that the passive optical network is a loop network, specifically,

The first OLT is configured to judge that the passive network is a loop network according to the identity information of all or some nodes on the loop in the loop communication message.

In the system, the first OLT is also used to send an instruction to the second OLT to instruct all or some ONUs to perform active-standby protection switching when detecting a failure of the main optical fiber or branch optical fiber.

The foregoing description shows and describes preferred embodiments of the present invention, but as previously stated, it should be understood that the present invention is not limited to the form disclosed herein, and should not be viewed as excluding other embodiments, but can be used in various Other combinations, modifications and circumstances, and can be modified within the scope of the inventive concept described herein, by the above teachings or by skill or knowledge in the relevant field. However, changes and changes made by those skilled in the art do not depart from the spirit and scope of the present invention, and should all be within the protection scope of the appended claims of the present invention.

Claims (12)

1. A passive optical network loop detection method, wherein the passive optical network adopts a full protection mode, is characterized in that the method comprises, The first optical line terminal sends a loop communication message to the active optical network unit, and after receiving the loop communication message, the active optical network unit sends the loop communication message to the backup optical network unit; After receiving the loop communication message sent by the backup optical network unit, the second optical line terminal forwards the loop communication message to the first optical line terminal; After receiving the loop communication message, the first optical line terminal determines that the passive optical network is a loop network; Wherein, the method further includes, if the first optical line terminal detects that the main optical fiber or the branch optical fiber fails, then sending an instruction to the second optical line terminal, instructing the second optical line terminal to notify all or part of the optical network units to perform master/backup protection switching. 2. The method according to claim 1, wherein the first optical line terminal determines that the passive optical network is a loop network, specifically, If the first optical line terminal determines that the loop communication message is consistent with the loop communication message sent by it, it determines that the passive network is a loop network. 3. The method according to claim 1, characterized in that, after receiving the loop communication message, the active optical network unit, backup optical network unit, and second optical line terminal add their identity information to the Send the above loop communication message. 4. The method according to claim 3, wherein the first optical line terminal determines that the passive optical network is a loop network, specifically, The first optical line terminal judges that the passive network is a loop network according to the identity information of all or some nodes on the loop in the loop communication message. 5. The method according to any one of claims 1 to 4, characterized in that, after the second optical line terminal receives the loop communication message sent by the backup optical network unit, it transmits the loop communication message through the network management node The communication message is forwarded to the first optical line terminal. 6. The method according to any one of claims 1 to 4, wherein the loop communication message is a physical layer operation, management and maintenance PLOAM message. 7. The method according to claim 6, wherein the loop communication message comprises, ID, message structure type and identity information of the optical network unit. 8. The method according to any one of claims 1 to 4, characterized in that, The main optical network unit and the standby optical network unit are two logical optical network units located inside the same optical network unit, or two passive optical network ports belonging to the same optical network unit, and the two logical optical network units Or the two passive optical network ports of the same optical network unit have their own optical modules and media access control chips respectively, and are managed by a common CPU. 9. A passive optical network loop detection system, characterized in that the system comprises, The first optical line terminal is configured to send a loop communication message to the active optical network unit, and determine that the passive optical network is a loop network after receiving the loop communication message; The active optical network unit is configured to send the loop communication message to the backup optical network unit after receiving the loop communication message; The backup optical network unit is configured to send the loop communication message to the second optical line terminal after receiving the loop communication message; The second optical line terminal is configured to forward the loop communication message to the first optical line terminal after receiving the loop communication message sent by the backup optical network unit; Wherein, the first optical line terminal is also used to send an instruction to the second optical line terminal to instruct all or part of the optical network units to perform active/standby protection switching when detecting a failure of the trunk optical fiber or the branch optical fiber. 10. The system according to claim 9, wherein the first optical line terminal is used to determine that the passive optical network is a loop network, specifically, The first optical line terminal is used to determine that the loop communication message is consistent with the loop communication message sent by it, and then determine that the passive network is a loop network. 11. The system according to claim 9, characterized in that, after receiving the loop communication message, the active optical network unit, backup optical network unit, and second optical line terminal add their identity information to the Send the above loop communication message. 12. The system according to claim 11, wherein the first optical line terminal is used to determine that the passive optical network is a loop network, specifically, The first optical line terminal is configured to determine that the passive network is a loop network according to the identity information of all or some nodes on the loop in the loop communication message.