WO2012136089A1

WO2012136089A1 - Loop detection method and system for passive optical network

Info

Publication number: WO2012136089A1
Application number: PCT/CN2012/072049
Authority: WO
Inventors: 张伟良; 耿丹
Original assignee: 中兴通讯股份有限公司
Priority date: 2011-04-08
Filing date: 2012-03-07
Publication date: 2012-10-11
Also published as: CN102740171A; CN102740171B

Abstract

The present invention provides a loop detection method for a passive optical network, comprising: a first optical line terminal sending a loop communication message to an active optical network unit, and after receiving the loop communication message, the active optical network unit sending the loop communication message to a standby optical network unit; after receiving the loop communication message sent by the standby optical network unit, a second optical line terminal forwarding the loop communication message to the first optical line terminal; and after receiving the loop communication message, the first optical line terminal determining that the passive optical network is a loop network. The present invention also provides a loop detection system for a passive optical network. According to the technical solutions provided in the present invention, after a fault occurs in the passive optical network in a full protection mode, communication can be restored rapidly between the OLT and the ONU.

Description

Passive optical network loop detection method and system

The present invention relates to the field of communications, and in particular, to a passive optical network (PON, Passive Optical Network) loop detection method and system. Background technique

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

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

In the PON system, the data transmission in the downlink direction (from the OLT to the ONU) is broadcast, and each ONU receives all the frames, and then according to the ONU identifier (ONU-ID) and the GPON encapsulation mode port identifier (GEM-Port ID, GPON Encapsulation Mode-Port Identity), and Alloc-ID (Allocation- Identity), Medium Access Control ID (MAC ID) or Logical Link Identity (LLID) Your own frame. For the data transmission in the uplink direction (from the ONU to the OLT), since each ONU needs to share the transmission medium, each ONU should transmit uplink data to the OLT to arrange its own time slot. The distance between each ONU and the OLT is different. To prevent the uplink data sent by each ONU from reaching the OLT at the same time, the OLT needs to perform the ONU in the registration activation phase. Ranging to achieve upstream transmission synchronization.

In the deployment 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 next level of requirements is that they can be interrupted in the service channel. After a quick recovery. This puts forward the requirements for protection paths and fast switching paths for passive optical networks carrying user services.

Figure 2 (a) is the first topology diagram of the full protection passive optical network, and Figure 2 (b) is the second topology diagram of the full protection passive optical network, as shown in Figure 2 (a) and Figure 2 ( b) OLT l and OLT 2 are respectively connected to two 1:N ODNs, each of which is connected to each ONU through an optical fiber in the downstream direction, and each ONU has two ONUs, which are primary ONUs and standbys respectively. ONU, OLT 1 is connected to each primary ONU through ODN 1, and OLT 2 is connected to each standby ONU through ODN 2; OLT 1 and OLT 2 can be two OLTs connected through a network management node, as shown in Figure 2 (a); It can also be two PON ports of the OLT, as shown in Figure 2 (b). In the initial state, the OLT 1 performs communication with all the active ONUs. When the OLT 1 fails or the optical fiber between the OLT 1 and the optical splitter 1 is interrupted, the OLT 2 and all the standby ONUs perform service communication; If a branch fiber under device 1 is interrupted, or if a primary ONU fails, it will communicate. In the above manner, full protection of the OLT, the ONU, and each segment of the optical fiber in the PON system is achieved. In the above full protection mode, after the optical fiber between the OLT 1 and the optical splitter 1 is interrupted, or a certain branch optical fiber under the optical splitter 1 is interrupted, each primary ONU detects a downlink signal interruption, and then performs protection switching, The upstream service is switched to the standby ONU, and the standby ONU communicates with the OLT 2. During the protection switching process, the primary ONU detects the line fault and performs protection switching. The switching process takes a long time and cannot meet the time sensitivity. The need for fast recovery after a service interruption does not provide a method for the OLT to determine whether a loop between the ONU and the ONU can communicate. Summary of the invention

In view of this, the technical problem to be solved by the present invention is to provide a passive optical network loop detection method. After the passive optical network fails in the full protection mode, the OLT and the ONU can quickly resume communication. . The invention also provides a passive optical network loop detection system.

The present invention provides a passive optical network loop detection method, where the passive optical network adopts a full protection mode, including:

The first OLT sends a loop communication message to the primary ONU, and after receiving the loop communication message, the primary ONU 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 determines that the passive optical network is a loop network. The above method, wherein the first OLT determines that the passive optical network is a loop network: when the first OLT determines that the loop communication message is consistent with a loop communication message sent by itself, determining that the The source network is a loop network.

In the above method, after the primary ONU, the standby ONU, and the second OLT receive the loop communication message, the identity information of the primary ONU is added to the loop communication message for transmission.

The above method, wherein the first OLT determines that the passive optical network is a loop network: the first OLT determines the passive network according to identity information of all nodes or partial nodes on the loop in the loop communication message. For the loop network.

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

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

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

The above method, wherein the method further includes: If the first OLT detects that the trunk fiber or the branch fiber fails, the second OLT sends an instruction to the second OLT to notify all or part of the ONUs to perform the active/standby protection switching.

The above method, wherein

The primary ONU and the standby ONU are two logical ONUs located inside the same ONU, or belong to two PON ports of the same ONU;

The two logical ONUs or the two PON ports of the same ONU have their own optical modules and media access control chips, and are managed by a common CPU.

The present invention also provides a passive optical network loop detection system, the system comprising: a first OLT, configured to send a loop communication message to the primary ONU, and after receiving the loop communication message, determine The passive optical network is a loop network;

The primary ONU is configured to send the loop communication message to the standby ONU after receiving the loop communication message;

The standby ONU is configured 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 standby ONU.

In the above system, the first OLT is configured to determine that the passive optical network is a loop network:

The first OLT is configured to determine that the passive network is a loop network when the loop communication message is consistent with the loop communication message sent by the first OLT.

In the above system, after the primary ONU, the standby ONU, and the second OLT receive the loop communication message, the identity information of the primary ONU is added to the loop communication message for transmission.

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

In the above system, the first OLT is further configured to send an instruction to the second OLT to detect that the trunk fiber or the branch fiber fails, and instruct the second OLT to notify all or part of the ONUs to perform the active/standby protection switching.

With the method and system of the present invention, the OLT determines the loop communication with the ONU. When the trunk fiber or the branch fiber is disconnected, the standby OLT notifies the ONU to perform protection switching, shortening the ONU protection switching time, and protecting the PON. The timely transmission of time-sensitive services in the system enables the ONU and the OLT to quickly resume communication and improve the service quality of the PON system. DRAWINGS

The drawings are intended to provide a further understanding of the invention, and are intended to be a part of the invention. In the drawing:

Figure 1 is a topological structure diagram of a PON system;

Figure 2 (a) is the first topological structure of the passive mode optical network in full protection mode;

Figure 2 (b) is a second topology diagram of a full protection passive optical network;

Figure 3 is a flow chart of Embodiment 1 of the present invention;

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

Figure 5 is a structural diagram of a passive optical network loop detection system. detailed description

The basic idea of the present invention is that the first optical line terminal sends a loop communication message to the primary optical network unit, and after receiving the loop communication message, the primary optical network unit sends the loop communication message to the standby light. 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; the first optical line terminal receives the After the loop communication message, determining that the passive optical network is a loop The internet.

The present invention will be further described in detail below with reference to the accompanying drawings and embodiments in order to make the present invention. It is understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Embodiment 1:

In Fig. 2 (a) and Fig. 2 (b), the OLT 1 is connected to all the main ONUs through the optical splitter 1. The registration of the ONU and the transmission of service data between the OLT and the ONU are performed between the OLT 1 and the primary ONU based on the GPON or the GPON-based next-generation PON. 3 is a flowchart of Embodiment 1 of the present invention. As shown in FIG. 3, the OLT 1 uses the following steps to determine whether a loop composed of the OLT 1, the primary ONU, the standby ONU, and the OLT 2 can communicate:

Step S301, the OLT 1 sends a loop communication Round_Trip_Correspondence message to the primary ONU, where the message uses a physical layer operation, management and maintenance (PLOAM) mechanism, and the PLOAM is applied to the fast and timely between the OLT and the ONU. Management maintains information interaction and processing. The format of the loop communication message is as shown in Table 1:

Table 1 Structure of the Round-Trip-Correspondence message

Roimd_Trip_Correspondencer message

Byte Content Description

1 ONU-ID1 The content of this byte is ONU-ID1, indicating the cancellation

The message is sent to the ONU whose ONU-ID value is ONU-ID1, or the message is the ONU-ID value.

ONU-ID1 sent by ONU

2 XXXXXXXX message type is

"Round_Trip_Correspondencer"

3-12 Data is reserved, or by the node that receives the message

Fill in your own identity information value (does not cover the identity information filled in by other nodes), or fill in your identity information value (override the identity information filled in by other nodes) by the node that received the 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 the ONU whose ONU-ID value is ONU-ID 1, or the message is the ONU-ID value of the ONU-ID. The content of the second byte indicates that the type of the PLOAM message is the type of the structure information of the Round_Trip_Correspondence message; the content of the third to twelfth bytes is reserved, or the node that receives the message is filled in order. The value of its own identity information (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 (overwriting the identity information filled in by other nodes).

Step S302: After receiving the round communication message Round_Trip_Correspondence message sent by the OLT 1, the primary ONU forwards the Round_Trip_Correspondence message directly to the standby ONU.

In step S303, after the ONU receives the Round_Trip_Correspondence message sent by the primary ONU, the Round_Trip_Correspondence message is directly forwarded to the OLT 2.

Step S304, after receiving the Round_Trip_Correspondence message sent by the standby ONU, the OLT 2 forwards the Round_Trip_Correspondence message directly to the OLT 1.

Step S305, after receiving the Round_Trip_Correspondence message sent by the OLT 2, the OLT 1 is the same as the Round_Trip_Correspondence message sent by itself, and the OLT1 determines the ring composed of the OLT 1, the primary ONU, the standby ONU, and the OLT 2. The road is communicable.

In this embodiment, the OLT 1 determines that the loop composed of the OLT 1, the primary ONU, the standby ONU, and the OLT 2 is communicable. In other embodiments, the OLT 1 can use the same method to determine the primary OLT and the primary. With the ONU, the standby ONU, the standby OLT, the network management node, and finally the loop to the primary OLT can communicate, when the OLT1 detects that the optical fiber between itself and the optical splitter 1 is disconnected, if the OLT1 determines that the OLT 1 and the primary The loop formed by the ONU, the standby ONU, the OLT 2, and the network management node cannot communicate, and the OLT 1 instructs the OLT 2 to notify the entire network through the network management node. The ONU performs protection switching; when the OLT 1 detects that part or all of the optical fiber between the optical splitter 1 and the primary ONU is disconnected, if the OLT 1 determines that the OLT 1, the primary ONU, the standby ONU, the OLT 2, and the network management node are composed of If the loop cannot communicate, the OLT 1 commands the OLT 2 through the network management node. In this embodiment, the transmission order of the Round_Trip_Correspondence message sent by the OLT 1 is OLT l, the primary ONU, the standby ONU, and the OLT 2 to the OLT 1 , in other In the embodiment, the transmission order of the Round_Trip_Correspondence message sent by the OLT1 may also be the primary OLT, the standby OLT, the standby ONU, and the primary ONU, and finally to the primary OLT; the primary OLT, the primary ONU, the standby ONU, and the standby are routed in the ring. When the OLT and the network management node are configured, the transmission order of the Round_Trip_Correspondence message sent by the OLT1 is the primary OLT, the primary ONU, the standby ONU, the standby OLT, and the network management node and finally to the primary OLT; the order of the Round_Trip_Correspondence message sent by the OLT 1 may also be The primary OLT, the network management node, the standby OLT, the standby ONU, and the primary ONU are finally used to the primary OLT.

In this embodiment, the standby ONU and the primary ONU are two logical ONUs located in the same ONU, or two PON ports belonging to the same ONU, and the two logical ONUs or two PON ports of the same ONU. Each has its own optical module and media 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 2:

In Fig. 2 (a) and Fig. 2 (b), the OLT 1 is connected to all the main ONUs through the optical splitter 1. The registration activation of the ONU and the transmission of service data between the OLT and the ONU are performed between the OLT 1 and the primary ONU based on GPON or a GPON-based next-generation PON. As shown in FIG. 4, the OLT 1 uses the following steps to determine whether a loop composed of the OLT 1, the primary ONU, the standby ONU, and the OLT 2 can communicate: Step S401, the OLT 1 sends a loop communication Round_Trip_Correspondence message to the primary ONU, adopting a 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 the ONU whose ONU-ID value is ONU-ID1, or the message is the ONU-ID value of 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 contents of the third to twelfth bytes are reserved, or the nodes that receive the message are filled in sequentially. The value of its own identity information (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 (overwriting the identity information filled in by other nodes).

Step S402, after receiving the Round_Trip_Correspondence message sent by the OLT 1, the primary ONU writes its ONU-ID value (or its own logical link identifier LLID value) to the first non-zero data (Data) of the Round_Trip_Correspondence message. The domain then forwards the Round_Trip_Correspondence message directly to the standby ONU. Step S403, after receiving the Round_Trip_Correspondence message sent by the primary ONU, the standby ONU writes its ONU-ID value (or its own logical link identifier LLID value) to the first non-zero Data field of the Round_Trip_Correspondence message, and then The Round_Trip_Correspondence message is forwarded directly to the OLT 2.

Step S404, after receiving the Round_Trip_Correspondence message sent by the standby ONU, the OLT 2 writes its own identity information value (for example, the PON identification value) to the first non-zero Data field of the Round_Trip_Correspondence message, and then the Round_Trip— The Correspondence message is forwarded directly to OLT 1.

Step S405: After receiving the Round_Trip_Correspondence message sent by the OLT 2, the OLT 1 determines a loop composed of the OLT 1, the primary ONU, the standby ONU, and the OLT 2 according to the identity information value filled in by all the nodes or department nodes in the Round_Trip_Correspondence message. It is possible to communicate.

In this embodiment, after receiving the Round_Trip_Correspondence message sent by the previous node, each node writes its identity information value to the first non-zero Data field of the Round_Trip_Correspondence message, and then sends it to the next node, in other In an embodiment, after receiving the Round_Trip_Correspondence message sent by the previous node, each node may write its own identity information value into the Data field of the Round_Trip_Correspondence message, that is, overwrite the identity information value written by the previous node, and then send To the next node, after receiving the Round_Trip_Correspondence message sent by the OLT 2, the OLT 1 judges the OLT 1, the primary ONU, and the standby according to the identity information value filled in by the OLT 2 in the Round-Trip_Correspondence message. The loop formed by the ONU and the OLT 2 is communicable.

In this embodiment, the OLT 1 determines that the loop composed of the OLT 1, the primary ONU, the standby ONU, and the OLT 2 is communicable. In other embodiments, the OLT 1 can use the same method to determine the primary OLT and the primary. Use ONU, standby ONU, standby OLT, network management node and finally to the main The loop of the OLT is communicable. When the OLT 1 detects that the optical fiber between itself and the optical splitter 1 is disconnected, if the OLT 1 determines that the OLT 1 , the primary ONU, the standby ONU, the OLT 2, and the network management node are If the loop cannot communicate, the OLT 1 instructs the OLT 2 to notify all ONUs to perform protection switching through the network management node; when the OLT 1 detects that some or all of the optical fibers between the optical splitter 1 and the primary ONU are disconnected, if the OLT 1 determines that the OLT 1 is The loop formed by the primary ONU, the standby ONU, the OLT 2, and the network management node cannot communicate. The OLT 1 instructs the OLT 2 to notify the OLT 2 that the delivery order of the Round_Trip_Correspondence message sent by the OLT 1 is OLT l, the primary use. The ONU, the standby ONU, and the OLT 2 are finally sent to the OLT 1. In other embodiments, the order of transmitting the Round_Trip_Correspondence message sent by the OLT 1 may also be the primary OLT, the standby OLT, the standby ONU, and the primary ONU, and finally to the primary OLT; When the ring is composed of the primary OLT, the primary ONU, the standby ONU, the standby OLT, and the network management node, the transmission order of the Round_Trip_Correspondence message sent by the OLT1 is the primary OLT, the primary ONU, and the standby. ONU, the OLT backup, and finally to the main network node with the OLT; delivery order Round_Trip_Correspondence OLT 1 transmits the message may be mainly used the OLT, the network management node, the OLT standby, standby ONU, ONU last primary to the master OLT.

Embodiment 3

As shown in FIG. 5, it is a structural diagram of a passive optical network loop detection system, where the system includes: a first OLT, configured to send a loop communication message to the primary ONU, and receive the loop After the communication message, determining that the passive optical network is a loop network;

The second OLT is configured to forward the loop communication message to the first OLT after receiving the loop communication message sent by the standby ONU. The first OLT is configured to determine that the loop communication message is consistent with the loop communication message sent by the first OLT, and determine that the passive network is a loop network.

After receiving the loop communication message, the primary ONU, the standby ONU, and the second OLT add identity information to the loop communication message for transmission. The first OLT is configured to determine, according to the identity information of all nodes or some nodes on the loop in the loop communication message, that the passive network is a loop network. And sending an instruction to the second OLT, instructing the second OLT to notify all or part of the ONUs to perform active/standby protection switching.

The above description shows and describes a preferred embodiment of the present invention, but as described above, it should be understood that the present invention is not limited to the form disclosed herein, and should not be construed as being Other combinations, modifications, and environments are possible and can be modified by the teachings of the above teachings or related art within the scope of the inventive concept described herein. All changes and modifications made by those skilled in the art are intended to be within the scope of the appended claims.

Claims

Claim

A passive optical network loop detection method, wherein the passive optical network adopts a full protection mode, and the method includes:

The first optical line terminal sends a loop communication message to the primary optical network unit, and after receiving the loop communication message, the primary optical network unit sends the loop communication message to the standby optical network unit; the second optical line After receiving the loop communication message sent by the standby optical network unit, the 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 ring network.

2. The method according to claim 1, wherein the first optical line terminal determines that the passive optical network is a loop network:

When the first optical line terminal determines that the loop communication message is consistent with the loop communication message sent by itself, it determines that the passive network is a loop network.

The method according to claim 1, wherein the primary optical network unit, the backup optical network unit, and the second optical line terminal, after receiving the loop communication message, add their own identity information to The loop communication message is sent.

The method according to claim 3, wherein the first optical line terminal determines that the passive optical network is a loop network:

The first optical line terminal determines that the passive network is a loop network according to identity information of all nodes or partial nodes on the loop in the loop communication message.

The method according to any one of claims 1 to 4, wherein after the second optical line terminal receives the loop communication message sent by the backup optical network unit, the loop is performed by the network management node. The communication message is forwarded to the first optical line terminal.

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.

The method according to claim 6, wherein the loop communication message comprises: an ID of an optical network unit, a message structure type, and identity information.

The method according to any one of claims 1 to 4, further comprising: if the first optical line terminal detects that the trunk optical fiber or the branch optical fiber fails, sending an instruction to the second optical line terminal, The second optical line terminal is instructed to notify all or part of the optical network unit to perform active/standby protection switching.

9. A method according to any one of claims 1 to 4, characterized in that

The primary optical network unit and the backup 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;

The two logical optical network units or the two passive optical network ports of the same optical network unit respectively have their own optical modules and medium access control chips, and are managed by a common CPU.

10. A passive optical network loop detection system, the system comprising: a first optical line termination, configured to send a loop communication message to a primary optical network unit, and receive the loop communication After the message, determining that the passive optical network is a loop network;

a primary optical network unit, configured to send the loop communication message to the standby optical network unit after receiving the loop communication message;

a backup optical network unit, configured to send the loop communication message to the second optical line terminal after receiving the loop communication message;

And 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 standby optical network unit.

The system according to claim 10, wherein the first optical line terminal is configured to determine that the passive optical network is a loop network:

The first optical line terminal is configured to determine that the passive network is a loop network when the loop communication message is consistent with the loop communication message sent by the first optical line terminal.

The system according to claim 10, wherein said main optical network unit, After receiving the loop communication message, the backup optical network unit and the second optical line terminal add their own identity information to the loop communication message for transmission.

The system according to claim 12, wherein the first optical line terminal is configured to determine that the passive optical network is a loop network:

The system according to any one of claims 10 to 13, wherein in the system, the command is sent to the second optical line terminal, and the second optical line terminal is instructed to notify all or part of the optical network unit to perform the active/standby operation. Protection switching.