WO2012119490A1 - Method and system for protecting passive optical network - Google Patents

Abstract

Disclosed are a method and a system for protecting a passive optical network (PON). The method comprises: a primary port and a backup port, after establishing connection with an optical network unit (ONU), detecting the port state; upon detecting a port alarm, the two ports alternately switching between the ON state and the OFF state; and upon finding the ONU, keeping the respective current ON or OFF state, the port in the ON state becoming the new primary port, and the port in the OFF state becoming the new backup port; and the new primary port synchronizing information of the ONU to the new backup port through the ONU. The present invention controls the state of a PON port according to alarm information thereof, performs state switching of the PON port, and implements, through an ONU, synchronization of ONU information of the primary and backup PON ports, the ONU information comprising information such as the state of the ONU and Eqd, thereby implementing fast cross-network element switching.

Description

 Method and system for protecting passive optical network

Technical field

 The present invention relates to a passive optical network, and in particular, to a method and system for protecting a passive optical network. Background technique

 Passive Optical Network (PON) is a pure medium network that can avoid the electromagnetic interference and lightning impact of external equipment, reduce the faults of lines and external equipment, improve system reliability, and save maintenance costs. The technology that the maintenance department has long expected. Passive optical networks mainly include Gigabit Passive Optical Network (GPON), Ethernet Passive Optical Network (EPON), Next Generation Passive Optical Network (NGPON), and Wavelength Division Multiplexed Passive Optical Network (WPON).

 In current passive optical network technologies, PON protection mainly uses protection between different ports on the same network element. In the same network element, PON protection is realized by simultaneously managing two PON ports. The following describes GPON as an example to describe the existing methods for implementing PON protection.

 In the GPON system, for the PON protection of the same network element, the information of the working port and the protection port are related to each other, and can be managed by one protection group. The optical network unit (ONU or ONT) connected to the working port or protection port is faulty or in a state. When changing, it can be synchronized to the associated port in real time, so that the status of the working port and the protection port can be managed at the same time.

When the ONU under the working port enters the active state or the deacitve state, the protection port is notified to record the status of the ONU. When a switchover occurs, the protection port sends a broadcast POPUP message to the ONU, informing the ONU to enter the ranging state, and then performing ranging on multiple ONUs in the actvie state. The successor or failure, the broadcast POPUP message is sent again, and then the next An ONU ranging is performed until the ONU is successfully measured. The difference between the backbone fibers is calculated, and the equalization delay (EqD) of all the ONUs is obtained, and then EqD is sent. The OLT obtains the Round-Trip Delay (RTD) of the ONU through the measurement process, so as to specify an appropriate Eqd value, so as to ensure that each ONU does not generate a rush on the optical splitter when transmitting data, and proposes an inter-network. Meta-protection method, however, there is currently no passive optical network A method of implementing cross-network element protection.

Summary of the invention

 The object of the present invention is to realize cross-network element protection of a passive optical network, which satisfies the requirements of fast, stable and reliable PON protection switching. To solve the above technical problem, the present invention provides a method for protecting a passive optical network, including: after the primary port and the standby port establish a connection with the optical network unit, the port state is detected, and when the port alarm is detected, The primary port and the alternate port are interleaved between an open state and a closed state, and when the port alarm disappears, the primary port and the standby port maintain their current open or closed states, wherein the open port is open. As the new primary port, the port in the closed state becomes the new standby port; and the new primary port synchronizes the information of the optical network unit to the new standby port through the optical network unit. The step of switching between the active port and the standby port in the open state and the closed state includes: when the primary port and the standby port detect the port alarm, if the current port is open, the port is closed, if the current port is closed In the state, the port is opened, and after a time value is turned on or off, the switching is turned on and off.

The time value of the primary port and the standby port being opened and closed each time is a reference time length plus a random time length. The information of the optical network unit includes status information and equalization delay parameters of the optical network unit. In the step of synchronizing the information of the optical network unit to the new standby port, the new primary port uses the optical network unit as an information transmission intermediary, and sends the information of the ONU in the activated state under the new primary port. And the sending, by the optical network unit of the new active port, a physical layer operation and maintenance management (Ploam) message, where the equalization delay parameter is carried in the Ploam message; and the active state is activated. After receiving the Ploam message, the optical network unit sends an acknowledgement message of the Ploam message to the new primary port and the new alternate port. In order to solve the above technical problem, the present invention further provides a protection system for a passive optical network, including a primary optical line terminal, a backup optical line terminal, and an optical network unit, wherein the primary optical line ends An active port is disposed on the end, and the standby optical line terminal is configured with a standby port, where the primary port and the standby port are respectively used to establish a connection with the optical network unit;

 After the primary port and the standby port establish a connection with the optical network unit, the port state is detected. When the port alarm is detected, the interlace is switched between the open state and the closed state, and when the port alarm is found to disappear, Keeping their current open or closed state, wherein the port in the open state becomes the new primary port, and the port in the closed state becomes the new standby port, and the new primary port passes the information of the optical network unit through the optical network unit. Synchronize to the new alternate port. The primary port and the standby port are switched between an open state and a closed state by: when the primary port and the standby port detect a port alarm, if the current port is open, the port is closed, and if the port is currently closed In the state, the port is opened, and after a time value is turned on or off, the switching is turned on and off.

 The time value of each of the primary port and the standby port being opened and closed each time is a reference time length plus a random time length. The information of the optical network unit includes status information and equalization delay parameters of the optical network unit. The new primary port synchronizes the information of the optical network unit to the new standby port by: sending the information of the ONU in the activated state under the new primary port to the new standby by using the optical network unit as an information transmission intermediary. The port includes: sending a physical layer operation and maintenance management (Ploam) message to the optical network unit under the new active port, and carrying the equalization delay parameter in the Ploam message; and the optical network in the activated state After receiving the Ploam message, the unit sends an acknowledgement message of the Ploam message to the new primary port and the new alternate port.

In summary, the present invention controls the state of the PON port according to the alarm information of the PON port, performs state switching of the PON port, and synchronizes the ONU information of the two PON ports through the ONU. The ONU information that needs to be synchronized includes the state of the ONU and the Eqd. Such information, so as to achieve fast switching across network elements, using the method of the present invention, can quickly and efficiently achieve fast switching across the OLT.

BRIEF abstract 2 is a flowchart of a protection method in a GPON according to an example of the present invention;

 FIG. 3 is a structural diagram of a protection system of a passive optical network according to an embodiment of the present invention. Preferred embodiment of the invention

 When the two NEs are in a relatively independent state, the two PON ports are on different NEs, so they cannot be managed uniformly. There are two problems as follows:

 First, neither the working port nor the protection port knows whether the other party is in the closed or open state. Therefore, it is impossible to determine what state it needs to be in. Because the working port is in the open state and the protection port is in the closed state, the ONU can go online normally. When the PON ports are open or closed at the same time, the ONU will not be able to go online stably.

 Second, the protection port is not clear about the working state of the ONU. The real-time synchronization of the ONU state cannot be achieved between the working port and the protection port. After the switchover, the ONU cannot recover quickly. Therefore, to perform fast switching, it is necessary to ensure that the ONU status of the working port and the protection port are synchronized with the Eqd. If it is not synchronized, the entire ONU should be re-ranged during the ranging process after the switching, which will cause the ONU to drop.

 In this embodiment, the state of the PON port is controlled according to the alarm information of the PON port, and the state of the PON port is switched, and the ONU information of the two PON ports is synchronized by the ONU, and the ONU information includes information such as the state of the ONU and Eqd, thereby implementing inter-networking. Quick switching of yuan.

 FIG. 1 is a method for implementing passive optical network protection according to an embodiment of the present invention, including:

 Step 101: The port state detection is performed on the PON port. When a port alarm is detected, such as an LOS (drop) alarm, the PON port is switched between switch states, and when the switch is switched, the on and off states are maintained for a time value. The opening and closing states of the working port and the protection port are staggered for a period of time until the ONU is found, and the alarm is restored;

 Since the PON port as the primary port or the standby port does not know the working state of the associated PON port, and the optical port connection is normal, the primary port and the standby port cannot simultaneously emit light, and therefore, the PON port is in the switch state. When the original primary port is in the closed state and the original standby port is in the open state, the switchover is complete and the alarm is restored.

The PON port in the open state can send a message to the ONU and can receive the ONU to send The PON port in the closed state can only receive the message sent by the ONU. The PON port in the closed state can discover the ONU by receiving the message of the ONU, and determine the state of the port according to whether the ONU message is received within the specified time, and generate the LOS. Alarms, etc.

 Step 102: After the ONU is online, the current working port periodically sends ONU information to the ONU, and the ONU sends the received ONU information to the connected working port and the protection port.

 In this embodiment, after the ONU is online, information such as the ONU status and Eqd is sent to the ONU, and then the ONU sends the information to the working port and the protection port to synchronize the ONU information to the protection port. For the upper message, the ONU uses unified processing, and does not distinguish between the working port and the protection port. By processing on the OLT side, the working port ignores the message, and the protection port saves the ONU information.

In the following, the active port P1 of the primary optical line terminal (OLT1) in the GPON is used as the working port, and the standby port P2 of the standby optical line terminal (OLT2) is used as the protection port as an example to further illustrate the embodiment of the present invention, including:

 Step 201: When P1 and P2 detect the LOS state, OLT1 and OLT2 enter the protection switching state, and OLT1 and OLT2 use the time window shown in Table 1 to open the optical module to find the ONU. When the ONU is found, the opened PON port serves as the working port. The closed PON port acts as a protection port;

 Table 1

In Table 1, Tl~Tn represents a specified reference time length, and Al~\n represents a random time length, and the random time length taken each time it is opened and closed may be different. When the OLT detects the LOS status, if the status of the port of the OLT is on, the port is closed (OFF) and turned on (ON) according to OLT1, and the port is first closed, and the closing time is Τ1+Δ1 (Δ1 indicates random Take the time value, the value of each time can be different). If the OLT detects the LOS status and the port status is OFF, the port is opened and closed according to OLT2. The port is first closed, and the closing time is Τ1+Δ1 (△1 indicates random time value, each time taken. Values can be different). Since the time for the OLT1 and the OLT2 to open the optical module are separated from each other, the downlink optical signal can be ensured that the downlink optical signal does not collide for a certain period of time, that is, one port is in an open state and one port is in a closed state.

 Assume that the OLT1 and the OLT2 have discovered the ONU at the T1 time. At this time, the OLT1 and the OLT2 enter the non-LOS state. Since the PON port of the OLT2 is opened during the T1 time period, the OLT2 enters the active working state, and the OLT1 enters the standby working state.

 The PON port that enters the active working state and the standby working state is no longer switched on and off according to the method in Table 1, but remains in the state. The opened PON port continues to accept other ONUs to go online and starts forwarding services at the same time; The downlink transmission is always turned off, and only the uplink optical signal is received, and the state of the backbone optical fiber is detected.

 Step 202: After the establishment of the Optical Network Unit Management and Control Channel (OMCC) of the PON port as the active working port, the physical layer operation and maintenance management including the Eqd value is sent to all ONUs of the PON port. Physical Layer OAM ;

 Step 203: After receiving the Ploam message, the ONU sends an acknowledgement message to the Ploam message to the working port and the protection port, where the Eqd value is carried in the confirmation message.

 The ONU responds to the Ploam message only when it is in the 05 state. Therefore, after receiving the acknowledgement message of the Ploam message, the protection port can know that the ONU is in the 05 state and can know the Eqd value from the message.

 At the working port, Eqd can be synchronized in a timed manner to ensure synchronization between the working port and the protection port. The message number of the PLOAM message defined in this embodiment is 0x89, and the specific structure of the PLOAM message is shown in Table 2:

 Table 2

 Octet Content Description Description

 1 ONU-ID ID currently assigned to the ONU

 2 10001001 Message Number

3 dddddddd MSB of delay ( Eqd highest byte) Dddddddd

 Dddddddd

 Dddddddd LSB of delay (Eqd lowest byte)

 0 reserved

The specific structure of the ACK for the PLOAM message returned by the ONU after receiving the PLOAM message is as shown in Table 3:

Octet Content Description

 1 ONU-ID ID currently assigned to the ONU

 2 00001001 Message identification "Acknowledge'

 (Message ID of the ACK of the ONU response)

 3 10001001 Message Number

 4 dddddddd MSB of delay

 5 dddddddd

 6 dddddddd

 7 dddddddd LSB of delay

 8-12 0 Reserved FIG. 3 is a protection system for a passive optical network according to the embodiment, including: a primary optical line terminal, a backup optical line terminal, and an optical network unit, wherein the primary optical line terminal is provided with a primary port, An alternate optical port is provided on the standby optical line terminal, and the primary port and the standby port are respectively used to establish a connection with the optical network unit;

 After the primary port and the standby port establish a connection with the optical network unit, the port status is detected. When the port alarm is detected, the interlace switches between the open state and the closed state, and when the port alarm disappears, the respective port is maintained. The current open or closed state, where the open port is the new primary port, and the closed port is the new standby port. The new primary port passes the information of the active optical network unit under the local port through the corresponding optical network. The unit returns to the new standby port; the information of the optical network unit includes status information and equalization delay parameters of the optical network unit.

The primary port and the alternate port are interleaved between the open state and the closed state as follows. Change: When the port alarm is detected on the primary port and the backup port, if the port is currently open, the port is closed. If the port is currently closed, the port is opened, and after a time value is turned on or off, the switch is turned on and off. The time value of the active port and the standby port being opened and closed may be different. The time values for opening and closing are the base time length plus the random time length.

 The new primary port sends the Ploam message to the optical network unit, and sends the information of the optical network unit to the optical network unit in the manner that the Ploam message carries the equalization delay parameter; the optical network unit in the activated state receives the specific After the Ploam message, the acknowledgment message of the Ploam message is sent to the new primary port and the new alternate port, and the acknowledgment message also includes the equalization delay parameter, and the new standby port receives the acknowledgment message and parses the message to obtain the new lord. Use the port information.

 Obviously, those skilled in the art should understand that the above modules and steps of the present invention can be implemented by a general computing device, which can be concentrated on a single computing device or distributed over a network composed of multiple computing devices. Alternatively, they may be implemented by program code executable by the computing device, such that they may be stored in the storage device by the computing device, or they may be separately fabricated into individual integrated circuit modules, or their Multiple modules or steps are implemented as a single integrated circuit module. Thus, the invention is not limited to any particular combination of hardware and software.

 The above is only the embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes can be made to the present invention. All modifications, equivalents, improvements, etc., made within the spirit and scope of the invention are intended to be included within the scope of the invention.

Industrial applicability

 Compared with the prior art, the present invention controls the state of the PON port according to the alarm information of the PON port, and synchronizes the ONU information of the two PON ports, including the status of the ONU and the Eqd, through the ONU, thereby achieving fast cross-network elements. Switching, using the method of the present invention, a fast switching across the OLT can be implemented simply and efficiently.

Claims

Claim 1. A method for protecting a passive optical network, comprising:  After the primary port and the standby port establish a connection with the optical network unit, the port state is detected. When the port alarm is detected, the primary port and the standby port are interleaved between the open state and the closed state, and are found. When the port alarm disappears, the primary port and the standby port remain in their current open or closed state, wherein the port that is in the open state becomes the new primary port, and the port that is in the closed state becomes the new standby port; and, the new The primary port synchronizes information of the optical network unit to the new alternate port through an optical network unit.  2. The method of claim 1, wherein the step of switching between the active port and the standby port in the open state and the closed state comprises:  When the primary port and the standby port detect the port alarm, if the port is currently open, the port is closed. If the port is currently closed, the port is opened, and after a time value is turned on or off, the switch is turned on and off. .  3. The method of claim 2, wherein  The time value of the primary port and the standby port being opened and closed each time is the reference time length plus the length of the random time. 4. The method according to claim 2, wherein the information of the optical network unit includes state information of the optical network unit and an equalization delay parameter. 5. The method according to claim 4, wherein the new primary port synchronizes information of the optical network unit to the new standby port, and the new primary port uses the optical network unit as an information transmission intermediary, The information of the ONU in the active state of the new active port is sent to the new standby port, including: sending a physical layer operation and maintenance management (Ploam) message to the optical network unit under the new primary port, and carrying the Ploam message in the Ploam message. Said equalization delay parameter; After receiving the Ploam message, the active optical network unit sends an acknowledgement message of the Ploam message to the new primary port and the new standby port. A protection system for a passive optical network, comprising a primary optical line terminal, a backup optical line terminal, and an optical network unit, wherein the primary optical line terminal is provided with an active port, and the standby optical line terminal is Providing a backup port, where the primary port and the backup port are respectively used to establish a connection with the optical network unit; wherein, the primary port and the standby port are in a port state after establishing a connection with the optical network unit. Detection: When a port alarm is detected, the interlace switches between the open state and the closed state, and when the port alarm disappears, the current open or closed state is maintained, and the port that is in the open state becomes the new active port, The closed state port becomes a new standby port, and the new primary port synchronizes information of the optical network unit to the new standby port through the optical network unit. 7. The system of claim 6, wherein the primary port and the standby port are switched between an open state and a closed state by interlacing as follows:  When the primary port and the standby port detect the port alarm, if the port is currently open, the port is closed. If the port is currently closed, the port is opened, and after a time value is turned on or off, the switch is turned on and off. . 8. The system of claim 7, wherein  The time value of each of the primary port and the standby port being opened and closed each time is a reference time length plus a random time length. 9. The system of claim 7, wherein the information of the optical network unit comprises state information and equalization delay parameters of the optical network unit. 10. The system according to claim 9, wherein the new primary port synchronizes information of the optical network unit to the new standby port by: using the optical network unit as an information transmission intermediary, and using the new primary The information of the ONU that is in the active state is sent to the new standby port, and includes: sending a physical layer operation and maintenance management (Ploam) message to the optical network unit under the new active port, where the equalization time is carried in the Ploam message. Delay parameter;  After receiving the Ploam message, the active optical network unit sends an acknowledgement message of the Ploam message to the new active port and the new standby port.