CN1728645A - Method for protecting operation of light transmission network - Google Patents

Abstract

The invention discloses a method for protecting optical transmission network services. The method at least includes the following steps: A: designate two or more transmission channels between the service source end and the sink end as the protection paths of the working paths; B : The service sink monitors the service signals from the working path and all protection paths. If the service signal of the working path is normal, it receives the service signal from the working path through the cross-connection selection matrix of the service sink; otherwise, switches the cross-connection selection matrix and selects a A service signal is received on a normal protection path of the service signal. The invention provides more than two protection paths, so that the service can still be protected when the service signal fails in the working path and a part of the protection paths.

Description

A method for protecting optical transmission network services

technical field

The invention relates to the field of optical transmission networks, in particular to a method for protecting optical transmission network services.

Background technique

With the progress of society and the development of science and technology, human beings have begun to enter the information age, and the highly developed information society requires higher quality information services to realize various information services. Synchronous Digital Hierarchy (SDH: Synchronous Digital Hierarchy) and Synchronous Optical Network (SONET: Synchronous Optical Network) are the development and application hotspots in the field of information transmission technology in the world today. As the transmission technology of the telecommunications backbone network, SDH/SONET has considered the importance of network reliability from the very beginning, and a series of protection technologies are included in the system, such as: Sub-Network Connection Protection (SNCP: Sub-Network Connection Protection), Multiplex section protection (MSP: Multiplex Section Protection) and so on. These protection technologies enable the user's business to switch to the protected path in a short period of time (generally within 50ms) when the optical fiber fails, so that the user's voice, data and other services can be quickly restored without being affected basically .

Figure 1a and Figure 1b are schematic diagrams of the working principle of the subnet connection protection technology. A and B are network elements of two optical transmission networks. A->B has two optical fibers, and B->A also has two optical fibers. There are service flows between NEs. The solid line is the optical fiber passed by the working path of the service, and the dotted line is the optical fiber passed by the protection path. Network element A sends the service sent to network element B to both the working path and the protection path at the same time, and network element B selects one of the two optical fibers from network element A to receive the service. Conversely, the service from network element B to network element A is similar. The optical fiber between network elements A and B can pass through various network topologies of the optical transmission network, not limited to an optical network self-healing ring (SHR: Self-healing Ring). When a fault occurs, for example: the optical fiber where the working path of A->B is faulty, at this time, the B network element can find that the service from the working path has failed, and automatically switch to receive the service from the protection path, thus ensuring the service. normal. However, the above-mentioned SNCP protection technical solution still has certain deficiencies. When the optical fibers of both the working path and the protection path fail, services will not be protected.

Figure 2a and Figure 2b are schematic diagrams of multiplex section protection technology. In this protection technology, half of the capacity of optical fibers in two directions is used as the protection capacity of the other. Transmit switching signaling through the K-byte overhead in the data frame of the optical transport network, and realize bridging at the source node of the service when the fiber is cut in a certain direction, and select and receive at the sink node of the service to complete the protection of the service. Essentially, from the point of view of the service sink node in the MSP ring, because each office direction has one incoming fiber and one outgoing fiber. There are still only two optical fibers that can input services from other nodes, that is, only two paths (working path and protection path) can choose to receive service signals. When the service signals of both the working path and the protection path fail, the service is still not protected.

In addition, in the above two solutions of the prior art, the two optical fibers protect each other, only one service is transmitted, and the utilization rate of the optical fiber capacity is low.

Contents of the invention

The present invention provides a method for protecting optical transmission network services with high reliability and high fiber utilization rate, comprising the following steps:

A: Designate two or more transmission channels between the service source and the sink as the protection path of the working path, and the service source copies and sends the service signal to the working path and the designated protection path at the same time;

B: The service sink monitors the service signals from the working path and all protection paths. If the service signal of the working path is normal, the service signal from the working path is selected through the cross-connection selection matrix of the service sink; otherwise, the cross-connection selection matrix is switched, Select a normal protection path of a certain service signal to receive the service signal.

The protection path is set with a priority, and when it is detected that the service signal of the working path fails, the cross-connection selection matrix is switched, and a protection path with a high-priority service signal and a normal protection path is selected to receive the service signal.

According to the above method of the present invention, after the service sink selects a protection path to receive the service signal, if the service signal of the working path is detected to be restored, after the set waiting recovery time, if the service signal of the working path still remains normal , the cross-connect selection matrix is switched, and the service signal is selected to be received from the working path.

In the step B, after the service sink selects a certain protection path to receive the service signal, if it detects that the service signal of the protection path is invalid, then switch the cross-connection selection matrix, and select another protection path with normal service signal to receive the service signal .

According to the above method of the present invention, if the service sink monitors that the service signal of a certain protection path fails, the protection path will be deleted from the specified protection path; if the service signal of the protection path is detected to be restored, the The protection path is rejoined to the specified protection path.

The physical media of the working path and the protection path are: optical fiber, cable, microwave.

The present invention also provides a method for protecting optical transmission network services, including the following steps:

A: Designate two or more transmission channels between the service source and the sink as the protection path of a working path, the main service signal is transmitted on the working path, and the additional service signal is transmitted on the protection path;

B: The service sink monitors the service signals of the working path and all protection paths. If the main service signal of the working path is normal, it will receive the main service signal from the working path through the cross-connection selection matrix of the service sink; if the main service signal of the working path If it fails, send a bridging request signaling to the service source through a normal protection path of a certain service signal;

C: The service source receives the signaling, cuts off the transmission of the extra service signal of the protection path, copies and sends the main service signal of the working path to the protection path, and sends the bridge confirmation signaling to the service sink through the protection path ;

D: The service sink receives the bridging confirmation signaling, switches the cross-connection selection matrix, and selects this protection path to receive the main service signal.

The protection path is set with a priority, and when the monitoring detects that the main service signal of the working path fails, a protection path with a high priority service signal and a normal service signal is selected to send a bridging request signaling to the service source.

According to the above method of the present invention, if the service sink cannot receive the confirmation signaling from the source within a set time, it will repeatedly send the bridging request signaling to the service source through the protection path; , the bridging request signaling is sent through another protection path.

According to above-mentioned method of the present invention, also comprise the following steps:

b1: After the service sink selects the protection path to receive the main service signal, if it detects that the service signal of the working path is restored, after the set waiting recovery time, if the service signal of the working path remains normal, switch the cross-connection selection matrix , choose to receive the main service signal from the working path, and send the cancel bridging request signaling to the service source through the working path;

b2: The service source end receives the cancel request signaling, cancels the bridging of all replication services, resumes the sending of additional services on the protection path, and sends the bridging cancellation confirmation signaling to the service sink end through the working path;

b3: After receiving the cancel confirmation signaling, the service sink resumes receiving the extra service.

If the service sink monitors that the service signal of a certain protection path fails, it will delete the protection path from the designated protection path; protection path.

The physical media of the working path and the protection path are: optical fiber, cable or microwave.

The method of the invention provides more reliable protection for the user's business, improves the survivability of the business and the self-healing ability of the network; for the protocol switching mode, while improving the protection reliability, it can also ensure the bandwidth under normal conditions. use efficiently.

Description of drawings

Figure 1a: A schematic diagram of the normal state of subnet connection protection in the prior art;

Figure 1b: Schematic diagram of switching when the subnet connection protection fiber fails in the prior art;

Figure 2a: Schematic diagram of the normal state of multiplex section protection in the prior art;

Figure 2b: Schematic diagram of switching when the multiplex section protection fiber fails in the prior art;

Figure 3: Schematic diagram of the normal business process in the non-protocol switching mode of the present invention;

Figure 4: Schematic diagram of the business process when the working path in the non-protocol switching mode of the present invention fails;

Figure 5: Schematic diagram of the business process when the working path and some protection paths fail in the non-protocol switching mode of the present invention;

Figure 6: Schematic diagram of the business process in the normal case of the protocol switching mode of the present invention;

Figure 7: The protocol switching mode signaling interaction process of the present invention;

Figure 8: Schematic diagram of the business process when the working path of the protocol switching mode of the present invention fails;

Figure 9: Schematic diagram of the business process when the working path and some protection paths fail in the protocol switching mode of the present invention.

Detailed ways

The present invention can have two application modes in the application. The first mode is the no-protocol switching mode, that is, the permanent bridging mode at the source end, and the protection path duplicates the services on the working path at any time. The second mode—protocol switching mode, that is, the dynamic bridging mode at the source end, the protection path can pass some extra service signals under normal conditions, and it is only used in the case of switching. The application schemes of the two modes are described below, taking the case where the working path is protected by two protection paths as an example.

1. No protocol switching mode

1. Business flow and selection under normal circumstances:

As shown in Figure 3, A and B are two network elements in the optical transmission network. A has one port input, three ports output to the optical fiber, B has three ports to input signals from the optical fiber, and one port to output to other devices (There are more input and output ports in reality, only a few ports used in this solution are described here). User services are input from network element A and finally output from network element B. At this time, network element A is the service source, and network element B is the service sink. The service signal is sent from the W path, and P1 and P2 are designated as the protection path. At the same time, the priority of P1 is higher than that of P2. If the priority of the protection service is not preset, the default protection path will be used for selection.

Network element A copies the service signal input from the input port and sends it to three output ports at the same time. The B network element monitors the service signal quality corresponding to each port of the service input path from the A network element. The monitoring conditions may be alarm information such as alarm indication signals, error code exceeding limit, and line signal loss. A cross-connection selection matrix is built inside the network element B. Under normal circumstances, the cross-connection selection matrix of network element B selects the signal from the working path W and outputs it through the output port.

2. Business flow and selection when the work path fails:

When the input port of network element B detects that the signal from the working path W fails, the network element B switches the cross-connect selection matrix to select the service signal from the protection path P1, as shown in Figure 4, and the service can be protected in time.

3. Business flow and selection when the working path and some protection paths fail:

When the protection path P1 fails, resulting in service signal failure, network element B switches the cross-connection selection matrix and selects to receive the service signal from the protection path P2, as shown in Figure 5, the service can still be protected.

4. Business flow and selection when some protection paths fail:

If the service signal of a protection path fails, the B network element will delete the protection path from the designated protection path; if the service signal of the protection path is detected to be restored, the protection path will be re-added to the designated protection path middle.

5. Business flow and selection after the work path recovers from failure to normal:

When the working path W returns to normal from failure, the B network element immediately monitors the recovery of the working path signal. After the set waiting recovery time, if the working path signal is still normal, switch the cross-selection connection matrix and select Traffic signals are received from the working path W. You can also choose not to restore to avoid multiple switchovers.

2. Protocol switching mode

1. Business flow and protocol processing under normal conditions:

Network elements A and B designate protection paths P1 and P2, and designate that the protection priority of P1 is higher than that of P2. As shown in Figure 6. W is the working path. At this time, network element A does not copy the main service signal and send it to the two protection paths P1 and P2. The two paths P1 and P2 can still transmit additional service signals. The B network element still needs to monitor the input port signals corresponding to the P1 and P2 protection paths.

2. Service flow and protocol processing when the working path failsafe path is normal:

When the working path fails, network element B immediately detects the failure of the signal. After the delay time, if the signal still fails, the network element B sends a bridging request signaling from the protection path P1 to notify the network element A to send the protected service signal from the P1 path, as shown in Figure 7;

After network element A receives the bridge request signaling sent by network element B through the P1 path, it copies the service signal of the working path and sends it to the protection path P1, and at the same time sends the bridge confirmation signaling for confirming the sending service to B from the P1 path network element;

Network element B receives the bridging confirmation signaling from network element A, switches the crossover selection matrix, and selects the port corresponding to the P1 path to receive service signals. As shown in Figure 8. At this point the extra signal from the P1 path is cut off.

Due to some unexpected reasons, the network element B does not receive the bridging acknowledgment signaling from the A network element within the timeout period, and then resends the bridging request signaling to the A network element. If no bridging acknowledgment signaling from network element A is received after sending the bridging request three times, the bridging request signaling is sent to the next protection path.

3. Business flow and protocol processing when the working path and some protection paths fail:

When the optical fiber of the P1 path fails, the port of the B network element corresponding to the P1 path should detect the failure of the service signal. If the failure condition of the signal still exists after the hold-off time, the B network element passes through the P2 The path sends a bridging request signaling to network element A. Network element A receives the bridging request signaling from network element B through the port corresponding to the P2 path, and then sends a confirmation bridging signaling to network element B through the P2 path, and at the same time copies the service sent to the W path and sends it to the P2 path. As shown in Figure 9.

After network element B receives the confirmation bridging signaling from network element A, it switches the cross-connect matrix, selects to receive service signals from the P2 path, and the service is restored. When due to some unexpected reasons, the B network element does not receive the confirmation bridging signaling from the A network element within the timeout period, and then resends the bridging request signaling to the A network element. If the bridging request is sent three times but no confirmation bridging signaling from network element A is received, the bridging request signaling (if any) is sent to the next protection path, and the above process is repeated. If it is already the last protection path, report a switching failure alarm.

4. Service flow and protocol processing when some protection paths fail:

If a part of the protection path fails, the protection path does not participate in the entire switching protocol when the working path fails. If the working path P1 fails, when W fails, it will switch directly to the P2 protection path through the protocol, and P1 will not participate in the entire switching process. The switching process is the same as the previous case. If the recovery of the service signal of the protection path is detected again, the protection path is re-added to the designated protection path.

5. Business flow and protocol processing after the working path recovers from failure to normal:

When the optical fiber of the W path is restored, the corresponding port of the B network element should immediately monitor the recovery of the service signal. After the set waiting time, if the service signal is still normal, then the B network element will switch the cross-connect matrix. , select and receive the service from the W path, and then send the "cancel bridging request" signaling to the A network element through the reverse optical fiber of the W path, as shown in Figure 7;

Network element A cancels the bridging of all duplication services, and restores the sending of additional services on the P1 and P2 paths. Then send a "bridge cancel confirmation" signaling through the optical fiber of W path A->B;

After the B network element receives the "bridge cancel confirmation" signaling from the A network element, it resumes receiving the extra service.

Due to some accidental reasons, when network element B does not receive the "bridge cancel confirmation" signaling from network element A within the agreed time, then resend the "bridge cancellation request" signaling to network element A. If the "Bridge Cancellation Request" signaling is sent three times, but the "Bridge Cancellation Confirmation" signaling from network element A is still not received, the additional service cross-connection will not be restored to prevent the wrong connection of the service, and an alarm will be reported to notify the user that the additional service cannot be used. Normal recovery.

This protection technology can adapt to a variety of service transmission media. The physical media passed by the working path and the protection path can be: optical fiber, cable, microwave, etc., as long as the source site of the service can copy and send the service to this path, and at the same time The sink network element can monitor the service quality of the physical or logical channel of the service, and select an appropriate path to receive, so as to complete the functions of this solution. Moreover, the working path, the protection path, and the protection paths may all be different media.

Since the method of the invention provides more than two protection paths, the business can still be protected when the working path and a part of the protection paths fail. Especially when the main protection path is unreliable due to some reasons (such as the aging of the optical path itself), but the entire protection path cannot be replaced, it provides more reliable protection for important services of users. At the same time, the protocol working mode of the SNCMP protection technology can not only improve the degree of protection, but also ensure the effective utilization of bandwidth.

Claims (12)

1, a kind of guard method of optical transport network business may further comprise the steps:

A: specify the protection path of two or more transmission channel as operating path between service source end and Su Duan, the service source end duplicates service signal and sends to simultaneously the protection path of operating path and appointment;

B: end monitoring in professional place is from the service signal in operating path and all protection paths, if the operating path service signal is normal, then the interconnection selection matrix by professional Su Duan selects the service signal of receiving from operating path; Otherwise, switch the interconnection selection matrix, select a certain service signal to protect the path to receive service signal normally.

2, the method for claim 1; it is characterized in that: described protection path is provided with priority; when the service signal that monitors operating path lost efficacy, switch described interconnection selection matrix, select the service signal of high priority to protect the path to receive service signal normally.

3, method as claimed in claim 1 or 2; it is characterized in that: also comprise the following steps: after professional place end selects a certain protection path to receive service signal; if monitoring the service signal of operating path recovers; after through the Wait to Restore Time of setting; if it is normal that the service signal of operating path still keeps; then switch the interconnection selection matrix, select to receive service signal from operating path.

4, method as claimed in claim 1 or 2; it is characterized in that: among the described step B; after professional place end selects a certain protection path to receive service signal; if monitoring the service signal in this protection path lost efficacy; then switch the interconnection selection matrix, select another service signal to protect the path to receive service signal normally.

5, the method for claim 1 is characterized in that: lost efficacy if professional Su Duan monitors the service signal in a certain protection path, then will protect the path to delete from the protection path of appointment; Recover if monitor the service signal in this protection path again, then will protect the path to join again in the protection path of appointment.

6, the method for claim 1 is characterized in that, the physical medium in described operating path and protection path is: optical fiber, cable or microwave.

7, a kind of guard method of optical transport network business may further comprise the steps:

A: between service source end and Su Duan, specify the protection path of two or more transmission channel, transmit the main business signal on the described operating path, transmit the extra traffic signal on the described protection path as an operating path;

B: the service signal in end monitoring path, professional place and all protections paths, if the main business signal of operating path is normal, then the interconnection selection matrix reception by professional Su Duan is from the main business signal of operating path; If the main business Signal Fail of operating path then protects the path to send the bridge joint demand signalling to the service source end by a certain service signal normally;

C: the service source termination is received this signaling, cuts off the transmission of the extra traffic signal in this protection path, with the main business signal replication of operating path and send to this protection path, simultaneously bridge joint is confirmed that signaling sends to professional Su Duan by this protection path;

D: professional place termination is received bridge joint and is confirmed signaling, switches the interconnection selection matrix, selects this protection path to receive the main business signal.

8, method as claimed in claim 7 is characterized in that: described protection path is provided with priority, when monitoring the main business Signal Fail of operating path, selects the service signal of high priority to protect the path to send the bridge joint demand signalling to the service source end normally.

9, as claim 7 or 8 described guard methods; it is characterized in that: if professional Su Duan does not receive the affirmation signaling of source end in a setting-up time; then repeat to send the bridge joint demand signalling to the service source end by this protection path; if still do not receive the affirmation signaling, then send the bridge joint demand signalling by another protection path.

10, guard method as claimed in claim 9 is characterized in that further comprising the steps of:

B1: after professional place end selects the protection path to receive the main business signal, if monitoring the service signal of operating path recovers, after through the Wait to Restore Time of setting, still keep normal as the operating path service signal, then switch the interconnection selection matrix, selection receives the main business signal from operating path, and sends cancellation bridge joint demand signalling by operating path to the service source end;

B2: the service source termination is received cancellation bridge joint demand signalling, cancels the bridge joint of all duplication services, recovers the transmission of extra traffic in the protection path, and confirms signaling by operating path to the cancellation of professional place end transmission bridge joint;

B3: after professional Su Duan receives that signaling is confirmed in this cancellation, the reception that recovers extra traffic.

11, method as claimed in claim 7 is characterized in that: lost efficacy if professional Su Duan monitors the service signal in a certain protection path, then will protect the path to delete from the protection path of appointment; Recover if monitor the service signal in this protection path again, then will protect the path to join again in the protection path of appointment.

12, method as claimed in claim 7 is characterized in that, the physical medium in described operating path and protection path is: optical fiber, cable or microwave.

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