WO2005064825A1

WO2005064825A1 - A method for restoring error linking service in optical transmission loop network

Info

Publication number: WO2005064825A1
Application number: PCT/CN2004/001395
Authority: WO
Inventors: Desheng Sun; Jun Yang
Original assignee: Zte Corporation
Priority date: 2003-12-29
Filing date: 2004-12-01
Publication date: 2005-07-14
Also published as: CN1287558C; CN1555163A

Abstract

The present invention discloses a method for restoring error linking service in optical transmission loop network, which includes: defining unique identifier for each configured service time slot; submitting the identifier information of each of said services to the net element that correlates to the service; continuously monitoring whether the net element in the optical transmission loop network enters ring switching; when detecting the net element that enters ring switching, determining the match state of the service transferred in protection channel with the service that the net element should receive, using the service identifier, and restoring service according to the match state. The method of the present invention can correct the possible error linking service according to whether track identifier of service time slot is matched or not, and make the service restored, so it is full simple and practicality.

Description

Recovery method for optical transmission ring network misconnection service

Technical field

The present invention relates to the field of optical transmission, and in particular, to a method for recovering a misconnected service after an optical transmission ring network element ring is switched. Background technique

Optical transmission ring networks have been widely used in the field of telecommunications. The self-healing ability is an important feature of optical transmission ring networks. ITU Recommendation ITU-TG.841 "Classification and Characteristics of SDH Network Protection Structures" describes the self-healing function of SDH / SONET optical transmission ring networks in detail. Among them, the two-fiber / four-fiber bidirectional multiplexing segment shared protection ring is the most important self-healing method. After the transmission ring network fails, the two-fiber / four-fiber bidirectional multiplexing segment shared protection ring optical transmission ring network initiates ring bridge switching, and Ϋ restores transmission services that were interrupted due to the failure. The so-called bridging is a measure that the network element sends services to the working service channel and the protection channel at the same time. The so-called switchover refers to that when the network element receives the service, the original way of receiving the service from the working service channel is changed to receiving the service from the corresponding protection channel. Measure ₀

However, if this kind of failure occurs in the transmission ring network, the entire transmission ring network is decommissioned, that is, from the perspective of physical connection or service transmission, the transmission ring network is broken down into several isolated ones. Partly, at this time, services transmitted through different cross-segments may compete for time slots on the same protection channel, which will lead to incorrect connection of the services, that is, misconnection.

As shown in the network shown in FIG. 1, under normal circumstances, network element B sends services to D along B-> A-> D (hereinafter referred to as B-> A-> D services), and network element D follows D-> A. -> B sends a service to B (hereinafter referred to as D-> A-> B service). When two services pass through network element A, timeslot crossing is performed, and the timeslot position is changed. ; 8->-> 0 services are transmitted in the B-> A segment as 1 # industry ^, which is the service transmitted on the 1 # channel), and in the A-> D section, they are transmitted as 2 # services (referred to as the services transmitted on the 2 # channel). To D; and the service of D-> A-> B is the 2 # service in D-> A section, and it is transferred to B as a service in-> 8 section.

Since the protection services correspond to the corresponding work services in number sequence, their channels Corresponding (for details, see the description of the multiplex segment shared protection ring in sections 6.1 and 7.2 of Recommendation ITU-TG.841), after the network element B and D are switched, the network element D will be protected from the 2 # service. Channel to restore services. Network element B will restore services from the protection channel corresponding to 1 # service.

As shown in Figure 2, when the optical fiber between NE A and NE B, and between NE A and NE D fails, NE 8 and D activate the two-fiber / four-fiber ring protection function, in the direction of B-A and D- A direction initiates ring bridge switching measures to restore the original 8->-> 0 and 0-> in->; 6 services. At this time, bridge switching occurs between network elements B and D, and network element C is in a through state. Network element B changes the protection channel corresponding to the 1 # service to send services to network element D along B-> C-> D, and network element D However, the service is received from the protection channel corresponding to the 2 # service in the D <-C direction. Similarly, the D network element sends the service to the network element B along the D-> C-> B from the protection channel corresponding to the 2 # service. B receives the service from the protection channel corresponding to the 1 # service in the direction of B <-C. As a result, the network elements B and D received not the specified protection service on the protection channel, and a service misconnection occurred. The main reason for the misconnection is that network elements B and D do not know how network element A crosses their time slots.

In order to ensure the security of the transmission service, when a misconnection occurs, it is required to immediately interrupt the misconnection service. The method of interrupting the service is usually to push the corresponding transmission channel (AIS). ITU-T G.841 recommends that this operation process is called squelching. For example, if the transmission channel is a management unit group (AUG), the management unit_alarm indication signal (AU_AIS) is pushed into the channel; if the transmission channel is a branch unit group (TUG), the branch is pushed into the channel Road Unit—Alarm Indication Signal (TU—AIS). When the service receiving end detects the AIS alarm indication, it automatically interrupts the received service. Chinese patent No. ZL 99123039, entitled "Mistaken Connection and Error Prevention Method in Ring SDH Optical Transmission Network", describes a method for identifying misconnection services and performing misconnection services through channel overhead bytes J1 or J2 The suppression method can effectively prevent the service misconnection phenomenon caused by time slot crossing, but cannot restore the service.

Slot crossing can make better use of the bandwidth of the ring network. Therefore, in the field of optical transmission, time slot crossing is a very common phenomenon. As disclosed in the above example, after a power failure, a core single board failure, an optical fiber interruption on both sides of the network element, and optical components in two directions, such as a time slot crossover, a service cannot be performed due to time slot crossover. Normal connection, in this case, although business and connection The protection channel receiving this service does not correspond, but it can still be transmitted to the destination, so there is a possibility of recovery. Summary of the invention

In view of this, the technical problem to be solved by the present invention is to provide a method for recovering the misconnection service of an optical transmission ring network, which can recover services that cannot be connected normally after certain faults occur due to timeslot crossing.

In order to solve the above technical problems, the present invention provides a method for recovering a misconnected service of an optical transmission ring network. The method assigns a unique identifier to each service time slot, and uses the identifier to control the occurrence of a ring in a related network element in the optical transmission ring network. Services are restored after the switchover.

Preferably, the method includes the following steps: designating a unique identifier for each configured service slot; delivering the identification information of each of the services to a network element related to the service; continuously monitoring the network element in the optical transmission ring network Whether a ring switch has occurred. When a ring switch is detected on the network element, the service identifier is used to determine the matching between the service transmitted in the protection channel and the network element should receive the service, and the service is restored based on the matching situation.

Preferably, the determining step further includes: determining whether the above-mentioned ring-switched network element determines whether the service transmitted in the protection channel corresponding to the network element and the identifier of the service that should be received stored in the network element match; When it is matched, the service transmitted by the corresponding protection channel is received; when the above determination result is that the identifiers do not match, all other protection channels are queried for the service that matches the service identifier stored in the network element. If a matching service is found, it is received The matching service, otherwise, suppress the services transmitted by the protection channel corresponding to the network element.

Preferably, the determining step further includes: when more than one service receiving identifier should be stored in the network element where the ring switching occurs, determining the matching situation of the transmission service in the protection channel for each service receiving in turn to perform the service restore.

Preferably, the determining step further includes: regularly detecting a network element ring switching condition in the optical transmission ring network.

Preferably, the timing detection step further includes: periodically detecting whether the ring switching of the network element is cancelled, and if the ring switching is cancelled, the method continues to monitor steps; if the ring switching is not cancelled, Then, it is detected whether the switching state of the optical transmission ring network changes, and if the change occurs, the determination step is performed again; otherwise, the timing detection step is continuously performed.

Preferably, the step of specifying further includes: presetting an identifier of a service to be received at each configuration of the photoelectric branch processing unit where the service is dropped.

Preferably, the designating and issuing steps are performed by a network management layer of the optical transmission ring network. Preferably, the service identifier is stored in the byte J1 or J2 of the channel overhead POH byte for channel tracking identifier.

On Preferably, the service-related network element comprises the service, and passes the network element NE ₀

It can be known from the above that, compared with the prior art, the method according to the present invention can correct a possibly misconnected service and restore it according to whether the tracking identifiers J1 / J2 of the service timeslots match; Staggered business is suppressed. The operation is simple and has good application value. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic diagram of a transmission ring network transmitting services under normal conditions;

FIG. 2 is a schematic diagram of a transmission ring network with a service misconnection in the case of a fault; FIG. 3 is a flowchart of a method according to an embodiment of the present invention. detailed description

In the STM-N (Synchronous Transport Module level N), there are two bytes of path overhead POH (Path Overhead) bytes for channel tracking identification, and byte J1 is used for VC3 / VC4. Channel tracking ID, byte J2 is used for the channel tracking ID of VC1 / VC2. When the service slot configuration of each network node is performed by the present invention, a unique and effective channel tracking identification byte is assigned to each inserted service (whether a high-order VC or a low-order VC), and is allocated in this service. The channel tracking identification byte to be received is preset at the optical tributary processing unit, and J1 / J2 remains unchanged during transmission. The invention solves the problem that services cannot be disabled after certain faults occur due to time slot crossing by judging J1 / J2. Problems with normal connection.

FIG. 3 is a flowchart of an embodiment of the present invention. As shown in the figure, the recovery method of this embodiment includes the following steps:

The network management layer assigns a unique identifier J1 / J2 for each configured service time slot, step 100; the network management layer sends the information of the service identifier J1 / J2 to the relevant network element, step 110;

Each network element detects whether a ring switch occurs, and if so, performs the next step, otherwise continues to detect, step 120;

The network element that has undergone the ring switch receives the service from the protection channel, and judges in advance whether the identification J1 / J2 of the service transmitted by the protection channel matches the standard ^ J1 / J2 of the service to be received, and if so, performs step 150a; Otherwise go to the next step, step 130;

Query the identity of all other protected channel services J1 / J2, if a matching service is found, go to step 150a, otherwise go to step 150b, step 140;

Receiving the service, step 150a;

Suppress the business, step 150b;

Determine whether all services have been processed, and if so, go to the next step, otherwise return to step 130, step 160;

Detect whether the ring switching of the ring network is canceled, and if so, return to step 120; otherwise, execute the next step, step 170;

Determine whether the current switching status of the ring network has changed. If yes, go back to step 130, otherwise go back to step 170 and step 180.

In order to understand the above process more clearly, the optical transmission ring network described in FIG. 1 and FIG. 2 is still taken as an example. Normally, the services of B-> A-> D, D-> A-> B are performed in network element A. Slots cross, where B-> A-> D's service B is sent as W service and D is received as 2 # service, D-> A-> B's service D is sent as 2 # service and B is 1 # After the service is received, then the fiber between A <-> B and A <-> D fails, and then A <-> B recovers, and finally A <-> D recovers. Analyze the specific implementation of the invention recovery method.

In step 100, the network management layer assigns a unique identifier to each configured service slot, which is generally specified during networking. It is assumed that the identifiers specified for the B->A-> D and D->A-> B services are respectively for JB and JD (for illustration only);

In step 110, the network management layer delivers the J1 / J2 information of each service to the relevant network elements. The relevant network elements refer to the network elements that are up, down, and passing through the service. Among them, B received 1 received from A-> B. # The identification of the service is JD; the identification of the 2 # service that D receives from the A-> D direction is JB.

In step 120, when the optical fibers between the network element A and the network element B, and between the network element A and the network element D are faulty, the network elements of the network elements B and D have detected that ring switching is to occur, and this process may refer to the provisions of G.841;

In step 130, in the process of performing the bridge switching, the network element B needs to receive services from the protection channel in the direction of B <-C to recover the faulty service originally transmitted in the direction of A-> B. Before receiving, it is necessary to judge the Whether the identification of the service matches the identification of the original A-> B transmission service. For the 1 # service transmitted in the original A-> B direction, its identification is JD, so after the bridge switchover, B will determine whether the label of the service transmitted by the 1 # service corresponding to the protection channel is only JD, because the original D- The service of> A-> B is transmitted along the protection channel corresponding to the 2 # service of D-> C-> B after D bridge (C is in the through state), so it does not match. Similarly, the protection channel corresponding to service # 2 of network element 0 cannot find the service identified as JB.

In step 140, B and D will query the service identifiers of the other protection channels. At this time, B will find a matching service with the identifier JD in the protection channel corresponding to the 2 # service; D will find the identifier in the protection channel corresponding to the W service. Matching business for JB;

Then, B and D will perform step 150a, that is, receive the found service, so that the service transmitted between the network elements B and D is restored; (at this time, if B and D cannot find the service after querying all the protection channels, Identifying a matching business, that is, suppressing it)

In step 160, B and D process all the services in the same manner;

When the fault between network elements A <-> B recovers, network element B's switchover is canceled and the service is received from the working channel instead. Network element A will detect that a ring switch is about to occur. D. When it is judged in steps 170 to 180, it is a case where the ring network ring switching is not cancelled but the switching status changes. The network element D can determine the current switching network element by judging the information such as protection switching signaling and alarms currently received. Becomes D, and the switching status changes. Therefore, the network element D will re-determine whether the service ID sent by the protection channel corresponding to the 2 # service is JB, that is, repeat steps 130 ~ 160 _0. The original A <-> D service is switched to A (protection channel) <-> B (protection channel) <-> C (protection channel) <-> D (protection channel), B after A and D bridge switching. , C will pass through the protection channel. The 8->-> 0 service identified by JB is sent from B, and takes channel 1 # to reach A, and after A is bridged (A's bridge and switching of services is performed according to the time slot crossover situation, and the network element A still needs to Crossing), enter the protection channel corresponding to the 2 # service in the A-> B direction, and follow the protection channel corresponding to the 2 # service when transmitting along A->B->C-> D, so D will be in the 2 # The service corresponding protection channel finds the matching service identified by JB and receives it. After all the services are processed, network element D continues to detect whether the current network element switching is cancelled and the switching status is changed. After ring switching of network element A, the same as the above-mentioned invention. Method to process the service; (If the fault between A-> B and A-> D is still the same, ^ D continues to detect whether the ring switch is cancelled)

When the fault between the network elements A <-> D is also recovered, the network elements A and D finally cancel the switching, and each network element normally sends and receives services, and detects whether a ring switching occurs, and returns to step 120.

It can be seen from the implementation process described above that the method of the present invention can recover the misconnection service caused by time slot crossing. Only when there is no way to rectify it is possible to suppress possible misconnections. The operation is simple and has good application value.

Claims

Rights request

What is claimed is: 1. A method for recovering a faulty connection service in an optical transmission ring network, characterized in that a unique identifier is assigned to each service time slot, and the identifier is used to control the service recovery of a related network element in the optical transmission ring network after ring switching.

2. The method according to claim 1, wherein the method comprises the following steps: assigning a unique identifier to each configured service slot;

Send the identification information "F of each service mentioned above to a network element related to the service;

Continuously monitor whether network switching occurs in the network elements in the optical transmission ring network;

When ring switching is detected in the network element, the service identifier is used to determine the matching between the service transmitted in the protection channel and the network element should receive the service, and the service is restored based on the matching situation.

3. The method according to claim 2, wherein the determining step further comprises: whether the identification of the service to be received stored in the network element matches;

When the foregoing determination result is a match, the service transmitted by the corresponding protection channel is received; when the foregoing determination result is an identifier mismatch, all other protection channels are queried for a service that matches the service identifier stored in the network element, and if a match is found The service receives the matching service; otherwise, the service transmitted by the protection channel corresponding to the network element is suppressed.

4. The method according to claim 2 or 3, wherein the determining step further comprises:

When there is more than one service receiving identity in the above-mentioned network element in which the ring switching occurs, the matching situation of the transmission service in the protection channel is determined for each service receiving in turn for service recovery.

5. The method according to claim 2 or 3, wherein the determining step further comprises:

Periodically detect the network element ring switching in the optical transmission ring network.

6. The method according to claim 5, wherein the timing detection step further comprises: Periodically detect whether the ring switching of the network element is cancelled,

If the ring switch is cancelled, the method continues the monitoring step;

If the ring switching is not canceled, it is detected whether the switching state of the optical transmission ring network has changed. If the switching state is changed, the determination step is performed again. Otherwise, the timing detection step is continuously performed.

7. The method according to claim 2, wherein the step of specifying further comprises: presetting an identifier of a service to be received at each of the optoelectronic branch processing units configured to insert service drops.

8. The method according to claim 2, wherein the designating and issuing steps are performed by a network management layer of the optical transmission ring network.

9. The method according to claim 1 or 2, wherein the service identifier is stored in a byte J1 or J2 of a channel overhead POH byte for a channel tracking identifier.

.

10. The method according to claim 1 or 2, characterized in that, the related network elements of the service include upper and lower network elements of the service and network elements that pass through.