KR100861765B1 - Method for establishing, restoring and protecting service connection in an optical network - Google Patents

Abstract

The present invention relates to a method of establishing, recovering and reporting a service connection in an optical network. The optical network includes a transmission plane plane system configured as a plurality of transmission network elements and a control plane system configured by a plurality of control nodes. By determining link connections and subnet connections, the control node establishes a regular service connection and a virtual connection in response to the service request. When a service error occurs, the service is recovered by establishing a virtual connection or dynamically rerouting. After the service error disappears, the service returns to the regular service connection in response to the service return request. In order to optimize the use of network resources, the connection, protection connection and virtual connection of the service layer supporting the client layer connection is dynamically established according to the needs of the client layer.

Description

Method for establishing, restoring and protecting service connection in an optical network

TECHNICAL FIELD The present invention relates to the field of optical networks, and more particularly, to a method for establishing, recovering, and protecting service connections in a reconfigurable optical network composed of SDH / SONET or WDM network devices.

In the early stages of the prior art of repairing service errors in optical networks, protection techniques such as multiplexing section protection mechanisms and end-to-end path protection mechanisms were mainly used. In this type of protection technology, when allocating working path resources in an optical network, a protection path for a protection service must be simultaneously allocated. This is because even without considering the dynamic bandwidth requirements of service protection and restoration, there is a significant waste of network bandwidth resources that are inefficient to protect the service.

To overcome the shortcomings of traditional protection techniques for repairing service failures, dynamic protection techniques have been applied to optical networks. That is, a working connection that supports a service connection in response to receiving a service request, and recovers the service by applying a predetermined route or a dynamic route when the original service connection error affects the service. And protect the service by setting up a protection connection. In order to increase the efficiency of service recovery, one may consider using a distributed control mechanism instead of a traditional central control mechanism. Furthermore, it may also be considered to provide a predetermined route when establishing a working connection so that an alternate connection can be established to quickly recover from a service failure. Furthermore, when using a distributed control technique, resource reservation is used for a predetermined route. More specifically, in order for an alternate connection to be established quickly by assigning a predetermined route resource and setting up a cross-connection of each node. All nodes traversed by route are formed by reserved route resources.

 US patent US5748611 discloses a path based on a recovery method for a gradually distributed stepwise route, the process of which is as follows.

(a) The source node broadcasts a PACK message that includes the source node, destination mode, and path ID information.

(b) When a tandem node receives the first copy of the PACK message, the serial node increases the number of hops in the message, where this number is also the number of spans, and the message Re-broadcasts the message through all spans except spans received. When a serial node receives a second copy of a PACK message, it only sends the received message through the span from which the first copy was received. The third and fourth copies of the PACK message are not broadcast again.

(c) When a destination node receives a PACK message through a span, the destination node responds with an ACK message to conservatively reserve bandwidth to that span for a recovery path.

(d) When the serial node receives the ACK message, it transmits the received ACK message along the recovery path indicated in the ACK message to reserve the bandwidth.

(e) When the source node receives the ACK message, the source node transmits a CONF message through the recovery path. Because each serial node sends a CONF message, the serial nodes connect redundant links corresponding to the messages to form a recovery path. When a CONF message is received at the destination node, a recovery path can be created and the stopped communication can be restored.

The method of the patent selectively broadcasts a recovery message to reduce message traffic. And because of conservative bandwidth reservations, recovery of interrupted paths only requires the reservation of the required resources. Thus, the actual usage rate of resources is increased. Because only recovery is available for segments where bandwidth is available, the selection speed of the segments is increased . However, this technique does not support the source route mode of the present invention.

In US Pat. No. 6,430,150 a mesh network service restoration technique is disclosed. This patent is characterized by the first aspect in which physical and logical topology information relating to the network as a whole is stored in each network element. When the network element checks for errors, it dynamically calculates an alternate route and then sends a command to perform time slot cross-connections. In addition, the patent provides that network elements store physical and logical topology information related to the entire network in advance, and further alternate routes to errors on each path. ) Is characterized by a second feature that is precomputed and stored. If a network element finds an error, time slot cross-connections are established directly corresponding to the alternate routes stored in that network element.

This patent is a table corresponding to resources allocated throughout the network, i.e., a time slot, referred to in this patent as a 'physical topology table' as shown in Figures 1A and 1B. The main features are the resources used and the extras stored in each network element.

On the other hand, each network element has information about a link path and capacity for a service to be formed-as shown in Figs. 2A and 2B, which is referred to as " logical topology table " Named at-additionally stored.

In the event of an error – either a line alarm indication signal (L-AIS) or a far end received failure (FERF) signal – a network element close to the point of failure can provide error information throughout the network. Broadcast The network element that receives the alert message uses the locally stored information to find an alternate path and routes it using a well-known algorithm (for example, the Dijkstra algorithm to find the shortest route). (route) Perform the calculation. Using this patented routing algorithm, it is believed that consistent computational results (alternate paths) will be obtained for each network element. In practice, however, this approach does not guarantee consistent results. In other words, there are still some problems in the feasibility and reliability of this method.

According to European patent EP1303934, it is possible to solve the complexity of the configuration of multiplexing section protection and to solve the problem of time consuming of the route based restoration. Paths based on the protection technology of interest are provided. Thus, each working connection formed corresponding to a route table that stores the protection connection for each working connection is particularly useful for protecting the MESH network and for fast recovery. Is characterized.

The motivation for this patent is to provide path protection techniques that solve the problems caused by the complexity of BLSR configuration and the problems associated with performing the restoration of the route based technique. . Although this technique is more efficient than the conventional technique, the process is complicated, especially at 10G or more speed, because it uses the root table, issues overhead in the path, and the root table must be constantly updated. This is even more true for a working network.

US patent US 20020097671 relates to a method of selecting a recovery route on a MESH telecommunications network, which advantageously presees a recovery path of a link according to link capacity at an early stage of initiating service connection. Calculate The method of selecting a recovery path includes searching for a link that is physically different from a service path, calculating weights according to the capacity of the links; Selecting an appropriate recovery path for service recovery based on the load. The main feature of this patent is the route based on the recovery method, but it does not guarantee the recovery time of the service.

US Patent US20020030864, which includes recent recovery techniques, generally relates to the method of controlling and managing connections in reconfigurable optical networks and to recovering services in the event of a failure. The main method according to this patent is to establish a working connection and a predetermined route in a distributed manner corresponding to a request requiring recovery in the event of an error and the predetermined Reserve channel capacity resources for all nodes traversed by the route. In order to realize fast recovery in the event of a working connection failure, nodes traversed by a predefined route allocate channels and establish lightpath cross-connections. ). Once the predetermined route is determined, the reserved resource is shared by all predefined nodes of different Shared Risk Link Groups, and the link capacity information (e.g., available capacity) is dynamically shared. It is noted that a protocol such as OSPF is required to update the reservation capacity and the like (it is noted that). However, in addition to the disadvantages described above for this patent, the following disadvantages still exist.

(1) The optimization of the working connection may not be guaranteed. Because, after a working connection is made, a predetermined route (i.e. alternate route) calculation and resource reservation for the alternate route are not guaranteed.

(2) If there is no reservation for link connection and there is reservation only for path resource, especially when signal terminal of transmitting device has multi-mode adaptive function, It may not be possible to effectively monitor the occurrence of an error on a given route. This is because a service connection is composed of a subnet connection and a link connection. If the link connection does not exist physically, the link connection cannot be effectively monitored.

(3) In starting the reserved connection (In setting up the reserved connection), the source node has a working connection corresponding to the reserved connection for all nodes traversed by a virtual connection ( It is not possible to notify the Share Risk Link Group information of the working connection. Thus, it is impossible for a node traversed by this connection to reserve path resources of other Share Risk Link Groups. In other words, reserved resources cannot be shared efficiently by such nodes.

Although it is currently practiced to dynamically establish a connection to dynamically utilize bandwidth resources at the request of a client, there are still some drawbacks to the technology for initiating service connections, recovering and protecting services as described above. do.

(a) Although telecommunications is a multi-layer network, traditional protection and recovery mechanisms are primarily for single layer networks, and the relationship between the client-service relationships of the network Without consideration, it results in a significant waste of path resources. For example, if protection and recovery are reserved for a VC-4 connection in the SDH VC-4 service layer network, but no client service is loaded on the VC-4 connection, Recovery scheduling obviously wastes resources in the path and leads to redundancy to the system. Further, it will seriously waste path resources without considering initiating a service layer connection based on the client layer's request.

(b) Current service recovery techniques may establish an alternate connection (but this is inefficient for recovery) to recover the service in the event of an error, or pre-alter the alternative connection. This is done by specifying and reserving path resources for alternate connections. However, the latter does not take into account dynamic changes in resource and network topology to determine an alternate connection reservation, and also without consideration for maintaining an alternate connection. Therefore, it is unlikely that the current alternate connection and reserved resources used in the event of an error can be effectively utilized. For example, if an alternate connection cannot be established successfully with a reserved resource for restoring a service, a mechanism for dynamically reestablishing an alternate connection as the network resources change can not be realized.

(c) The prior art does not provide a solution to avoid new errors in the process of returning the service itself after removing the first error.

(d) Current solutions do not completely solve the resource conflict problem. This is because the entire network does not have a unique priority in order to establish a service connection in case of a conflict between resources. For example, if resource allocation for a link connection conflicts in the process of establishing a service link across the link, the traditional method is to determine the priority based on the network element's ID priority at both ends of the link. will be. However, this priority is not unique for all connections throughout the network, and ends up with a conflict problem that cannot be resolved. For example, a network element located at the left end of link L1 (ie 'A end') may have a higher ID priority than a network element located at the right end of link L1 (ie 'Z end'). Can be. On the other hand, for link L2, the network element located at the left end of link L2 (that is, 'end A') is higher than the network element located at the right end of link L2 (ie 'Z end'). May have priority. During the process of setting up the end-to-end connection c1 and c2, if c1 crosses the A end of link L1 and c2 crosses the Z end of link L1, a common link connection resource is established. Because there is a conflict between c1 and c2 as they are competing a common link connection resource. According to the priority, c1 has a priority to obtain a link connection resource, and c2 must give up the link connection resource. However, if c1 and c2 are competing for link link resources again at link L2, and if c2 is first passing A end of link L2, c2 has priority to obtain link connection resources. Since these two similar service connections have relatively different priorities on the two competing processors described above, no connection may be established to avoid collisions.

Summary of the Invention An object of the present invention is to efficiently utilize a transmission channel resource for establishing a service connection in an optical network in a reconfigurable network including an SDH / SONET or WDM network element, and when an error occurs in the optical network. Service connection establishment, which has a stable and efficient mechanism for efficiently recovering services, affecting them, optimizing network resources during recovery and recovery, and restoring services when errors on the optical network are eliminated. setting up, service recovery and service protection.

It is yet another object of the present invention to use a virtual connection technique to recover service errors in an optical network, and to consider the relationship between client layer connection and service layer connection. And dynamically establish a service layer connection, and then recover and protect the service layer connection in response to a request for protection and recovery of the client layer connection, It provides a method of setting up a service connection setting (service connection setting up), a method of recovering a service, and a method of protecting a service that can use all optical network resources.

In order to achieve the above object, to establish, protect and restore service connection in an optical network including a transmission plane system and a control plane system 1. A method comprising: wherein the transport plane system comprises a plurality of transmission network elements, each network transport network element uniquely corresponding to a control node of the control plane system,

Step 1: starting a timer to establish a virtual connection to each control node;

Step 2: As soon as a service request is received, a link connection and a subnet connection are determined by the control node to establish a regular connection supporting the requested service. And establish or assign the link connection and notify the transport plane system to establish the subnet connection;

Step 3: After the timer for establishing the virtual connection at the control node expires, start searching for a service request for which the virtual connection needs to be established, and matching the condition for establishing the virtual connection. Starting a process of establishing a virtual connection for each retrieved service request, and then restarting a timer to establish a new virtual connection;

Step 4: determining a route in a source route mode to establish a virtual connection for the service;

Step 5: in the event of a service error caused by a failure in normal service connection, initiating service recovery according to the service priority; And

Step 6: performing a process of returning to the regular service connection in response to a service-revertible request according to removing an error occurring in the original regular service connection after service recovery is completed. Provides a way to set up, protect, and recover a connection.

According to an aspect of the present invention, if it is necessary to apply the virtual connection to recover a service error according to the strategy of the control system or the priority of the service, the service connection is maintained after establishing a regular service connection. The timer for starting the virtual connection of step 1 is started during or during the initialization of the control plane system.

According to one aspect of the invention, the step 2, when the control plane system receives a service request from a client layer, to the service layer to establish a connection for the current service If the client layer connection resources currently provided are insufficient, the service layer connection request is activated in a dynamic manner, first a service layer connection is established to support the client layer, and then The client layer is established, wherein a protection connection and a virtual connection of the service layer connection are dynamically established or released in response to a request for protection and restoration of the client layer service.

According to an aspect of the present invention, when a series of client layer services having the protection and repair request are transmitted on the same service layer connection, the working connection for the service and the protection in case of insufficient network resources The connection is allowed to partially share a common route, and the working connection and the protected connection may use common link connection sources on a common route.

According to one aspect of the invention, during or after the process of establishing the service layer connection, the transport network located at both ends of the service layer connection through exchanging information of the adaptive client layer paths at both ends of the service layer connection. Corresponding to the element, information about all link connection relations included in the service layer connection is captured by the control node.

According to an aspect of the present invention, the virtual connection for the service of step 3 depends on the following conditions.

<Condition>

(1) The regular service connection is established.

(2) A virtual connection mode is required to be used to provide a reliable fault restoration mechanism for the service according to the service priority or the control system strategy.

According to one aspect of the invention, the step of establishing a virtual connection in the step 4 comprises the steps of determining a virtual connection route in the source root mode; And after the virtual connection route is determined, determining a selection of a link connection source, determining the subnet connection relationship by the control node corresponding to each of the network elements traversed by the virtual connection, Notifying the transmission plane to establish or assign the link connection and to establish the subnet connection.

According to one aspect of the invention, the strategy of determining the route in step 4 is considered in the extent to which the dissolution of routes including disjoint of nodes and links is possible in order to establish virtual connections and regular service connections. The virtual connection route should not include the virtual connection route in a shared risk linkage group of the regular connection route to the extent possible, and the virtual service of the same service when the network resource is insufficient. Sharing a portion of a common route between a connection and the regular connection, wherein the strategy of selecting the link connection resource constituting the virtual connection is that the link connection resource traversed by the virtual connection is another virtual connection. Can be shared by other clients and snatched by other regular service connections. And the strategy for notifying the transmission plane to select a link connection resource after configuring the link connection resource constituting the virtual connection, if the transport network element passes through the virtual connection. If the link connection can be monitored independently, the transmitting network element is notified to establish a link connection and not to establish a subnet connection.

According to an aspect of the present invention, the strategies for selecting the link connection resource constituting the virtual connection are shared by the source control node in the risk sharing group of the regular service connection at the beginning step of configuring the virtual connection. Notifying the control nodes to be traversed by the virtual link with information of a Risk Link Group); Storing in each control node information about the shared risk link group of the regular service connection corresponding to the virtual connection for each link connection used by the virtual connection; When the virtual connection and the regular connection share a part of a common route, sharing a common link connection resource by a virtual connection and a regular service connection of the same service when the network resource is insufficient; If the Shared Risk Link Groups of the regular connections of two services are different, sharing a common link connection resource by two virtual connections of the two services; If the Shared Risk Link Groups of the regular connections of the two services are partially different, not sharing as much of the common link connection resource as possible by the two virtual connections of the two services ; And if the Shared Risk Link Groups of the regular connections of the two services are the same, not sharing a common link connection resource by two virtual connections of the two services.

According to one aspect of the present invention, in order to update the network topology as the link information broadcasted along each layer of the link changes, the control node is configured to establish a connection of each link during the establishment of the service connection. Broadcast the link state information.

The link information includes the number of spare link connections, the number of link connections that can be snatched, and the number of spare link connections that can be used by the virtual connections.

According to an aspect of the present invention, the link state information is equal to 1 when the number of link resources that can be shared by the virtual connections and the number of the virtual connections that share the common link connection resource reach a maximum value. The number of link resources shared by the virtual connection to be subtracted further.

According to an aspect of the present invention, the starting of the service recovery of the step 5 may include starting a recovery wait timer; When the recovery wait timer expires, searching for the existence of an error-free virtual connection if an error still exists among all the regular service connections; If there is a virtual connection, the service source control node sends a " USE " command from each control node that receives the " USE " command to the control node of the next transmitting network element traversed by the virtual connection. Sending a "USE" command to the control node of the next transport network element traversed by the virtual connection, and performing the "USE" action of the virtual connection, wherein the "USE" processing of the virtual connection is performed by: Notifying the transport network element to establish subnet connections by a source control node and all the control nodes that have received a “USE” command; Sending additional notifications to the transport network elements to establish the link connection if there is no link connection established prior to the virtual connection establishment in the transport plane system; If the virtual connection includes corresponding subnet connections and link connections in the transport plane system, executing as a replacement connection changing the virtual connection to a real connection; If the virtual connection is successfully changed to the real connection and there is currently no error in the virtual connection, changing the service from the regular connection to the alternate connection to recover a service error; If there is no available virtual connection without errors or the establishment of the virtual connection fails, dynamically rerouting to establish a new alternate connection to recover from a service error; And if the service error is not cleared when the recovery wait timer expires, changing the service from the regular connection to the alternate connection for transmission to recover the service error.

According to one aspect of the invention, if the service connection to be recovered is a service layer connection and there are two opposite ends traversed by signals of multiple client layer connections, the replacement After the establishment of service layer connections all client layer connections are changed to the alternate service layer connection,

According to one aspect of the invention, if the service connection fails and does not transmit a client layer connection signal, then the current service connection is a service layer connection and the use of the service layer connection by the client layer connection When the control node recognizes that it is controlling, the recovery does not begin.

According to one aspect of the present invention, if the restored service does not include a service return request, the attribute of the replacement connection is changed to the regular connection and the original regular connection is deleted or the original normal connection is deleted. The alternate connection together constitutes a regular service connection consisting of a working connection and a protected connection, or the original regular connection is changed to the virtual connection of the service,

If the recovered service includes a service return request, when the original regular service connection error is eliminated, the service returns to the normal connection, and the return process starts a return wait timer; If the original regular connection was deleted during the recovery, establishing a regular connection according to the information of the original regular connection stored in the control node; If the original regular connection is not deleted during the recovery and changed to the virtual connection, first changing the virtual connection to the real connection to reconfigure the original regular connection; And when the return waiting timer expires, if the original regular connection has been established, returning the service to the original regular connection for transmission.

According to an aspect of the present invention, in order to prevent a new error caused by a large time difference in performing a recovery process between the source network element and the destination network elements, before disconnecting the replacement connection, The forwarding process and the preceding reception are performed at the source end and destination end of the service.

According to one aspect of the invention, if a service error occurs after the recovery and there is an alternate connection, the alternate connection is deleted and recovery resumes.

According to one aspect of the invention, the method of any one of claims 1, 16 or 17, wherein the step 2 includes the establishment of the virtual connection, the establishment of the service connection is the allocation of the link connection resources The process further includes, in order to resolve an allocation conflict of link resources, the allocation process is performed based on a unitied competition rule for the entire network, wherein the criterion of the competition rule is (1). Competing based on the service connection priority, (2) using a source transmission network element ID of the connection as the connection priority, and (3) if the source of the connection is the same In the case of a transport network element a different connection ID for different connections by the control nodes and the priority by the designated connection ID Including those decisions.

According to one aspect of the present invention, the method according to any one of claims 1, 16 or 17, wherein the control node is provided to the corresponding control node and topology information of each layer of the optical network including link information. Channel resource state information of each optical transmission network element controlled by the same, but having the same type of signal of the link connection included in all links included in the topology information of each layer.

According to one aspect of the invention, the transmission network element of any one of claims 1, 16 or 17 is exchanged with a subnet consisting of a plurality of network elements.

1A and 1B illustrate physical topology information of a conventional optical network.

2A and 2B illustrate logical paths and logical topology information of a conventional optical network.

3 is a diagram illustrating a configuration of an optical network system according to an embodiment of the present invention.

4 illustrates the application of a virtual connection according to an embodiment of the invention.

FIG. 5 illustrates a relationship of service-client layer link connection according to an embodiment of the present invention. FIG.

6 illustrates an exemplary application of a service-client layer network connection in accordance with an embodiment of the present invention.

 3 is a diagram illustrating a simplified exemplary configuration of an optical network system according to an embodiment of the present invention. Here, the optical network is a reconfigurable network composed of SDH / SONET (Synchronous Digital Hierarchy / Synchronous Optical Network) network elements (NEs) or Wavelength Division Multiplexing (WDM) network elements (NEs).

Here, 'reconfigurable' means that it is possible for network elements to establish a cross-connection. In other words, in order to adapt to a channel that can be selectively used to establish a link connection that can be used in real time, the transmission signal is transmitted in a manner that crosses each other from one channel to another channel, and the various network elements are different from each other. This means that it has multiplexing capabilities. These channels are various signal transmission channels such as channels of reconfigured and multiplexing sections, signal channels and wavelength channels under the multicasting section, supported by SDH / SONET devices or WDM devices. In the context of the present specification, channel cross-connection is called a sub connection, and the network element is considered a mini-sized subnet according to the present invention.

Referring to FIG. 3, an optical network according to the present invention includes a control plane system 10 and a transmission plane system 20.

The transport plane system 20 is a reconfigurable optical network composed of a plurality of transport network elements 21, which are scheduled to assign or establish link connections and subnet connections. The transport network elements 21 here are selected from SDH / SONET network elements or WDM network elements. Communication is established between control nodes 11 corresponding to adjacent transport network elements 21 and corresponds to transport network elements 21 adjacent to transport network element 21 controlled by control node 11. Thus, the address of the other control node 11 is stored in each control node 11.

The control plane system 10 comprises a plurality of control nodes 11, each control node 11 corresponding to only one transport network element 21. Each control node 11 stores topology information for each layer of the entire optical network and channel resource status information (e.g., channel availability) for transport network elements under the control of the control node, and stores the connection. This information is used to set up and maintain and control the system to update network topology information over time.

The information of this topology includes information of the topology for each layer of the optical network, and the information of the topology of each layer includes link information and channel resource state information of the optical transmission network element controlled by each control node. Here, the link connection signals included in all links included in the information of each layer topology are the same. Furthermore, each control node 11 stores connection information of the transmission network elements controlled by the above-described control node 11. Communication is established between the control nodes 11 in correspondence with adjacent transport network elements 21, and each one of the control nodes 11 is controlled by the control node 11 described above. Since the addresses of the other control nodes 11 of the transport network elements 21 adjacent to are stored, therefore communication can be established directly between adjacent nodes, and messages can also be transmitted between non-adjacent nodes. Communication may also be established through serial control nodes to achieve the same. In addition, several control nodes 11 are responsible for maintaining the information of the topology for the entire network as well as for calculating the route during connection establishment for the entire network.

The main function of the control plane is to establish, release, and maintain end-to-end connections. Here, the end-to-end connection consists of a link connection and a subnet connection according to the present invention, and also simply called a connection.

All control nodes 11 can further communicate with the corresponding transport network element 21 to control the channel resources used by the transport network element 21, and state information (eg, links) of the channel resources. Error), and control the transport network element 21 to establish link and subnet connections. During the establishment of an end-to-end connection supporting a service, all control nodes 11 of the entire network are different in order to determine a connection consisting of multiple link connections and subnet connections. In cooperation with the control node, the transport network elements 21 corresponding to the respective control nodes then complete assigning or establishing link connections and subnet connections. The control node 11 here may be included in a corresponding transport network element that is controlled solely, or may be a separate, substantially hardware device or application software implemented in the network elements.

If the control plane decides to use a link connection that does not exist in the transport plane, a notification must be sent to the transport plane to establish this link connection, and if the control plane needs to use a link connection that exists in the transport plane It should be explained that the notification assigning this link should be sent to the transport plane. The link connection is determined as the channel address across the link in the service layer.

Furthermore, for the sake of simplicity, the definition of virtual connection in the present invention is an end-to-end connection established across multiple networks by a control plane system. From the control plane's point of view, the link connection and subnet connection are determined, even if the link connection in the transport plane is not established or assigned, that is, the connection is only left in the control plane, even if no physical connection exists. Planar network elements have not yet been notified to establish a subnet connection.

In contrast to a virtual connection, a practical connection is a connection that exists simultaneously in both the transmission plane and the control plane. For the sake of simplicity, the actual connection is also referred to as the above-mentioned connection, and unless otherwise specified below, the connection is a brief representation of the actual connection.

"Service" in the present invention means providing a connection between the first channel position of the source network element and the second channel position of the destination network element for the transmission signal to pass therethrough, the service being a one-way or two-way service. to be. In order to support the transmission of service signals, an end-to-end connection must be established to carry service signals, so the service request is also called a service connection in the specification of the present invention.

The inventive method used in the optical network according to the present invention has four basic operations: establishment, protection, restoration and reversion. Setting up a service connection includes establishing a regular service connection, a virtual service connection, and an alternate service connection. The protection, recovery and reversion of service connections depend on the establishment, maintenance and cancellation of service connections. Here, the service connection is achieved by establishing a working connection and a protection connection at the same time, and service recovery is to dynamically establish an alternate connection for the original regular service connection in case of a service failure. According to the invention, a regular service connection is established upon receipt of a service request, which may be a working connection only or connections consisting of a working connection and a protected connection.

According to the present invention, a method for establishing, restoring and protecting a service connection in an optical network mainly includes the following steps.

Step 1, starting a timer to establish a virtual connection to each control node

Step 2, as a control node, upon receiving a service request, determines a link connection and a subnet connection as a control node to establish a regular connection supporting the requested service. , Establishing or allocating a link connection, and notifying the transport plane system to establish a subnet connection.

Step 3, after the timer for establishing a virtual connection of the control node expires, it initiates a search for service requests that require the virtual connection to be established, and each retrieved that matches the conditions for establishing a virtual connection. Starting a processor to establish a virtual connection for the service request, and then restarting a timer to establish a new virtual connection

Step 4, determining the route in source root mode to establish a virtual connection for the service.

Step 5, in the event of a service failure caused by a failure in the regular service connection, starting service recovery according to the service priority

Performing a process of returning to the regular service connection in response to a service-revertible request by removing an error occurring in the original regular service connection after the service recovery is completed.

Here, in step 1, a timer for establishing a virtual connection can be started following completion of initialization of the control plane system, which also applies the virtual connection to recover service failures according to the strategy of the control system or the priority of the service. Every time it is needed, or after completion of a regular service connection establishment can also be started while it is present. The timer for the control node is responsible for establishing all virtual connections for the nodes of the network elements together with the service resources controlled by the control node. The timer may be omitted if there is no request to establish a virtual connection.

In step two, the regular connection can be only a working connection or can be connections consisting of a working connection and a protection connection.

Service connection and protection connection routes are determined in source route mode which supports 'explicitroute', and disassembly of routes including the dissolution of nodes and links should be considered to the extent possible.

To the extent possible, two connections in a common Share Risk Link Group should not use the same link linking resource, but if network resources are limited, the working link and service protection link will be part of the common root. It is allowed to share, and can also use common link aggregation resources on a common route without any interference with each other. The working connection and the protective connection are fully operable under the responsibility of the transmission plane in the same way as transmitting in parallel and preferentially receiving.

When the control plane receives a service request, if the service request is for a service layer connection, the transport plane system dynamically establishes or dissolves the protection connection and the virtual connection in response to the service connection request from the client layer. If the current service layer connection does not have enough client layer connection resources to support the client layer service to establish the connection, the service layer connection to support the client layer connection may be established in a dynamic way, and the client layer The connection can be established later. In order to properly use the service layer resource, depending on the distribution of network resources, the service layer connection may not be established at the initial network configuration, but may be established upon receiving a request from the client layer. When no longer used by the client layer service, the service layer connection type established in response to the client layer's request may be dismissed. Connection establishment using the mechanism according to the present invention can support two-way signaling, so there is no need to establish two end-to-end connections in two opposite directions to support two-way service.

Furthermore, corresponding to the transport network elements at both ends of the service layer connection, the control nodes must be aware of the type of client layer link connection supported by the service layer connection, and for this purpose, the two ends of the service layer connection The control nodes corresponding to transport network elements in NN are informed about all link connection relationships of a service layer connection acting as a link by exchanging information relating to the appropriate client layer path at both ends of the service layer connection. Will get

Setting up a regular connection includes the following steps.

a) upon receiving the service request, determining to establish a strategy of end-to-end connection according to the priority of the service request by the control node

b) initiating the establishment of a connection as a control node corresponding to the transport network elements, and requesting service through interaction between the control node and other control nodes, and between transport network elements controlled by the control node and the control node; Steps to set up a regular connection for

Moreover, during the establishment of the service connection, since the control node is asked to broadcast link information, and the optical network is a multi-layer network, when the service layer link includes multiple layers of link connection, each link is the same layer. In order to include the link connections of the link, that is to say that the signal form of all the link connections in the links is the same, the service layer link will be further divided into a plurality of links, where the signal form of the link Match the bandwidth type or channel type. Broadcast of link information is performed along all links. For example, considering more of its various and appropriate capacities, a link having a port rate of STM-1 can be divided into five SNPP links: link STM-1, link VC-4, link VC. -3, link VC-12 and link VC-11.

In step 3, when the timer for establishing a virtual connection has expired, all services must be checked from the service sources of network elements controlled by the control nodes, and the virtual connection for one service can only be It can be set according to these.

(1) Regular service connection should already be established,

(2) The virtual connection mode is used to provide a reliable error recovery mechanism for the service, and according to the service priority and the strategy controlling the system, one service can be established with a plurality of virtual connections, another service It would be possible to set up virtual connections for the clients in parallel.

After all service virtual connections have been established, a new timer is rearranged to establish the virtual connection. In general, the length of the timer is longer than the time used to establish the connection. The reason for rearranging the timer is to monitor whether there are new service requests to establish a virtual connection, and on the other hand, if a previous error in this virtual connection establishment occurs because network resources are changing dynamically. In order to successfully establish a virtual connection, it is prompted to establish a virtual connection again at another time.

In order to establish a virtual connection for a service, source root mode is first used to determine the route. The strategy for determining the route is as follows.

Decommissioning of roots, including the dismantling of nodes and links, should be considered as much as possible in order to establish virtual connections and regular service connections. Virtual connection routes should not be included, and in case of insufficient network resources, some of the common routes can be shared between virtual connections and regular connections of the same service.

When a virtual connection route is determined in establishing a virtual connection, each control node corresponding to the network element traversed by the virtual connection is responsible for determining the selection of the leak connection through the network elements and for determining the subnet connection relationship. After all the link connection and the subnet connection relationship requested by the virtual connection are determined, the virtual connection is determined.

Since the subnet connection is determined by the link connection, the key to establishing a virtual connection relies on the determination of all the link connection sources for establishing the virtual connection, and the strategy for determining the link connection resource is the resource of the link connection through which the virtual connection passes. May be shared by other virtual connections and may be caught by other regular service connections. The detailed strategy is as follows. (1) If the regular links of two services are included in different Shared Risk Link Groups, it may be applicable that the virtual links of the two services share a common link link resource. (2) If the regular linking of two services is partly part of Shared Risk Link Groups, virtual links for the two services shall not share a common link linking resource as much as possible. (3) If the shared risk link groups of the two services' regular links are the same, the two service virtual links cannot share a common link link resource. (4) In order to consider the use of Shared Risk Link Groups, each control node shall record the information of Shared Risk Link Groups of regular service links included in the same service along with the virtual connections. Furthermore, the source control node should inform the control nodes that are traversed by the virtual connection about the shared risk link groups of the regular service connection. The information of the shared risk link groups for the service may be configured by a plurality of shared risk link groups.

In addition, if the transport network element can independently monitor the failure of the link connection traversal by the virtual connection, that is, if the transport network element can monitor the link connection without relying on the service layer link, the transport network element can establish the link connection. May be notified, and may not notify the transmitting network element to establish a subnet connection.

4 is a diagram illustrating a typical application of a virtual connection, wherein an exemplary optical network consists of transport network elements 21 of A, B, C, D, E and F, where each of the two services for There are two regular connections c1 and c2 (indicated by the dotted line at 25) and two virtual connections c1 'and c2' (indicated by the dotted line at 27). The subnet point (SNP) 23 is located in the channel or the channel destination corresponding to the service source. Similar to the regular connections c1 and c2, the virtual connections c1 'and c2' are also composed of their respective subnet connections and link connections, the difference is that the subnet connection of the virtual connection is gassy, ie the network elements It does not open the switch of the cross connection that supports the connection. As shown in FIG. 4, although the regular connections c1 and c2 are not included in the shared risk link groups, the virtual links c1 'and c2' may share a common link.

Furthermore, in order to update network topology information in time, when the transmission link information changes, the control node must broadcast the link information (eg, broadcast the link information through OSPF). The link information broadcasted includes information about (1) the number of spare link connections, (2) the number of link connections that can be obtained, and (3) the number of spare link connections that can be used by the virtual connections. Furthermore, in order to take into account the sharing of common link resources between virtual connections in the route calculation, the link information may also include the number of link resources that are shared between the virtual connections. Too many virtual connections share a common link connection at the same time, so that the maximum number of link resources shared by the virtual connections can be predefined in order to avoid any error to recover. When the number of virtual connections sharing a common link connection reaches the maximum number of shares, the number of link connections shared by the virtual connections of the link must be subtracted by one. Further, when the original link disappears, that is, if the above-mentioned link is deleted from the network, the link information should be recorded.

The action of establishing, releasing, and maintaining actual and virtual connections can be accomplished by using the RSVP and CR-LDP protocols. From the control plane's point of view, the structure of the virtual connection and the actual connection is exactly the same, and therefore their operation and maintenance are mostly the same, including the processor of the error information. As mentioned above, the virtual connection with respect to the operation further includes the following processor.

(1) indicating the nature of the connection, whether it is a real connection or a virtual connection in the connection request.

(2) adding an instruction of "changing the actual connection to the virtual connection" in connection with the actual connection.

(3) adding a command for "changing the virtual connection to the actual connection" in connection with the virtual connection.

(4) The source control node determines whether the connection should be deleted according to the information (e.g., the virtual connection may be deleted if it has been obtained by a regular service connection), so that the resources of the virtual connection are different from the actual connection Notifying the source control node with information as to whether or not it has been obtained by the user.

(5) notifying other virtual connections of the shared link connection resource when the virtual connection is changed to the actual connection.

5 is a diagram illustrating a service-client layer link connection. The service layer connection 30 includes a plurality of client layer connections, such as client layer connections c1 and c2 (refer to reference numeral 31), which may traverse a plurality of transport network elements. Subnet points (SNPs) 23 are located at both ends of the service layer connection 30, that is, for each pair of SNPs, an assignable and configurable physical link connection 32 is present in the transport plane. .

If the service connection belongs to a service layer connection that is directly established by the control plane in response to a connection request of a client layer service, or in response to a notification from a network administrator through the control plane, or a connection establishment of the control plane is considered. If a service connection belongs to a link that is not connected, the control plane may dynamically establish a service layer protection connection and a service layer virtual connection for a service layer connection, also called a service layer working connection. If the control node finds that the service layer connection involves a client layer connection that needs to be protected, then the service layer protection connection and the service layer virtual connection corresponding to the service layer connection are established. Furthermore, since the service layer working connection is dynamically established by the control node in response to the service request of the client layer, if the service layer connection does not carry the client layer service connection, the service layer protection connection and the virtual connection are released. Can be. Additionally, when the service layer working connection does not carry any client layer connection, the service layer working connection may also be released. The service layer protection connection and the service layer virtual connection are established in the same manner as described above above. To use network resources more efficiently, client layer services of a set of protection and recovery requests can be sent on the same service layer connection.

If a recovery request is determined according to the priority of the service when a service error occurs caused by the error of the regular service connection, the service recovery should be started. Here, the service source control node (that is, the control node corresponding to the service source network element) is responsible for service recovery. Here, the error refers to an error in service transmission caused by an error in a transport plane for supporting a service connection.

After starting recovery, a recovery wait timer is first provided to avoid any vibration caused by errors in the transmission plane. If an error exists among all regular connections of the service, when the recovery wait timer expires, the next step is to check whether there is an error free virtual connection. If there is an intact virtual connection, the service source control node sends a "USE" command to the next network element through which the virtual connection passes, and each control node "USE" to the next transport network element through which the virtual connection passes. It is responsible for sending the command, so that the source control node and all control nodes that each receive the "USE" command notify the transmitting network elements to establish subnet connections. If the link connection established in preference to the virtual connection is not in the transport plane, an additional notification must be sent to the transmitting network element to establish the link connection in order to change the virtual connection to the actual connection.

If the virtual connection is successfully changed to an actual connection, also called an alternate connection, and the alternate connection is currently error free, then the service will change from the regular connection to the alternate connection, and recovery is finally completed.

If a service failure cannot be repaired by a virtual connection, for example, if there are no virtual connections available without errors, or if the establishment of the virtual connection fails, routing is dynamically rerouted to recover from the service failure. The new alternate connection will be established.

In the above recovery process, if the service connection to be recovered is a service layer connection and there are two opposite ends through which multiple client layer connections pass, all client layers after establishment of alternate service layer connections The connections are changed to alternate service layer connections. To use the optical network resources more efficiently, when the control node recognizes that the current service connection is a service layer connection and is controlling the use of the service layer connection by a client layer connection, it needs to be protected on the service layer connection. If an error occurs that does not accompany the client layer connection signal, the recovery will not start.

During the recovery phase, the regular connection may be deleted prior to or after the establishment of the alternate connection. However, if service recovery is a service-revertible connection to be returned, that is, if the service needs to be returned to the regular connection after the error has been removed from the original regular connection, then the regular connection is not deleted, Or the actual connection can be changed to a virtual connection during the initial recovery process. In other words, a network element traversed by a virtual connection may dismiss the subnet connection, but may not break the link connection. If the service recovery does not include a service-revertible request, the attribute of the alternate connection is changed to a regular connection and the original regular connection is deleted, or the original regular and alternate connection together with the wicking connection. Configure a regular service connection consisting of a working connection and a protection connection, or change the original regular connection to a service's virtual connection. If there is a service-revertible request, the regular connection may be dropped to avoid impacting recovery due to insufficient network resources, but the source control node may have all root information of the regular connection included in the regular connection. It should be noted that the information of channels and channels should be recorded.

To make recovery more efficient, the action of "USE" on virtual connections or dynamic reroute (hereafter referred to as 'reroute') is replaced during the wait phase of recovery. It may proceed to establish a path, but after the recovery wait timer expires, the service should only change from a regular connection to an alternate connection.

If a service error occurs again after recovery, additional service recovery may proceed, and the additional operations are to first delete the replacement connection if there is a replacement connection, and then repeat the above-mentioned recovery steps.

For a service that has completed recovery, when the error disappears on the regular connection of the service, if the service has a request to return the service, the service will be returned to the regular connection. If the regular connection is deleted during recovery, the control node will establish a regular connection according to the information of the regular connection stored in the control node. If a regular connection is changed to a virtual connection during recovery, the virtual connection must first be changed to a regular connection. Finally, the service can be returned to the original regular connection for transmission. In order to avoid new errors in the return process, for example, when the time difference between the source and destination network elements is sufficient to commit a new service error, both ends are sent in parallel and preferentially received. The process is performed first, and only after the completion of the process of transmitting in parallel and preferentially receiving at both ends, an alternative path can be left. In addition, the alternate path may not be deleted according to the strategy after recovery, for example, the alternate path may be changed to a virtual connection or a service protected connection. In order to avoid repetitive recovery and recovery due to an unstable error condition, a wait for return timer is provided after the service connection error disappears. When the timer expires, if no error occurs that affects the regular connection again, the service can be returned to the regular connection.

As described above, during the establishment of the service connection and also during the establishment of the virtual connection, the link connection resource may be allocated or established. Since the source for starting the connection process is control nodes corresponding to different transport network elements, an allocation conflict of link resources may occur. To solve this conflict problem, a unified competition rule should be used across the entire network. It includes the following rules of this competition rule.

(1) compete on the basis of service linking priority;

(2) Use the source transport network element ID of the connection as the connection priority, for example, the lower the numerical value of the network element ID, the higher the priority level.

(3) If the source of the connection is the same transport network element, specify different connection IDs for different connections by the control node and determine priority as the designated ID.

A connection with a higher service priority has the right to use a link connection resource in advance for a connection with a lower service priority. For connections with the same service priority level, the connection with the higher priority of the source connection network element ID has the authority to use the link connection resource ahead of the connection with the lower priority of the source connection network element ID. For connections that have the same service privilege level and the same source connection network element, the precedence of link connection resource usage is determined by the designated connection ID for the connections. This law of competition determines the unique precedence for the entire network, which obviously solves the conflict problem as a whole. Instead of using the connection network element ID as a priority for competition, the only priority applied for the entire network can also be used, which is to apply unique priority through control nodes gathered at the center of the entire network in various ways. However, this method has proved to be of low efficiency and high complexity in the prototyping process.

If an error occurs in the service layer connection, the control node will coordinate the operation with the relationship information of the service-client layer connection for error recovery of the service-client layer network. When an error in the service layer connection affects the client layer connection with the request that it needs to be repaired in the event of an error, if the service layer cannot repair the error on its own, the client layer can Notified and service recovery will be initiated by the client tier, or other error recovery will be initiated by the service tier without notifying the error information prior to the client tier.

If service layer recovery fails, the client layer is suspended for error information, and then the client layer network will begin service recovery.

According to the application of the technical solution according to the present invention, the nodes of the network element can be further replaced by a general subnet which can be composed of a plurality of network elements, and ingenious to control the transport plane system constituted by the general subnet. The method can also be applied.

In the following, detailed operational steps of service protection and service recovery will be described with reference to FIG. 4, where all transport network elements support service connection establishment based on VC-4 granularity.

(1) A timer is started to establish a virtual connection by each control node to control the corresponding transport network element.

(2) Control node A 'of network element A receives two service requests, the first request of service 1 being a VC-4 signaling service that traverses network elements of A and C across the network, The second request is a VC-4 signaling service that traverses the network elements of A and D across the network.

Depending on the service priority level of the service requests, the control node determines a strategy for establishing end-to-end connections of the service, where the strategy is to establish a regular connection and a virtual connection, and to recover service errors if a service error occurs. .

 (3) The control node A 'of network element A uses the signal of RSVP (or CR-LDP) to initiate the establishment of the connection. As shown in FIG. 4, connections c1 and c2 of service 1 and service 2 are established through interaction between the control node and other control nodes or between control nodes and the transport network elements.

(4) When the virtual connection establishment timer of control node A 'expires, a search for a service that needs to establish a virtual connection starts. As a result, service 1 or service 2 needs to establish a virtual connection, and the control node then calculates the route of the virtual connection. For Service 1, the Share Risk Link Group traversed by the virtual link is clearly different from the regular link. In other words, virtual links should not have a common link with the A → B → C routes. Therefore, the virtual connection of service 1 is determined as A → F → C. For service 2, since there is no link connection resource available for virtual connection on the link between network elements F and D, the virtual connection of service 2 is not established at that time.

(5) Here, the control node A 'is responsible for establishing the virtual connection c1 of service 1 by sending a request for establishing a virtual connection to other control nodes using the signal of RSVP. The control nodes of the transport network element traversed by the virtual connection interact with each other, exchange information stored in them, and determine all subnet connections and link connections that make up the virtual connection c1 '. Since the network element can monitor the failure of one link connection, in order to further increase the efficiency for repairing service failures, if the link connection is determined during the establishment of the virtual connection, the control node sends a link connection to the transmitting network element. You will be notified to set it up. Furthermore, the control node must record the root of the canonical connection of the virtual connection using this link connection.

(6) When the next timer for establishing the virtual connection of control node A 'has expired, service 2 is found with the request of the virtual connection establishment, and therefore the root of the virtual connection must be determined first. Depending on the current state of network resources, the Share Risk Link Group traversed by the virtual link must not be identical to that of the regular link (in other words, the virtual link is a common link in the root, such as A → E → D). Must be used, and the route to establish a virtual connection is determined as A → F → D.

(7) The control node A 'starts to establish the virtual connection c2 of service 2 using the signal of the RSVP, and the virtual connection through the interaction and information exchange between the control nodes of the transport network elements traversed by the virtual connections. All link connections and subnet connections that make up c2 'are determined. During the process of establishing the virtual connection c2 ', the control node A' searches for the link connection used by the virtual connection c1 'on the link between the network element A and the network element E. The root of the regular service connection c1 'for the virtual connection c1' and the root of the regular service connection for the virtual connection c2 'are separate and independent. In other words, the roots of c1 and c2 do not belong to the same shared risk link group, so virtual links c2 'and c1' share this link link to make the best use of the link resource. During the process of establishing the virtual connection c2 ', the network element can monitor the failure of one link connection, so that to improve the efficiency of service recovery, if the link connection is determined during the establishment of the virtual connection, the control node links It will notify the sending network element to establish a connection.

(8) When an error occurs in the link between the network element E and the network element D, the network element D recognizes the error of the connection c2, and then transmits the above-mentioned error information to the control node A 'via a signal, and then controls. The node starts the recovery process. First, a wait timer for recovery is started. If the error oscillation caused by the faulty device is not frequent enough of sufficient magnitude, since the original strategy has been determined in advance, an alternate path will be established once an error occurs. Thus, according to the strategy, control node A 'starts to establish an alternate connection. First, control node A 'knows whether a virtual connection for this service has already been established, is error free and available, so control node A' sends a "USE" command to the other control nodes, and the virtual connection All network elements are informed by the control nodes corresponding to the network elements traversed by to establish a cross connection, and finally the virtual connection is changed to a real connection. During the virtual connection c2 'process, the control node A' retrieves that the connection resource has been consumed / obtained by the virtual connection c1 ', and thus the virtual connection is recorded as "consumed / obtained".

(9) When the timer for waiting for recovery expires, and if service errors continue to exist, the service is changed from connection c2 to the alternate connection, and thus the recovery process is completed.

Here, with reference to FIG. 6, a process for dynamically establishing a service layer connection that satisfies the request of the client layer connection is described in detail below. As shown in FIG. 6, the transport network 60 is constituted by a number of network elements 61-65. The transport network consists of a service layer network supporting VC-4 in the horizontal direction, and the client layer signals VC-3, VC-12 and VC-11 can access the network in the vertical direction. In this network, client layer signaling can only access the network via a VC-4 end-to-end connection, that is, the number of network elements that cross a client layer end-to-end connection is only two. Here, the reason why the network does not support the client layer signal end-to-end connection in the horizontal direction is to protect the network from the adverse effect on the stability caused by the frequent dynamic action of the client layer end-to-end connection. The process is as follows.

Step 1: First, control node A 'of transport network element node A receives an interactive service connection request of a client layer VC-12 signal, the source VC-12 channel of this connection request is located in A, and the destination VC-12 channel is Located in C

Step 2: Control node A 'detects that the transport network of network element A 61 only supports VC-4 signal link connection in the horizontal direction, so control node A' is connected to A 61 and C 63 It is determined whether there is a service layer connection c in between, and whether the service connection c includes an extra client layer connection VC-12. If no, then go to the next step, otherwise go to step 4.

Step 3: Control node A 'finds an available VC-4 connection route from A (61) to C (63) (e.g., A (61)-> E (65)-> C (63)) Control node A 'then starts establishing the corresponding VC-4 connection, and VC-4 connection c is established using RSVP signals by the control nodes corresponding to all network transport elements traversed by this connection. do.

Step 4: Control node A 'sends a request to establish control VC-12 connection to control nodes C' of network element C 63, and control node A then sends VC- included in service layer connection c. In order to select a 12 link connection, control node A works in cooperation with control node C ', notifies network element A 61 and network element C 63 to establish a physical and physical VC-12 connection, And finally, control nodes A 'and C' each include the VC-12 signal in the client layer VC-2 connection, so that the VC-12 end-to-end connection is established.

The above-described embodiments of the present invention are disclosed for the purpose of illustration, and those skilled in the art may make various modifications, changes, and additions within the spirit and scope of the present invention. Should be considered to be within the scope of the following claims.

Compared with the prior art, the present invention considers the dynamic change of the request for service layer connection, and advantageously uses the virtual connection technology, includes resource sharing of the virtual connections, and dynamically uses the optical network resources. It provides a method related to service connection establishment, service error recovery, and protection that increases the reliability of service recovery by further optimizing the effect, and transmitting and prioritizing in parallel. In particular, the present invention provides a method for resolving a conflict problem when a resource allocation conflict problem occurs during the connection establishment process of the entire network.

Claims (28)

A method of establishing, protecting and recovering a service connection in an optical network including a transmission plane system and a control plane system, wherein the transmission plane system Includes a plurality of transmission network elements, each network transmission network element uniquely corresponding to a control node of the control plane system, Step 1: starting a timer to establish a virtual connection to each control node; Step 2: As soon as a service request is received, a link connection and a subnet connection are determined by the control node to establish a regular connection supporting the requested service. And establish or assign the link connection and notify the transport plane system to establish the subnet connection; Step 3: After the timer for establishing the virtual connection at the control node expires, start searching for a service request for which the virtual connection needs to be established, and matching the condition for establishing the virtual connection. Starting a process of establishing a virtual connection for each retrieved service request, and then restarting a timer to establish a new virtual connection; Step 4: determining a route in a source route mode to establish a virtual connection for the service; Step 5: in the event of a service error caused by a failure in normal service connection, initiating service recovery according to the service priority; And Step 6: performing a process of returning to the regular service connection in response to a service-revertible request according to removing an error occurring in the original regular service connection after service recovery is completed. How to set up, protect, and recover a connection. The method of claim 1, If it is necessary to apply the virtual connection to recover a service error according to the strategy of the control system or the priority of the service, A method for establishing, protecting and restoring a service connection in which the timer is started for establishing the virtual connection of step 1 while the service connection is maintained after establishing a regular service connection or subsequent to the initialization of the control plane system. . The method according to claim 1 or 2, Step 2, When the control plane system receives a service request from a client layer, client layer connection resources provided by the service layer to establish a connection for the current service. ), The service layer connection request is activated in a dynamic way, first a service layer connection is established that supports the client layer, and then the client layer is established. And establishing, protecting, and restoring a service connection in which a protection connection and a virtual connection of the service layer connection are dynamically established or released in response to a request for protection and restoration of the client layer service. The method of claim 3, wherein When a series of client layer services with the protection and repair request are sent on the same service layer connection, in the event of insufficient network resources, the working connection and the protection connection for the service partially share a common route. And the working connection and the protected connection are allowed to use common link connection sources on a common route. The method of claim 4, wherein During or after establishing the service layer connection, the service layer connection corresponding to the transport network element located at both ends of the service layer connection through exchanging information of an adaptive client layer path at both ends of the service layer connection. A method for establishing, protecting, and restoring a service connection in which information on all link connection relations contained in the data is acquired by the control node. The method of claim 1, And the virtual connection for the service of step 3 is dependent upon the following conditions. <Condition> (1) The regular service connection is established. (2) A virtual connection mode is required to be used to provide a reliable fault restoration mechanism for the service according to the service priority or the control system strategy. The method of claim 6, In step 4, establishing a virtual connection Determining a virtual connection route in source route mode; And After the virtual connection route is determined, determining a selection of a link connection source, determining the subnet connection relationship by the control node corresponding to each of the network elements traversed by the virtual connection, Informing the transmission plane to establish or assign the link connection and to establish the subnet connection. The method of claim 7, wherein In step 4 above The strategy for determining the route should be considered to the extent that disassembly of the routes, including disjoints of nodes and links, should be considered in order to establish virtual connections and regular service connections, and the virtual connection route is to the extent possible. The shared risk linkage group of a regular connection route should not include the virtual connection route, and share part of the common route between the virtual connection and the regular connection of the same service when the network resources are insufficient. Bins are allowed, The strategy of selecting the link connection resource constituting the virtual connection is that the link connection resource traversed by the virtual connection can be shared by other virtual connections, and snatched by other regular service connections. Can be The strategy for whether to notify the transmission plane to establish a link connection after selecting the link connection resource constituting the virtual connection is independent of the link connection through which the transport network element passes. And if so, the transmitting network element is notified to establish a link connection, and not to establish a subnet connection. The method of claim 8, Strategies for selecting the link connection resource constituting the virtual connection In the starting step of configuring the virtual connection, notifying the control nodes to be traversed by the virtual connection with information of the shared risk link group of the regular service connection by the source control node; ; Storing in each control node information about the shared risk link group of the regular service connection corresponding to the virtual connection for each link connection used by the virtual connection; When the virtual connection and the regular connection share a part of a common route, sharing a common link connection resource by a virtual connection and a regular service connection of the same service when the network resource is insufficient; If the Shared Risk Link Groups of the regular connections of two services are different, sharing a common link connection resource by two virtual connections of the two services; If the Shared Risk Link Groups of the regular connections of the two services are partially different, not sharing as much of the common link connection resource as possible by the two virtual connections of the two services ; And If the Shared Risk Link Groups of the regular connections of the two services are the same, service linking comprising not sharing a common link connection resource by two virtual connections of the two services How to set up, protect and recover. The method according to claim 1 or 9, In order to update the network topology as the link information broadcast along each layer of the link changes, the control node broadcasts the link state information of each link while establishing the service connection. How to set up, secure, and repair service connections. The method of claim 10, Wherein the link information comprises a number of spare link connections, a number of link connections that can be snatched, and a number of spare link connections that can be used by virtual connections. The method of claim 11, The link state information is determined by the virtual connection to be subtracted by one when the number of link resources that can be shared by the virtual connections and the number of the virtual connections that share the common link connection resource reach a maximum value. A method of establishing, protecting and recovering a service connection further comprising a number of shared link resources. The method of claim 1, Starting the service recovery of step 5 is Starting a recovery wait timer; When the recovery wait timer expires, searching for the existence of an error-free virtual connection if an error still exists among all the regular service connections; If there is a virtual connection, the service source control node sends a " USE " command from each control node that receives the " USE " command to the control node of the next transmitting network element traversed by the virtual connection. Sending a "USE" command to the control node of the next transport network element traversed by the virtual connection, and performing the "USE" action of the virtual connection, wherein the "USE" processing of the virtual connection is performed by: Notifying the transport network element to establish subnet connections by a source control node and all the control nodes that have received a “USE” command; Sending additional notifications to the transport network elements to establish the link connection if there is no link connection established prior to the virtual connection establishment in the transport plane system; If the virtual connection includes corresponding subnet connections and link connections in the transport plane system, executing as a replacement connection changing the virtual connection to a real connection; If the virtual connection is successfully changed to the real connection and there is currently no error in the virtual connection, changing the service from the regular connection to the alternate connection to recover a service error; If there is no available virtual connection without errors or the establishment of the virtual connection fails, dynamically rerouting to establish a new alternate connection to recover from a service error; And If the service error is not cleared when the recovery wait timer expires, setting the service connection further comprising changing the service from the regular connection to the alternate connection for transmission to recover the service error. How to protect, recover. The method of claim 13, If the service connection to be recovered is a service layer connection and there are two opposite ends traversed by signals of multiple client layer connections, then all clients after establishment of the alternate service layer connections Layer connections are changed to the alternate service layer connection, If an error occurs in the service connection and does not transmit a client layer connection signal, the control node indicates that the current service connection is a service layer connection and the use of the service layer connection is controlled by the client layer connection. When aware, the method of establishing, protecting, and recovering a service connection in which recovery is not initiated. The method of claim 13, If the restored service does not include a service return request, the attribute of the alternate connection is changed to the regular connection and the original regular connection is deleted, or the original regular connection and the alternate connection are working together. a regular service connection consisting of a working connection and a protection connection, or the original regular connection is changed to the virtual connection of the service, If the recovered service includes a service return request, when the original regular service connection error is eliminated, the service returns to the regular connection, and the return process Starting a return wait timer; If the original regular connection was deleted during the recovery, establishing a regular connection according to the information of the original regular connection stored in the control node; If the original regular connection is not deleted during the recovery and changed to the virtual connection, first changing the virtual connection to the real connection to reconfigure the original regular connection; And When the return wait timer expires, if the original regular connection has been established, returning the service to the original regular connection for transmission, comprising establishing, protecting, and restoring a service connection. Way. The method of claim 15, In order to prevent a new error caused by a large time difference in performing a recovery process between the source network element and the destination network elements, parallel transmission and preceding reception before releasing the replacement connection. Establishing, protecting, and recovering a service connection performed at a source end and a destination end of the service. The method of claim 13, If a service error occurs after the recovery and an alternate connection exists, the alternate connection is deleted and the recovery is restarted. The method of claim 1, Step 2 above Setting up the service connection including setting up the virtual connection further includes allocating the link connection resource; In order to resolve the allocation conflict of link resources, the allocation process is performed based on a unitied competition rule for the entire network. The criteria of the competition rule (1) to compete on the basis of the service connection priority; (2) use the source transmission network element ID of the connection as the connection priority; (3) specifying a different connection ID for different connections by the control nodes if the source of the connection is the same transport network element and determining the priority by the specified connection ID. How to set up, protect, and recover The method of claim 1, The control node Topology information of each layer of the optical network including link information and channel resource state information of each optical transport network element controlled by a corresponding control node, And the same type of signal of the link connection included in all the links included in the topology information of each layer. The method of claim 1, And said transport network element is exchanged for a subnet of a plurality of network elements. The method of claim 5, And the virtual connection for the service of step 3 is dependent upon the following conditions. <Condition> (1) The regular service connection is established. (2) A virtual connection mode is required to be used to provide a reliable fault restoration mechanism for the service according to the service priority or the control system strategy. The method of claim 12, Starting the service recovery of step 5 is Starting a recovery wait timer; When the recovery wait timer expires, searching for the existence of an error-free virtual connection if an error still exists among all the regular service connections; If there is a virtual connection, the service source control node sends a “USE” command to the control node of the next transmitting network elements traversed by the virtual connection, and from each control node that receives the “USE” command Sending a “USE” command to the control node of the next transport network element traversed by the virtual connection, and performing the “USE” action of the virtual connection—wherein the “USE” processing of the virtual connection is performed by the; Notifying the transport network element to establish subnet connections by a source control node and all the control nodes that have received a “USE” command; Sending additional notifications to the transport network elements to establish the link connection if there is no link connection established prior to the virtual connection establishment in the transport plane system; If the virtual connection includes corresponding subnet connections and link connections in the transport plane system, executing as a replacement connection changing the virtual connection to a real connection; If the virtual connection is successfully changed to the real connection and there is currently no error in the virtual connection, changing the service from the regular connection to the alternate connection to recover a service error; If there is no available virtual connection without errors or the establishment of the virtual connection fails, dynamically rerouting to establish a new alternate connection to recover from a service error; And If the service error is not cleared when the recovery wait timer expires, setting the service connection further comprising changing the service from the regular connection to the alternate connection for transmission to recover the service error. How to protect, recover. The method of claim 16, Step 2 above Setting up the service connection including setting up the virtual connection further includes allocating the link connection resource; In order to resolve the allocation conflict of link resources, the allocation process is performed based on a unitied competition rule for the entire network. The criteria of the competition rule (1) to compete on the basis of the service connection priority; (2) use the source transmission network element ID of the connection as the connection priority; (3) specifying a different connection ID for different connections by the control nodes if the source of the connection is the same transport network element and determining the priority by the specified connection ID. How to set up, protect, and recover. The method of claim 17, Step 2 above Setting up the service connection including setting up the virtual connection further includes allocating the link connection resource; In order to resolve the allocation conflict of link resources, the allocation process is performed based on a unitied competition rule for the entire network. The criteria of the competition rule (1) to compete on the basis of the service connection priority; (2) use the source transmission network element ID of the connection as the connection priority; (3) specifying a different connection ID for different connections by the control nodes if the source of the connection is the same transport network element and determining the priority by the specified connection ID. How to set up, protect, and recover. The method of claim 16, The control node Topology information of each layer of the optical network including link information and channel resource state information of each optical transport network element controlled by a corresponding control node, And the same type of signal of the link connection included in all the links included in the topology information of each layer. The method of claim 17, The control node Topology information of each layer of the optical network including link information and channel resource state information of each optical transport network element controlled by a corresponding control node, And the same type of signal of the link connection included in all the links included in the topology information of each layer. The method of claim 16, And wherein said transport network element is exchanged for a subnet of a plurality of network elements. The method of claim 17, And wherein said transport network element is exchanged for a subnet of a plurality of network elements.

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