Abstract:
The present invention discloses a method for error connection and error prevention of service in an Automatically Switched Optical Network (ASON), to resolve the technical problems that the conventional method for error connection and error prevention cannot realize rapid automatic configuration and the efficiency is low and other problems. Through automatically completing the configuration of the error connection and error prevention information of the start node and the end node by the control plane, the present invention overcomes the defect that manual setting is error prone; it is rapid and simple to implement the interaction of the error prevention information between the start node and the end node by protocol exchange. Because the present invention can automatically complete the configuration of the error connection and error prevention information of the start node and the end node by the control plane, and can cite, when an error connection alarm occurs, the error prevent information of the original connection over a new connection of the service under the conditions of different error prevention policies, the present invention enhances the system availability and the service robustness to a great extent.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to the field of optical communications, and in particular relates to a method and system for error connection and error prevention of service in an Automatically Switched Optical Network (ASON). 
       BACKGROUND 
       [0002]    With the development of network technology and substantial increase of network communication capacity, the demands on the performance of a transport network become increasingly higher, through imparting intelligent attributes to an optical network by means of adding an automatically controlled protocol in the optical domain, it is expected to make the network architecture more flexible, the network management flexible and uniform, bandwidth utilization ratio higher, survivability and expansibility stronger, and make the network be capable of providing dynamic connection and intelligent scheduling, thus an Automatically Switched Optical Network (ASON) is developed to satisfy the above demands. 
         [0003]    The ASON consists of a control plane, a transport plane, a Data Communication Network (DCN) and a management plane. 
         [0004]    The ASON embodies functional separation of the control plane from the transport plane, wherein the control plane is responsible for establishing connections in the transport plane through a signaling routing mechanism and performing re-routing recovery when the connection fails, while the transport plane is responsible for service transmission and failure detection. The DCN is responsible for the transmission of the signaling routing messages in the control plane. The management plane is responsible for performing configuration management of the control plane and the transport plane. 
         [0005]    Under the condition that the service routing in the ASON is provided by a multiplex section shared protection ring, a node failure or a multi-span section failure in the multiplex section shared protection ring may result in the occurrence of service error connection. At this moment, the transport plane is required to prevent error by configuring path error prevention information, e.g. preventing error through a Trace Identification Mismatch (TIM) alarm generated by a path trace byte (Jx byte). In this way, the control plane may take subsequent measures (e.g. re-routing) according to the actual failure state of the service. To make it brief, “configure Jx bytes” and “configure error prevention information” have the same meaning herein. 
         [0006]    The control plane realizes automatic configuration based on the technology of error connection and error prevention of the transport plane. Currently, error prevention is performed through configuring a Jx byte alarm in the transport plane error connection and error prevention technology. 
         [0007]    In the conventional method for error connection and error prevention, configuration is performed by the management plane in the transport plane, thus the efficiency is low and rapid automatic configuration cannot be realized. For example, when recovery occurs in the service, if this case is reported to the management plane and then a Jx byte is set, the recovery time cannot be ensured, which makes the recovery meaningless. Thus, it is required to configure the Jx byte in time so as to guarantee normality of the service. It is essential to realize a rapid, automatic and safe configuration in the ASON. However, currently there is a lack of technologies related to error connection and error prevention in the field of ASON. 
       SUMMARY OF THE INVENTION 
       [0008]    In view of the problem above, one of the main objectives of the prevent invention is to provide a method for error connection and error prevention of service in an ASON, to solve the technical problems that the conventional methods for error connection and error prevention cannot realize rapid automatic configuration and the efficiency is low and other problems. In order to achieve the above objective, the technical solution of the present invention is realized by the following way. 
         [0009]    A method for error connection and error prevention of service in an ASON comprises: 
         [0010]    step A: a control plane configures service error prevention information for a transport plane; 
         [0011]    step B: the transport plane reports error connection alarm information to the control plane after detecting an error connection according to the service error prevention information; 
         [0012]    step C: the control plane acquires, after receiving the error connection alarm information, an error prevention policy of a service in which an error connection alarm is generated, and performs a corresponding error prevention operation. 
         [0013]    Further, the step that the control plane configures the service error prevention information for the transport plane may comprise: 
         [0014]    step A 1 : the control plane of a start node or an end node of a service issues a configuration request to the transport plane of the corresponding node after acquiring the service error prevention information; 
         [0015]    step A 2 : the start node or the end node of the service that initiates an operation of configuring service error prevention information sends the service error prevention information to an opposite node of the service; 
         [0016]    step A 3 : the opposite node of the service issues a configuration request to the transport plane of the opposite node of the service after receiving the service error prevention information; 
         [0017]    step A 4 : the start node and end node of the service, after being successfully configured with the service error prevention information, report configuration success messages to the control plane; 
         [0018]    Further, the service error prevention information may refer to a path trace byte, the control plane may need to set a sending value and an expected value when configuring the path trace byte, the setting method may comprise: 
         [0019]    for a one-way service, the sending value is set in a sending direction of the start node of the service, and the expected value is set in a receiving direction of the end node of the service; the sending value is the same as the expected value; 
         [0020]    For a two-way service, the sending value is set in the sending directions of the start node and the end node of the service; the expected value is set in the receiving directions of the start node and the end node of the service; the sending value is the same as the expected value; 
         [0021]    Further, the start node or the end node of the service that initiates configuration of the service error prevention information may use a Notify message in an RSVP or an OEM message in an LMP to bear the service error prevention information and send the message to the opposite node of the service. 
         [0022]    Further, the error prevention policy may be a re-routing recovery policy and the step C may specifically comprise: 
         [0023]    step C 11 : the control plane searches for a service in which an error connection alarm is generated, according to the error connection alarm information reported by the transport plane; 
         [0024]    step C 12 : the control plane acquires the error prevention policy of the service in which the error connection alarm is generated and establishes a recovery connection; 
         [0025]    step C 13 : the control plane configures the service error prevention information for the transport plane on the recovery connection according to the service error prevention information of an original connection; 
         [0026]    step C 14 : the service in which the error connection alarm is generated is switched from the original connection to the recovery connection after the error prevention information of the recovery connection is successfully configured. 
         [0027]    Further, the error prevention policy may be a protection switching policy and the step C may specifically comprise: 
         [0028]    step C 21 : the control plane searches for a service in which an error connection alarm is generated according to the error connection alarm information reported by the transport plane, and determines a destination connection to which the service needs to be switched to; 
         [0029]    step C 22 : the control plane acquires the error prevention policy of the service in which the error connection alarm is generated; 
         [0030]    step C 23 : the control plane configures the service error prevention information of the original connection on the destination connection; 
         [0031]    step C 24 : the service in which the error connection alarm is generated is switched from the original connection to the destination connection after the error prevention information of the destination connection is successfully configured. 
         [0032]    Another objective of the present invention is to provide a system for error connection and error prevention of service in an ASON. In order to achieve the above objective, a technical solution of the present invention is implemented in the following way. 
         [0033]    A system for error connection and error prevention of service in an ASON comprises: 
         [0034]    an error prevention information configuring module, arranged to configure service error prevention information for an error connection detecting and alarming module located in a transport plane; 
         [0035]    the error connection detecting and alarming module, arranged to detect an error connection in a service according to the service error prevention information configured by the error prevention information configuring module, and inform, after an error connection is detected, an error prevention policy executing module located in a control plane; 
         [0036]    the error prevention policy executing module, arranged to acquire, after receiving error connection alarm information reported by the error connection detecting and alarming module, an error prevention policy of the service in which an error connection alarm is generated and execute a corresponding error prevention operation. 
         [0037]    Further, the error prevention information configuring module may be located in the control plane, and may comprise: 
         [0038]    a service start node error prevention information configuring module, arranged to configure service error prevention information for the transport plane at a service start node; 
         [0039]    a service end node error prevention information configuring module, arranged to configure service error prevention information for the transport plane at the service end node; 
         [0040]    the service start node error prevention information configuring module or the service end node error prevention information configuring module, after initiating an operation of configuring service error prevention information, may need to send the service error prevention information to an opposite node of the service, and the opposite node of the service, after receiving the service error prevent information, may configure the service error prevention information for the transport plane of the opposite node of the service. 
         [0041]    Further, the service error prevention information may refer to a path trace byte, the control plane, when configuring the path trace byte, needs to set a sending value in the sending directions of the start node and the end node of the service and set an expected value in the receiving directions; 
         [0042]    the start node or the end node of the service that initiates configuration of the service error prevention information may use a Notify message in an RSVP or an OEM message in an LMP to bear the service error prevention information and send the message to the opposite node of the service. 
         [0043]    Further, the error prevention policy executing module may comprise: 
         [0044]    a failing service determining unit, arranged to determine a service that fails according to the service error connection alarm information of the service reported by the error connection detecting and alarming module; 
         [0045]    a policy acquiring unit, arranged to acquire an error prevention policy from service-related information of the service according to the service determined by the failing service determining unit; 
         [0046]    a policy executing unit, arranged to execute a corresponding error prevention operation according to the error prevention policy acquired by the policy acquiring unit; 
         [0047]    the error prevention policy may be a re-routing recovery policy or a protection switching policy. 
         [0048]    Through automatically completing the configuration of the error connection and error prevention information of the start node and the end node by the control plane, the present invention overcomes the defect that manual setting is error prone; it is rapid and simple to implement the interaction of the error prevention information between the start node and the end node by protocol exchange. Because the present invention can automatically complete the configuration of the error connection and error prevention information of the start node and the end node by the control plane, and can cite, when an error connection alarm occurs, the error prevention information of the original connection over a new connection of the service under the conditions of different error prevention policies, therefore, the present invention enhances the system availability and the service robustness to a great extent. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0049]      FIG. 1  shows a diagram of an application scenario of a method for error connection and error prevention in a normal condition according to Embodiment 1 of the present invention; 
           [0050]      FIG. 2  shows a schematic diagram of establishing a recovery connection when an error connection occurs in the service according to Embodiment 1 of the present invention; 
           [0051]      FIG. 3  shows a flow of configuring error prevention information by a control plane when the service works normally according to Embodiment 1 of the present invention; 
           [0052]      FIG. 4  shows a flow of preventing error by a control plane when an error connection occurs in the service according to Embodiment 1 of the present invention; 
           [0053]      FIG. 5  shows a diagram of an application scenario of a method for error connection and error prevention in a normal condition according to Embodiment 2 of the present invention; 
           [0054]      FIG. 6  shows a schematic diagram of the scenario of applying a protection switching policy when an error connection occurs in the service according to Embodiment 2 of the present invention; 
           [0055]      FIG. 7  shows a flow of preventing error by a control plane when an error connection occurs in the service according to Embodiment 2 of the present invention; 
           [0056]      FIG. 8  shows a system structure diagram of a system for error connection and error prevention according to the present invention; 
           [0057]      FIG. 9  shows a composite structure diagram of an error prevention policy executing module in a system for error connection and error prevention according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0058]    The present invention, through automatically completing configuration of error connection and error prevention information of the start node and the end node of the service by the control plane, can implement error prevention of the service and rapidly recover the service to be normal when an error connection occurs in the service, wherein establishment of the service, re-routing recovery of the service, switching of the service and determining of error connection alarm information are all performed by the control plane of the ASON, while error connection detection is performed by the transport plane. 
       Embodiment 1 
       [0059]      FIG. 1  shows a diagram of an application scenario of a method for error connection and error prevention in a normal condition according to a preferred embodiment of the present invention. The Mesh network consists of network elements A, B, C, D, E, Z and a sub-network SNC-A and the links between these nodes, wherein the solid line connection between the network element A and the network element B, and the solid line connection between the network element D and the network element Z are link connections, and the dotted line connection between the network element B and the network element D, and the dotted line connection between the network element C and the network element E are sub-network connections (the graphic symbols in  FIG. 1 ,  FIG. 2 ,  FIG. 5  and  FIG. 6  are the same and will not be repeated hereinafter). The ASON control plane has established an one-way service connections A-B-D-Z (also called original connections), with the start node of the connection being A, and the end node of the connection being Z. In this embodiment, the error prevention policy of the service between A and Z employs a re-routing recovery policy, i.e., the service connection between A and Z has a recovery level, so that when the connection fails, the service may be switched to a recovery connection by establishing the recovery connection. The service connection between A and Z employs a “return” method. In case of failure of the original connection, after the service is switched to the recovery connection by establishing the recovery connection, if the failure of the original connection disappears, the service will be switched back to the original connection. 
         [0060]    In the embodiments of the present invention, in the technology of detecting an error connection by the transport plane, the Jx byte-based method for error connection and error prevention of the service is employed. Therefore, the service error prevention information in the embodiment refers to the Jx byte. Of course, other detection methods may also be applied. In the present invention, establishment of the service, re-routing recovery of the service, switching of the service and determining of the error connection alarm information are all performed by the ASON control plane, while error connection detection is performed by the transport plane. 
         [0061]    The present invention is characterized in that the configuration of service error prevention information of the start node and end node of the service is automatically completed by the control plane; the node that initiates configuration of the service error prevention information may be the start node or the end node of the service; the node that initiates the configuration needs to send the service error prevention information to the opposite node of the service (the opposite node of the service refers to a counterpart service node of the service node that initiates the configuration; if the start node of the service initiates the configuration process, then the opposite node of the service is the end node of the service); the start node and end node of the service respectively issue a configuration request to their respective transport planes to configure the service error prevention information on the start node and end node of the service. 
         [0062]    The service error prevention information can only be valid after being successfully configured on both the start node and the end node. The process of synchronously configuring the service error prevention information and reporting the configuration result between the start node and the end node of the service comprises the following steps: 
         [0063]    ( 1 ) the control plane of a start node or an end node of the service issues a configuration request to the corresponding node after acquiring the service error prevention information; 
         [0064]    ( 2 ) The start node or end node of the service that initiates the configuration of the service error prevention information sends the service error prevention information to the opposite node of the service; 
         [0065]    the service error prevention information only refers to the interaction between the start node and the end node. In order to ensure automatic and rapid configuration of the start node and end node, a certain protocol is needed to be as a support, but it is not limited to using which private signaling and protocol, e.g., a Notify message in the Resource ReSerVation Protocol (RSVP), or an OEM message in the Link Management Protocol (LMP); 
         [0066]    ( 3 ) The opposite node of the service issues a configuration request to the transport plane of the opposite node of the service after receiving the service error prevention information; 
         [0067]    ( 4 ) The start node and the end node of the service report a configuration success message to the control plane after the service error prevention information is successfully configured on both the start node and the end node. 
         [0068]      FIG. 3  shows a flow of configuring error prevention information by the control plane when the service works normally. The flow is the process in which the service node executes the configuration of error prevention information at the service node after receiving the request of configuring the service error prevention information, the flow specifically comprises: 
         [0069]    step  301 : the control plane receives a request of configuring service error prevention information; 
         [0070]    the service error prevention information may be provided by the management plane or automatically generated by the transport plane according to a certain policy; 
         [0071]    step  302 : the control plane determines the type of the service, acquires the service-related information, and determines the set points of the sending value and the expected value; 
         [0072]    step  303 : the transport plane is requested to configure the service error prevention information; 
         [0073]    the transport plane sets the service error prevention information at set points of the sending value and the expected value according to the set points of the sending value and the expected value which are determined by the control plane; 
         [0074]    for a one-way service, the sending value is set in the sending direction of the start node of the service, and the expected value is set in the receiving direction of the end node of the service; the sending value is the same as the expected value; 
         [0075]    for a two-way service, the sending value is set in the sending directions of both the start node and end node of the service; the expected value is set in the receiving directions of both the start node and end node of the service; the sending value is the same as the expected value; 
         [0076]    if the sending value is set, the expected value may not be set. However, if the expected value is set, the corresponding sending value must be set. 
         [0077]    Referring to  FIG. 1 , the step of configuring error prevention information on the start node A and end node B of the service comprises: 
         [0078]    step  1 : the sending value of the path trace byte (Jx byte) is set as Work in the sending direction of the node A; 
         [0079]    step  2 : the expected value of the path trace byte (Jx byte) is set as Work in the receiving direction of the node Z; 
         [0080]    step  3 : the service error prevention information is successfully configured after the node A receives a response of successful configuration from the node A and the node Z; the interaction between the node A and the node Z is performed via the DCN. 
         [0081]    step  304 : it is determined whether the transport plane successfully configures the Jx byte, if so, the step  305  is executed; otherwise, the step  306  is executed; 
         [0082]    step  305 : the control plane activates the function of the error connection and error prevention; 
         [0083]    Step  306 : reporting to the management plane, the configuration fails. 
         [0084]      FIG. 2  shows a schematic diagram of establishing a recovery connection when an error connection occurs in the service according to a preferred embodiment of the present invention. Failure of a node or link in the sub-network SNC-A causes an error connection in the service. At the node Z, an error connection alarm is generated in the path of the original connection. The Node Z sends the alarm information to the node A. After the node A receives the alarm information from the node Z, the processing steps are illustrated in  FIG. 4 : 
         [0085]    step  401 : the node A determines the failing service according to the reported or received error connection information; 
         [0086]    step  402 : the node A acquires an error prevention policy of the service in which an error connection alarm is generated; 
         [0087]    the error prevention policy of the service may be pre-configured by the control plane or a certain error prevention policy dynamically selected by the control plane according to the current network state. In this embodiment, the re-routing recovery policy is used as an error prevention policy, then the control plane starts the recovery; 
         [0088]    step  403 : the control plane starts the recovery and establishes a recovery connection; 
         [0089]    as shown in  FIG. 2 , after the error connection occurs in the connection (A-B-D-Z), the control plane establishes the recovery connection (A-C-E-Z) according to the error prevention policy; 
         [0090]    step  404 : the control plane configures the error prevention information for the new established recovery connection; 
         [0091]    Before the service is switched from the original connection to the recovery connection, the control plane of the start node and end node of the service configures the service error prevention information for the new established recovery connection according to the service error prevention information of the original connection; 
         [0092]    step  405 : the service is switched from the original connection to the recovery connection after the service error prevention information is successfully configured; 
         [0093]    after the service error prevention information is successfully configured on both the start node and end node of the service, the control plane switches the service from the original connection (A-B-D-Z) to the recovery connection (A-C-E-Z). 
         [0094]    If the service error connection failure of the original connection has been repaired and the node Z detects that the alarm of error connection has disappeared, the node Z sends the alarm information to the node A of the connection. After receiving the alarm information from the node Z, the node A switches the service from the recovery connection to the original connection, deletes the recovery connection, and releases the resource. 
       Embodiment 2 
       [0095]    In this embodiment, the Mesh network as shown in  FIG. 5  consists of network elements A, B, C, D, E, F, G, Z, and a sub-network SNC-A and the links between these nodes. The ASON control plane has successfully established the following services and connections: working connection  1 : one-way service and connection A-B-D-Z; working connection  2 : one-way service and connection A-C-E-Z; protection connection  1 : one-way service and connection from A-F-G-Z. These three service connections form a protection group of M:N (M=1, N=2), wherein the working connections comprise the working connection  1  and working connection  2 , and the protection connection comprises protection connection  1 . The start node of the connection is A and the end node of the connection is Z. 
         [0096]    The step of configuring the service error prevention information for the working connection  1  by the control plane is the same as the configuration step of Embodiment 1. As shown in  FIG. 3 , the main steps of configuring the service error prevention information comprises: 
         [0097]    step  1 : the sending value of the path trace byte (Jx) is set as Work 1  in the sending direction of the node A; 
         [0098]    step  2 : the expected value of the path trace byte (Jx) is set as Work 1  in the receiving direction of the node Z; 
         [0099]    step  3 : the service error prevention information is successfully configured after the node A receives responses of successful configuration from the node A and node Z. 
         [0100]    The interaction between the node A and node Z is performed via the DCN. 
         [0101]    The step of configuring the service error prevention information for working connection  2  by the control plane is the same as above; the only difference is that the sending value and the expected value are both set as Work 2 . 
         [0102]    The step of configuring the service error prevention information for protection connection  1  by the control plane is the same as above. The only difference is that the sending value and the expected value are both set as Pro 1 . 
         [0103]    In this embodiment, failure of a certain node or link in the sub-network SNC-A causes an error connection in the service. At the node Z, an error connection alarm is generated in the working connection  1 . As shown in  FIG. 6 , the node Z sends the alarm information to the node A of the connection. After the node A receives the alarm information from the node Z, the processing steps are illustrated in  FIG. 7 : 
         [0104]    step  701 : the node A determines the failing service according to the reported or received service error connection alarm information; 
         [0105]    step  702 : the node A acquires an error prevention policy of the service; 
         [0106]    step  703 : it is determined whether a protection switching policy is used; if yes, step  704  is executed; otherwise, step  706  is executed; 
         [0107]    step  704 : the control plane configures the service error prevention information (Jx byte) for the switched destination connection; 
         [0108]    the control plane starts the switching mechanism. Before the working connection  1  is switched to the protection connection  1 , the control plane configures the service error prevention information for the protection connection  1 . The service error prevention information is the service error prevention information of the working connection  1 ; 
         [0109]    step  705 : the control plane starts, after the error prevention information of the protection connection  1  is successfully configured, the switching to switch the service from the working connection  1  to the destination connection (i.e. protection connection  1 ); 
         [0110]    step  706 : processing of other error prevention policies is performed if other error prevention policies are applied. 
         [0111]    In this embodiment, if the service error connection failure of the working connection  1  has been repaired and the node Z detects that the alarm of the error connection has disappeared, the node Z sends alarm information to the node A of the connection. The node A receives the alarm information from the node Z, the control plane switches the service from the protection connection  1  to the working connection  1  and recovers the original service error prevention information. 
         [0112]      FIG. 8  shows a system structure diagram of a system for error connection and error prevention according to the present invention. The system for error connection and error prevention according to the present invention comprises an error prevention information configuring module, an error connection detecting and alarming module and an error prevention policy executing module. The error prevention information configuring module and the error prevention policy executing module are located in the control plane and the error connection detecting and alarming module is located in the transport plane. 
         [0113]    The error prevention information configuring module is arranged to configure service error prevention information for the error connection detecting and alarming module located in the transport plane; the error connection detecting and alarming module is arranged to detect an error connection in a service according to the service error prevention information configured by the error prevention information configuring module, and inform, after an error connection is detected, the error prevention policy executing module located in the control plane; the error prevention policy executing module is arranged to acquire, after receiving error connection alarm information reported by the error connection detecting and alarming module, an error prevention policy of the service in which an error connection alarm is generated and execute a corresponding error prevention operation. 
         [0114]    The error prevention information configuring module further comprises a service start node error prevention information configuring module arranged to configure service error prevention information for the transport plane at a service start node, and a service end node error prevention information configuring module arranged to configure service error prevention information for the transport plane at the service end node. The service start node error prevention information configuring module or the service end node error prevention information configuring module, after initiating an operation of configuring the service error prevention information, needs to send the service error prevention information to the opposite node of the service; the opposite node of the service configures, after receiving the service error prevention information, the service error prevention information for the transport plane of the opposite node of the service. 
         [0115]      FIG. 9  shows a composite structure diagram of an error prevention policy executing module in a system for error connection and error prevention according to the present invention. The error prevention policy executing module comprises a failing service determining unit, a policy acquiring unit and a policy executing unit. 
         [0116]    The failing service determining unit is arranged to determine a service that fails according to the error connection alarm information of the service reported by the error connection detecting and alarming module; the policy acquiring unit is arranged to acquire an error prevention policy from service-related information of the service according to the service determined by the failing service determining unit; the policy executing unit is arranged to execute a corresponding error prevention operation according to the error prevention policy acquired by the policy acquiring unit; the error prevention policy may be a re-routing recovery policy or a protection switching policy or other error prevention policies. 
         [0117]    What are described above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, various modifications and changes may be made without departing from the principles of the present invention. These modifications and changes should be included in the protection scope of the present invention.