Abstract:
A disclosed example method to identify a failure in a logical circuit involves receiving non-requested trap data from a plurality of switches forming a logical circuit. The logical circuit spans first, second, and third logical networks. The example method also involves polling first and second switches of the logical circuit exclusive of others of the plurality of switches of the logical circuit. The first switch forms a first network-to-network interface between the first logical network and the second logical network. The second switch forms a second network-to-network interface between the second logical network and the third logical network. The first and second switches are selected for polling based on the trap data indicating a problem at the first and second switches. The example method also involves identifying a failure of the logical circuit without manual intervention based on the polling.

Description:
PRIORITY APPLICATION 
     This patent arises from a continuation of U.S. patent application Ser. No. 10/745,170, filed Dec. 23, 2003, now U.S. Pat. No. 8,203,933, which is hereby incorporated herein by reference in its entirety. 
     CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is related to U.S. patent application Ser. No. 10/348,077, entitled “Method and System for Obtaining Logical Performance Data for a Circuit in a Data Network,” filed on Jan. 21, 2003, and U.S. patent application Ser. No. 10/348,592, entitled “Method and System for Provisioning and Maintaining a Circuit in a Data Network,” filed on Jan. 21, 2003. This application is also related to and filed concurrently with U.S. patent application Ser. No. 10/745,117, entitled “Method And System For Providing A Failover Circuit For Rerouting Logical Circuit Data In A Data Network,” filed on Dec. 23, 2003, U.S. patent application Ser. No. 10/744,281, entitled “Method And System For Utilizing A Logical Failover Circuit For Rerouting Data Between Data Networks,” filed on Dec. 23, 2003, U.S. patent application Ser. No. 10/745,047, entitled “Method And System For Automatically Renaming Logical Circuit Identifiers For Rerouted Logical Circuits In A Data Network,” filed on Dec. 23, 2003, U.S. patent application Ser. No. 10/744,921, entitled “Method And System For Automatically Rerouting Logical Circuit Data In A Data Network,” filed on Dec. 23, 2003, U.S. patent application Ser. No. 10/745,168, entitled “Method And System For Automatically Rerouting Logical Circuit Data In A Virtual Private Network,” filed on Dec. 23, 2003, U.S. patent application Ser. No. 10/745,116, entitled “Method And System For Automatically Rerouting Data From An Overbalanced Logical Circuit In A Data Network,” filed on Dec. 23, 2003, U.S. patent application Ser. No. 10/744,283, entitled “Method And System For Real Time Simultaneous Monitoring Of Logical Circuits In A Data Network,” filed on Dec. 23, 2003, U.S. patent application Ser. No. 10/744,555, entitled “Method And System For Prioritized Rerouting Of Logical Circuit Data In A Data Network,” filed on Dec. 23, 2003. All of the above-referenced applications are assigned to the same assignee as the present application and are expressly incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to the routing of data using logical circuits in a data network. More particularly, the present invention is related to automatically identifying a failure in a logical circuit in a data network. 
     BACKGROUND 
     Data networks contain various network devices, such as switches, for sending and receiving data between two locations. For example, frame relay and Asynchronous Transfer Mode (“ATM”) networks contain interconnected network devices that allow data packets or cells to be channeled over a circuit through the network from a host device to a remote device. For a given network circuit, the data from a host location is delivered to the network through a physical circuit such as a T1 line that links to a switch of the network. The remote device that communicates with the host through the network also has a physical circuit to a switch of the network. The communication path between the switches associated with the host and the remote device that passes through the network is a logical circuit. 
     In frame relay and ATM networks, end devices do not select different routes for data packets or cells sent between the host and the remote location, but always send the data packets or cells through the same path. A host device may have many logical circuits, such as permanent virtual circuits (“PVCs”) or switched virtual circuits (“SVCs”), linked to many remote locations. For example, a PVC sends and receives data packets or cells through the same path leading to the switch of the remote device&#39;s physical connection. 
     In large-scale networks, the host and remote end devices of a network circuit may be connected across different local access and transport areas (“LATAs”) which may in turn be connected to one or more Inter-Exchange Carriers (“IEC”) for transporting data between the LATAs. These connections are made through physical trunk circuits utilizing fixed logical connections known as Network-to-Network Interfaces (“NNIs”). 
     Periodically, failures may occur to the trunk circuits or the NNIs of network circuits in large-scale networks causing lost data. Currently, such network circuit failures are handled by dispatching technicians on each end of the network circuit (i.e., in each LATA) in response to a reported failure. The technicians manually access a logical element module to troubleshoot the logical circuit portion of the network circuit. The logical element module communicates with the switches in the data network and provides the technician with the status of the logical connections which make up the logical circuit. Once the technician determines the status of a logical connection at one end of a logical circuit (e.g., the host end), the technician then must access a network database to determine the location of the other end of the logical circuit so that its status may also be ascertained. If the technician determines the logical circuit is operating properly, the technician then accesses a physical element module to troubleshoot the physical circuit portion of the network circuit to determine the cause of the failure and then repair it. 
     Current methods of determining network circuit failures, however, suffer from several drawbacks. One drawback is that troubleshooting the logical and physical circuits is time consuming and results in dropped data packets or cells until the failure is isolated and repaired. For example, isolating a logical circuit failure requires that a technician access a database to identify the logical connections which make up the logical circuit. Once the logical connections are identified, their status is ascertained and the logical circuit is repaired. The database records, however, are manually entered and thus subject to human error which, if present, increases circuit downtime until the logical connections making up the failed logical circuit are identified. Furthermore troubleshooting the physical circuit often requires taking the network circuit out of service to perform testing, thus increasing the downtime and loss of data in the network circuit. 
     It is with respect to these considerations and others that the present invention has been made. 
     SUMMARY 
     In accordance with the present invention, the above and other problems are solved by methods for automatically identifying a logical circuit failure in a data network. According to one method, a logical circuit in the data network is periodically monitored for status information pertinent to the logical circuit. The data network may be a frame relay network or an asynchronous transfer mode (“ATM”) network. The logical circuit may include one more logical connections for communicating data in the data network. The logical circuit may be a permanent virtual circuit (“PVC”) or a switched virtual circuit (“SVC”). A failure of the logical circuit is then identified, based on the status information, without manual intervention. 
     The periodic monitoring of the logical circuit may include periodically monitoring one or more logical connections in the logical circuit. The periodic monitoring of the logical connections in the logical circuit may include periodically requesting trap data for each logical connection. The trap data may include status information for each logical connection in the logical circuit. Identifying a failure of the logical circuit may include analyzing the status information for the each logical connection. If the status information for the at least one logical connection indicates that a logical connection is no longer communicating data, then determining that the logical connection has failed. After determining that the logical connection has failed, waiting a predetermined time period to determine whether the failed logical connection has been restored. If after the predetermined time period, the logical connection has not been restored, then determining that the logical circuit has failed. 
     The method may further include identifying a logical identifier for the logical circuit and based on the logical identifier, accessing a database to identify each logical connection in the logical circuit. The logical identifier may be a data link connection identifier (“DLCI”) or a virtual path/virtual circuit identifier (“VPI/VCI”). Each logical connection may include a network-to-network interface. 
     In accordance with other aspects, the present invention relates to a system for automatically identifying a logical circuit failure in a data network. The system includes a network device for collecting trap data for the logical circuit in the data network, a logical element module in communication with the network device for receiving the trap data for the logical circuit, and a network management module in communication with the logical element module. The network management module is utilized to periodically retrieving the trap data for the logical circuit and identify a failure of the logical circuit based on the trap data, without manual intervention. 
     These and various other features as well as advantages will be apparent from a reading of the following detailed description and a review of the associated drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an illustrative data network according to an embodiment of the invention. 
         FIG. 2  illustrates a local access and transport area (“LATA”) and a network  20  management system which may be utilized to automatically identify a failure in a logical circuit in the data network of  FIG. 1 , according to an embodiment of the invention. 
         FIG. 3  illustrates a flowchart describing logical operations for automatically identifying a failure in a logical circuit in the data network of  FIG. 1 , according to an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Embodiments of the present invention provide for a method and system automatically identifying a failure in a logical circuit in a data network. In the following detailed description, references are made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration specific embodiments or examples. Referring now to the drawings, in which like numerals represent like elements through the several figures, aspects of the present invention and the exemplary operating environment will be described. 
     Embodiments of the present invention may be generally employed in a data network  2  as shown in  FIG. 1 . The data network  2  includes local access and transport areas (“LATAs”)  5  and  15  which are connected by an Inter-Exchange Carrier (“IEC”)  10 . It should be understood that the LATAs  5  and  15  may be operated by a commonly owned Local Exchange Carrier (“LEC”). It should be further understood that the IEC  10  may include one or more data networks which may be operated by a commonly owned IEC. It will be appreciated by those skilled in the art that the data network  2  may be a frame relay network, asynchronous transfer mode (“ATM”) network, or any other network capable of communicating data conforming to Layers 2-4 of the Open Systems Interconnection (“OSI”) model developed by the International Standards Organization, incorporated herein by reference. It will be appreciated that these networks may include, but are not limited to, communications protocols conforming to the Multiprotocol Label Switching Standard (“MPLS”) networks and the Transmission Control Protocol/Internet Protocol (“TCP/IP”), which are known to those skilled in the art. 
     The data network  2  includes a network circuit which channels data between a host device  112  and a remote device  114  through the LATA  5 , the IEC  10 , and the LATA  15 . It will be appreciated by those skilled in the art that the host and remote devices  112  and  114  may be local area network (“LAN”) routers, LAN bridges, hosts, front end processors, Frame Relay Access Devices (“FRADs”), or any other device with a frame relay, ATM, or network interface. It will be further appreciated that in the data network  2 , the LATAs  5  and  15  and the IEC  10  may include network elements (not shown) which support interworking to enable communications between host and remote devices supporting dissimilar protocols. Network elements in a data network supporting interworking may translate frame relay data packets or frames sent from a host FRAD to ATM data packets or cells so that a host device may communicate with a remote device having an ATM interface. The LATAs  5  and  15  and the IEC  10  may further include one or more interconnected network elements, such as switches (not shown), for transmitting data. 
     The network circuit between the host device  112  and the remote device  114  in the data network  2  includes a physical circuit and a logical circuit. As used in the foregoing description and the appended claims, a physical circuit is defined as the physical path that connects the end point of a network circuit to a network device. For example, the physical circuit of the network circuit between the host device  112  and the remote device  114  includes the physical connection  121  between the host device  112  and the LATA  5 , the physical connection  106  between the LATA  5  and the IEC  10 , the physical connection  108  between the IEC  10  and the LATA  15 , and the physical connection  123  between the LATA  15  and the remote device  114 . Router and switches within the LATAs  5  and  15  and the IEC  10  carry the physical signal between the host and remote end devices  112  and  114  through the physical circuit. 
     It should be understood that the host and remote devices may be connected to the physical circuit described above using user-to-network interfaces (“UNIs”). As is known to those skilled in the art, an UNI is the physical demarcation point between a user device (e.g, a host device) and a public data network. It will further be understood by those skilled in the art that the physical connections  106  and  108  may include trunk circuits for carrying the data between the LATAs  5  and  15  and the IEC  10 . It will be further understood by those skilled in the art that the connections  121  and  123  may be any of various physical communications media for communicating data such as a 56 Kbps line or a T1 line carried over a four-wire shielded cable or over a fiber optic cable. 
     As used in the foregoing description and the appended claims, a logical circuit is defined as a portion of the network circuit wherein data is sent over variable communication data paths or logical connections established between the first and last network devices in a LATA or IEC network and over fixed communication data paths or logical connections between LATAs (or between IECs). Thus, no matter what path the data takes within each LATA or IEC, the beginning and end of each logical connection between networks will not change. For example, the logical circuit of the network circuit in the data network  2  may include a variable communication path within the LATA  5  and a fixed communication path (i.e., the logical connection  102 ) between the LATA  5  and the IEC  10 . It will be understood by those skilled in the art that the logical connections  102  and  104  in the data network  2  may include network-to-network interfaces (“NNIs”) between the last sending switch in a LATA and the first receiving switch in an IEC. 
     As is known to those skilled in the art, each logical circuit in a data network may be identified by a unique logical identifier. In frame relay networks, the logical identifier is called a Data Link Connection Identifier (“DLCI”) while in A TM networks the logical identifier is called a Virtual Path Identifier/Virtual Circuit Identifier (“VPI/VCI”). In frame relay networks, the DLCI is a  10 -bit address field contained in the header of each data frame and contains identifying information for the logical circuit as well as information relating to the destination of the data in the frame and service parameters for handling network congestion. For example, in the data network  2  implemented as a frame relay network, the designation DLCI  100  may be used to identify the logical circuit between the host device  112  and the remote device  114 . It will be appreciated that in data networks in which logical circuit data is communicated through more than one carrier (e.g., an LEC and an IEC) the DLCI designation for the logical circuit may change in a specific carrier&#39;s network. For example, in the data network  2 , the designation DLCI  100  may identify the logical circuit in the LATA  5  and LATA  15  but the designation DLCI  800  may identify the logical circuit in the IEC  10 . 
     Illustrative service parameters which may be included in the DLCI include a Committed Information Rate (“CIR”) parameter and a Committed Burst Size (“Bc”) parameter. As is known to those skilled in the art, the CIR represents the average capacity of the logical circuit and the Bc represents the maximum amount of data that may be transmitted. It will be appreciated that the logical circuit may be provisioned such that when the CIR or the Bc is exceeded, the receiving switch in the data network will discard the frame. It should be understood that the logical circuit parameters are not limited to CIR and Bc and that other parameters known to those skilled in the art may also be provisioned, including, but not limited to, Burst Excess Size (“Be”) and Committed Rate Measurement Interval (“Tc”). In ATM networks, the VPI/VCI is an address field contained in the header of each ATM data cell and contains identifying information for the logical circuit as well as information specifying a data cell&#39;s destination and specific bits which may indicate, for example, the existence of congestion in the network and a threshold for discarding cells. 
     It should be understood that the logical circuit in the data network  2  may be a permanent virtual circuit (“PVC”) available to the network at all times or a temporary or a switched virtual circuit (“SVC”) available to the network only as long as data is being transmitted. It should be understood that the data network  2  may further include additional switches or other interconnected network elements (not shown) creating multiple paths within each LATA and IEC for defining each PVC or SVC in the data network. It will be appreciated that the data communicated over the logical connections  102  and  104  may be physically carried by the physical connections  106  and  108 . 
     The data network  2  may also include a failover network  17  for rerouting logical circuit data, according to an embodiment of the invention. The failover network  17  may include a network failover circuit including physical connections  134  and  144  and logical connections  122  and  132  for rerouting logical circuit data in the event of a failure in the network circuit between the host device  112  and the remote device  114 . The data network  2  may also include a network management system  175  in communication with the LATA  5  and the LATA  15  which may be utilized to obtain status information for the logical and physical circuit between the host device  112  and the remote device  114 . The network management system  175  may also be utilized for rerouting logical data in the data network  2  between the host device  112  and the remote device  114 . The network management module  176  will be discussed in greater detail in the description of  FIG. 2  below. 
     Turning now to  FIG. 2 , an illustrative data carrier (i.e., the LATA  5 ) and the network management system  175 , contained in the data network described in  FIG. 1  above, will now be described. As shown in  FIG. 2 , the LATA  5  includes interconnected network devices such as switches  186 ,  187 , and  188 . It will be appreciated that the data network  2  may also contain other interconnected network devices and elements (not shown) such as digital access and cross connect switches (“DACS”), channel service units (“CSUs”), and data service units (“DSUs”). As discussed above in the description of  FIG. 1 , the connection data paths of a logical circuit within a data network may vary between the first and last network devices in a data network. For example, as shown in  FIG. 2 , the logical circuit in the LATA  5  may include the communication path  185  between the switches  186  and  188  or the communication path  184  between the switches  186 ,  187 , and  188 . As discussed above, it should be understood that the actual path taken by data through the LATA  5  is not fixed and may vary from time to time, such as when automatic rerouting takes place. 
     It will be appreciated that the switches  186 ,  187 , and  188  may include a signaling mechanism for monitoring and signaling the status of the logical circuit in the data network  2 . Each time a change in the status of the logical circuit is detected (e.g., a receiving switch begins dropping frames), the switch generates an alarm or “trap” which may then be communicated to a management station, such as a logical element module (described in detail below), in the network management system  175 . In one embodiment, the signaling mechanism may be in accord with a Local Management Interface (“LMI”) specification, which provides for the sending and receiving of “status inquiries” between a data network and a host or remote device. The LMI specification includes obtaining status information through the use of special management frames (in frame relay networks) or cells (in ATM networks). In frame relay networks, for example, the special management frames monitor the status of logical connections and provide information regarding the health of the network. In the data network  2 , the host and remote devices  112  and  114  receive status information from the individual LATAs they are connected to in response to a status request sent in a special management frame or cell. The LMI status information may include, for example, whether or not the logical circuit is congested or whether or not the network circuit has failed. It should be understood that the parameters and the signaling mechanism discussed above are optional and that other parameters and mechanisms may also be utilized to obtain connection status information for a network circuit. 
     As discussed above in, the LATA  5  may be connected to the network management system  175  which, as shown in  FIG. 2 , includes a service order system  160 , a network database  170 , a logical element module  153 , a physical element module  155 , a network management module  176 , and a test module  180 . The service order system  160  is utilized in the data network  2  for receiving service orders for provisioning network circuits. The service order includes information defining the transmission characteristics (i.e., the logical circuit) of the network circuit. The service order also contains the access speed, CIR, burst rates, and excess burst rates. The service order system  160  communicates the service order information to a network database  170  over management trunk  172 . The network database  170  assigns and stores the parameters for the physical circuit for the network circuit such as a port number on the switch  186  for transmitting data over the physical connection  121  to and from the host device  112 . 
     The network database  170  may also be in communication with an operations support system (not shown) for assigning physical equipment to the network circuit and for maintaining an inventory of the physical assignments for the network circuit. An illustrative operations support system is “TIRKS” ® (Trunks Integrated Records Keeping System) marketed by TELECORDIA™ TECHNOLOGIES, Inc. of Morristown, N.J. The network database  170  may also be in communication with a Work Force Administration and Control system (“WFA/C”) (not shown) used to assign resources (i.e., technicians) to work on installing the physical circuit. 
     The network management system  175  also includes the logical element module  153  which is in communication with the switches  186 ,  187 , and  188  through management trunks  185 . The logical element module  153  runs a network management application program to monitor the operation of logical circuits which includes receiving trap data generated by the switches which indicate the status of logical connections. The trap data may be stored in the logical element module  153  for later analysis and review. The logical element module  153  is also in communication with the network database  170  via management trunks  172  for accessing information regarding logical circuits such as the logical identifier data. The logical identifier data may include, for example, the DLCI or VPI/VCI header information for each data frame or cell in the logical circuit including the circuit&#39;s destination and service parameters. The logical element module  153  may consist of terminals (not shown) that display a map-based graphical user interface (“GUI”) of the logical connections in the data network. An illustrative logical element module is the NAVISCORE™ system marketed by LUCENT TECHNOLOGIES, Inc. of Murray Hill, N.J. 
     The network management system  175  further includes the physical element module  155  in communication with the physical connections of the network circuit via management trunks (not shown). The physical element module  155  runs a network management application program to monitor the operation and retrieve data regarding the operation of the physical circuit. The physical element module  155  is also in communication with the network database  170  via management trunks  172  for accessing information regarding physical circuits, such as line speed. Similar to the logical element module  153 , the physical logical element module  155  may also consist of terminals (not shown) that display a map-based GUI of the physical connections in the LATA  5 . An illustrative physical element module is the Integrated Testing and Analysis System (“INTAS”), marketed by TELECORDIA™ TECHNOLOGIES, Inc. of Morristown, N.J., which provides flow-through testing and analysis of telephony services. 
     The physical element module  155  troubleshoots the physical connections for the physical circuit by communicating with test module  180 , which interfaces with the physical connections via test access point  156 . The test module  180  obtains the status of the physical circuit by transmitting “clean” test signals to test access point  156  which “loopback” the signals for detection by the test module  180 . It should be understood that there may be multiple test access points on each of the physical connections for the physical circuit. 
     The network management system  175  further includes the network management module  176  which is in communication with the service order system  160 , the network database  170 , the logical element module  153 , and the physical element module  155  through communications channels  172 . The communications channels  172  may be on a LAN. The network management module  176  may consist of terminals (not shown), which may be part of a general-purpose computer system that displays a map-based GUI of the logical connections in data networks. The network management module  176  may communicate with the logical element module  153  and the physical element module  155  using a Common Object Request Broker Architecture (“CORBA”). As is known to those skilled in the art, CORBA is an open, vendor-independent architecture and infrastructure which allows different computer applications to work together over one or more networks using a basic set of commands and responses. The network management module  176  may also serve as an interface for implementing logical operations to provision and maintain network circuits. The logical operations may be implemented as machine instructions stored locally or as instructions retrieved from the element modules  153  and  155 . An illustrative method detailing the provisioning and maintenance of network circuits in a data network is presented in U.S. patent application Ser. No. 10/348,592, entitled “Method And System For Provisioning And Maintaining A Circuit In A Data Network,” filed on Jan. 23, 2003, and assigned to the same assignee as this application, which is expressly incorporated herein by reference. An illustrative network management module is the Broadband Network Management System® (“BBNMS”) marketed by TELECORDIA™ TECHNOLOGIES, Inc. of Morristown, N.J. 
     It should be understood that in one embodiment, the network management system  175  may also be in communication with the LATA  15 , the IEC  10 , and the failover network  17 . 
       FIG. 3  illustrates a flowchart describing logical operations  300  for automatically identifying a failure in a logical circuit in the data network  2  of  FIG. 1 , according to an embodiment of the invention. The logical operations  300  begin at operation  305  where the network management module  176  communicates with the logical element module  153  to request trap data indicating the status of a logical connection making up the logical circuit in the data network  2 . It should be understood that although the trap data is continuously generated by the switches in the data network  2  and then communicated to the logical element module  153  each time a change in status occurs, in this embodiment, the network management module  176  may be configured so that the trap data is only requested periodically (e.g., once every hour) so that system resources are conserved. It will be appreciated that in another embodiment of the invention, the trap data could be processed passively from the switches by the logical element module  153  (where the trap data is stored). The network management module  176 , in communication with the logical element module  153 , may then be configured to actively poll only those switches carrying logical circuits indicating trouble (e.g., dropped frames or cells) to further conserve system resources. Once the request for trap data is made, all of the trap data collected in the last time period (e.g., one hour) is communicated to the network management module  176  from the logical element module  153 . 
     For example, in one embodiment, the network management module  176  may be configured to check the status of the NNI or logical connection  102  in the data network  2  by requesting the trap data generated by the switches  186 ,  187 , and  188  in the LATA  5 . It will be appreciated that in one embodiment, the network management module  176  may be configured to first request trap data for a logical connection on one end of a logical circuit (e.g., the host end) and then identify the logical connection for the other end of the logical circuit (e.g., the remote end) based on the logical identifier (i.e., the DLCI or VPI/VCI information) for the logical circuit. It will be appreciated that the network management module  176  may obtain the logical identifier by polling the logical element module  153 . Once the logical identifier for the logical circuit has been obtained, the network management module  176  may then access the network database  170  to “lookup” the NNI or logical connection on the far end of the logical circuit and request the trap data for that logical connection. 
     After requesting trap data for a logical connection (or logical connections) in the data network  2  at operation  305 , the logical operations  300  continue at operation  310  where the network management module  176  analyzes the received trap data and identifies a logical connection failure at operation  315 . As discussed above in the description of  FIG. 2 , trap data indicating a logical connection failure may include status information indicating that a switch in the data network is discarding frames or cells. Such an event may occur, for example, when the maximum CIR or Bc (as specified in the DLCI of a frame in a frame relay network, for example) is exceeded. If at operation  315 , it is determined that a logical connection failure has not occurred, the logical operations  300  then return to operation  305  where the network management module  176  again requests trap data from the logical element module  153  during the next predetermined period (e.g., the beginning of the next hour). If, however, at operation  315  it is determined that a logical connection failure has occurred, the logical operations continue from operation  315  to operation  320  where the network management module  176  waits a predetermined period (e.g., five minutes) to determine whether the failed logical connection has been restored (i.e., the communication of data over the logical connection has resumed). For example, in the data network  2  illustrated in  FIG. 2 , the “X” marking the logical connections  102  and  104  indicates that the logical connection is “down beyond” (i.e., not communicating data) the NNIs for the logical circuit in the LATAs  5  and  15 . 
     If at operation  320 , the network management module  176  determines that the failed logical connection has been restored, the logical operations  300  return to operation  305  where the network management module  176  again requests trap data from the logical element module  153  during the next predetermined period. If, however, at operation  320  the network management module  176  determines that the failed logical connection has not been restored during the predetermined wait period, the logical operations  300  continue to operation  325  where the network management module  176  indicates that the logical circuit has failed. 
     Once the network management module  176  has indicated a logical circuit failure it may initiate an automatic reroute procedure using the failover network  17 . An illustrative method detailing rerouting logical circuit data over a failover network is presented in U.S. patent application Ser. No. 10/744,921, entitled “Method And System For Automatically Rerouting Logical Circuit Data In A Data Network,” filed on Dec. 23, 2003, and assigned to the same assignee as this application, which is expressly incorporated herein by reference. 
     It will be appreciated that the embodiments of the invention described above provide for a method and system for automatically identifying a failure in a logical circuit in a data network. The various embodiments described above are provided by way of illustration only and should not be construed to limit the invention. Those skilled in the art will readily recognize various modifications and changes that may be made to the present invention without following the example embodiments and applications illustrated and described herein, and without departing from the true spirit and scope of the present invention, which is set forth in the following claims.