# Patent

## Title
Methods and systems for automatically rerouting logical circuit data from a logical circuit failure to a dedicated backup circuit in a data network

## Abstract

An example method involves rerouting a logical circuit from a first set of switches to a second set of switches to communicate data between network devices without breaking the logical circuit. The logical circuit includes variable communication paths, and the second set of switches are to form a route associated with the variable communication paths that is not predefined and that is dynamically defined at a time of automatic rerouting. The example method also involves detecting a failure of the logical circuit based on at least one of a committed information rate or a committed burst size having been exceeded. In addition, the data is rerouted from the logical circuit to a logical failover circuit in the data network in response to detecting the failure of the logical circuit. The logical failover circuit includes an alternative communication path to communicate the data.

## Background
PRIORITY APPLICATIONS
This is a continuation of U.S. patent application Ser. No. 12/334,248, filed Dec. 12, 2008, now U.S. Pat. No. 8,345,537, which is a continuation of U.S. patent application Ser. No. 10/829,795, filed on Apr. 22, 2004, now U.S. Pat. No. 7,466,646, all of which are hereby incorporated herein by reference in their entireties.
CROSS-REFERENCE TO RELATED APPLICATIONS
This patent 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 patent 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. 10/745,170, entitled “Method And System For Automatically Identifying A Logical Circuit Failure In A Data Network,” filed on Dec. 23, 2003, and “Method And System For Automatically Rerouting 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 this patent and are expressly incorporated herein by reference.


FIELD OF THE DISCLOSURE
The present invention relates to the routing of data using logical circuits in a data network. More particularly, the present invention is related to automatically rerouting logical circuit data from a logical circuit failure to a dedicated backup 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 device 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. A network circuit also includes a logical circuit which includes a variable communication path for data between the switches associated with the host and the remote device.
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”). For example, a network circuit from Birmingham to Miami may have connections from a host device in the Birmingham LATA to an IEC and then from the IEC to a remote device in the Miami LATA.
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.
In order to reduce downtime associated with repairing network circuits, some network circuit providers offer network circuit customers a “backup service” plan. Currently, these backup service plans include providing a backup or standby physical circuit between a host device and a remote device for manually rerouting data from one or more failed logical circuits in a data network, until the primary network circuit has been repaired. However, current backup services provided by network circuit providers do not offer backup logical circuits provisioned over the backup physical circuit prior to a network circuit failure. Thus, a backup logical circuit must be manually provisioned over the backup physical circuit after a failure is determined, before logical circuit data may be rerouted from the failed network circuit. This provisioning process increases the time it will take to reroute the logical circuit data over the backup logical circuits. Moreover, logical circuits designated for backup service are identified by “services names” rather than the logical circuit identifiers typically required to identity and reroute logical circuits in a data network. As a result, prior to rerouting data from an affected logical circuit, a technician must manually access a network database to determine the logical circuit identifier associated with the circuit's “services name,” thereby further increasing the time before logical circuit data may be rerouted.
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 a method and system for automatically rerouting logical circuit data from a logical circuit failure to a dedicated backup circuit in a data network. When a failure in a logical circuit is detected, a label or services name associated with the logical circuit is automatically associated with a logical circuit identifier utilized for identifying the logical circuit in the data network. Once the logical circuit is associated with the logical circuit identifier, the logical circuit data may be automatically rerouted to a “failover network,” thereby minimizing lost data until the failure in the logical circuit is resolved.
One method includes determining a failure in a logical circuit in the data network. The logical circuit defines a communication path for communicating data. The method further includes automatically accessing a database to associate a label assigned to the failed logical circuit with a logical circuit identifier for the failed logical circuit, identifying an existing logical failover circuit including an alternate communication path for communicating the data from the failed logical circuit, and rerouting the data from the failed logical circuit to the logical failover circuit in the data network.
The method may further include, after rerouting the data to a logical failover circuit, determining whether the failure in the corresponding logical circuit has been corrected, and if the failure has been corrected, then rerouting the data from the logical failover circuit back to the logical circuit in the data network without manual intervention. The logical circuit identifier may be a data link connection identifier (“DLCI”) or a virtual path/virtual circuit identifier (“VPI/VCI”). In rerouting the data to the logical failover circuit in the data network, the method may further include rerouting the data to a backup physical circuit for communicating the data for the logical failover circuit. Each logical circuit may be either a permanent virtual circuit (“PVC”) or a switched virtual circuit (“SVC”). The data network may be either a frame relay or asynchronous transfer mode (“ATM”) network.
In accordance with other aspects, the present invention relates to a system for automatically rerouting logical circuit data from a logical circuit failure to a dedicated backup circuit in a data network. The system includes a network device for establishing a data communication path for the logical circuit in the data network and a logical element module, in communication with the network device, for storing a database. The database stores one or more records which include a label associated with the logical circuit and a logical circuit identifier. The system further includes a network management module, in communication with the logical element module, for determining a failure in the logical circuit, automatically accessing the database to associate the label assigned with the logical circuit identifier, identifying an existing logical failover circuit including an alternate communication path for communicating the data from the failed logical circuit, rerouting the data from the failed logical circuit to the logical failover circuit in the data network, after rerouting the data to the logical failover circuit, determining whether the failure in the logical circuit has been corrected, and if the failure in the logical circuit has been corrected, then rerouting the data from the logical failover circuit to the logical circuit in the data network.
These and various other features as well as advantages, which characterize the present invention, 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 a data network according to an embodiment of the invention.
FIG. 2 illustrates a local access and transport area (“LATA”) in the data network of FIG. 1, according to an embodiment of the invention.
FIG. 3 illustrates a network management system which may be utilized to automatically rerouting logical circuit data from a logical circuit failure to a dedicated backup circuit in the data network of FIG. 1, according to an embodiment of the invention.
FIG. 4 illustrates a failover data network for rerouting logical circuit data in the data network of FIG. 1, according to an embodiment of the invention.
FIG. 5 illustrates a flowchart describing logical operations for automatically rerouting logical circuit data from a logical circuit failure to a dedicated backup circuit in the data network of FIG. 1, according to an embodiment of the invention.



DETAILED DESCRIPTION
Embodiments of the present invention provide for a method and system for automatically rerouting logical circuit data from a logical circuit failure to a dedicated backup circuit in a data network. When a failure in a logical circuit is detected, a label or services name associated with the logical circuit is automatically associated with a logical circuit identifier utilized for identifying the logical circuit in the data network. Once the logical circuit is associated with the logical circuit identifier, the logical circuit data may be automatically rerouted to a “failover network,” thereby minimizing lost data until the failure in the logical circuit is resolved. 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 data networks 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 24 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. An illustrative LATA data network will be discussed in greater detail in the description of FIG. 2 below.
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.
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 within 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 ATM 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'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'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 backup physical connections 127 and 129, 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 failover network 17 will be described in greater detail in the description of FIG. 4 below. The data network 2 may also include a network management system 175 in communication with the LATA 5, the LATA 15, and the failover network 17. The network management system 175 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 system 175 will be discussed in greater detail in the description of FIG. 3 below.
FIG. 2 illustrates the LATA 5 in the data network 2 described in FIG. 1 above, according to an embodiment of the present invention. 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 in the description of FIG. 3 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 logical 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 logical circuit.
FIG. 3 illustrates the network management system 175 which may be utilized to automatically reroute logical circuit data from a physical circuit failure in the data network of FIG. 1, according to an embodiment of the invention. The network management system 175 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 TELECORDIATM 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 in the data network 2 through management trunks 183. 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'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 NAVISCORETM 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 graphical user interface (“GUI”) of the physical connections in the LATA 5. An illustrative physical element module is the Integrated Testing and Analysis System (“INTAS”), marketed by TELECORDIATM 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 a 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 (shown in FIG. 2) which “loops back” 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. It should be understood that in one embodiment, the network management system 176 may also be in communication with the LATA 15, the IEC 10, and the failover network 17. The communications channels 172 may be on a local area network (“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 graphical user interface (“GUI”) of the logical connections in data networks. The network management module 175 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 logical and physical 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 patent, which is expressly incorporated herein by reference. An illustrative network management module is the Broadband Network Management System® (BBNMS) marketed by TELECORDIATM TECHNOLOGIES, Inc. of Morristown, N.J.
FIG. 4 illustrates a failover data network for rerouting logical circuit data, according to one embodiment of the present invention. As shown in FIG. 4, the failover network 17 includes an IEC 20, a LATA 25, and an IEC 30. The failover network further includes a network failover circuit which includes a physical failover circuit and a logical failover circuit. The physical failover circuit includes the backup physical connection 127 between the host device 112 and the LATA 5 (shown in FIG. 1), the physical connection 134 between the LATA 5 (shown in FIG. 1) and the IEC 20, the physical connection 136 between the IEC 20 and the LATA 25, the physical connection 138 between the LATA 25 and the IEC 30, the physical connection 144 between the IEC 30 and the LATA 15 (shown in FIG. 1), and the physical connection 129 between the LATA 15 and the remote device 114. Similarly, the logical failover circuit may include the logical connection 122 between the LATA 5 (shown in FIG. 1) and the IEC 20, the logical connection 124 between the IEC 20 and the LATA 25, the logical connection 126 between the LATA 25 and the IEC 30, and the logical connection 132 between the IEC 30 and the LATA 15 (shown in FIG. 1). It should be understood that in one embodiment, the network failover circuit illustrated in the failover network 17 may include a dedicated physical circuit and a dedicated logical circuit provisioned by a network service provider serving the LATAs 5, 15, and 25 and the IECs 20 and 30, for rerouting logical data from a failed logical circuit.
FIG. 5 illustrates a flowchart describing logical operations 500 for automatically rerouting logical circuit data from a logical circuit failure to a dedicated backup circuit in a data network, according to an embodiment of the invention. It will be appreciated that the logical operations 500 may be initiated by a customer report of a network circuit failure received in the data network 2. For example, a customer at the remote device 114 may determine that the remote device 114 is not receiving any data (e.g., frames or cells) sent from the host device 112 (e.g., by reviewing LMI status information in the host device). After receiving the customer report, the network service provider providing the network circuit may open a trouble ticket in the service order system 160 to troubleshoot the logical circuit. It will be appreciated that, in one embodiment, the logical circuit of the network circuit may be associated with a network “backup service” for rerouting data to a dedicated backup network circuit in the data network 2. For example, the backup network circuit may include the backup physical connections 127 and 129 between the host device 112 and the remote device 114. Those skilled in the art will appreciate that the logical circuit associated with the backup service may be associated with a label also known as a “services name.”
The logical operations 500 begin at operation 505 where the network management module 176 determines whether a logical circuit failure has occurred. It will be appreciated that in one embodiment, this determination may be made by the network management module 176 communicating with the logical element module 153 to request trap data generated by one or more switches in the data network which indicate the status of one or more logical connections making up the logical circuit. It should be understood that a logical circuit failure occurs when one or more logical connections in a logical circuit have failed. 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. For example, in the data network 2 shown in FIG. 1, the “X” marking the logical connections 102 and 104 indicate that both connections are “down beyond” (i.e., not communicating data) the NNIs for the logical circuit in the LATA data networks 5 and 15. In this example, such a condition may indicate that the logical circuit failure lies in the IEC data network 10. The logical operations 500 then continue from operation 505 to operation 510.
At operation 510, the network management module 176 accesses the database in the logical element module 153 to identify the logical circuit identifier associated with the label or services name associated with the failed physical circuit. It will be appreciated that the network management module 176 may be configured to automatically identify the logical circuit identifier by accessing a database in the logical element module 153 or in the network database 170, which lists service names for logical circuits along with their corresponding logical circuit identifications. The logical operations 500 then continue from operation 510 to operation 515.
At operation 515, the network management module 176 identifies an existing logical failover circuit for rerouting the data from the failed logical circuit in the data network. It will be appreciated that in one embodiment, the logical failover circuit selected may be a dedicated logical circuit provisioned in a backup physical circuit in the data network 2. For example, as shown in FIG. 1, the logical failover circuit may communicate data over a backup physical circuit including the physical connections 127, 124, 134, and 129. The logical operations 500 then continue from operation 515 to operation 520.
At operation 520 the network management module 176 reroutes the data from the failed logical circuit to the logical failover circuit. It will be appreciated that the reroute of the data may be accomplished from the logical management module 153 or the network management module 176 which, in communication with the switches in the data network 2 (and the failover network 17), sends instructions to reroute the logical data from the NNIs or logical connections 102 and 104 to the failover NNIs or logical connections 122, 124, 126, and 132 in the logical failover circuit. The logical operations 500 then continue from operation 520 to operation 525.
At operation 525, the network management module 176 determines the failed logical circuit has been restored. This determination may be made, for example, by continuous or periodic logical circuit monitoring of the link status of the failed logical circuit, which may be performed by the logical element module 153 in communication with the network management module 176, to establish that the logical connections 102 (at the LATA 5) and 104 (at the LATA 15) are successfully communicating data. If at operation 525 it is determined that the failed logical circuit has not been restored, the logical operations 500 return to operation 520 where the rerouting of the data is maintained on the logical failover circuit. If however, at operation 525, it is determined that the failed logical circuit has been restored (i.e., the primary physical circuit has been repaired), then the logical operations 525 continue to operation 530 where the data on the logical failover circuit is rerouted back to the restored logical circuit. Similar to the rerouting of the logical data onto the logical failover circuit, the rerouting of the logical data back onto the restored logical circuit may be accomplished from the network management module 176 which, in communication with the switches in the data network 2 (and the failover network 17) sends instructions to reroute the data from the failover NNIs or logical connections 122, 124, 126, and 132 to the restored NNIs or logical connections 102 and 104 in the restored logical circuit. The logical operations 500 then end.
It will be appreciated that the embodiments of the invention described above provide for a method and system for automatically rerouting logical circuit data from a logical circuit failure to a dedicated backup circuit in a data network. When a failure in a logical circuit is detected, a label or services name associated with the logical circuit is automatically associated with a logical circuit identifier utilized for identifying the logical circuit in the data network. Once the logical circuit is associated with the logical circuit identifier, the logical circuit data may be automatically rerouted to a “failover network,” thereby minimizing lost data until the failure in the logical circuit is resolved. 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.

## Claims

1. A method of rerouting data, comprising:
rerouting a logical circuit from a first set of switches to a second set of switches to communicate data between network devices without breaking the logical circuit, the logical circuit comprising variable communication paths, and the second set of switches to form a route associated with the variable communication paths that is not predefined and that is dynamically defined at a time of automatic rerouting;
detecting a failure of the logical circuit based on at least one of a committed information rate or a committed burst size having been exceeded; and
rerouting the data from the logical circuit to a logical failover circuit in the data network in response to detecting the failure of the logical circuit, wherein the logical failover circuit comprises an alternative communication path to communicate the data.

2. A method as defined in claim 1, wherein the logical circuit comprises variable logical connections.

3. A method as defined in claim 1, wherein the logical failover circuit comprises a dedicated physical circuit and a dedicated logical circuit.

4. A method as defined in claim 1, further comprising determining that the at least one of the committed information rate or the committed burst size has been exceeded by:
receiving a header associated with the data communicated via the logical circuit; and
determining the exceeded committed information rate or the exceeded committed burst size based on threshold information in the header.

5. A method as defined in claim 1, further comprising:
receiving a service order specifying the at least one of the committed information rate or the committed burst size; and
provisioning the logical circuit based on the at least one of the committed information rate or the committed burst size.

6. A method as defined in claim 1, further comprising receiving trap data generated by a network switch, and determining the exceeded committed information rate or the exceeded committed burst size based on the trap data.

7. A method as defined in claim 6, wherein the network switch generates the trap data in response to detecting dropped data.

8. A method as defined in claim 1, further comprising:
communicating a test signal to at least one of a plurality of test points associated with the logical circuit; and
receiving a loop back signal from the at least one of the plurality of test points indicating the exceeded committed information rate or the exceeded committed burst size.

9. A method as defined in claim 1, further comprising determining the exceeded committed information rate or the exceeded committed burst size based on a customer report of a network circuit failure.

10. A system to reroute data, comprising:
a processor; and
a memory storing machine readable instructions that cause the processor to perform a method comprising:
rerouting a logical circuit from a first set of switches to a second set of switches to communicate data between network devices while maintaining the logical circuit, the logical circuit comprising variable communication paths, and the second set of switches to form a route associated with the variable communication paths that is not predefined and that is dynamically defined at a time of automatic rerouting of the variable communication paths;
detecting a failure of the logical circuit based on at least one of a committed information rate or a committed burst size having been exceeded; and
rerouting the data from the logical circuit to a logical failover circuit in the data network in response to detecting the failure of the logical circuit, wherein the logical failover circuit comprises an alternative communication path to communicate the data.

11. A system as defined in claim 10, wherein the method further comprises:
receiving a service order specifying the at least one of the committed information rate or the committed burst size; and
provisioning the logical circuit based on the at least one of the committed information rate or the committed burst size.

12. A system as defined in claim 10, wherein the method further comprises receiving trap data generated by a network switch, and determining the exceeded committed information rate or the exceeded committed burst size based on the trap data.

13. A system as defined in claim 12, wherein the network switch generates the trap data in response to detecting dropped data.

14. A system as defined in claim 10, wherein the method further comprises communicating a test signal to at least one of the plurality of test points, and receiving a loop back signal from the at least one of the plurality of test points, the loop back signal being indicative of the exceeded committed information rate or the exceeded committed burst size.

15. A tangible machine accessible storage device or storage disc comprising instructions that cause a machine to perform a method comprising:
rerouting a logical circuit from a first set of switches to a second set of switches to communicate data between network devices in an absence of a failure of the logical circuit, the logical circuit comprising variable communication paths, and the second set of switches to form a route associated with the variable communication paths that is not predefined and that is dynamically defined at a time at which the variable communication paths are automatically rerouted while maintaining the logical circuit through the second set of switches;
detecting a failure of the logical circuit based on at least one of a committed information rate or a committed burst size having been exceeded; and
rerouting the data from the logical circuit to a logical failover circuit in the data network in response to detecting the failure of the logical circuit, wherein the logical failover circuit comprises an alternative communication path to communicate the data.

16. A tangible machine accessible storage device or storage disc as defined in claim 15, wherein the method further comprises determining the exceeded committed information rate or the exceeded committed burst size by:
receiving a header associated with the data communicated via the logical circuit; and
determining the exceeded committed information rate or the exceeded committed burst size based on threshold information in the header.

17. A tangible machine accessible storage device or storage disc as defined in claim 15, wherein the method further comprises determining the exceeded committed information rate or the exceeded committed burst size by:
communicating a test signal to at least one of a plurality of test points associated with the logical circuit; and
receiving a loop back signal from the at least one of the plurality of test points, wherein the loop back signal is indicative of the exceeded committed information rate or the exceeded committed burst size.

18. A tangible machine accessible storage device or storage disc as defined in claim 15, wherein the method further comprises receiving trap data generated by a network switch, and determining the exceeded committed information rate or the exceeded committed burst size based on the trap data.

19. A tangible machine accessible storage device or storage disc as defined in claim 18, wherein the network switch generates the trap data in response to detecting dropped data.

20. A tangible machine accessible storage device or storage disc as defined in claim 15, wherein the method further comprises determining the exceeded committed information rate or the exceeded committed burst size based on a customer report of a network circuit failure.