# Patent

## Title
Method and system for providing a failover circuit for rerouting logical circuit data in a data network

## Abstract

A method and system are provided for providing a failover circuit for rerouting logical circuit data in a data network. An alternate communication path is identified for routing data for a logical circuit in the data network. An inactive logical circuit is then selected in the data network for communicating the data over the alternate communication path. The inactive logical circuit is then designated as a failover circuit for rerouting the data for the logical circuit in the data network. The inactive logical circuit may be selected by selecting a currently unused logical connection in the data network for communicating the data. The inactive logical circuit may also be selected by provisioning an inactive logical circuit in the data network. The inactive logical circuit may be provisioned by sending configuration data describing a logical data path over the alternate communication path to a network device in the data network.

## Background
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. 10/744,281, 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. 10/745,170, entitled “Method And System For Automatically Identifying A Logical Circuit Failure 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 this patent and are expressly incorporated herein by reference.
TECHNICAL FIELD
The present invention relates to rerouting data in a data network. More particularly, the present invention is related to providing a failover circuit for rerouting logical circuit data in a data network.
BACKGROUND OF THE INVENTION
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'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 circuit. 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. These current methods, 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 repaired. Furthermore, in most instances, troubleshooting the physical circuit requires taking the network circuit out of service to perform testing, thus increasing the downtime and loss of data in the network circuit. Moreover, if the failure cannot be isolated by the technicians in a LATA, or the failure is located at the interface to the IEC, cooperative testing with the IEC must also be coordinated to isolate the failure leading to a further increase in 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 OF THE INVENTION
In accordance with the present invention, the above and other problems are solved by methods for providing a failover circuit for rerouting logical circuit data in a data network. According to one method, an alternate communication path is identified for routing data for a logical circuit in the data network. An inactive logical circuit is then selected in the data network for communicating the data over the alternate communication path. The inactive logical circuit is then designated as a failover circuit for rerouting the data for the logical circuit in the data network.
The alternate communication path may be identified by identifying a logical identifier for the logical circuit. Based on the logical identifier, a first end and a second end of the logical circuit in the data network are determined. Finally, an alternate communication path including the first end and the second end of the logical circuit is identified in the data network. The inactive logical circuit may be selected by selecting a currently unused logical connection in the data network for communicating the data. The inactive logical circuit may also be selected by provisioning an inactive logical circuit in the data network. The inactive logical circuit may be provisioned by sending configuration data describing a logical data path over the alternate communication path to a network device in the data network.
The data network may be a frame relay network or an asynchronous transfer mode (“ATM”) network. The logical circuit may be a permanent virtual circuit (“PVC”) or a switched virtual circuit (“SVC”). 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 providing a failover circuit for rerouting logical circuit data in a data network. The system includes a network device for establishing a communication path for logical circuits in the data network and a logical element module in communication with the network device for configuring logical circuits in the data network. The system further includes a network management module in communication with the logical element module. The network management module is operative to identify an alternate communication path for routing data for the a logical circuit in the data network, select an inactive logical circuit in the data network for communicating the data over the alternate communication path, and designate the inactive logical circuit as a failover circuit for rerouting the data for the logical circuit in the data network.
The network management module, in identifying an alternate communication path for routing data for a logical circuit in the data network, is operative to access a network database to identify a logical identifier for the logical circuit, based on the logical identifier, determine a first end and a second end of the logical circuit in the data network, and identify an alternate communication path including the first end and the second end of the logical circuit. The network management module, in selecting an inactive logical circuit in the data network for communicating the data over the alternate communication path, is operative to transmit a request to the logical element module to provision the inactive logical circuit. The logical element module, in provisioning the inactive logical circuit, is operative to send data describing a logical data path over the alternate communication path to the network device to provision the inactive logical circuit.
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 provide a failover circuit for rerouting logical circuit data in a data network, according to an embodiment of the invention.
FIG. 4 illustrates a failover data network for rerouting logical circuit data over a logical failover circuit, according to an embodiment of the invention.
FIG. 5 illustrates a flowchart describing logical operations for providing a failover circuit for rerouting logical circuit data in a data network, according to an embodiment of the invention.



DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention provide for a method and system for providing a failover circuit for rerouting logical circuit data 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 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 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. 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. Routers 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 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 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 to provision failover circuits 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”). It should be understood that the switches 186, 187, and 188 establish the communication or connection data paths for logical circuits in a data network. 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 provision failover circuits for rerouting logical circuit data from a failed logical circuit in the data network 2 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 in communication with the switches 186, 187, and 188 through management trunks 183. The logical element module 153 may be utilized to provision logical circuits in the data network 2 by programming ports contained in the switches 186, 187, and 188. 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 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 175 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 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 logical and physical element modules 153 and 155. 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 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, and the physical connection 144 between the IEC 30 and the LATA 15 (shown in FIG. 1). 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 providing a failover circuit for rerouting logical circuit data in a data network, according to an embodiment of the invention. The logical operations 500 begin at operation 505 where the network management module 176 identifies an alternate communication path for a logical circuit in the data network 2. The alternate communication path may be determined by identifying a logical connection or NNI in the logical circuit. Information related to each logical connection in a logical circuit may be stored in the database 170 including the first and second ends of the logical circuit to which the logical connection belongs. Once the ends of a logical circuit are determined by accessing the database 170, the network management module 176 may select an alternate communication path including the first and second ends of the logical circuit for rerouting data. For example, an the network management module 176 may identify the alternate path between the host device 112 and the remote device 114 which includes the logical connections 122, 124, 126, and 132 (as shown in FIG. 4) as an alternate communication path for the logical circuit shown in FIG. 1 which includes the logical connections 102 and 104. The logical operations 500 then continue from operation 505 to operation 510.
At operation 510, the network management module 176 selects a logical failover circuit in the data network 2 to reroute the logical circuit data over the previously identified alternate communication path. It will be appreciated that in one embodiment, the logical failover circuit may be selected by provisioning an inactive logical circuit (i.e., the logical circuit which does not carry any data) as the logical failover circuit. In this embodiment, the network management module 176 may provision the logical failover circuit by communicating configuration data to the logical element module 153 with instructions to provision the logical failover circuit. The logical element module 153 locates the appropriate switches in the data network and programs the appropriate ports to provision the logical failover circuit.
For example, in data network 2, the-logical element module 153 would access and program the ports in the switches 186, 187, and 188 in the LATA 5 to communicate data from the host device 112 to the remote device 114 over the logical connection 122. Similarly, the logical element module 153 would access and program the ports in the switches (not shown) in the LATA 25 to deliver data from the LATA 5 over the logical connections 124 and 126 (shown in the failover network 17 of FIG. 2). It will be appreciated that the in this embodiment, the network management module 176, in conjunction with the logical element module 153, may be configured to provision logical circuits automatically. An illustrative method detailing the automatic provisioning of logical 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.
It will be appreciated that in another embodiment, the logical failover circuit may be selected by utilizing an existing logical circuit which is normally utilized for communicating data traffic in the data network 2 but which is currently inactive. In this embodiment, the selection of the logical failover circuit may also include determining whether one or more logical connections in the logical circuit are currently communicating data traffic or are currently unused. If currently unused, the logical connections may be selected for rerouting logical data. For example, a technician at the logical element module 153 or the network management module 176 may utilize a map-based GUI displaying the logical connections in the LATA data networks 5 and 15 and their status. A currently unused logical circuit may then be selected as a logical failover circuit for communicating logical circuit data from a failed logical circuit. The logical operations 500 then continue from operation 510 to operation 515.
At operation 515, the network management module 176 designates the previously selected inactive logical circuit as a logical failover circuit for rerouting logical circuit data. The logical operations 500 then end. It will be appreciated that the network management module 176 may be utilized to reroute data to the logical failover circuit after identifying a logical circuit failure in the data network 2. An illustrative method detailing a method for automatically identifying a logical circuit failure in a data network is presented in 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 assigned to the same assignee as this patent, which is expressly incorporated herein by reference. Once the network management module 176 has identified 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 patent, which is expressly incorporated herein by reference.
It will be appreciated that the embodiments of the present invention provide for a method and system for providing a failover circuit for rerouting logical circuit data 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.

## Claims

1. A method for providing a failover circuit for rerouting logical circuit data in a data network, the method comprising:
receiving, via a network management system, status information indicating a network circuit failure in the data network, the status information indicating that a switch in the data network is discarding frames or cells, wherein the network management system is separate from switches of the data network used to communicate data through the data network;
in response to the status information, identifying, via the network management system, an alternate communication path for routing the data for a logical circuit in the data network, wherein the logical circuit includes a communication path through first and second local access and transport areas and an inter-exchange carrier between the first and second local access and transport areas;
selecting, via the network management system, an inactive logical circuit in the data network for communicating the data over the alternate communication path, wherein selecting the inactive logical circuit in the data network for communicating the data over the alternate communication path comprises selecting a currently unused logical connection in the data network for communicating the data, and wherein selecting the currently unused logical connection comprises selecting the currently unused logical connection through a failover network to reroute the data around the inter-exchange carrier; and
designating, via the network management system, the inactive logical circuit as a failover circuit for rerouting the data for the logical circuit in the data network.

2. The method of claim 1, wherein identifying the alternate communication path for routing data for the logical circuit in the data network comprises:
identifying a logical identifier for the logical circuit;
based on the logical identifier, determining a first end and a second end of the logical circuit in the data network; and
identifying the alternate communication path including the first end and the second end of the logical circuit.

3. The method of claim 1, wherein selecting the inactive logical circuit in the data network comprises provisioning the inactive logical circuit in the data network.

4. The method of claim 1, wherein the currently unused logical connection comprises a network-to-network interface.

5. The method of claim 1, wherein the failover circuit is a permanent virtual circuit.

6. The method of claim 1, wherein the failover circuit is a switched virtual circuit.

7. The method of claim 2, wherein the logical identifier is a data link connection identifier (DLCI).

8. The method of claim 2, wherein the logical identifier is a virtual path/virtual circuit identifier (VPI/VCI).

9. A system for providing a failover circuit for rerouting logical circuit data in a data network, the system comprising:
a logical element module in communication with at least one network device for configuring at least one logical circuit in a data network, wherein the at least one logical circuit includes a communication path through first and second local access and transport areas and an inter-exchange carrier between the first and second local access and transport areas; and
a network management module, in communication with the logical element module and separate from switches of the data network used to communicate data through the data network, for:
receiving status information indicating a network circuit failure in the data network, the status information indicating that a switch in the data network is discarding frames or cells;
in response to the status information, identifying an alternate communication path for routing the data for the at least one logical circuit in the data network;
selecting an inactive logical circuit in the data network for communicating the data over the alternate communication path, wherein selecting the inactive logical circuit in the data network for communicating the data over the alternate communication path comprises transmitting a request to the logical element module to provision the inactive logical circuit, and wherein the logical element module is to provision the inactive logical circuit through a failover network to reroute the data around the inter-exchange carrier; and
designating the inactive logical circuit as a failover circuit for rerouting the darn for the logical circuit in the data network.

10. The system of claim 9, wherein the network management module, in identifying the alternate communication path for routing the data for the at least one logical circuit in the data network, is operative to:
access a network database to identify a logical identifier for the at least one logical circuit;
based on the logical identifier, determine a first end and a second end of the at least one logical circuit in the data network; and
identify the alternate communication path including the first end and the second end of the at least one logical circuit.

11. The system of claim 9, wherein the logical element module, in provisioning the inactive logical circuit, is operative to send data describing a logical data path over the alternate communication path to the at least one network device to provision the inactive logical circuit.

12. The system of claim 9, wherein the at least one logical circuit comprises at least one logical connection.

13. The system of claim 12, wherein the at least one logical connection comprises a network-to-network interface.

14. The system of claim 9, wherein the failover circuit is a permanent virtual circuit.

15. The system of claim 9, wherein the failover circuit is a switched virtual circuit.

16. The system of claim 9, wherein the data network is a frame relay logical network.

17. The system of claim 10, wherein the logical identifier is a data link connection identifier (DLCI).

18. The system of claim 10, wherein the logical identifier is a virtual path/virtual circuit identifier (VPI/VCI).

19. A method for providing a failover circuit for rerouting logical circuit data in a data network, the method comprising:
receiving, via a network management system, a customer report indicating a network circuit failure in the data network, wherein indicating the network circuit failure comprises receiving trap data indicating the network circuit failure, wherein the trap data comprises status information indicating that a switch in the data network is discarding frames or cells, wherein the network management system is separate from switches of the data network used to communicate data through the data network;
in response to the customer report, identifying, via the network management system, an alternate communication path for routing the data for a logical circuit in the data network, wherein the logical circuit includes a communication path through first and second local access and transport areas and an inter-exchange carrier between the first and second local access and transport areas;
selecting, via a network management system, an inactive logical circuit in the data network for communicating the data over the alternate communication path, wherein selecting the inactive logical circuit in the data network for communicating the data over the alternate communication path comprises provisioning the inactive logical circuit in the data network, and wherein provisioning the inactive logical circuit comprises provisioning the inactive logical circuit through a failover network to reroute the data around the inter-exchange carrier; and
designating, via a network management system, the inactive logical circuit as a failover circuit for rerouting the data for the logical circuit in the data network.

20. The method of claim 19, wherein identifying the alternate communication path for routing the data for the logical circuit in the data network comprises:
identifying a logical identifier for the logical circuit;
based on the logical identifier, determining a first end and a second end of the logical circuit in the data network; and
identifying the alternate communication path including the first end and the second end of the logical circuit.

21. The method of claim 19, wherein provisioning the inactive logical circuit in the data network comprises sending configuration data describing a logical data path over the alternate communication path to a network device in the data network.

22. The method of claim 1, wherein the network management system is configured to monitor a plurality of other logical circuits to detect a failure in any of the plurality of other logical circuits and at least one of select or provision any of a plurality of other failover circuits in the failover network in response to detecting that any of the plurality of other logical circuits has failed.

23. The method of claim 9, wherein the logical element module is further configured to monitor a plurality of other logical circuits to detect a failure in any of the plurality of other logical circuits, and wherein the network management module is further configured to identify any of a plurality of other failover circuits in the failover network in response to the logical element module detecting that any of the plurality of other logical circuits has failed.