Abstract:
Restoration of an inoperative network element ( 12 ) such as a digital cross-connect system is accomplished by receiving updates from each element as they occur in a local controller network ( 18 ). The local controller network forwards the updates to a DCS-Operations support system ( 22 ) that generates a restoration map for each element in its native language, and thereafter updates each map upon receipt of each update. In response to a user command, the DCS-operation system directs (transmits) the update map either to directly the inoperative element or to an intermediate element to achieve restoration.

Description:
RELATED APPLICATIONS 
     This application claims priority to Provisional U.S. Patent Application Serial No. 60/060,276, filed Sep. 29, 1997. 
    
    
     TECHNICAL FIELD 
     This invention relates to a technique for restoring cross-connection information in a digital cross-connect system. 
     BACKGROUND ART 
     Most present-day telecommunications networks typically include one or more Digital Cross-Connect Systems (DCSs) for electronically cross-connecting various incoming trunks to selected outgoing trunks in much the same way as a telecommunications switching system. With a DCS, the connections are set up in advance of the call, and typically remain in place thereafter until such time as a technician alters such connections to de-provision old service and/or provision new service. In some instances, the DCS connections become lost when the DCS becomes inoperative due to a disaster, such as a fire, flood, earthquake, or explosion. Moreover, during certain types of maintenance operations, a telecommunications service provider may purposely remove a DCS from service, causing a loss of such connections. Restoration of service requires that the cross-connections be restored, either by restoration of DCS itself, or by replicating the cross-connections on another DCS. 
     Restoration of the DCS cross-connections is usually a time-consuming operation. In case of a disaster, spare DCS capacity may no longer exist on site. Under such circumstances, one or more restoration DCSs must be transported to the disaster site. Thereafter, technicians must replicate the cross-connections on the restorations DCSs. U.S. Pat. No. 5,420,917, “Automated Recovery of Telecommunications Network Elements”, issued on May 30, 1995, in the name of Richard Guzman, and assigned to AT&amp;T Corp., the assignee of the present invention, describes a method for automated restoration of one or more inoperative DCSs in a telecommunications network. In accordance with the teachings of the &#39;917 patent (herein incorporated by reference), restoration of one or more inoperative DCSs is accomplished by first connecting the restoration DCSs through guided media, in the form of cables, radio channels or the like, to the inoperative DCSs. Thereafter, the profile of each inoperative DCS (i.e., its cross-connection data) is obtained from a network database, referred to as the DCS Operation Support System (DCS-OSS) that stores circuit orders (cross-connect data) in a state database (SDB). A technician then translates the cross-connections needed to restore the each inoperative DCS into a circuit map in accordance with the cross-connect capability of each restoration DCS. The circuit map is ported to the restoration DCSs and is thereafter executed by such DCSs to restore service. 
     While the restoration technique disclosed in the &#39;917 patent is effective, the technique nevertheless suffers from the drawback that the profile of each inoperative DCS may not always be accurate. In practice, the profile for each DCS is obtained by periodically reconnoitering that DCS. Depending on the traffic it carries and its location, a DCS may only be reconnoitered no more often than every six months. Between such six-month intervals, a telecommunications network service provider will likely re-provision a DCS to alter its cross-connections to add, remove or modify service. Hence, there is a significant likelihood that the stored profile for a given DCS will not include such recent provisioning information. Hence, that restoration of a DCS using its stored profile often did not result in a complete restoration of all service. Moreover, manual extraction of the circuit mappings and subsequent translation into a format appropriate for a particular DCS often took significant time. Thus, not only were the restoration mappings potentially inaccurate, but such mappings took significant time to acquire. 
     Thus, there is need for a technique for achieving network restoration that overcomes the disadvantages of the prior art. 
     BRIEF SUMMARY OF THE INVENTION 
     Briefly, in accordance with the invention, a method is provided for restoring a network element, such as a Digital Cross-connect system (DCS) in case such element loses its circuit mappings. In accordance with the invention, updates from network elements indicative of a change in each network element&#39;s configuration, i.e., a change in the element cross-connections, are received at a local controller network. A restoration map is then established for each network element in a language corresponding to that element by a DCS Operation Support System (DCS-OSS) for storage in a database associated with the DCS-OSS. In case of the need to restore a selected element, the database is queried to obtain the map for the selected element. Thereafter, the map for the selected network element is appropriately directed (communicated) to effect restoration. In some instances, the map is directed to the selected element itself. In other instances, the restoration map is directed to an intermediate network element (e.g., a DCS in a laboratory environment) having the same configuration. From the intermediate element, a technician can generate a restoration map on a storage medium, such as a floppy disk, for example, for subsequent transfer to the selected element. Alternatively, the map may be directed to a target network element on which the service is restored in place of the selected element. Upon receipt of the restoration map, restoration is accomplished via the target element. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block schematic diagram of a system for obtaining update information for elements in a network and for generating restoration maps in accordance with the invention; 
     FIG. 2 illustrates the manner in which the system of FIG. 1 directs the restoration map to achieve network element restoration; 
     FIG. 3 illustrates in flowchart form the steps executed by the system of FIG. 1 to effect restoration in accordance with the invention; 
     FIG. 4 illustrates in flowchart form the steps executed by the system of FIG. 1 to achieve different levels of restoration; and 
     FIG. 5 illustrates in flowchart form the steps executed by the system of FIG. 1 to direct the restoration map to different targets. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 illustrates a block schematic diagram of a portion of a telecommunications network  10  that includes at least one network element  12 . In the illustrative embodiment, the element  12  comprises Digital Cross-connect system (DCS) known in the art. The DCS  12  provide cross-connections (circuits) between selected ones of trunks  14  and  16 . The trunks  14  and  16  may carry DS 1 , sub DS 1 , Intermediate Bit Rate, sub-rate, 2-point and multi-point circuits. Alternatively, the element  12  could comprise a SONET/SDH Add/Drop Multiplexer (ADM) (not shown) that has cross-connect capability and equippage data (i.e., circuit pack information). Such ADMs can carry signals at trunk rates of DS 3 , OC 3  or OC 12  while transmitting signals at rates of OC-48 or higher. 
     As taught in co-pending U.S. patent application Ser. No. 08/926,614, filed Sep. 10, 1997 and assigned to AT&amp;T (incorporated by reference herein), a Local Controller (LC) network  18 , such as a LAN, couples the DCS  12  to a Local Controller Electronic Message Alert (LCEMA) Library (e.g., storage facility)  20 . In turn, the LCMEA  20  is connected to a DCS Operation Support System (DCS-OSS)  22  that includes a processor  23  and an associated database  24 . The LC  18  network receives each provisioning update made to each network element, such as the DCS  12 , in real time and thereafter supplies that provisioning update to the LCEMA library  20  for subsequent transfer to the DCS-OSS  22 . (Under some circumstances, the LC network  18  could provide the provisioning updates directly to the DCS-OSS  22  rather than store such information in the LC EMA library  20 .) 
     In practice, the telecommunication network service provider responsible for the DCS  12  will provision it by modifying the cross-connections to add, delete or modify service for one or more subscribers. As each provisioning change is made to the DCS  12 , the LC network  18  communicates that change to the LCEMA library  20 . The LCEMA library  20  provides the provisioning updates (depicted as LC Alerts in FIG. 1) to the DCS-OSS  22  which as will be explained below creates and stores restoration maps. Each map represents configuration information descriptive of the cross-connections (circuits) needed to restore that DCS should it become inoperative. In response to a provisioning update received from the LC EMA library  20 , the processor  23  within the DCS OSS  22  updates the map for each corresponding DCS. In accordance with invention, the processor  23  creates and updates the map in a language associated with the particular DCS. By doing so, the processor  23  can make available, in substantially real time, a restoration map for a particular DCS that is readily usable by that DCS, thus avoiding the need for subsequent translation, as was required previously. Additionally, the DCS-OSS  22  may also receive updates about a particular DCS from the LCEMA library  22  in response to information received through the LC network  18  from other network mapping and management systems, such as system  25 . In response to updates from the system  25 , the processor  23  within the DCS-OSS  22  also generates a new restoration map for each affected element. 
     In the past, the DCS-OSS  22  obtained the circuit map for a particular DCS by periodically reconnoitering that DCS to obtain its cross-connection information. However, such reconnoitering occurred infrequently, usually not more often than every six months. Thus, in the past, provisioning changes made between reconnoitering intervals were not normally made available to the DCS-OSS  22 . Hence, reliance on the circuit information obtained only through reconnoitering each DCS was often insufficient to fully restore service. 
     However, as described in co-pending application Ser. No. 08/926,614 (incorporated by reference herein), the LC network  18  and LCEMA library  20  assure that the DCS-OSS  22  always receives the most up-to-date information about each DCS, such as DCS  12 . As discussed above, the LC network  18  and LC EMA library  20  cooperate to provide the DCS-OSS  22  with real-time provisioning changes as each change is made to each DCS (or other network element). Thus, should a DCS, such as DCS  12 , become inoperative, either because of a disaster, or because of planned maintenance, the DCS-OSS  22  can readily provide the most up-to-date map of the DCS cross-connects for restoration purposes. In this way, full service restoration can be achieved, even for provisioning changes made very shortly before the element became inoperative. 
     Referring now to FIG. 2, a user  26 , such as a technician, can access the DCS OSS  22  and direct restoration maps to various different destinations in accordance with the invention. For example, the user  26  can direct (i.e., request transmission of) a restoration map for receipt on the user&#39;s own terminal, thus permitting the user to subsequently forward the map to a remote (laboratory) DCS  120  that has the same configuration as the inoperative DCS  12 . Using the DCS  120 , a technician can create a restoration program on a transportable storage medium, such as a floppy disk or the like, for transport to and loading on, the inoperative DCS  12 . 
     Alternatively, the user  26  can request the DCS-OSS  22  to direct the restoration map to the inoperative DCS  12  directly. In response, the DCS-OSS  22  will transmit the restoration map via the LC network  18  to the inoperative DCS  12 . Rather than direct the restoration map to the DCS  12 , the user  26  can request that the DCS-OCS  22  transmit the map to a target DSC  1200  having the same configuration as and physically located in close proximity to, the inoperative DCS  12 . Once loaded with the restoration map, the target DCS  1200  can now be placed in service to substitute for the inoperative DCS  12 . With the restoration map for the inoperative DCS  12 , the target DCS  1200  can itself restore service. 
     FIG. 3 illustrates in flow-chart form the general steps associated with the restoration method of the invention. At the outset, the user  26  of FIG. 2 initiates the restoration process (step  200 ) by entering the appropriate command to the DCS-OSS  22 . After initiating restoration, the user  26  of FIG. 2 then identifies the element, (e.g., the inoperative DCS  12  of FIG. 1) for which the restoration map is sought (step  210 ). In response to the identification of the element, the DCS-OSS  22  accesses its database  23  of FIGS. 1 and 2 to retrieve the restoration map for the identified element. 
     Once the DCS-OSS  22  has acquired the restoration map for the identified element, the user  26  will then issue a command to the DCS-OSS  22  identifying the destination for the restoration map (Step  220 ). In response, the DCS-OSS  22  sends the restoration map to the target (step  230 ) designated by the user as discussed previously with respect to FIG.  2 . Thereafter, the restoration method ends (step  240 ). 
     The restoration process of FIG. 3 advantageously allows the user  26  of FIG. 2 to initiate either partial or full restoration. In other words, the user may choose to restore all of the circuit connections or to restore a portion of such connections. FIG. 4 illustrates in flow-chart form the manner in which a user may effect either partial or full restoration. Following element identification during step  210 , the user  26  of FIG. 2 is queried during step  211  of FIG. 4 to whether full restoration is desired. If the user selects full restoration during step  211 , then the user is thereafter prompted to select among the various command types associated with full restoration (step  212 . 1 ). Thereafter, the user previews the command (step  212 . 2 ) before initiating downloading of the commands during step  212 . 3 . Following step  212 . 3 , program execution reverts to step  220 . 
     If the user does not select full restoration during step  211  of FIG. 4, then the user is queried during step  213  whether partial restoration is desired. Should the user select full restoration during step  211 , then the user is thereafter prompted to select the command types for partial restoration (step  214 . 1 ). Thereafter, the user inputs the desired start and end units (i.e., the selected sub-set of circuit connections) during step  214 . 2  before previewing the commands during step  214 . 3 . Thereafter, the user initiates downing loading of the commands during step  214 . 4  before program execution branches to step  220 . 
     If full or partial restoration is not selected during steps  211  and  213 , respectively, then the user is prompted during step  215  whether to write the restoration map file to the user&#39;s terminal or personal computer (PC). Once the user has opted to write the file during step  215 , the user is then prompted to select the command types associated with writing the file to the user&#39;s terminal or PC (step  216 . 1 ). Thereafter, the user previews the commands (step  216 . 2 ) before selecting the file for writing during step  216 . 3 . Following step  216 . 3 , the user initiates file downloading during step  216 . 4 . Upon completion of step  216 . 4 , program execution reverts to step  220 . 
     As discussed above, a user may direct the restoration map to one of several destinations during step  230  of FIG.  2 . FIG. 5 illustrates in flow chart form the steps associated with sending the restoration map to different destinations. Following step  230 , the DCS-OSS system  22  of FIGS. 1 and 2 executes step  231  of FIG.  5  and determines whether the target identified during step  230  is the same as the element for which the restoration map was sought. If so, then following step  231 , step  232 . 1  is executed and the user is prompted to confirm the element identification before the DCS-OSS system  22  initiates downloading during step  232 . 2 . Thereafter, program execution branches to step  240 . 
     If the DCS-OSS  22  of FIGS. 1 and 2 determines during step  231  that the target element is not the same, then the DCS-OSS determines whether the target element is similar during step  233 . Upon finding the target element is similar, then step  234 . 1  is executed and the user is prompted to confirm the element identification before the DCS-OSS system  22  initiates downloading during step  234 . 2 . Thereafter, program execution branches to step  240 . 
     Upon finding that the target element is not the same or even similar during steps  231  and  233 , respectively, the DCS-OSS  22  of FIGS. 1 and 2 determines whether the identified target is the user&#39;s terminal or PC (step  235 ). If not, the program execution branches back to step  230 , prompting the user to re-identify the target. Otherwise, the user is prompted to confirm the element identification during step  236 . 1  before the DCS-OSS system initiates downloading during step  236 . 2 . Thereafter, program execution branches to step  240 . 
     The foregoing discloses a technique for achieving restoration of a network element, such as digital cross-connect system. 
     The above-described embodiments merely illustrate the principles of the invention. Those skilled in the art may make various modifications and changes that will embody the principles of the invention and fall within the spirit and scope thereof.