Patent Publication Number: US-7711811-B1

Title: Filtering approach for network system alarms based on lifecycle state

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
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   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
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   REFERENCE TO A MICROFICHE APPENDIX 
   Not applicable. 
   FIELD OF THE INVENTION 
   The present invention relates to the management of network alarms. More particularly, embodiments of the present invention provide a method and apparatus for automatically filtering the alarms in a network based on the lifecycle state of the network elements generating the alarms. 
   BACKGROUND OF THE INVENTION 
   Telecommunications networks, computer networks, and other networks typically include elements such as ATM switches, frame relay switches, voice switches, digital cross connect switches, multiplexers, routers, servers, and other equipment for processing and transmitting data. Network elements typically contain self-monitoring circuitry and software that can detect internal and external conditions affecting the elements and activate messages that document these conditions. Many of these messages indicate potentially abnormal or erroneous conditions from the local perspective of the reporting resource. Depending on the context, these messages might represent predictable noise requiring no action or might indicate a major network failure requiring immediate attention. Any type of message that conveys evidence that an error condition might exist can be referred to as an alarm. Technicians typically investigate a certain number of alarms to determine their cause and undertake corrective action. However, in large networks, the number of alarms can overwhelm the staff of technicians charged with operating and maintaining the network. The wide variety of protocols, such as SNMP, CMIP, CORBA, log files, Telnet/command line interfaces, and proprietary interfaces, used to deliver alarm information can increase the difficulty of gathering and handling of alarm data. Since manually investigating large numbers of different types of alarms to distinguish significant alarms from insignificant alarms can be time-consuming, labor-intensive, expensive, and often impossible, technicians often attempt to focus their efforts on the most severe alarms, ignoring a significant number of messages. This can leave many problems undetected until specific complaints are received from impacted network users. 
   SUMMARY OF THE INVENTION 
   An embodiment of the invention is a method for creating an updateable report representing the alarm status of a network. The method can comprise tracking the lifecycle state of at least a portion of the elements within the network, categorizing at least a portion of the alarms generated in the network based on the lifecycle state of the elements generating the alarms, and removing selected alarms from an updateable report based on the lifecycle state of the elements generating the alarms. Alternatively, all alarms generated by network elements having a tracked lifecycle state can be categorized based on the lifecycle state of the elements generating the alarms. The alarms removed from the updateable report can include alarms generated by elements with a non-operational lifecycle state, alarms generated by elements with a maintenance lifecycle state, or alarms generated by elements with either the non-operational or the maintenance lifecycle state. Alternatively, alarms generated by elements with a normal lifecycle state can be removed from the updateable report. Of the remaining alarms, alarms generated by elements with a maintenance lifecycle state can be removed from the updateable report. Of the alarms remaining at that point, alarms generated by elements with either a pre-acceptance lifecycle state or a post-acceptance lifecycle state can be selected. The lifecycle states can comprise operational and non-operational. The non-operational states can comprise pre-acceptance and post-acceptance, where the pre-acceptance states can comprise planned, deployed, and tested, and the post-acceptance states can comprise blocked and defective. The operational states can comprise normal and maintenance where the maintenance states can comprise testing, scheduled maintenance, emergency recovery, and reallocated. The network can comprise the interconnected networks of an enterprise or the interconnected networks of a single domain of an enterprise. The domain can comprise a business domain or an operating system domain of the enterprise. Alternatively, the network can comprise a group of client computers connected to a server computer. The report can be displayed on a computer screen or sent to another location for further processing. 
   In an alternative embodiment, after selected alarms have been removed from the report based on the lifecycle state of the elements generating the alarms, the remaining alarms can be categorized based on their source and type. The remaining alarms can then be placed in a linkage-based filtering system, wherein the linkage-based filtering system replaces selected alarms with alarm representations. The report can then be updated with the alarm representations. Alternatively, all alarms generated by network elements having a tracked lifecycle state can be categorized based on the lifecycle state of the elements generating the alarms. Linkage-based filtering can include internal linkage-based filtering, external linkage-based filtering, or both. 
   In another alternative embodiment, after selected alarms have been removed from the report based on the lifecycle state of the elements generating the alarms, the remaining alarms can be categorized based on their source and type. The remaining alarms can then be placed in at least one filtering system based on their source and type. The filtering system can replace selected alarms with alarm representations and can include both a temporal filtering system and a non-temporal filtering system. The report can then be updated with the alarm representations. Alternatively, all alarms generated by network elements having a tracked lifecycle state can be categorized based on the lifecycle state of the elements generating the alarms. Temporal filtering can include frequency-based filtering, cycling-based filtering, or both. Non-temporal filtering can include de-duplication, clear message mapping, or both. In addition to temporal and non-temporal filtering, the filtering system can also include a linkage-based filtering system, a classification filtering system, or both. Linkage-based filtering can include internal linkage-based filtering, external linkage-based filtering, or both. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a flowchart showing steps in an embodiment of the filtering approach for network system alarms. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The filtering approach for network system alarms reduces the manual intervention needed to manage alarms. All network alarms are captured and then categorized based on the source and the type of the alarm. Depending on their category, alarms are then sent through one or more filtering systems that can reduce the number of alarms displayed by replacing the underlying alarms coming from the network with alarm representations. The reduction in the number of alarms may be referred to herein as removing alarms meeting certain criteria or selecting alarms meeting certain criteria. These terms are intended to be understood as effectively complementary, where selecting for certain criteria is intended to have the same meaning as removing all alarms which do not meet those criteria. The filtering systems may be viewed as components of a single overall filtering system or as a sequence of separate filtering systems working in concert or as a combination of the two. The use of the term system in this disclosure is not intended to provide an indication of whether the coding is integrated, distributed, or modular. In a preferred embodiment, both alarms and alarm representations are retained even when not selected for display or when filtered from display. For the purposes of this disclosure, an alarm is recognized as a report from a network element. By comparison, an alarm representation is a system report based on an alarm or a plurality of alarms providing information to system technicians or operators either in addition to the simple alarm or in a more concise fashion than a collection of simple alarms. In this sense, an alarm representation may be defined as a single alarm that acts as a surrogate for multiple underlying alarms and as a newly generated alarm providing additional information about underlying or companion alarms. The use of alarm representations rather than the underlying alarms reduces the volume of alarm-related information, thus reducing the effort required to process alarms. This reduction occurs by hiding the underlying alarms associated with an alarm representation from view, allowing a technician to see only a single message. In an embodiment of the invention, the underlying alarms associated with an alarm representation can be examined by specific request. In some embodiments, for the purposes of filtering, both alarms and alarm representations may be acted upon. Thus, an alarm representation created by one filtering process may be, in turn, itself filtered and/or replaced by another alarm representation. 
   The type of alarm representation depends on the type of filtering system. For example, some filtering systems may allow one alarm of a particular type to pass through but mask out all other alarms of the same type. Other filtering systems may generate a new alarm to substitute for multiple alarms of a particular type. The alarm representations can be used to update a report that represents the status of the network. The report can take the form of a display that appears on a computer screen, a message which is transmitted or otherwise made available for review, or a message that is transmitted elsewhere for automated processing. The report can be updated each time a new alarm representation is generated so that technicians can easily see high-frequency alarms summarized into a single alarm representation. For the purposes of this disclosure, the use of a single alarm while masking duplicate alarms constitutes the use of a single alarm representation. In one embodiment, the masked duplicate alarms remain accessible as underlying information linked to the single alarm representation. 
   In an embodiment of the invention, seven different types of filtering can be used to process network alarms. Each type of filtering can be used independently or any combination of the seven types can be used. The first five of the filtering types may be generally categorized as non-temporal and temporal filters, where non-temporal filters do not expressly rely on a time component. Temporal filters, by comparison, consider time factors underlying events as a threshold to accomplish a more complex level of filtering. 
   In one type of non-temporal filtering, which can be referred to as de-duplication, repetitive alarms are eliminated. Many elements retransmit previously sent alarms until the conditions that triggered the alarm are cleared. These additional alarms can become noise, masking other problems. With de-duplication, a defined set of matching fields is given to each alarm type and these fields are embedded in the alarm messages. These fields allow specific types of alarms to be easily identified so that multiple alarms of the same type can be replaced by a single alarm representation. In an embodiment of the invention, a counter can be displayed to keep track of the number of similar alarms that have been masked. 
   One type of temporal filtering deals with the frequency of alarm arrival. Repeated alarms may arrive at different rates. Alarms of a given type from a given source may be of no significance when the rate of arrival is infrequent, but may become critical when the arrival frequency rises sharply. Even informational alarms may become significant if their rate of arrival peaks. In frequency-based alarm filtering, policies on alarm frequency are created. A counting system determines the number of alarms that occur in a period of time and compares that number to a number established in a policy. Alarm messages that arrive at a frequency lower than that specified in the policy can be ignored. Alternatively, such alarms can be aggregated into a single representation. When the frequency of an alarm exceeds the established threshold, an additional alarm can be generated and used as an additional (potentially higher priority) alarm representation. In one embodiment, different policies and thresholds can be applied to alarms from different sources or of different types. 
   De-duplication and frequency-based filtering are similar in that they both deal with representing multiple alarms of the same or similar type by a single alarm. The difference between the two types of filtering is that frequency-based filtering is concerned with the temporal aspect of the alarms. In de-duplication, repetitive alarms of a particular type are masked regardless of when other alarms of that type occurred. In frequency-based filtering, it is the number of alarms of a particular type or from a particular source that occur over a particular time period that determines whether or not an alarm representation is generated. 
   Elements can send “clear” messages to indicate that a previous alarm condition no longer exists. In a non-temporal filtering system that can be referred to as clear message mapping, mapping tables can be maintained that relate clear messages to the types of alarms to which they apply. Software-based logic can be used to search the mapping tables and automatically flag previously received alarms as cleared, indicating that they have become inactive. This can eliminate the need for manual intervention. Clear messages typically originate from the same element as the original alarm and thus contain identifiers of their source, eliminating the need for matching alarms with element topology data from an external source. Based on this, the cleared alarm or alarm representation may be removed from the alarm status report. 
   Under certain circumstances, an element can enter a cyclic pattern of alarm activation and clearing. That is, an alarm can be followed closely by a clear message and this pattern can continuously repeat. Such a scenario can indicate a problem requiring direct intervention. In a temporal filtering system that can be referred to as cycling-based filtering, policies on cycling frequency are created. A counting mechanism determines the number of alarm/clear cycles that occur in a period of time and compares that number to a number established in a policy. When the number of alarm/clear cycles exceeds the established level, an additional alarm can be generated as the alarm representation. A severity escalation mechanism can also be included so that when the number of alarm/clear cycles exceeds the established level, the severity (also referred to as the priority) of the additional alarm representation is increased beyond the level of the original alarms. 
   As is the case with de-duplication and frequency-based filtering, clear message mapping and cycling-based filtering are similar except for the temporal aspect of how they deal with alarms. In clear message mapping, clear messages are mapped to the alarms to which they correspond regardless of how often the clear messages, or their base alarms, occur. In cycling-based filtering, it is the frequency at which alarms are activated and then cleared that determines whether or not an alarm representation is generated. 
   An additional type of non-temporal filtering which may be employed is Classification filtering. Classification filtering may be applied against the source (for example element type or geographic region) of the message or may also be applied against the type of message being sent regardless of source. Classification filtering may be used by an operations group to mask alarms that are not meaningful to particular staff roles. For example, although the entire staff may use a common tool for monitoring, particular sub-teams may be assigned to monitor only specific types of network elements. For these individuals, classification filters can be used to remove all alarms and alarm representations from display that do not result directly from the elements types within their domain of interest. Alternatively, groups might be assigned to support elements within a specific geographic region, so all alarms from elements outside that region would not be displayed to them. 
   Classification by message type is a more fined-grained version of the same principle. Some elements may produce informational messages of no interest in a particular operations context. For example, a switch might send a message each time its cabinet door is opened or closed. When no policy or business rule has been developed that would make an alarm meaningful, many groups prefer to remove that alarm type from display. For one organization the opening or closing of a cabinet door can be used as evidence of human presence which could then be checked against security policies, especially for unmanned sites, where a violation of policy might trigger intervention, like a call to the police or to a security firm for investigation. Yet others might have no such requirements and simply want the door-related messages removed from the display. In almost every case, a scenario can be imagined where a message type provides useful information, yet in practical settings, certain types of alarms are of no value. Environmental alarms might be handled by one organization while service-related alarms are handled by another; each would use an appropriate message type based filter. 
   Internal linkage-based filtering deals with messages that come from different components within the same element. It requires a model of the element, including internal components, to determine alarm relationships. When a component fails, some elements will send an alarm for that failed component and a separate alarm for each of the other locally impacted components or services. While these additional messages can be helpful for impact analysis, they can often distract and confuse operators searching for root causes. Systematically hiding these additional messages from surveillance displays and downstream processes allows for faster problem correction. The original alarm from the original failed component can then act as the alarm representation. Internal linkage-based filtering requires the existence of a topology that describes the interconnections among all components within an element. Information regarding which alarms are generated by which components is also needed, as well as a model of which alarm types relate to each other. An additional alarm can be generated to notify operators that other alarms have been suppressed. 
   As an example of internal linkage-based filtering, within a network element, such as an ATM switch or a frame relay switch, several circuit cards might be present on a single backplane. Within each ATM card, for example, multiple ports might be present. The failure of an ATM card would result in each of the ports on the card becoming inoperable. The network element might have been designed to generate separate alarms for the failure of the card and for the failure of each of its ports. From the perspective of a network technician responsible for diagnosing and repairing equipment problems, the additional port alarms distract from the root problem. With internal linkage-based filtering, the alarms from the ports can be masked and/or subordinated to the card alarm. Software can be present that examines the topology of the ATM card and its component parts and recognizes that the alarms coming from the ports are likely to have been caused by the failure of the ATM card. The software can then ignore or remove from the display the alarms for the ports and use the alarm from the ATM card itself as an alarm representation. Alternatively, the alarms can be sent to a display where they can be examined by a technician who can decide whether the alarms from the ports can be safely removed from display. 
   External linkage-based filtering relates messages from multiple elements. Many protocols require synchronization signals or periodic status exchanges among elements in a network. These often specify that alarms be generated when signals are not properly received. Some protocols require the forwarding of special signals along the entire communications path of a service when a failure occurs at any point in the path. This signal forwarding alerts all elements along the path that a problem has occurred. Thus, a failure at one point in a network can cause alarms to propagate and cause sympathetic alarms to be generated by elements not actually responsible for the failure. External linkage-based filtering is intended to systematically hide sympathetic alarms from alarm monitoring mechanisms and downstream processes, while focusing operator attention on the most likely causes of the original alarm. In many cases, this may require the creation of a new alarm representation documenting the reason for the grouping of the other alarms. Knowledge of network element topology is needed to determine alarm relationships. Generally, this interconnected view of topology must be provided from an external source, such as a network model maintained within one or more network provisioning systems. 
   As an example of external linkage-based filtering, a communications chain between two points can comprise multiple elements connected in a serial fashion. Data can flow from one end point to the other through each of the elements in turn. Each element can have the capability to generate an alarm if it does not receive data when it expects to or if the data it receives appears to be invalid. Thus, if one element in a chain ceases to transmit data it can generate an alarm and can cause subsequent elements in the chain to also generate alarms when they fail to receive data from the previous element in the chain. The alarms from the subsequent elements can be considered superfluous since they would be generated by the fact that the original element ceased to transmit data and that element would have already generated its own alarm. With external linkage-based filtering, the alarms from the subsequent elements can be identified as related to one another and masked and/or subordinated under a single alarm representation. Software can be present that examines the topology of the elements in the chain and recognizes that the alarms coming from subsequent elements of the chain are likely to have been caused by the failure of the original element to transmit data. The software can then suppress the subsequent alarms and use the original alarm as an alarm representation. 
   While the preceding example used a simple serial chain of elements for illustrative purposes, in actual practice the topology of the elements is likely to be more complicated. Each element might be connected to numerous other elements in a highly complex configuration. In addition, numerous different types of alarms might occur. This means that an accurate topological map and a thorough understanding of all alarms that might occur are preferable in order for external linkage-based filtering to be fully implemented. 
   Internal linkage-based filtering and external linkage-based filtering can be referred to collectively as linkage filtering. The two types of linkage filtering are similar in that both involve the display masking and/or subordination of an alarm in an element or component that results from conditions in another element or component. The difference between the two types of linkage filtering is that internal linkage-based filtering deals with components within a single element. Alarms from dependent components within the element are consolidated into a single alarm representation. External linkage-based filtering deals with multiple elements. Alarms from dependent components across multiple elements are consolidated into a single alarm representation. 
   For either or both of the linkage-based filtering approaches, partial implementations may provide advantages even in the absence of full implementation. Since each typically involves detailed or complex rule making and/or mapping, rules or maps may be constructed for alarms or networks or components which are causing particular issues to assist in reducing noise from those places. As more time and resources are available and as different or new issues come to the fore as ripe for filtering, additional linkages for filtering may be added. This kind of incremental implementation for linkage based filtering may provide the same advantages with a more practical budget and flexible approach in moving towards incrementally improving the alarm status report and the environment for the technicians using the alarm status report. 
   The seven types of filtering can be implemented individually or in any combination. In one embodiment, non-temporal filtering (such as de-duplication, clear-message mapping, and/or classification filtering) and temporal filtering (such as frequency-based filtering and/or cycling-based filtering) are used in combination with linkage filtering (such as external-linkage filtering and/or internal linkage filtering). In a preferred embodiment, de-duplication, frequency-based filtering, clear message mapping, and cycling-based filtering are used in combination with linkage filtering. In this embodiment, when an alarm is generated it is captured and categorized according to the type of filtering that can be performed on it. The appropriate type or types of filtering are then performed on the alarm. Filters can be applied in any order and in either a serial or a parallel manner. After the filters have been applied, a report can be created that displays the alarm representations that represent the underlying alarms. This process can continue in an iterative manner in which the report is continuously updated as alarms are generated, captured, categorized, and filtered. 
   In an embodiment, the underlying alarms can be included in a report in addition to the alarm representations. This gives an alarm-monitoring technician the ability to view the underlying alarms if desired. If the report is displayed on a computer screen or other visual medium, an option can be provided that allows the viewing of the underlying alarms, the alarm representations, or both. In a preferred embodiment, both alarm representations and underlying alarms that have not been subordinately linked to an alarm representation are displayed. In this embodiment, if the proper criteria for subsequent filter rules are met, alarm representations may be aggregated under other alarm representations in a manner similar to the way underlying alarms can be aggregated under an alarm representation. 
   An embodiment of the filtering process is illustrated in  FIG. 1 . In box  12 , an alarm is generated by an element or a component of an element in a network. The alarm is captured in box  14 . In box  16 , the alarm is categorized according to which type or types of filtering can be performed on it. If de-duplication can be done on the alarm, de-duplication is performed in box  18 . If frequency-based filtering can be done on the alarm, frequency-based filtering is performed in box  20 . If clear message mapping can be done on the alarm, clear message mapping is performed in box  22 . If cycling-based filtering can be done on the alarm, cycling-based filtering is performed in box  24 . If classification filtering can be done on the alarm, classification filtering is performed in box  26 . If internal linkage-based filtering can be done on the alarm, internal linkage-based filtering is performed in box  28 . If external linkage-based filtering can be done on the alarm, external linkage-based filtering is performed in box  30 . Any one type or any combination of types of filtering shown in boxes  18 ,  20 ,  22 ,  24 ,  26 ,  28 , or  30  can be performed. After any type of filtering or any combination of filtering types is performed, a report can be updated as shown in box  32 . This process of alarm generation, alarm capture, alarm categorization, alarm filtering, and report updating can occur in a loop that repeats to handle all new and existing alarms. 
   In addition to the seven types of alarm filtering described above, alarms can be filtered based on the operational or lifecycle state of the elements in a network. State-based filters can block from the display (or can specifically filter for depending on the needs of the particular user) elements not yet fully deployed or in a maintenance state. At the highest level the general categories of lifecycle state can be defined as: operational and non-operational. Non-operational states may be generally divided into pre-acceptance and post-acceptance. Pre-acceptance non-operational states may include one of the following: planned (not yet deployed), deployed (physically fielded, but not yet verified), or tested (verified, but not yet operationally accepted). Post-acceptance states may include one of the following: blocked (physically present but inhibited from use) and defective (physically present, but unusable). Operational states may be generally divided into normal (operating as intended) or maintenance. Maintenance states may include testing (currently being tested), scheduled maintenance (currently being maintained), emergency recovery (unscheduled maintenance), or reallocated (temporarily reconfigured differently than recorded by provisioning records, for example to act as a work-around to solve a problem with another portion of the network). These states may be recorded and updated (or tracked) independently for all or selected resources. They may be recorded and updated as an element of a network model (topology, inventory, or combination of both) modeling the network which includes the subject resources. They may be recorded and updated as an element of a provisioning or configuration record which includes the subject resources. The filtering system can then refer to the model, records, or independently stored state information to assist in evaluating various alarms and/or alarm representations. Any of a number of possible approaches to this storage and access would be understood to those of skill in the art, and would provide many or all of the advantages sought from incorporating state-based filtering. States could be tracked for at least a portion of the elements in a network or for all of the elements in a network. At least a portion of the alarms generated by elements for which the lifecycle state is tracked may be filtered for state or all of the alarms generated by tracked elements may be filtered for state. 
   States can be used to provide different alarm filtering views, useful in addressing different operational tasks. Many alarms can occur during the pre-acceptance processes of installing and deploying new elements. These are typically of interest only to operational personnel validating and accepting new elements and can be filtered out of the standard alarm monitoring process or actively selected for more specialized tasks. For example, a remote operator working with field technicians to verify the correct configuration of newly configured elements can use a filtered view focusing on elements in the pre-acceptance state of deployed. However, for monitoring of normal operations, alarms from all resources that are not in an operational state are typically filtered as noise. 
   Even within the operational state, there may be transient changes to resources which may be helpful to distinguish and filter for. These temporary state changes relate to what may be referred to here collectively as maintenance activities, by which is meant activities required to effectively operate, maintain, and repair a network including testing, maintenance, emergency recovery, and reallocation. Generally these activities temporarily disrupt normal network operations, and often cause conditions that trigger the generation of additional network alarms. Because of the special nature of these activities and the predictable alarm responses, it may be desirable to separate these alarms from normal monitoring to prevent confusion. These alarms might otherwise cause an operator to attempt unnecessary repairs that might compromise the other special-purpose activities that indirectly caused the alarms. Network maintenance is an example of an activity that can also trigger additional alarms. During network change activity, selected resources may be disconnected or changed as part of a larger reconfiguration activity. These intermediate changes often leave services or resources in abnormal states until other configuration activities are completed. In some embodiments, alarms from these resources can be treated as the expected side effects of the maintenance activities and can also be filtered from standard alarm monitoring. However, special maintenance views can also be helpful in answering questions about whether particular resources should be a concern or not during a maintenance period, say in response to an unexpected customer complaint that arrives during a maintenance period. In one embodiment of operations, some combination of state-based filtering may be used independently from the seven filters previously discussed. In other embodiments of operation, a combination of state-based filtering and any or all of the components or sub-components of non-temporal, temporal, and linkage-based filtering as described above may be used. 
   In an alternative improvement to the alarm status report and alarm status filtering and reporting system, technicians may be provided the ability to manually group related alarms under a single alarm representation for reporting purposes. In this manner, a technician may reduce the number of reported alarms based on his own evaluation of related alarms. This could simplify the display for other technicians and also reduce the chance that multiple technicians will end up working on the same problem by starting from different, but related, alarms. In yet an additional embodiment, records could be kept of the alarms manually combined and where consistent or repeating patterns are observed, plans could be made to implement new filters where practical, particularly linkage-based filters, to group these alarms automatically in the future. 
   Although only a few embodiments of the present invention have been described, it should be understood that the present invention may be embodied in many other specific forms without departing from the spirit or the scope of the present invention. The present examples are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein, but may be modified within the scope of the appended claims along with their full scope of equivalents.