ietf-alarms

This module defines an interface for managing alarms. Main inputs to the module design are the 3GPP Alarm Integration Reference...

  • Version: 2019-09-11

    ietf-alarms@2019-09-11


    
      module ietf-alarms {
    
        yang-version 1.1;
    
        namespace
          "urn:ietf:params:xml:ns:yang:ietf-alarms";
    
        prefix al;
    
        import ietf-yang-types {
          prefix yang;
          reference
            "RFC 6991: Common YANG Data Types.";
    
    
        }
    
        organization "IETF CCAMP Working Group";
    
        contact
          "WG Web:   <https://trac.ietf.org/trac/ccamp>
    WG List:  <mailto:ccamp@ietf.org>
    
    Editor:   Stefan Vallin
    	  <mailto:stefan@wallan.se>
    
    Editor:   Martin Bjorklund
    	  <mailto:mbj@tail-f.com>";
    
        description
          "This module defines an interface for managing alarms.  Main
    inputs to the module design are the 3GPP Alarm Integration
    Reference Point (IRP), ITU-T X.733, and ANSI/ISA-18.2 alarm
    standards.
    Main features of this module include:
    
      * Alarm list:
    	    A list of all alarms.  Cleared alarms stay in
    	    the list until explicitly purged.
    
      * Operator actions on alarms:
    	    Acknowledging and closing alarms.
    
      * Administrative actions on alarms:
    	    Purging alarms from the list according to specific
    	    criteria.
    
      * Alarm inventory:
    	    A management application can read all
    	    alarm types implemented by the system.
    
      * Alarm shelving:
    	    Shelving (blocking) alarms according
    	    to specific criteria.
    
      * Alarm profiles:
    	    A management system can attach further
    	    information to alarm types, for example,
    	    overriding system-default severity
    	    levels.
    
    This module uses a stateful view on alarms.  An alarm is a state
    for a specific resource (note that an alarm is not a
    notification).  An alarm type is a possible alarm state for a
    resource.  For example, the tuple:
    
      ('link-alarm', 'GigabitEthernet0/25')
    
    is an alarm of type 'link-alarm' on the resource
    'GigabitEthernet0/25'.
    
    Alarm types are identified using YANG identities and an optional
    string-based qualifier.  The string-based qualifier allows for
    dynamic extension of the statically defined alarm types.  Alarm
    types identify a possible alarm state and not the individual
    notifications.  For example, the traditional 'link-down' and
    'link-up' notifications are two notifications referring to the
    same alarm type 'link-alarm'.
    
    With this design, there is no ambiguity about how alarm and
    alarm clear correlation should be performed; notifications that
    report the same resource and alarm type are considered updates
    of the same alarm, e.g., clearing an active alarm or changing
    the severity of an alarm.  The instrumentation can update the
    severity and alarm text on an existing alarm.  The above alarm
    example can therefore look like the following:
    
      (('link-alarm', 'GigabitEthernet0/25'),
       warning,
       'interface down while interface admin state is up')
    
    There is a clear separation between updates on the alarm from
    the underlying resource, like clear, and updates from an
    operator, like acknowledging or closing an alarm:
    
      (('link-alarm', 'GigabitEthernet0/25'),
       warning,
       'interface down while interface admin state is up',
       cleared,
       closed)
    
    Administrative actions like removing closed alarms older than a
    given time is supported.
    
    This YANG module does not define how the underlying
    instrumentation detects and clears the specific alarms.  That
    belongs to the Standards Development Organization (SDO) or
    enterprise that owns that specific technology.
    
    The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL
    NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'NOT RECOMMENDED',
    'MAY', and 'OPTIONAL' in this document are to be interpreted as
    described in BCP 14 (RFC 2119) (RFC 8174) when, and only when,
    they appear in all capitals, as shown here.
    
    Copyright (c) 2019 IETF Trust and the persons identified as
    authors of the code.  All rights reserved.
    
    Redistribution and use in source and binary forms, with or
    without modification, is permitted pursuant to, and subject to
    the license terms contained in, the Simplified BSD License set
    forth in Section 4.c of the IETF Trust's Legal Provisions
    Relating to IETF Documents
    (https://trustee.ietf.org/license-info).
    
    This version of this YANG module is part of RFC 8632; see
    the RFC itself for full legal notices.";
    
        revision "2019-09-11" {
          description "Initial revision.";
          reference
            "RFC 8632: A YANG Data Model for Alarm Management";
    
        }
    
    
        feature operator-actions {
          description
            "This feature indicates that the system supports operator
    states on alarms.";
        }
    
        feature alarm-shelving {
          description
            "This feature indicates that the system supports shelving
    (blocking) alarms.
    
    Alarm shelving may have an impact on server processing
    resources in order to match alarms against shelf
    criteria.";
        }
    
        feature alarm-history {
          description
            "This feature indicates that the server maintains a history
    of state changes for each alarm.  For example, if an alarm
    toggles between cleared and active 10 times, these state
    changes are present in a separate list in the alarm.
    
    Keeping the alarm history may have an impact on server
    memory resources.";
        }
    
        feature alarm-summary {
          description
            "This feature indicates that the server summarizes the number
    of alarms per severity and operator state.";
        }
    
        feature alarm-profile {
          description
            "The system enables clients to configure further information
    to each alarm type.";
        }
    
        feature severity-assignment {
          description
            "The system supports configurable alarm severity levels.";
          reference
            "ITU-T Recommendation M.3100:
              Generic network information model
            ITU-T Recommendation M.3160:
              Generic, protocol-neutral management information model";
    
        }
    
        feature root-cause-analysis {
          description
            "The system supports identifying candidate root-cause
    resources for an alarm, for example, a disk partition
    root cause for a logger failure alarm.";
        }
    
        feature service-impact-analysis {
          description
            "The system supports identifying candidate-impacted
    resources for an alarm, for example, an interface state change
    resulting in a link alarm, which can refer to a link as being
    impacted.";
        }
    
        feature alarm-correlation {
          description
            "The system supports correlating/grouping alarms
    that belong together.";
        }
    
        identity alarm-type-id {
          description
            "Base identity for alarm types.  A unique identification of
    the alarm, not including the resource.  Different resources
    can share alarm types.  If the resource reports the same
    alarm type, it is considered to be the same alarm.  The alarm
    type is a simplification of the different X.733 and 3GPP Alarm
    IRP correlation mechanisms, and it allows for
    hierarchical extensions.
    
    A string-based qualifier can be used in addition to the
    identity in order to have different alarm types based on
    information not known at design time, such as values in
    textual SNMP Notification varbinds.
    
    Standards and vendors can define sub-identities to clearly
    identify specific alarm types.
    
    This identity is abstract and MUST NOT be used for alarms.";
        }
    
        typedef resource {
          type union {
            type instance-identifier;
            type yang:object-identifier;
            type string;
            type yang:uuid;
          }
          description
            "This is an identification of the alarming resource, such as an
    interface.  It should be as fine-grained as possible to both
    guide the operator and guarantee uniqueness of the alarms.
    
    If the alarming resource is modeled in YANG, this type will
    be an instance-identifier.
    
    If the resource is an SNMP object, the type will be an
    'object-identifier'.
    
    If the resource is anything else, for example, a distinguished
    name or a Common Information Model (CIM) path, this type will
    be a string.
    
    If the alarming object is identified by a Universally Unique
    Identifier (UUID), use the uuid type.  Be cautious when using
    this type, since a UUID is hard to use for an operator.
    
    If the server supports several models, the precedence should
    be in the order as given in the union definition.";
        }
    
        typedef resource-match {
          type union {
            type yang:xpath1.0;
            type yang:object-identifier;
            type string;
          }
          description
            "This type is used to match resources of type 'resource'.
    Since the type 'resource' is a union of different types, the
    'resource-match' type is also a union of corresponding types.
    
    If the type is given as an XPath 1.0 expression, a resource
    of type 'instance-identifier' matches if the instance is part
    of the node set that is the result of evaluating the XPath 1.0
    expression.  For example, the XPath 1.0 expression:
    
     /ietf-interfaces:interfaces/ietf-interfaces:interface
         [ietf-interfaces:type='ianaift:ethernetCsmacd']
    
    would match the resource instance-identifier:
    
     /if:interfaces/if:interface[if:name='eth1'],
    
    assuming that the interface 'eth1' is of type
    'ianaift:ethernetCsmacd'.
    
    If the type is given as an object identifier, a resource of
    type 'object-identifier' matches if the match object
    identifier is a prefix of the resource's object identifier.
    For example, the value:
    
     1.3.6.1.2.1.2.2
    
    would match the resource object identifier:
    
     1.3.6.1.2.1.2.2.1.1.5
    
    If the type is given as an UUID or a string, it is interpreted
    as an XML Schema regular expression, which matches a resource
    of type 'yang:uuid' or 'string' if the given regular
    expression matches the resource string.
    
    If the type is given as an XPath expression, it is evaluated
    in the following XPath context:
    
      o  The set of namespace declarations is the set of prefix
         and namespace pairs for all YANG modules implemented by
         the server, where the prefix is the YANG module name and
         the namespace is as defined by the 'namespace' statement
         in the YANG module.
    
         If a leaf of this type is encoded in XML, all namespace
         declarations in scope on the leaf element are added to
         the set of namespace declarations.  If a prefix found in
         the XML is already present in the set of namespace
         declarations, the namespace in the XML is used.
    
      o  The set of variable bindings is empty.
    
      o  The function library is the core function library, and
         the functions are defined in Section 10 of RFC 7950.
    
      o  The context node is the root node in the data tree.";
          reference
            "XML Schema Part 2: Datatypes Second Edition,
              World Wide Web Consortium Recommendation
              REC-xmlschema-2-20041028";
    
        }
    
        typedef alarm-text {
          type string;
          description
            "The string used to inform operators about the alarm.  This
    MUST contain enough information for an operator to be able to
    understand the problem and how to resolve it.  If this string
    contains structure, this format should be clearly documented
    for programs to be able to parse that information.";
        }
    
        typedef severity {
          type enumeration {
            enum "indeterminate" {
              value 2;
              description
                "Indicates that the severity level could not be
    determined.  This level SHOULD be avoided.";
            }
            enum "warning" {
              value 3;
              description
                "The 'warning' severity level indicates the detection of a
    potential or impending service-affecting fault, before any
    significant effects have been felt.  Action should be
    taken to further diagnose (if necessary) and correct the
    problem in order to prevent it from becoming a more
    serious service-affecting fault.";
            }
            enum "minor" {
              value 4;
              description
                "The 'minor' severity level indicates the existence of a
    non-service-affecting fault condition and that corrective
    action should be taken in order to prevent a more serious
    (for example, service-affecting) fault.  Such a severity
    can be reported, for example, when the detected alarm
    condition is not currently degrading the capacity of the
    resource.";
            }
            enum "major" {
              value 5;
              description
                "The 'major' severity level indicates that a service-
    affecting condition has developed and an urgent corrective
    action is required.  Such a severity can be reported, for
    example, when there is a severe degradation in the
    capability of the resource and its full capability must be
    restored.";
            }
            enum "critical" {
              value 6;
              description
                "The 'critical' severity level indicates that a service-
    affecting condition has occurred and an immediate
    corrective action is required.  Such a severity can be
    reported, for example, when a resource becomes totally out
    of service and its capability must be restored.";
            }
          }
          description
            "The severity level of the alarm.  Note well that the value
    'clear' is not included.  Whether or not an alarm is cleared
    is a separate boolean flag.";
          reference
            "ITU-T Recommendation X.733: Information Technology
              - Open Systems Interconnection
              - System Management: Alarm Reporting Function";
    
        }
    
        typedef severity-with-clear {
          type union {
            type enumeration {
              enum "cleared" {
                value 1;
                description
                  "The alarm is cleared by the instrumentation.";
              }
            }
            type severity;
          }
          description
            "The severity level of the alarm including clear.  This is used
    only in notifications reporting state changes for an alarm.";
        }
    
        typedef writable-operator-state {
          type enumeration {
            enum "none" {
              value 1;
              description
                "The alarm is not being taken care of.";
            }
            enum "ack" {
              value 2;
              description
                "The alarm is being taken care of.  Corrective action not
    taken yet or has failed";
            }
            enum "closed" {
              value 3;
              description
                "Corrective action taken successfully.";
            }
          }
          description
            "Operator states on an alarm.  The 'closed' state indicates
    that an operator considers the alarm being resolved.  This is
    separate from the alarm's 'is-cleared' leaf.";
        }
    
        typedef operator-state {
          type union {
            type writable-operator-state;
            type enumeration {
              enum "shelved" {
                value 4;
                description
                  "The alarm is shelved.  Alarms in /alarms/shelved-alarms/
    MUST be assigned this operator state by the server as
    the last entry in the 'operator-state-change' list.  The
    text for that entry SHOULD include the shelf name.";
              }
              enum "un-shelved" {
                value 5;
                description
                  "The alarm is moved back to 'alarm-list' from a shelf.
    Alarms that are moved from /alarms/shelved-alarms/ to
    /alarms/alarm-list MUST be assigned this state by the
    server as the last entry in the 'operator-state-change'
    list.  The text for that entry SHOULD include the shelf
    name.";
              }
            }
          }
          description
            "Operator states on an alarm.  The 'closed' state indicates
    that an operator considers the alarm being resolved.  This is
    separate from the alarm's 'is-cleared' leaf.";
        }
    
        typedef alarm-type-id {
          type identityref {
            base alarm-type-id;
          }
          description
            "Identifies an alarm type.  The description of the alarm type
    id MUST indicate whether or not the alarm type is abstract.
    An abstract alarm type is used as a base for other alarm type
    ids and will not be used as a value for an alarm or be present
    in the alarm inventory.";
        }
    
        typedef alarm-type-qualifier {
          type string;
          description
            "If an alarm type cannot be fully specified at design time by
    'alarm-type-id', this string qualifier is used in addition to
    fully define a unique alarm type.
    
    The definition of alarm qualifiers is considered to be part of
    the instrumentation and is out of scope for this module.  An
    empty string is used when this is part of a key.";
        }
    
        grouping common-alarm-parameters {
          description
            "Common parameters for an alarm.
    
    This grouping is used both in the alarm list and in the
    notification representing an alarm-state change.";
          leaf resource {
            type resource;
            mandatory true;
            description
              "The alarming resource.  See also 'alt-resource'.  This could
    be, for example, a reference to the alarming interface";
          }
    
          leaf alarm-type-id {
            type alarm-type-id;
            mandatory true;
            description
              "This leaf and the leaf 'alarm-type-qualifier' together
    provide a unique identification of the alarm type.";
          }
    
          leaf alarm-type-qualifier {
            type alarm-type-qualifier;
            description
              "This leaf is used when the 'alarm-type-id' leaf cannot
    uniquely identify the alarm type.  Normally, this is not the
    case, and this leaf is the empty string.";
          }
    
          leaf-list alt-resource {
            type resource;
            description
              "Used if the alarming resource is available over other
    interfaces.  This field can contain SNMP OIDs, CIM paths, or
    3GPP distinguished names, for example.";
          }
    
          list related-alarm {
            if-feature alarm-correlation;
            key "resource alarm-type-id alarm-type-qualifier";
            description
              "References to related alarms.  Note that the related alarm
    might have been purged from the alarm list.";
            leaf resource {
              type leafref {
                path
                  "/alarms/alarm-list/alarm/resource";
                require-instance false;
              }
              description
                "The alarming resource for the related alarm.";
            }
    
            leaf alarm-type-id {
              type leafref {
                path
                  "/alarms/alarm-list/alarm[resource=current()/../resource]/alarm-type-id";
                require-instance false;
              }
              description
                "The alarm type identifier for the related alarm.";
            }
    
            leaf alarm-type-qualifier {
              type leafref {
                path
                  "/alarms/alarm-list/alarm[resource=current()/../resource][alarm-type-id=current()/../alarm-type-id]/alarm-type-qualifier";
                require-instance false;
              }
              description
                "The alarm qualifier for the related alarm.";
            }
          }  // list related-alarm
    
          leaf-list impacted-resource {
            if-feature service-impact-analysis;
            type resource;
            description
              "Resources that might be affected by this alarm.  If the
    system creates an alarm on a resource and also has a mapping
    to other resources that might be impacted, these resources
    can be listed in this leaf-list.  In this way, the system
    can create one alarm instead of several.  For example, if an
    interface has an alarm, the 'impacted-resource' can
    reference the aggregated port channels.";
          }
    
          leaf-list root-cause-resource {
            if-feature root-cause-analysis;
            type resource;
            description
              "Resources that are candidates for causing the alarm.  If the
    system has a mechanism to understand the candidate root
    causes of an alarm, this leaf-list can be used to list the
    root-cause candidate resources.  In this way, the system can
    create one alarm instead of several.  An example might be a
    logging system (alarm resource) that fails; the alarm can
    reference the file system in the 'root-cause-resource'
    leaf-list.  Note that the intended use is not to also send
    an alarm with the 'root-cause-resource' as an alarming
    resource.  The 'root-cause-resource' leaf-list is a hint and
    should not also generate an alarm for the same problem.";
          }
        }  // grouping common-alarm-parameters
    
        grouping alarm-state-change-parameters {
          description
            "Parameters for an alarm-state change.
    
    This grouping is used both in the alarm list's status-change
    list and in the notification representing an alarm-state
    change.";
          leaf time {
            type yang:date-and-time;
            mandatory true;
            description
              "The time the status of the alarm changed.  The value
    represents the time the real alarm-state change appeared in
    the resource and not when it was added to the alarm
    list.  The /alarm-list/alarm/last-changed MUST be set to the
    same value.";
          }
    
          leaf perceived-severity {
            type severity-with-clear;
            mandatory true;
            description
              "The severity of the alarm as defined by X.733.  Note that
    this may not be the original severity since the alarm may
    have changed severity.";
            reference
              "ITU-T Recommendation X.733: Information Technology
                - Open Systems Interconnection
                - System Management: Alarm Reporting Function";
    
          }
    
          leaf alarm-text {
            type alarm-text;
            mandatory true;
            description
              "A user-friendly text describing the alarm-state change.";
            reference
              "ITU-T Recommendation X.733: Information Technology
                - Open Systems Interconnection
                - System Management: Alarm Reporting Function";
    
          }
        }  // grouping alarm-state-change-parameters
    
        grouping operator-parameters {
          description
            "This grouping defines parameters that can be changed by an
    operator.";
          leaf time {
            type yang:date-and-time;
            mandatory true;
            description
              "Timestamp for operator action on the alarm.";
          }
    
          leaf operator {
            type string;
            mandatory true;
            description
              "The name of the operator that has acted on this alarm.";
          }
    
          leaf state {
            type operator-state;
            mandatory true;
            description
              "The operator's view of the alarm state.";
          }
    
          leaf text {
            type string;
            description
              "Additional optional textual information provided by the
    operator.";
          }
        }  // grouping operator-parameters
    
        grouping resource-alarm-parameters {
          description
            "Alarm parameters that originate from the resource view.";
          leaf is-cleared {
            type boolean;
            mandatory true;
            description
              "Indicates the current clearance state of the alarm.  An
    alarm might toggle from active alarm to cleared alarm and
    back to active again.";
          }
    
          leaf last-raised {
            type yang:date-and-time;
            mandatory true;
            description
              "An alarm may change severity level and toggle between
    active and cleared during its lifetime.  This leaf indicates
    the last time it was raised ('is-cleared' = 'false').";
          }
    
          leaf last-changed {
            type yang:date-and-time;
            mandatory true;
            description
              "A timestamp when the 'status-change' or
    'operator-state-change' list was last changed.";
          }
    
          leaf perceived-severity {
            type severity;
            mandatory true;
            description
              "The last severity of the alarm.
    
    If an alarm was raised with severity 'warning' but later
    changed to 'major', this leaf will show 'major'.";
          }
    
          leaf alarm-text {
            type alarm-text;
            mandatory true;
            description
              "The last reported alarm text.  This text should contain
    information for an operator to be able to understand the
    problem and how to resolve it.";
          }
    
          list status-change {
            if-feature alarm-history;
            key "time";
            min-elements 1;
            description
              "A list of status-change events for this alarm.
    
    The entry with latest timestamp in this list MUST
    correspond to the leafs 'is-cleared', 'perceived-severity',
    and 'alarm-text' for the alarm.
    
    This list is ordered according to the timestamps of alarm
    state changes.  The first item corresponds to the latest
    state change.
    
    The following state changes create an entry in this
    list:
    - changed severity (warning, minor, major, critical)
    - clearance status; this also updates the 'is-cleared'
      leaf
    - alarm-text update";
            uses alarm-state-change-parameters;
          }  // list status-change
        }  // grouping resource-alarm-parameters
    
        grouping filter-input {
          description
            "Grouping to specify a filter construct on alarm information.";
          leaf alarm-clearance-status {
            type enumeration {
              enum "any" {
                value 0;
                description
                  "Ignore alarm-clearance status.";
              }
              enum "cleared" {
                value 1;
                description
                  "Filter cleared alarms.";
              }
              enum "not-cleared" {
                value 2;
                description
                  "Filter not-cleared alarms.";
              }
            }
            mandatory true;
            description
              "The clearance status of the alarm.";
          }
    
          container older-than {
            presence "Age specification";
            description
              "Matches the 'last-status-change' leaf in the alarm.";
            choice age-spec {
              description
                "Filter using date and time age.";
              leaf seconds {
                type uint16;
                description
                  "Age expressed in seconds.";
              }
              leaf minutes {
                type uint16;
                description
                  "Age expressed in minutes.";
              }
              leaf hours {
                type uint16;
                description
                  "Age expressed in hours.";
              }
              leaf days {
                type uint16;
                description
                  "Age expressed in days.";
              }
              leaf weeks {
                type uint16;
                description
                  "Age expressed in weeks.";
              }
            }  // choice age-spec
          }  // container older-than
    
          container severity {
            presence "Severity filter";
            description
              "Filter based on severity.";
            choice sev-spec {
              description
                "Filter based on severity level.";
              leaf below {
                type severity;
                description
                  "Severity less than this leaf.";
              }
              leaf is {
                type severity;
                description
                  "Severity level equal to this leaf.";
              }
              leaf above {
                type severity;
                description
                  "Severity level higher than this leaf.";
              }
            }  // choice sev-spec
          }  // container severity
    
          container operator-state-filter {
            if-feature operator-actions;
            presence "Operator state filter";
            description
              "Filter based on operator state.";
            leaf state {
              type operator-state;
              description
                "Filter on operator state.";
            }
    
            leaf user {
              type string;
              description
                "Filter based on which operator.";
            }
          }  // container operator-state-filter
        }  // grouping filter-input
    
        container alarms {
          description
            "The top container for this module.";
          container control {
            description
              "Configuration to control the alarm behavior.";
            leaf max-alarm-status-changes {
              type union {
                type uint16;
                type enumeration {
                  enum "infinite" {
                    value 0;
                    description
                      "The status-change entries are accumulated
    infinitely.";
                  }
                }
              }
              default "32";
              description
                "The 'status-change' entries are kept in a circular list
    per alarm.  When this number is exceeded, the oldest
    status change entry is automatically removed.  If the
    value is 'infinite', the status-change entries are
    accumulated infinitely.";
            }
    
            leaf notify-status-changes {
              type enumeration {
                enum "all-state-changes" {
                  value 0;
                  description
                    "Send notifications for all status changes.";
                }
                enum "raise-and-clear" {
                  value 1;
                  description
                    "Send notifications only for raise, clear, and
    re-raise.  Notifications for severity-level changes or
    alarm-text changes are not sent.";
                }
                enum "severity-level" {
                  value 2;
                  description
                    "Only send notifications for alarm-state changes
    crossing the level specified in
    'notify-severity-level'.  Always send clear
    notifications.";
                }
              }
              must
                ". != "severity-level" or ../notify-severity-level" {
                description
                  "When notify-status-changes is 'severity-level', a value
    must be given for 'notify-severity-level'.";
              }
              default "all-state-changes";
              description
                "This leaf controls the notifications sent for alarm status
    updates.  There are three options:
    
    1.  Notifications are sent for all updates, severity-level
        changes, and alarm-text changes.
    
    2.  Notifications are only sent for alarm raise and clear.
    
    3.  Notifications are sent for status changes equal to or
        above the specified severity level.  Clear
        notifications shall always be sent.  Notifications
        shall also be sent for state changes that make an
        alarm less severe than the specified level.
    
    For example, in option 3, assume that the severity level
    is set to major and that the alarm has the following state
    changes:
    
    [(Time, severity, clear)]:
    [(T1, major, -), (T2, minor, -), (T3, warning, -),
     (T4, minor, -), (T5, major, -), (T6, critical, -),
     (T7, major.  -), (T8, major, clear)]
    
    In that case, notifications will be sent at times
    T1, T2, T5, T6, T7, and T8.";
            }
    
            leaf notify-severity-level {
              when
                "../notify-status-changes = "severity-level"";
              type severity;
              description
                "Only send notifications for alarm-state changes crossing
    the specified level.  Always send clear notifications.";
            }
    
            container alarm-shelving {
              if-feature alarm-shelving;
              description
                "The 'alarm-shelving/shelf' list is used to shelve
    (block/filter) alarms.  The conditions in the shelf
    criteria are logically ANDed.  The first matching shelf is
    used, and an alarm is shelved only for this first match.
    Matching alarms MUST appear in the
    /alarms/shelved-alarms/shelved-alarm list, and
    non-matching /alarms MUST appear in the
    /alarms/alarm-list/alarm list.  The server does not send
    any notifications for shelved alarms.
    
    The server MUST maintain states (e.g., severity
    changes) for the shelved alarms.
    
    Alarms that match the criteria shall have an
    operator state 'shelved'.  When the shelf
    configuration removes an alarm from the shelf, the server
    shall add the operator state 'un-shelved'.";
              list shelf {
                key "name";
                ordered-by user;
                description
                  "Each entry defines the criteria for shelving alarms.
    Criteria are ANDed.  If no criteria are specified,
    all alarms will be shelved.";
                leaf name {
                  type string;
                  description
                    "An arbitrary name for the alarm shelf.";
                }
    
                leaf-list resource {
                  type resource-match;
                  description
                    "Shelve alarms for matching resources.";
                }
    
                list alarm-type {
                  key "alarm-type-id alarm-type-qualifier-match";
                  description
                    "Any alarm matching the combined criteria of
    'alarm-type-id' and 'alarm-type-qualifier-match'
    MUST be matched.";
                  leaf alarm-type-id {
                    type alarm-type-id;
                    description
                      "Shelve all alarms that have an 'alarm-type-id' that
    is equal to or derived from the given
    'alarm-type-id'.";
                  }
    
                  leaf alarm-type-qualifier-match {
                    type string;
                    description
                      "An XML Schema regular expression that is used to
    match an alarm type qualifier.  Shelve all alarms
    that match this regular expression for the alarm
    type qualifier.";
                    reference
                      "XML Schema Part 2: Datatypes Second Edition,
                        World Wide Web Consortium Recommendation
                        REC-xmlschema-2-20041028";
    
                  }
                }  // list alarm-type
    
                leaf description {
                  type string;
                  description
                    "An optional textual description of the shelf.  This
    description should include the reason for shelving
    these alarms.";
                }
              }  // list shelf
            }  // container alarm-shelving
          }  // container control
    
          container alarm-inventory {
            config false;
            description
              "The 'alarm-inventory/alarm-type' list contains all possible
    alarm types for the system.
    
    If the system knows for which resources a specific alarm
    type can appear, it is also identified in the inventory.
    The list also tells if each alarm type has a corresponding
    clear state.  The inventory shall only contain concrete
    alarm types.
    
    The alarm inventory MUST be updated by the system when new
    alarms can appear.  This can be the case when installing new
    software modules or inserting new card types.  A
    notification 'alarm-inventory-changed' is sent when the
    inventory is changed.";
            list alarm-type {
              key "alarm-type-id alarm-type-qualifier";
              description
                "An entry in this list defines a possible alarm.";
              leaf alarm-type-id {
                type alarm-type-id;
                description
                  "The statically defined alarm type identifier for this
    possible alarm.";
              }
    
              leaf alarm-type-qualifier {
                type alarm-type-qualifier;
                description
                  "The optionally dynamically defined alarm type identifier
    for this possible alarm.";
              }
    
              leaf-list resource {
                type resource-match;
                description
                  "Optionally, specifies for which resources the alarm type
    is valid.";
              }
    
              leaf will-clear {
                type boolean;
                mandatory true;
                description
                  "This leaf tells the operator if the alarm will be
    cleared when the correct corrective action has been
    taken.  Implementations SHOULD strive for detecting the
    cleared state for all alarm types.
    
    If this leaf is 'true', the operator can monitor the
    alarm until it becomes cleared after the corrective
    action has been taken.
    
    If this leaf is 'false', the operator needs to validate
    that the alarm is no longer active using other
    mechanisms.  Alarms can lack a corresponding clear due
    to missing instrumentation or no logical
    corresponding clear state.";
              }
    
              leaf-list severity-level {
                type severity;
                description
                  "This leaf-list indicates the possible severity levels of
    this alarm type.  Note well that 'clear' is not part of
    the severity type.  In general, the severity level
    should be defined by the instrumentation based on the
    dynamic state, rather than being defined statically by
    the alarm type, in order to provide a relevant severity
    level based on dynamic state and context.  However, most
    alarm types have a defined set of possible severity
    levels, and this should be provided here.";
              }
    
              leaf description {
                type string;
                mandatory true;
                description
                  "A description of the possible alarm.  It SHOULD include
    information on possible underlying root causes and
    corrective actions.";
              }
            }  // list alarm-type
          }  // container alarm-inventory
    
          container summary {
            if-feature alarm-summary;
            config false;
            description
              "This container gives a summary of the number of alarms.";
            list alarm-summary {
              key "severity";
              description
                "A global summary of all alarms in the system.  The summary
    does not include shelved alarms.";
              leaf severity {
                type severity;
                description
                  "Alarm summary for this severity level.";
              }
    
              leaf total {
                type yang:gauge32;
                description
                  "Total number of alarms of this severity level.";
              }
    
              leaf not-cleared {
                type yang:gauge32;
                description
                  "Total number of alarms of this severity level
    that are not cleared.";
              }
    
              leaf cleared {
                type yang:gauge32;
                description
                  "For this severity level, the number of alarms that are
    cleared.";
              }
    
              leaf cleared-not-closed {
                if-feature operator-actions;
                type yang:gauge32;
                description
                  "For this severity level, the number of alarms that are
    cleared but not closed.";
              }
    
              leaf cleared-closed {
                if-feature operator-actions;
                type yang:gauge32;
                description
                  "For this severity level, the number of alarms that are
    cleared and closed.";
              }
    
              leaf not-cleared-closed {
                if-feature operator-actions;
                type yang:gauge32;
                description
                  "For this severity level, the number of alarms that are
    not cleared but closed.";
              }
    
              leaf not-cleared-not-closed {
                if-feature operator-actions;
                type yang:gauge32;
                description
                  "For this severity level, the number of alarms that are
    not cleared and not closed.";
              }
            }  // list alarm-summary
    
            leaf shelves-active {
              if-feature alarm-shelving;
              type empty;
              description
                "This is a hint to the operator that there are active
    alarm shelves.  This leaf MUST exist if the
    /alarms/shelved-alarms/number-of-shelved-alarms is > 0.";
            }
          }  // container summary
    
          container alarm-list {
            config false;
            description
              "The alarms in the system.";
            leaf number-of-alarms {
              type yang:gauge32;
              description
                "This object shows the total number of
    alarms in the system, i.e., the total number
    of entries in the alarm list.";
            }
    
            leaf last-changed {
              type yang:date-and-time;
              description
                "A timestamp when the alarm list was last
    changed.  The value can be used by a manager to
    initiate an alarm resynchronization procedure.";
            }
    
            list alarm {
              key "resource alarm-type-id alarm-type-qualifier";
              description
                "The list of alarms.  Each entry in the list holds one
    alarm for a given alarm type and resource.  An alarm can
    be updated from the underlying resource or by the user.
    The following leafs are maintained by the resource:
    'is-cleared', 'last-change', 'perceived-severity', and
    'alarm-text'.  An operator can change 'operator-state' and
    'operator-text'.
    
    Entries appear in the alarm list the first time an alarm
    becomes active for a given alarm type and resource.
    Entries do not get deleted when the alarm is cleared.
    Clear status is represented as a boolean flag.
    
    Alarm entries are removed, i.e., purged, from the list by
    an explicit purge action.  For example, purge all alarms
    that are cleared and in closed operator state that are
    older than 24 hours.  Purged alarms are removed from the
    alarm list.  If the alarm resource state changes after a
    purge, the alarm will reappear in the alarm list.
    
    Systems may also remove alarms based on locally configured
    policies; this is out of scope for this module.";
              uses common-alarm-parameters;
    
              leaf time-created {
                type yang:date-and-time;
                mandatory true;
                description
                  "The timestamp when this alarm entry was created.  This
    represents the first time the alarm appeared; it can
    also represent that the alarm reappeared after a purge.
    Further state changes of the same alarm do not change
    this leaf; these changes will update the 'last-changed'
    leaf.";
              }
    
              uses resource-alarm-parameters;
    
              list operator-state-change {
                if-feature operator-actions;
                key "time";
                description
                  "This list is used by operators to indicate the state of
    human intervention on an alarm.  For example, if an
    operator has seen an alarm, the operator can add a new
    item to this list indicating that the alarm is
    acknowledged.";
                uses operator-parameters;
              }  // list operator-state-change
    
              action set-operator-state {
                if-feature operator-actions;
                description
                  "This is a means for the operator to indicate the level
    of human intervention on an alarm.";
                input {
                  leaf state {
                    type writable-operator-state;
                    mandatory true;
                    description
                      "Set this operator state.";
                  }
    
                  leaf text {
                    type string;
                    description
                      "Additional optional textual information.";
                  }
                }
              }  // rpc set-operator-state
    
              notification operator-action {
                if-feature operator-actions;
                description
                  "This notification is used to report that an operator
    acted upon an alarm.";
                uses operator-parameters;
              }  // notification operator-action
            }  // list alarm
    
            action purge-alarms {
              description
                "This operation requests that the server delete entries
    from the alarm list according to the supplied criteria.
    
    Typically, this operation is used to delete alarms that
    are in closed operator state and older than a specified
    time.
    
    The number of purged alarms is returned as an output
    parameter.";
              input {
                uses filter-input;
              }
    
              output {
                leaf purged-alarms {
                  type uint32;
                  description
                    "Number of purged alarms.";
                }
              }
            }  // rpc purge-alarms
    
            action compress-alarms {
              if-feature alarm-history;
              description
                "This operation requests that the server compress
    entries in the alarm list by removing all but the
    latest 'status-change' entry for all matching alarms.
    Conditions in the input are logically ANDed.  If no
    input condition is given, all alarms are compressed.";
              input {
                leaf resource {
                  type resource-match;
                  description
                    "Compress the alarms matching this resource.";
                }
    
                leaf alarm-type-id {
                  type leafref {
                    path "/alarms/alarm-list/alarm/alarm-type-id";
                    require-instance false;
                  }
                  description
                    "Compress alarms with this 'alarm-type-id'.";
                }
    
                leaf alarm-type-qualifier {
                  type leafref {
                    path "/alarms/alarm-list/alarm/alarm-type-qualifier";
                    require-instance false;
                  }
                  description
                    "Compress the alarms with this
    'alarm-type-qualifier'.";
                }
              }
    
              output {
                leaf compressed-alarms {
                  type uint32;
                  description
                    "Number of compressed alarm entries.";
                }
              }
            }  // rpc compress-alarms
          }  // container alarm-list
    
          container shelved-alarms {
            if-feature alarm-shelving;
            config false;
            description
              "The shelved alarms.  Alarms appear here if they match the
    criteria in /alarms/control/alarm-shelving.  This list does
    not generate any notifications.  The list represents alarms
    that are considered not relevant by the operator.  Alarms in
    this list have an 'operator-state' of 'shelved'.  This
    cannot be changed.";
            leaf number-of-shelved-alarms {
              type yang:gauge32;
              description
                "This object shows the total number of current
    alarms, i.e., the total number of entries
    in the alarm list.";
            }
    
            leaf shelved-alarms-last-changed {
              type yang:date-and-time;
              description
                "A timestamp when the shelved-alarm list was last changed.
    The value can be used by a manager to initiate an alarm
    resynchronization procedure.";
            }
    
            list shelved-alarm {
              key "resource alarm-type-id alarm-type-qualifier";
              description
                "The list of shelved alarms.  Shelved alarms can only be
    updated from the underlying resource; no operator actions
    are supported.";
              uses common-alarm-parameters;
    
              leaf shelf-name {
                type leafref {
                  path "/alarms/control/alarm-shelving/shelf/name";
                  require-instance false;
                }
                description
                  "The name of the shelf.";
              }
    
              uses resource-alarm-parameters;
    
              list operator-state-change {
                if-feature operator-actions;
                key "time";
                description
                  "This list is used by operators to indicate the state of
    human intervention on an alarm.  For shelved alarms, the
    system has set the list item in the list to 'shelved'.";
                uses operator-parameters;
              }  // list operator-state-change
            }  // list shelved-alarm
    
            action purge-shelved-alarms {
              description
                "This operation requests that the server delete entries from
    the shelved-alarm list according to the supplied criteria.
    In the shelved-alarm list, it makes sense to delete alarms
    that are not relevant anymore.
    
    The number of purged alarms is returned as an output
    parameter.";
              input {
                uses filter-input;
              }
    
              output {
                leaf purged-alarms {
                  type uint32;
                  description
                    "Number of purged alarms.";
                }
              }
            }  // rpc purge-shelved-alarms
    
            action compress-shelved-alarms {
              if-feature alarm-history;
              description
                "This operation requests that the server compress entries
    in the shelved-alarm list by removing all but the latest
    'status-change' entry for all matching shelved alarms.
    Conditions in the input are logically ANDed.  If no input
    condition is given, all alarms are compressed.";
              input {
                leaf resource {
                  type leafref {
                    path "/alarms/shelved-alarms/shelved-alarm/resource";
                    require-instance false;
                  }
                  description
                    "Compress the alarms with this resource.";
                }
    
                leaf alarm-type-id {
                  type leafref {
                    path "/alarms/shelved-alarms/shelved-alarm/alarm-type-id";
                    require-instance false;
                  }
                  description
                    "Compress alarms with this 'alarm-type-id'.";
                }
    
                leaf alarm-type-qualifier {
                  type leafref {
                    path "/alarms/shelved-alarms/shelved-alarm/alarm-type-qualifier";
                    require-instance false;
                  }
                  description
                    "Compress the alarms with this
    'alarm-type-qualifier'.";
                }
              }
    
              output {
                leaf compressed-alarms {
                  type uint32;
                  description
                    "Number of compressed alarm entries.";
                }
              }
            }  // rpc compress-shelved-alarms
          }  // container shelved-alarms
    
          list alarm-profile {
            if-feature alarm-profile;
            key "alarm-type-id alarm-type-qualifier-match resource";
            ordered-by user;
            description
              "This list is used to assign further information or
    configuration for each alarm type.  This module supports a
    mechanism where the client can override the system-default
    alarm severity levels.  The 'alarm-profile' is also a useful
    augmentation point for specific additions to alarm types.";
            leaf alarm-type-id {
              type alarm-type-id;
              description
                "The alarm type identifier to match.";
            }
    
            leaf alarm-type-qualifier-match {
              type string;
              description
                "An XML Schema regular expression that is used to match the
    alarm type qualifier.";
              reference
                "XML Schema Part 2: Datatypes Second Edition,
                  World Wide Web Consortium Recommendation
                  REC-xmlschema-2-20041028";
    
            }
    
            leaf resource {
              type resource-match;
              description
                "Specifies which resources to match.";
            }
    
            leaf description {
              type string;
              mandatory true;
              description
                "A description of the alarm profile.";
            }
    
            container alarm-severity-assignment-profile {
              if-feature severity-assignment;
              description
                "The client can override the system-default severity
    level.";
              reference
                "ITU-T Recommendation M.3100:
                  Generic network information model
                ITU-T Recommendation M.3160:
                  Generic, protocol-neutral management information model";
    
              leaf-list severity-level {
                type severity;
                ordered-by user;
                description
                  "Specifies the configured severity level(s) for the
    matching alarm.  If the alarm has several severity
    levels, the leaf-list shall be given in rising severity
    order.  The original M3100/M3160 ASAP function only
    allows for a one-to-one mapping between alarm type and
    severity, but since YANG module supports stateful
    alarms, the mapping must allow for several severity
    levels.
    
    Assume a high-utilization alarm type with two thresholds
    with the system-default severity levels of threshold1 =
    warning and threshold2 = minor.  Setting this leaf-list
    to (minor, major) will assign the severity levels as
    threshold1 = minor and threshold2 = major";
              }
            }  // container alarm-severity-assignment-profile
          }  // list alarm-profile
        }  // container alarms
    
        notification alarm-notification {
          description
            "This notification is used to report a state change for an
    alarm.  The same notification is used for reporting a newly
    raised alarm, a cleared alarm, or changing the text and/or
    severity of an existing alarm.";
          uses common-alarm-parameters;
    
          uses alarm-state-change-parameters;
        }  // notification alarm-notification
    
        notification alarm-inventory-changed {
          description
            "This notification is used to report that the list of possible
    alarms has changed.  This can happen when, for example, a new
    software module is installed or a new physical card is
    inserted.";
        }  // notification alarm-inventory-changed
      }  // module ietf-alarms
    

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