NMOP Working Group                                                 T. Hu
Internet-Draft                                                      CMCC
Intended status: Standards Track                        L. M. C. Murillo
Expires: 24 October 2024                                  Telefonica I+D
                                                                   Q. Wu
                                                                  Huawei
                                                                N. Davis
                                                                   Ciena
                                                                 C. Feng
                                                           22 April 2024


           A YANG Data Model for Network Incident Management
              draft-feng-nmop-network-incident-yang-03

Abstract

   A network incident refers to an unexpected interruption of a network
   service, degradation of a network service quality, or sub-health of a
   network service.  Different data sources including alarms, metrics
   and other anomaly information can be aggregated into few amount of
   network incidents by data correlation analysis and the service impact
   analysis.

   This document defines YANG Modules for the network incident lifecycle
   management.  The YANG modules are meant to provide a standard way to
   report, diagnose, and resolve network incidents for the sake of
   network service health and root cause analysis.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 24 October 2024.

Copyright Notice

   Copyright (c) 2024 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components
   extracted from this document must include Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction
   2.  Conventions and Definitions
   3.  Sample Use Cases
     3.1.  Incident-Based Trouble Tickets dispatching
     3.2.  Incident Derivation from L3VPN services Unavailability
     3.3.  Multi-layer Fault Demarcation
     3.4.  Security events Automated Noise reduction based on
           Situation awareness
   4.  Network Incident Management Architecture
     4.1.  Interworking with Alarm Management
     4.2.  Interworking with SAIN
     4.3.  Relationship with RFC8969
     4.4.  Relationship with Trace Context
   5.  Functional Interface Requirements between the Client and the
           Server
     5.1.  Incident Identification
     5.2.  Incident Diagnosis
     5.3.  Incident Resolution
   6.  Incident Data Model Concepts
     6.1.  Identifying the Incident Instance
     6.2.  The Incident Lifecycle
       6.2.1.  Incident Instance Lifecycle
       6.2.2.  Operator Incident Lifecycle
   7.  Incident Data Model Design
     7.1.  Overview
     7.2.  Incident Notifications
     7.3.  Incident Acknowledge
     7.4.  Incident Diagnose
     7.5.  Incident Resolution
   8.  Network Incident Management YANG Module
   9.  Security Considerations
   10. IANA Considerations
     10.1.  The "IETF XML" Registry
     10.2.  The "YANG Module Names" Registry
   Acknowledgments
   References
     Normative References
     Informative References
   Appendix A.  Changes between Revisions
   Contributors
   Authors' Addresses

1.  Introduction

   [RFC8969] defines a framework for Automating Service and Network
   Management with YANG to full life cycle network management.  A set of
   YANG data models have already been developed in IETF for Network
   performance monitoring and fault monitoring,e.g.,A YANG [RFC7950]
   data model for alarm management [RFC8632] defines a standard
   interface for alarm management.  A data model for Network and VPN
   Service Performance Monitoring [RFC9375] defines a standard interface
   for network performance management.  In addition, distributed tracing
   mechanism defined in [W3C-Trace-Context] can also be used to analyze
   and debug operations, such as configuration transactions, across
   multiple distributed systems.

   However these YANG data models for network maintenance are based on
   specific data source information and manage alarms and performance
   metrics data separately by different layers in various different
   management systems.  In addition, the frequency and quantity of
   alarms and performance metrics data reported to Operating Support
   System (OSS) are increased dramatically (in many cases multiple
   orders of magnitude) with the growth of service types and complexity
   and greatly overwhelm OSS platforms; with existing known dependency
   relation between fault, alarm and events at each layer (e.g.,packet
   layer or optical layer), , it is possible to compress a series of
   alarms into fewer incidents and there are many solutions in the
   market today that essentially do this to some degree.  However
   traditional solutions such as data compression are time-consuming and
   labor-intensive, usually rely on maintenance engineers' experience
   for data analysis, which result in low processing efficiency,
   inaccurate root cause identification and duplicated tickets.  In
   addition, it is also difficult to assess the impact of alarms,
   performance metrics and other anomaly data on network services
   without known relation across layer of the network topology data or
   the relation with other network topology data.

   To address these challenges, a network wide incident-centric solution
   is proposed to establish dependency relation with both network
   service and network topology at different layers , which not only can
   be used at specific layer in specific domain but also can be used to
   span across layer for multi-layer network troubleshooting.  A network
   incident refers to an unexpected interruption of a network service,
   degradation of a network service quality, or sub-health of a network
   service [TMF724A].  Different data sources including alarms, metrics
   and other anomaly information can be aggregated into few amount of
   incidents irrespective layer by correlation analysis and the service
   impact analysis.  For example, the protocols related to the interface
   fail to work properly due to Service Level Objective (SLO) violation,
   large amount of alarms may be reported to upper layer management
   system and aggregated into one or a few incidents when some network
   services may be affected by this incident (e.g.  L3VPN services
   related with the interface will become unavailable
   [I-D.ietf-ippm-pam] ).  An incident may also be raised through the
   analysis of some network performance metrics, for example, as
   described in SAIN [RFC9417] , network services can be decomposed to
   several sub-services, specific metrics are monitored for each sub-
   service, symptoms will occur if services/sub-services are unhealthy
   (after analyzing metrics), these symptoms may raise one incident when
   it causes degradation of the network services.

   In addition, Artificial Intelligence (AI) and Machine Learning (ML)
   play a important role in the processing of large amounts of data with
   complex data correlations.  For example, Neural Network Algorithm or
   Hierarchy Aggregation Algorithm can be used to replace manual alarm
   data correlation.  Through online and offline learning, these
   algorithms can be continuously optimized to improve the efficiency of
   fault diagnosis.

   This document defines a YANG data model for network incident
   lifecycle management, which improves troubleshooting efficiency,
   ensures network service quality, and improves network automation
   [RFC8969].

2.  Conventions and Definitions

   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 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

   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 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

   The following terms are defined in [RFC8632] and are not redefined
   here:

   *  alarm

   The following terms are defined in this document:

   Network Incident: An unexpected interruption of a network service,
   degradation of network service quality, or sub-health of a network
   service [TMF724A].

   Problem: The cause of one or more incidents.  The cause is not
   usually known when a problem record is created, and the problem
   management process is responsible for further investigation
   [TMF724A].

   Incident management: Lifecycle management of incidents including
   incident identification, reporting, acknowledge, diagnosis, and
   resolution.

   Incident management system: An entity which implements incident
   management.  It include incident management server and incident
   management client.

   Incident management server: An entity which provides some functions
   of incident management.  For example, it can detect an incident,
   perform incident diagnosis, resolution and prediction,etc.

   Incident management client: An entity which can manage incidents.
   For example, it can receive incident notifications, query the
   information of incidents, instruct the incident management server to
   diagnose, resolve, etc.

3.  Sample Use Cases

3.1.  Incident-Based Trouble Tickets dispatching

   Traditionally, the dispatching of trouble tickets is mostly based on
   alarms data analysis and need to involve operators' maintenance
   engineers.  These operators' maintenance engineers are able to
   monitor and detect that alarms at both end devices of specific
   network tunnel or at both optical layer and IP layer which are
   associated with the same network fault.  Therefore, they can
   correlate these alarms to the same trouble ticket, which is in the
   low automation.  If there are more alarms, then the human costs for
   network maintenance are increased accordingly.

   Some operators preconfigure whitelist and adopt some coarse
   granularity data correlation rules for the alarm management.  It
   seems to improve fault management automation.  However, some trouble
   tickets could be missed if the filtering conditions are too strict.
   If the filtering conditions are not strict, it might end up with
   multiple trouble tickets being dispatched to the same network fault.

   It is hard to achieve a perfect balance between the network
   management automation and duplicated trouble tickets under the
   traditional working situations.  However, with the help of the
   network incident management, massive alarms can be aggregated into a
   few network incidents based on service impact analysis, the number of
   trouble tickets will be greatly reduced.  At the same time, the
   efficiency of network troubleshooting can be largely improved. which
   address the pain point of traditional trouble ticket dispatching.

3.2.  Incident Derivation from L3VPN services Unavailability

   The service attachment points defined in [RFC9408] represent the
   network reference points where network services can be delivered to
   customers.

   SLOs can be used to characterize the ability of a particular set of
   nodes to communicate according to certain measurable expectations
   [I-D.ietf-ippm-pam].  For example, an SLA might state that any given
   SLO applies to at least a certain percentage of packets, allowing for
   a certain level of packet loss and exceeding packet delay threshold
   to take place.  An SLA might establish a multi-tiered SLO of end to
   end latency as follows:

   *  not to exceed 30 ms for any packet;

   *  not to exceed 25 ms for 99.999% of packets;

   *  not to exceed 20 ms for 99% of packets.

   This SLA information can be bound with two or multiple service
   attachment point defined in [RFC9408], so that the service
   orchestration layer can use these interfaces to commit the delivery
   of a service on specific point to point service topology or point to
   multi-point topology.  Upon specific levels of a threshold of an SLO
   is violated, a specific network incident, associated with,let's say
   L3VPN service will be derived.

3.3.  Multi-layer Fault Demarcation

   When a fault occurs in a network that contains both packet-layer
   devices and optical-layer devices, it may cause correlative faults in
   both layers, i.e., packet layer and optical layer.  Specifically,
   fault propagation could be classified into three typical types.
   First, fault occurs at a packet-layer device will further cause fault
   (e.g.,WDM (wavelength division multiplexing) client fault) at an
   optical-layer device.  Second, fault occurs at an optical-layer
   device will further cause fault (e.g., L3 link down) at a packet-
   layer device.  Third, fault occurs at the inter-layer link between a

   packet-layer device and an optical-layer device will further cause
   faults at both devices.  Traditionally, multiple operation teams are
   needed to first analyze huge amount of alarms (triggered by the above
   mentioned faults) from single network layer independently, then
   cooperate to locate the root cause through manually analyzing multi-
   layer topology data and service data, thus fault demarcation becomes
   more complex and time-consuming in multi-layer scenario than in
   single-layer scenario.

   With the help of network incident management, the management systems
   first automatically analyze root cause of the alarms at each single
   network layer and report corresponding incidents to the upper layer,
   then multi-layer management system comprehensively analyzes the
   topology relationship and service relationship between the root
   causes of both layers.  The inner relationship among the alarms will
   be identified and finally the root cause will be located among
   multiple layers.  By cooperating with the integrated Optical time-
   domain reflectometer (OTDR) within the network device, we can
   determine the target optical exchange station before site visits.
   Therefore, the overall fault demarcation process is simplified and
   automated, the analyze result could be reported and visualized in
   time.  In this case, operation teams only have to confirm the analyze
   result and dispatch site engineers to perform relative maintenance
   actions (e.g., splice fiber) based on the root cause.

3.4.  Security events Automated Noise reduction based on Situation
      awareness

   In the continuous data driven monitoring, tools used by the Security
   Operation Center (SoC) scan the network 24/7 to flag any
   abnormalities or suspicious activities.  As the SoC adds more tools
   for security events detection, the volume of security events or
   alerts grows continually. the overwhelming number of threat alerts
   can cause threat fatigue.  In addition, many of these alerts do not
   provide sufficient intelligence, context to investigate, or are false
   positives.  False positives not only drain time and resources, but
   can also distract teams from real incidents.

   With the help of the network incident management, BERT(Bidirectional
   Encoder Representations from Transformers) [BERT] classifier can be
   adopted to analyses the suspicious activity and understands the
   significance of the gathered data (through both facts and inferences)
   and help operation and maintenance engineers focus on handling
   important security events and avoid wasting resources on false
   alerts, e.g., automatically determine whether 10,000 network security
   events are real incidents and give reasonable explanations.
   Progressively, Llama interpreter can be used to explain the reason
   why such alerts are picked out and marked significant, what could be
   the potential security implications that exist yet remain
   undiscovered.

4.  Network Incident Management Architecture

              +----------------------+-------------------+
              |                                          |
              |         Incident Management Client       |
              |                                          |
              |                                          |
              +------------+---------+---------+---------+
                 ^         |         |         |
                 |Incident |Incident |Incident |Incident
                 |Report   |Ack      |Diagnose |Resolve
                 |         |         |         |
                 |         V         V         V
              +--+-------------------+---------+----------+
              |                                           |
              |                                           |
              |        Incident Management Server         |
              |                                           |
              |                                           |
              |                                           |
              |                                           |
              +-------------------------------+-----------+
                    ^       ^Abnormal         ^
                    |Alarm  |Operations       |Metrics
                    |Report |Report           |/Telemetry
                    |       |                 V
         +----------+-------+-----------------+------------------+
         |                                                       |
         |                     Network                           |
         |                                                       |
         +------------------------------------+------------------+

             Figure 1: Network Incident Management Architecture

   Figure 1 illustrates the network incident management architecture.
   Two key components for the incident management are incident
   management client and incident management server.

   Incident management server can be deployed in network analytics
   platform, controllers and provides functionalities such as incident
   identification, report, diagnosis, resolution, querying for incident
   lifecycle management.

   Incident management client can be deployed in the network OSS or
   other business systems of operators and invokes the functionalities
   provided by incident management server to meet the business
   requirements of fault management.

   A typical workflow of network incident management is as follows:

   *  Some alarms or abnormal operations, network performance metrics
      are reported from the network.  Incident management server
      receives these alarms/abnormal operations/metrics and try to
      analyze the correlation of them, if the incidents are identified,
      it will be reported to the client.  The impact of network services
      will be also analyzed and will update the incident.

   *  Incident management client receives the incident raised by server,
      and acknowledge it.  Client may invoke the "incident diagnose" rpc
      to diagnose this incident to find the root causes.

   *  If the root causes have been found, the client can resolve this
      incident by invoking the 'incident resolve' rpc operation,
      dispatching a ticket or using other functions (e.g. routing
      calculation,configuration)

4.1.  Interworking with Alarm Management

                        +-----------------------------+
                        |         OSS                 |
                        |+-------+      +-----------+ |
                        ||alarm  |      | incident  | |
                        ||handler|      |  client   | |
                        |+-------+      +-----------+ |
                        +---^---------------^---------+
                            |               |
                            |alarm          |incident
                        +---|---------------|---------+
                        |   |  controller   |         |
                        |   |               |         |
                        |+--+---++      +-----------+ |
                        ||alarm  |      |           | |
                        ||process+----->|  incident | |
                        ||       |alarm |   server  | |
                        |+------++      +-----------+ |
                        |   ^              ^          |
                        +---+--------------|----------+
                            |alarm         | metrics/trace/etc.
                            |              |
                        +---+--------------+----------+
                        |         network             |
                        |                             |
                        +-----------------------------+

                Figure 2: Interworking with alarm management

   YANG model for the alarm management [RFC8632] defines a standard
   interface to manage the lifecycle of alarms.  Alarms represent the
   undesirable state of network resources, alarm data model also defines
   the root causes and impacted services fields, but there may lack
   sufficient information to determine them in lower layer system
   (mainly in devices level), so alarms do not always tell the status of
   services or the root causes.  As described in [RFC8632], alarm
   management act as a starting point for high-level fault management.
   While incident management often works at the network level, so it's
   possible to have enough information to perform correlation and
   service impact analysis.  Alarms can work as one of data sources of
   incident management and may be aggregated into few amount of
   incidents by correlation analysis, network service impact and root
   causes may be determined during incident process.

   Incident also contains some related alarms,if needed users can query
   the information of alarms by alarm management interface [RFC8632].
   In some cases, e.g. cutover scenario, incident server may use alarm
   management interface [RFC8632] to shelve some alarms.

   Alarm management may keep the original process, alarms are reported
   from network to network controller or analytics and then reported to
   upper layer system(e.g.  OSS).  Upper layer system may store these
   alarms and provide the information for fault analysis (e.g. deeper
   analysis based on incident).

   Compared with alarm management, incident management provides not only
   incident reporting but also diagnosis and resolution functions, it's
   possible to support self-healing and may be helpful for single-domain
   closed-loop control.

   Incident management is not a substitute for alarm management.
   Instead, they can work together to implement fault management.

4.2.  Interworking with SAIN

                               +----------------+
                               | incident client|
                               +----------------+
                                       ^
                                       |incident
                               +-------+--------+
                               |incident server |
                               +----------------+
                                       ^
                                       |symptoms
                               +-------+--------+
                               |     SAIN       |
                               |                |
                               +----------------+
                                       ^
                                       |metrics
                         +-------------+-------------+
                         |                           |
                         |         network           |
                         |                           |
                         +---------------------------+

                      Figure 3: Interworking with SAIN

   SAIN [RFC9417] defines the architecture of network service assurance.
   A network service can be decomposed into some sub-services, and some
   metrics can be monitored for sub-services.  For example, a tunnel
   service can be decomposed into some peer tunnel interface sub-
   services and IP connectivity sub-service.  If some metrics are
   evaluated to indicate unhealthy for specific sub-service, some
   symptoms will be present.  Incident server may identify the incident
   based on symptoms, and then report it to upper layer system.  So,
   SAIN can be one way to identify incident, services, sub-services and
   metrics can be preconfigured via APIs defined by service assurance
   YANG model [RFC9418] and incident will be reported if symptoms match
   the condition of incident.

4.3.  Relationship with RFC8969

   [RFC8969] defines a framework for network automation using YANG, this
   framework breaks down YANG modules into three layers, service layer,
   network layer and device layer, and contains service deployment,
   service optimization/assurance, and service diagnosis.  Incident
   works at the network layer and aggregates alarms, metrics and other
   information from device layer, it's helpful to provfide service
   assurance.  And the incident diagnosis may be one way of service
   diagnosis.

4.4.  Relationship with Trace Context

   W3C defines a common trace context [W3C-Trace-Context] for
   distributed system tracing,
   [I-D.rogaglia-netconf-trace-ctx-extension] defines a netconf
   extension for [W3C-Trace-Context] and
   [I-D.quilbeuf-opsawg-configuration-tracing] defines a mechanism for
   configuration tracing.  If some errors occur when services are
   deploying, it's very easy to identify these errors by distributed
   system tracing, and an incident should be reported.

5.  Functional Interface Requirements between the Client and the Server

5.1.  Incident Identification

                                +--------------+
                             +--|  Incident1   |
                             |  +--+-----------+
                             |     |  +-----------+
                             |     +--+  alarm1   |
                             |     |  +-----------+
                             |     |
                             |     |  +-----------+
                             |     +--+  alarm2   |
                             |     |  +-----------+
                             |     |
                             |     |  +-----------+
                             |     +--+  alarm3   |
                             |        +-----------+
                             |  +--------------+
                             +--|  Incident2   |
                             |  +--+-----------+
                             |     |  +-----------+
                             |     +--+  metric1  |
                             |     |  +-----------+
                             |     |  +-----------+
                             |     +--+  metric2  |
                             |        +-----------+
                             |
                             |  +--------------+
                             +--|  Incident3   |
                                    +--+-----------+
                                       |  +-----------+
                                       +--+ alarm1    |
                                       |  +-----------+
                                       |
                                       |  +-----------+
                                       +--| metric1   |
                                          +-----------+

                     Figure 4: Incident Identification

   As described in Figure 4, multiple alarms, metrics, or hybrid can be
   aggregated into an incident after analysis.

   The network incident management server MUST be capable of identifying
   incidents.  Multiple alarms, metrics and other information are
   reported to incident server, and the server must analyze it and find
   out the correlations of them, if the correlation match the incident
   rules, incident will be identified and reported to the client.
   Service impact analysis will be performed if an indent is identified,
   and the content of incident will be updated if impacted network
   services are detected.

   AI/ML may be used to identify the incident.  Expert system and online
   learning can help AI to identify the correlation of alarms, metrics
   and other information by time-base correlation algorithm, topo-based
   correlation algorithm, etc.  For example, if interface is down, then
   many protocol alarms will be reported, AI will think these alarms
   have some correlations.  These correlations will be put into
   knowledge base, and the incident will be identified faster according
   to knowledge base next time.

   As mentioned above, SAIN is another way to implement incident
   identification.  Observation timestamp defined in
   [I-D.tgraf-yang-push-observation-time] and trace context defined in
   [W3C-Trace-Context] may be helpful for incident identification.

                    +----------------------+
                    |                      |
                    |     Orchestrator     |
                    |                      |
                    +----+-----------------+
                         ^VPN A Unavailable
                         |
                     +---+----------------+
                     |                    |
                     |     Controller     |
                     |                    |
                     |                    |
                     +-+-+-+----------+---+
                       ^ ^            ^
                   IGP | |Interface   |IGP Peer
                  Down | |Down        | Abnormal
                       | |            |
           VPN A       | |            |
           +-----------+-+------------+------------------------+
           | \  +---+       ++-++         +-+-+        +---+  /|
           |  \ |   |       |   |         |   |        |   | / |
           |   \|PE1+-------| P1+X--------|P2 +--------|PE2|/  |
           |    +---+       +---+         +---+        +---+   |
           +---------------------------------------------------+

               Figure 5: Example 1 of Incident Identification

   As described in Figure 5, vpn a is deployed from PE1 to PE2, if a
   interface of P1 is going down, many alarms are triggered, such as
   interface down, igp down, and igp peer abnormal from P2.

   These alarms are aggregated and analyzed by the controller/incident
   management server, and then the incident 'vpn unavailable' is
   triggered by the controller/incident management server.

   Note that incident management server can rely on data correlation
   technology such as service impact analysis and data analytic
   component to evaluate the real effect on the relevant service and
   understand whether lower level or device level network anomaly, e.g.,
   igp down, has impact on the service.

                          +----------------------+
                          |                      |
                          |     Orchestrator     |
                          |                      |
                          +----+-----------------+
                                   ^VPN A Degradation
                                   |
                           +---+----------------+
                           |                    |
                           |     controller     |
                           |                    |
                           |                    |
                           +--+------------+----+
                              ^            ^
                              |Packet      |Path Delay
                              |Loss        |
                              |            |
          VPN A               |            |
          +-------------------+------------+-------------------+
          | \  +---+       ++-++         +-+-+        +---+  / |
          |  \ |   |       |   |         |   |        |   | /  |
          |   \|PE1+-------|P1 +---------|P2 +--------|PE2|/   |
          |    +---+       +---+         +---+        +---+    |
          +----------------------------------------------------+

               Figure 6: Example 2 of Incident Identification

   As described in Figure 6, controller collect the network metrics from
   network elements, it finds the packet loss of P1 and the path delay
   of P2 exceed the thresholds, an incident 'VPN A degradation' may be
   triggered after service impact analysis.

5.2.  Incident Diagnosis

   After an incident is reported to the network incident management
   client, the client MAY diagnose the incident to determine the root
   cause.  Some diagnosis operations may affect the running network
   services.  The client can choose not to perform that diagnosis
   operation after determining the impact is not trivial.  The network
   incident management server can also perform self-diagnosis.  However,
   the self-diagnosis MUST not affect the running network services.
   Possible diagnosis methods include link reachability detection, link
   quality detection, alarm/log analysis, and short-term fine-grained
   monitoring of network quality metrics, etc.

5.3.  Incident Resolution

   After the root cause is diagnosed, the client MAY resolve the
   incident.  The client MAY choose resolve the incident by invoking
   other functions, such as routing calculation function, configuration
   function, dispatching a ticket or asking the server to resolve it.
   Generally, the client would attempt to directly resolve the root
   cause.  If the root cause cannot be resolved, an alternative solution
   SHOULD be required.  For example, if an incident caused by a physical
   component failure, it cannot be automatically resolved, the standby
   link can be used to bypass the faulty component.

   Incident server will monitor the status of incident, if the faults
   are fixed, the server will update the status of incident to
   'cleared', and report the updated incident to the client.

   Incident resolution may affect the running network services.  The
   client can choose not to perform those operations after determining
   the impact is not trivial.

6.  Incident Data Model Concepts

6.1.  Identifying the Incident Instance

   An incident ID is used as an identifier of an incident instance, if
   an incident instance is identified, a new incident ID is created.
   The incident ID MUST be unique in the whole system.

6.2.  The Incident Lifecycle

6.2.1.  Incident Instance Lifecycle

   From an incident instance perspective, an incident can have the
   following lifecycle: 'raised', 'updated', 'cleared'.  When an
   incident is generated, the status is 'raised'.  If the status changes
   after the incident is generated, (for example, self-diagnosis,
   diagnosis command issued by the client, or any other condition causes
   the status to change but does not reach the 'cleared' level.) , the
   status changes to 'updated'.  When an incident is successfully
   resolved, the status changes to 'cleared'.

6.2.2.  Operator Incident Lifecycle

   From an operator perspective, the lifecycle of an incident instance
   includes 'acknowledged', 'diagnosed', and 'resolved'.  When an
   incident instance is generated, the operator SHOULD acknowledge the
   incident.  And then the operator attempts to diagnose the incident
   (for example, find out the root cause and affected components).
   Diagnosis is not mandatory.  If the root cause and affected
   components are known when the incident is generated, diagnosis is not
   required.  After locating the root cause and affected components,
   operator can try to resolve the incident.

7.  Incident Data Model Design

7.1.  Overview

   There are two YANG modules in the model.  The first module, "ietf-
   incident-type", provides common definitions such as incident domain,
   incident category, incident priority.  The second module, "ietf-
   incident", defines technology independent abstraction of network
   incident construct for alarm, log, performance metrics, etc.  The
   information reported in the incident include Root cause,
   priority,impact, suggestion, etc.  At the top of "ietf-incident"
   module is the Network Incident.  Network incident is represented as a
   list and indexed by "incident-id".  Each Network Incident is
   associated with a service instance, domain and sources.  Under
   sources, there is one or more sources.  Each source corresponds to
   node defined in the network topology model and network resource in
   the network device,e.g., interface.  In addition, "ietf-incident"
   support one general notification to report incident state changes and
   three rpcs to manage the network incidents.

 module: ietf-incident
 +--ro incidents
    +--ro incident* [incident-id]
           +--ro incident-id string
           +--ro csn? uint64
           +--ro service-instance* string
           +--ro name? string
           +--ro type? enumeration
           +--ro domain? identityref
           +--ro priority? int:incident-priority
           +--ro status? enumeration
           +--ro ack-status? enumeration
           +--ro category? identityref
           +--ro detail? string
           +--ro resolve-advice? string
           +--ro sources
           ...
           +--ro root-causes
           ...
           +--ro root-events
           ...
           +--ro events
           ...
           +--ro raise-time? yang:date-and-time
           +--ro occur-time? yang:date-and-time
           +--ro clear-time? yang:date-and-time
           +--ro ack-time? yang:date-and-time
           +--ro last-updated? yang:date-and-time
 rpcs:
   +---x incident-acknowledge
   ...
   +---x incident-diagnose
   ...
   +---x incident-resolve

 notifications:
   +---n incident-notification
          +--ro incident-id?
                          -> /inc:incidents/inc:incident/inc:incident-id
          ...
          +--ro time? yang:date-and-time

7.2.  Incident Notifications

 notifications:
   +---n incident-notification
          +--ro incident-id?
                          -> /inc:incidents/inc:incident/inc:incident-id
          +--ro csn? uint64
          +--ro service-instance* string
          +--ro name? string
          +--ro type? enumeration
          +--ro domain? identityref
          +--ro priority? int:incident-priority
          +--ro status? enumeration
          +--ro ack-status? enumeration
          +--ro category? identityref
          +--ro detail? string
          +--ro resolve-advice? string
          +--ro sources
          |  +--ro source* [node-ref]
          |     +--ro node-ref  leafref
          |     +--ro network-ref?  -> /nw:networks/network/network-id
          |     +--ro resource* [name]
          |        +--ro name al:resource
          +--ro root-causes
          |  +--ro root-cause* [node-ref]
          |     +--ro node-ref  leafref
          |     +--ro network-ref?  -> /nw:networks/network/network-id
          |     +--ro resource* [name]
          |     |  +--ro name al:resource
          |     |  +--ro cause-name? string
          |     |  +--ro detail? string
          |     +--ro cause-name? string
          |     +--ro detail? string
          +--ro root-events
          |  +--ro root-event* [type event-id]
          |     +--ro type -> ../../../events/event/type
          |     +--ro event-id leafref
          +--ro events
          |  +--ro event* [type event-id]
          |     +--ro type enumeration
          |     +--ro event-id string
          |     +--ro (event-type-info)?
          |        +--:(alarm)
          |        |  +--ro alarm
          |        |     +--ro resource? leafref
          |        |     +--ro alarm-type-id? leafref
          |        |     +--ro alarm-type-qualifier? leafref
          |        +--:(notification)
          |        +--:(log)
          |        +--:(KPI)
          |        +--:(unknown)
          +--ro time? yang:date-and-time

   A general notification, incident-notification, is provided here.
   When an incident instance is identified, the notification will be
   sent.  After a notification is generated, if the network incident
   management server performs self diagnosis or the client uses the
   interfaces provided by the network incident management server to
   deliver diagnosis and resolution actions, the notification update
   behavior is triggered, for example, the root cause objects and
   affected objects are updated.  When an incident is successfully
   resolved, the status of the incident would be set to 'cleared'.

7.3.  Incident Acknowledge

   +---x incident-acknowledge
   |  +---w input
   |  |  +---w incident-id*
   |  |          -> /inc:incidents/inc:incident/inc:incident-id

   After an incident is generated, updated, or cleared, (In some
   scenarios where automatic diagnosis and resolution are supported, the
   status of an incident may be updated multiple times or even
   automatically resolved.)  The operator needs to confirm the incident
   to ensure that the client knows the incident.

   The incident-acknowledge rpc can confirm multiple incidents at a time

7.4.  Incident Diagnose

   +---x incident-diagnose
   |  +---w input
   |  |  +---w incident-id*
   |  |          -> /inc:incidents/inc:incident/inc:incident-id

   After an incident is generated, incident diagnose rpc can be used to
   diagnose the incident and locate the root causes.  Diagnosis can be
   performed on some detection tasks, such as BFD detection, flow
   detection, telemetry collection, short-term threshold alarm,
   configuration error check, or test packet injection.

   After the diagnosis is performed, a incident update notification will
   be triggered to report the latest status of the incident.

7.5.  Incident Resolution

   +---x incident-resolve
    +---w input
    |  +---w incident-id*
    |          -> /inc:incidents/inc:incident/inc:incident-id

   After the root causes and impacts are determined, incident-resolve
   rpc can be used to resolve the incident (if the server can resolve
   it).  How to resolve an incident instance is out of the scope of this
   document.

   Incident resolve rpc allows multiple incident instances to be
   resolved at a time.  If an incident instance is successfully
   resolved, a notification will be triggered to update the incident
   status to 'cleared'.  If the incident content is changed during this
   process, a notification update will be triggered.

8.  Network Incident Management YANG Module

   This module imports types defined in [RFC6991], [RFC8345], [RFC8632].

   <CODE BEGINS> file "ietf-incident@2024-03-02.yang"
   module ietf-incident {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-incident";
     prefix inc;
     import ietf-yang-types {
       prefix yang;
       reference
         "RFC 6991: Common YANG Data Types";
     }

     import ietf-alarms {
       prefix al;
       reference
         "RFC 8632: A YANG Data Model for Alarm Management";
     }

     import ietf-network {
     prefix nw;
     reference
           "RFC 8345: A YANG Data Model for Network Topologies";
     }

     organization
       "IETF OPSAWG Working Group";
     contact
       "WG Web:   <https://datatracker.ietf.org/wg/opsawg/>;
        WG List:  <mailto:opsawg@ietf.org>
        Author:   Chong Feng  <mailto:frank.fengchong@huawei.com>
        Author:   Tong Hu  <mailto:hutong@cmhi.chinamobile.com>
        Author:   Luis Miguel Contreras Murillo <mailto:
                  luismiguel.contrerasmurillo@telefonica.com>
        Author :  Qin Wu   <mailto:bill.wu@huawei.com>
        Author:   Chaode Yu   <mailto:yuchaode@huawei.com>
        Author:   Nigel Davis   <mailto:ndavis@ciena.com>";

    description
       "This module defines the interfaces for incident management
        lifecycle.

        This module is intended for the following use cases:
        * incident lifecycle management:
          - incident report: report incident instance to client
                             when an incident instance is detected.
          - incident acknowledge: acknowledge an incident instance.
          - incident diagnose: diagnose an incident instance.
          - incident resolve: resolve an incident instance.

        Copyright (c) 2024 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 Revised 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 XXXX
        (https://www.rfc-editor.org/info/rfcXXXX); ; see the RFC
        itself for full legal notices.

        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. ";

     revision 2024-03-02 {
       description "Merge incident yang with incident type yang
       and fix broken ref.";
       reference "RFC XXX: YANG module for network incident management.";
     }

       //identities
     identity incident-domain {
       description "The abstract identity to indicate the domain of
                    an incident.";
     }
     identity single-domain {
       base incident-domain;
       description "single domain.";
     }
     identity access {
       base single-domain;
       description "access domain.";
     }
     identity ran {
       base access;
       description "radio access network domain.";
     }
     identity transport {
       base single-domain;
       description "transport domain.";
     }
     identity otn {
       base transport;
       description "optical transport network domain.";
     }
     identity ip {
       base single-domain;
       description "ip domain.";
     }
     identity ptn {
       base ip;
       description "packet transport network domain.";
     }

     identity cross-domain {
       base incident-domain;
       description "cross domain.";
     }
     identity incident-category {
       description "The abstract identity for incident category.";
     }
     identity device {
       base incident-category;
       description "device category.";
     }
     identity power-environment {
       base device;
       description "power environment category.";
     }
     identity device-hardware {
       base device;
       description "hardware of device category.";
     }
     identity device-software {
       base device;
       description "software of device category";
     }
     identity line {
       base device-hardware;
       description "line card category.";
     }
     identity maintenance {
       base incident-category;
       description "maintenance category.";
     }
     identity network {
       base incident-category;
       description "network category.";
     }
     identity protocol {
       base incident-category;
       description "protocol category.";
     }
     identity overlay {
       base incident-category;
       description "overlay category";
     }
     identity vm {
       base incident-category;
       description "vm category.";
     }
     identity event-type {
           description "The abstract identity for Event type";
     }
     identity alarm {
           base event-type;
           description "alarm event type.";
     }
     identity notif {
           base event-type;
           description "Notification event type.";
     }
     identity log {
           base event-type;
           description "Log event type.";
     }
     identity KPI {
           base event-type;
           description "KPI event type.";
     }
     identity unknown {
           base event-type;
           description "Unknown event type.";
     }
     identity incident-class {
           description "The abstract identity for Incident category.";
     }
     identity problem {
           base incident-class;
           description
             "It indicates the class of the incident is a problem
             (i.e.,cause of the incident) for example an interface
             fails to work.";
     }
     identity sla-violation {
           base incident-class;
           description
             "It indicates the class of the incident is a sla
             violation, for example high CPU rate may cause
             a fault in the future.";
     }
     //typedefs
     typedef incident-priority {
       type enumeration {
         enum critical {
           description "the incident MUST be handled immediately.";
         }
         enum high {
           description "the incident should be handled as soon as
                        possible.";
         }
         enum medium {
           description "network services are not affected, or the
                        services are slightly affected,but corrective
                        measures need to be taken.";
         }
         enum low {
           description "potential or imminent service-affecting
                        incidents are detected,but services are
                        not affected currently.";
         }
       }
       description "define the priority of incident.";
     }

     typedef incident-ref {
           type leafref {
             path "/inc:incidents/inc:incident/inc:incident-id";
           }
       description "reference a network incident.";
     }

     //groupings
     grouping root-cause-info {
           description "The information of root cause.";
           leaf cause-name {
         type string;
             description "the name of cause";
           }
           leaf detail {
         type string;
             description "the detail information of the cause.";
           }
     }
     grouping resources-info {
       description "the grouping which defines the network
                    resources of a node.";
       uses nw:node-ref;
       list resource {
         key name;
         description "the resources of a network node.";
         leaf name {
            type al:resource;
            description "network resource name.";
         }
       }
     }

     grouping incident-time-info {
       description "the grouping defines incident time information.";
       leaf raise-time {
         type yang:date-and-time;
         description "the time when an incident instance is raised.";
       }
       leaf occur-time {
         type yang:date-and-time;
         description "the time when an incident instance occurs.
                      It's the occur time of the first event during
                      incident detection.";
       }
       leaf clear-time {
         type yang:date-and-time;
         description "the time when an incident instance is
                      resolved.";
       }
       leaf ack-time {
         type yang:date-and-time;
         description "the time when an incident instance is
                      acknowledged.";
       }
       leaf last-updated {
         type yang:date-and-time;
         description "the latest time when an incident instance is
                      updated";
       }
     }

     grouping incident-info {
       description "the grouping defines the information of an
                    incident.";
       leaf incident-no {
         type uint64;
         mandatory true;
         description "The unique identifier of the incident instance.";
       }
       leaf-list service-instance {
         type string;
         description "the related network service instances of
                      the incident instance.";
       }
       leaf name {
         type string;
         mandatory true;
         description "the name of an incident.";
       }
       leaf type {
         type identityref {
         base incident-class;
         }
       mandatory true;
         description "The type of an incident.";
       }
       leaf domain {
         type identityref {
           base incident-domain;
         }
         mandatory true;
         description "the domain of an incident.";
       }
       leaf priority {
         type incident-priority;
         mandatory true;
         description "the priority of an incident instance.";
       }

       leaf status {
         type enumeration {
           enum raised {
             description "an incident instance is raised.";
           }
           enum updated {
             description "the information of an incident instance
                          is updated.";
           }
           enum cleared {
             description "an incident is cleared.";
           }
         }
         default raised;
         description "The status of an incident instance.";
       }
       leaf ack-status {
         type enumeration {
           enum acknowledged {
             description "The incident has been acknowledged by user.";
           }
           enum unacknowledged {
             description "The incident hasn't been acknowledged.";
           }
         }
         default unacknowledged;
         description "the acknowledge status of an incident.";
       }
       leaf category {
         type identityref {
           base incident-category;
         }
         mandatory true;
         description "The category of an incident.";
       }
       leaf detail {
         type string;
         description "detail information of this incident.";
       }
       leaf resolve-advice {
         type string;
         description "The advice to resolve this incident.";
       }
       container sources {
         description "The source components.";
         list source {
           key node-ref;
           uses resources-info;
           min-elements 1;
           description "The source components of incident.";
         }
       }

       container root-causes{
         description "The root cause objects.";
         list root-cause {
           key node-ref;
           description "the root causes of incident.";
           uses resources-info {
             augment resource {
               description "augment root cause information.";
               //if root cause object is a resource of a node
               uses root-cause-info;
             }
           }
           //if root cause object is a node
           uses root-cause-info;
         }
       }
       container root-events {
         description "the root events of the incident.";
         list root-event {
           key "type event-id";
           description "the root event of the incident.";
           leaf type {
             type leafref {
               path "../../../events/event/type";
             }
             description "the event type.";
           }
           leaf event-id {
             type leafref {
               path "../../../events/event[type = current()/../type]"
                   +"/event-id";
             }
             description "the event identifier, such as uuid,
                          sequence number, etc.";
           }
         }
       }
       container events {
         description "related events.";
         list event {
           key "type event-id";
           description "related events.";
           leaf type {
             type identityref {
                     base event-type;
                     }
             description "event type.";
           }
           leaf event-id {
             type string;
             description "the event identifier, such as uuid,
                          sequence number, etc.";
           }
           choice event-type-info {
             description "event type information.";
             case alarm {
               when "derived-from-or-self(type, 'alarm')" {
               description
               "Only applies when type is alarm.";
               }
               container alarm {
                 description "alarm type event.";
                 leaf resource {
                   type leafref {
                     path "/al:alarms/al:alarm-list/al:alarm"
                         +"/al:resource";
                   }
                   description "network resource.";
                   reference "RFC 8632: A YANG Data Model for Alarm
                              Management";
                 }
                 leaf alarm-type-id {
                   type leafref {
                     path "/al:alarms/al:alarm-list/al:alarm"
                         +"[al:resource = current()/../resource]"
                         +"/al:alarm-type-id";
                   }
                   description "alarm type id";
                   reference "RFC 8632: A YANG Data Model for Alarm
                               Management";
                 }
                 leaf alarm-type-qualifier {
                   type leafref {
                     path "/al:alarms/al:alarm-list/al:alarm"
                         +"[al:resource = current()/../resource]"
                         +"[al:alarm-type-id = current()/.."
                         +"/alarm-type-id]/al:alarm-type-qualifier";
                   }
                   description "alarm type qualitifier";
                   reference "RFC 8632: A YANG Data Model for Alarm
                              Management";
                 }
               }
             }
             case notification {
               //TODO
             }
             case log {
             //TODO
             }
             case KPI {
             //TODO
             }
             case unknown {
             //TODO
             }
           }
         }

       }

     }

     //data definitions
     container incidents {
       config false;
       description "the information of incidents.";
       list incident {
         key incident-no;
         description "the information of incident.";
         leaf incident-id {
           type string;
           description "the qualifier of an incident instance type.";
         }
         uses incident-info;
         uses incident-time-info;
       }
     }

     // notifications
     notification incident-notification {
       description "incident notification. It will be triggered when
                    the incident is raised, updated or cleared.";
       leaf incident-id {
             type incident-ref;
         description "the identifier of an incident instance.";
       }
       uses incident-info;
       leaf time {
         type yang:date-and-time;
         description "occur time of an incident instance.";
       }
     }
     // rpcs
     rpc incident-acknowledge {
       description "This rpc can be used to acknowledge the specified
                    incidents.";
       input {
         leaf-list incident-id {
           type incident-ref;
           description "the identifier of an incident instance.";
         }
       }
     }
     rpc incident-diagnose {
       description "This rpc can be used to diagnose the specified
                    incidents. The result of diagnosis will be reported
                    by incident notification.";
       input {
         leaf-list incident-id {
           type incident-ref;
           description
             "the identifier of an incident instance.";
         }
       }
     }

     rpc incident-resolve {
       description "This rpc can be used to resolve the specified
                    incidents. The result of resolution will be reported
                    by incident notification.";
       input {
         leaf-list incident-id {
           type incident-ref;
           description
             "the identifier of an incident instance.";
         }
       }
     }
   }
   <CODE ENDS>

9.  Security Considerations

   The YANG modules specified in this document define a schema for data
   that is designed to be accessed via network management protocol such
   as NETCONF [RFC6241] or RESTCONF [RFC8040].  The lowest NETCONF layer
   is the secure transport layer, and the mandatory-to-implement secure
   transport is Secure Shell (SSH) [RFC6242].  The lowest RESTCONF layer
   is HTTPS, and the mandatory-to-implement secure transport is TLS
   [RFC8446].

   The Network Configuration Access Control Model (NACM) [RFC8341]
   provides the means to restrict access for particular NETCONF or
   RESTCONF users to a preconfigured subset of all available NETCONF or
   RESTCONF protocol operations and content.

   There are a number of data nodes defined in this YANG module that are
   writable/creatable/deletable (i.e., config true, which is the
   default).  These data nodes may be considered sensitive or vulnerable
   in some network environments.  Write operations (e.g., edit-config)
   to these data nodes without proper protection can have a negative
   effect on network operations.  These are the subtrees and data nodes
   and their sensitivity/vulnerability:

   Some of the readable data nodes in this YANG module may be considered
   sensitive or vulnerable in some network environments.  It is thus
   important to control read access (e.g., via get, get-config, or
   notification) to these data nodes.  These are the subtrees and data
   nodes and their sensitivity/vulnerability:

   Some of the RPC operations in this YANG module may be considered
   sensitive or vulnerable in some network environments.  It is thus
   important to control access to these operations.  These are the
   operations and their sensitivity/vulnerability:

10.  IANA Considerations

10.1.  The "IETF XML" Registry

   This document registers one XML namespace URN in the 'IETF XML
   registry', following the format defined in [RFC3688].

   URI: urn:ietf:params:xml:ns:yang:ietf-incident Registrant Contact:
   The IESG.  XML: N/A, the requested URIs are XML namespaces.

10.2.  The "YANG Module Names" Registry

   This document registers one module name in the 'YANG Module Names'
   registry, defined in [RFC6020].

   name: ietf-incident prefix: inc namespace:
   urn:ietf:params:xml:ns:yang:ietf-incident RFC: XXXX // RFC Ed.:
   replace XXXX and remove this comment

Acknowledgments

   The authors would like to thank Mohamed Boucadair, Robert Wilton,
   Benoit Claise, Oscar Gonzalez de Dios, Adrian Farrel, Mahesh
   Jethanandani, Balazs Lengyel, Bo Wu, Qiufang Ma, Haomian Zheng,
   YuanYao,Wei Wang, Peng Liu, Zongpeng Du, Zhengqiang Li, Andrew Liu ,
   Joe Clark, Roland Scott, Alex Huang Feng, Kai Gao, Jensen Zhang,
   Ziyang Xing for their valuable comments and great input to this work.

References

Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/rfc/rfc2119>.

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              DOI 10.17487/RFC3688, January 2004,
              <https://www.rfc-editor.org/rfc/rfc3688>.

   [RFC6020]  Bjorklund, M., Ed., "YANG - A Data Modeling Language for
              the Network Configuration Protocol (NETCONF)", RFC 6020,
              DOI 10.17487/RFC6020, October 2010,
              <https://www.rfc-editor.org/rfc/rfc6020>.

   [RFC6241]  Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
              and A. Bierman, Ed., "Network Configuration Protocol
              (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
              <https://www.rfc-editor.org/rfc/rfc6241>.

   [RFC6242]  Wasserman, M., "Using the NETCONF Protocol over Secure
              Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
              <https://www.rfc-editor.org/rfc/rfc6242>.

   [RFC6991]  Schoenwaelder, J., Ed., "Common YANG Data Types",
              RFC 6991, DOI 10.17487/RFC6991, July 2013,
              <https://www.rfc-editor.org/rfc/rfc6991>.

   [RFC8040]  Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
              Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
              <https://www.rfc-editor.org/rfc/rfc8040>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.

   [RFC8341]  Bierman, A. and M. Bjorklund, "Network Configuration
              Access Control Model", STD 91, RFC 8341,
              DOI 10.17487/RFC8341, March 2018,
              <https://www.rfc-editor.org/rfc/rfc8341>.

   [RFC8345]  Clemm, A., Medved, J., Varga, R., Bahadur, N.,
              Ananthakrishnan, H., and X. Liu, "A YANG Data Model for
              Network Topologies", RFC 8345, DOI 10.17487/RFC8345, March
              2018, <https://www.rfc-editor.org/rfc/rfc8345>.

   [RFC8446]  Rescorla, E., "The Transport Layer Security (TLS) Protocol
              Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
              <https://www.rfc-editor.org/rfc/rfc8446>.

   [RFC8632]  Vallin, S. and M. Bjorklund, "A YANG Data Model for Alarm
              Management", RFC 8632, DOI 10.17487/RFC8632, September
              2019, <https://www.rfc-editor.org/rfc/rfc8632>.

Informative References

   [BERT]     "BERT (language model)", n.d.,
              <https://en.wikipedia.org/wiki/BERT_(language_model)>.

   [I-D.ietf-ippm-pam]
              Mirsky, G., Halpern, J. M., Min, X., Clemm, A., Strassner,
              J., and J. François, "Precision Availability Metrics for
              Services Governed by Service Level Objectives (SLOs)",
              Work in Progress, Internet-Draft, draft-ietf-ippm-pam-09,
              1 December 2023, <https://datatracker.ietf.org/doc/html/
              draft-ietf-ippm-pam-09>.

   [I-D.quilbeuf-opsawg-configuration-tracing]
              Quilbeuf, J., Claise, B., Graf, T., Lopez, D., and S.
              Qiong, "External Trace ID for Configuration Tracing", Work
              in Progress, Internet-Draft, draft-quilbeuf-opsawg-
              configuration-tracing-02, 10 July 2023,
              <https://datatracker.ietf.org/doc/html/draft-quilbeuf-
              opsawg-configuration-tracing-02>.

   [I-D.rogaglia-netconf-trace-ctx-extension]
              Gagliano, R., Larsson, K., and J. Lindblad, "NETCONF
              Extension to support Trace Context propagation", Work in
              Progress, Internet-Draft, draft-rogaglia-netconf-trace-
              ctx-extension-03, 6 July 2023,
              <https://datatracker.ietf.org/doc/html/draft-rogaglia-
              netconf-trace-ctx-extension-03>.

   [I-D.tgraf-yang-push-observation-time]
              Graf, T., Claise, B., and A. H. Feng, "Support of Network
              Observation Timestamping in YANG Notifications", Work in
              Progress, Internet-Draft, draft-tgraf-yang-push-
              observation-time-00, 4 March 2023,
              <https://datatracker.ietf.org/doc/html/draft-tgraf-yang-
              push-observation-time-00>.

   [RFC7950]  Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
              RFC 7950, DOI 10.17487/RFC7950, August 2016,
              <https://www.rfc-editor.org/rfc/rfc7950>.

   [RFC8969]  Wu, Q., Ed., Boucadair, M., Ed., Lopez, D., Xie, C., and
              L. Geng, "A Framework for Automating Service and Network
              Management with YANG", RFC 8969, DOI 10.17487/RFC8969,
              January 2021, <https://www.rfc-editor.org/rfc/rfc8969>.

   [RFC9375]  Wu, B., Ed., Wu, Q., Ed., Boucadair, M., Ed., Gonzalez de
              Dios, O., and B. Wen, "A YANG Data Model for Network and
              VPN Service Performance Monitoring", RFC 9375,
              DOI 10.17487/RFC9375, April 2023,
              <https://www.rfc-editor.org/rfc/rfc9375>.

   [RFC9408]  Boucadair, M., Ed., Gonzalez de Dios, O., Barguil, S., Wu,
              Q., and V. Lopez, "A YANG Network Data Model for Service
              Attachment Points (SAPs)", RFC 9408, DOI 10.17487/RFC9408,
              June 2023, <https://www.rfc-editor.org/rfc/rfc9408>.

   [RFC9417]  Claise, B., Quilbeuf, J., Lopez, D., Voyer, D., and T.
              Arumugam, "Service Assurance for Intent-Based Networking
              Architecture", RFC 9417, DOI 10.17487/RFC9417, July 2023,
              <https://www.rfc-editor.org/rfc/rfc9417>.

   [RFC9418]  Claise, B., Quilbeuf, J., Lucente, P., Fasano, P., and T.
              Arumugam, "A YANG Data Model for Service Assurance",
              RFC 9418, DOI 10.17487/RFC9418, July 2023,
              <https://www.rfc-editor.org/rfc/rfc9418>.

   [TMF724A]  "Incident Management API Profile v1.0.0", 2023,
              <https://www.tmforum.org/resources/standard/tmf724a-
              incident-management-api-profile-v1-0-0/>.

   [W3C-Trace-Context]
              "W3C Recommendation on Trace Context", 2021,
              <https://www.w3.org/TR/2021/REC-trace-context-
              1-20211123/>.

Appendix A.  Changes between Revisions

   v02 - v03 * Fix pyang compilation issue and yang lint issue.

   v01 - v02 * Fix Broken ref by using node-ref defined in RFC8345.

   *  Update YANG data model based on issues raised in issue tracker of
      the github.

   *  Shorten the list of authors to 5 based on chairs' comment and move
      additional authors to top 3 contributors.

   v00 - v01

   *  Merge ietf-incident-type.yang into ietf-incident.yang

   *  Fix enumeration on leaf type

   *  Clarify the scope in the abstract and introduction and make the
      scope focus on YANG data model

   *  Provide text around figure 5 to clarify how the incident server
      know the real effect on the relevant services.

   *  Other editorial changes.

   v00 (draft-feng-nmop-network-incident-yang)

   *  Change draft name from draft-feng-opsawg-incident-management into
      draft-feng-nmop-netwrok-incident-yang

   *  Change title into A YANG Data Model for Network Incident
      Management

   *  open issues is tracked in https://github.com/billwuqin/network-
      incident/issues

   v03 - v04 (draft-feng-opsawg-incident-management)

   *  Update incident defintion based on TMF incident API profile
      specification.

   *  Update use case on Multi-layer Fault Demarcation based on side
      meeting discussion and IETF 119 session discussion.

   *  Update section 5.1 to explain how network incident is generated
      based on other factors.

   *  Add one new use cases on Security Events noise reduction based on
      Situation Awareness.

   *  Other Editorial changes.

   v02 - v03 (draft-feng-opsawg-incident-management)

   *  Add one new use cases on Incident Generation.

   *  Add reference to Precision Availability Metric defined in IPPM PAM
      WG document.

   v01 - v02

   *  A few Editorial change to YANG data models in section 8.

   *  Add some text to the model design overview.

   *  Revise sample use cases section to focus on two key use cases.

   *  Motivation and goal clarification in the introduction section.

   v00 - v01 (draft-feng-opsawg-incident-management)

   *  Modify the introduction.

   *  Rename incident agent to incident server.

   *  Add the interworking with alarm management.

   *  Add the interworking with SAIN.

   *  Add the relationship with RFC8969.

   *  Add the relationship with observation timestamp and trace context.

   *  Clarify the incident identification process.

   *  Modify the work flow of incident diagnosis and resolution.

   *  Remove identities and typedefs from ietf-incident YANG module, and
      create a new YANG module called ietf-incident-types.

   *  Modify ietf-incident YANG module, for example, modify incident-
      diagnose rpc and incident-resolve rpc.

Contributors

   Thomas Graf
   Swisscom
   Binzring 17CH-8045
   CH- Zurich
   Switzerland
   Email: thomas.graf@swisscom.com


   Zhenqiang Li
   CMCC
   Email: li_zhenqiang@hotmail.com


   Yanlei Zheng
   China Unicom
   Email: zhengyanlei@chinaunicom.cn


   Yunbin Xu
   CAICT
   Email: xuyunbin@caict.ac.cn


   Xing Zhao
   CAICT
   Email: zhaoxing@caict.ac.cn


   Chaode Yu
   Huawei
   Email: yuchaode@huawei.com


   MingShuang Jin
   Huawei Technologies
   Email: jinmingshuang@huawei.com


   Chunchi Liu
   Huawei Technologies
   Email: liuchunchi@huawei.com


   Aihua Guo
   Futurewei Technologies
   Email: aihuaguo.ietf@gmail.com


   Zhidong Yin
   Huawei
   Email: yinzhidong@huawei.com


   Guoxiang Liu
   Huawei
   Email: liuguoxiang@huawei.com


   Kaichun Wu
   Huawei
   Email: wukaichun@huawei.com


Authors' Addresses

   Tong Hu
   CMCC
   Building A01, 1600 Yuhangtang Road, Wuchang Street, Yuhang District
   Hangzhou
   311121
   China
   Email: hutong@cmhi.chinamobile.com


   Luis Miguel Contreras Murillo
   Telefonica I+D
   Madrid
   Spain
   Email: luismiguel.contrerasmurillo@telefonica.com


   Qin Wu
   Huawei
   101 Software Avenue, Yuhua District
   Nanjing
   210012
   China
   Email: bill.wu@huawei.com


   Nigel Davis
   Ciena
   Email: ndavis@ciena.com


   Chong Feng
   Email: fengchongllly@gmail.com