YANG models for VN/TE Performance Monitoring Telemetry and Scaling Intent Autonomics

The YANG model discussed in is used to operate customer-driven Virtual Networks (VNs) during the VN instantiation, VN computation, and its life-cycle service management and operations. YANG model discussed in is used to operate TE-tunnels during the tunnel instantiation, and its life-cycle management and operations. The models presented in this draft allow the applications hosted by the customers to subscribe to and monitor their key performance data of their interest on the level of VN or TE-tunnel . The key characteristic of the models presented in this document is a top-down programmability that allows the applications hosted by the customers to subscribe to and monitor key performance data of their interest and autonomic scaling intent mechanism on the level of VN as well as TE-tunnel. According to the classification of , the YANG data models presented in this document can be classified as customer service models, which is mapped to CMI (Customer Network Controller (CNC)- Multi-Domain Service Coordinator (MSDC) interface) of ACTN . describes key network performance data to be considered for end-to-end path computation in TE networks. Key performance indicator (KPI) is a term that describes critical performance data that may affect VN/TE-tunnel service. The services provided can be optimized to meet the requirements (such as traffic patterns, quality, and reliability) of the applications hosted by the customers. This document provides YANG data models generically applicable to any VN/TE-Tunnel service clients to provide an ability to program their customized performance monitoring subscription and publication data models and automatic scaling in/out intent data models. These models can be utilized by a client network controller to initiate these capability to a transport network controller communicating with the client controller via a NETCONF or a RESTCONF interface. The term performance monitoring being used in this document is different from the term that has been used in transport networks for many years. Performance monitoring in this document refers to subscription and publication of streaming telemetry data. Subscription is initiated by the client (e.g., CNC) while publication is provided by the network (e.g., MDSC/PNC) based on the client's subscription. As the scope of performance monitoring in this document is telemetry data on the level of client's VN or TE- tunnel, the entity interfacing the client (e.g., MDSC) has to provide VN or TE-tunnel level information. This would require controller capability to derive VN or TE-tunnel level performance data based on lower-level data collected via PM counters in the Network Elements (NE). How the controller entity derives such customized level data (i.e., VN or TE-tunnel level) is out of the scope of this document. The data model includes configuration and state data according to the new Network Management Datastore Architecture . [Editor's Note: A suggestion is made to remove the word KPI from the name of the model. Further discussion is needed.]

Refer to , , and for the key terms used in this document. Key Performance Data: This refers to a set of data the customer is interested in monitoring for their instantiated VNs or TE-tunnels. Key performance data and key performance indicators are inter- exchangeable in this draft. Scaling: This refers to the network ability to re-shape its own resources. Scale out refers to improve network performance by increasing the allocated resources, while scale in refers to decrease the allocated resources, typically because the existing resources are unnecessary. Scaling Intent: To declare scaling conditions, scaling intent is used. Specifically, scaling intent refers to the intent expressed by the client that allows the client to program/configure conditions of their key performance data either for scaling out or scaling in. Various conditions can be set for scaling intent on either VN or TE- tunnel level. Network Autonomics: This refers to the network automation capability that allows client to initiate scaling intent mechanisms and provides the client with the status of the adjusted network resources based on the client's scaling intent in an automated fashion.

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 when, and only when, they appear in all capitals, as shown here.

A simplified graphical representation of the data model is used in Section 5 of this this document. The meaning of the symbols in these diagrams is defined in .

In this document, names of data nodes and other data model objects are prefixed using the standard prefix associated with the corresponding YANG imported modules, as shown in Table 1. Prefix YANG module Reference te ietf-te te-types ietf-te-types te-tel ietf-te-kpi-telemetry [RFCXXXX] vn ietf-vn vn-tel ietf-vn-kpi-telemetry [RFCXXXX] Note: The RFC Editor will replace XXXX with the number assigned to the RFC once this draft becomes an RFC. Further, the following additional documents are refrenced in the model defined in this document - - OSPF Traffic Engineering (TE) Metric Extensions. - IS-IS Traffic Engineering (TE) Metric Extensions. - Performance-Based Path Selection for Explicitly Routed Label Switched Paths (LSPs) Using TE Metric Extensions.

describes use-cases relevant to this draft. It introduces the dynamic creation, modification and optimization of services based on the performance monitoring. Figure 1 shows a high-level workflows for dynamic service control based on traffic monitoring.

Some of the key points from are as follows: Network traffic monitoring is important to facilitate automatic discovery of the imbalance of network traffic, and initiate the network optimization, thus helping the network operator or the virtual network service provider to use the network more efficiently and save the Capital Expense (CAPEX) and the Operating Expense (OPEX). Customer services have various Service Level Agreement (SLA) requirements, such as service availability, latency, latency jitter, packet loss rate, Bit Error Rate (BER), etc. The transport network can satisfy service availability and BER requirements by providing different protection and restoration mechanisms. However, for other performance parameters, there are no such mechanisms. In order to provide high quality services according to customer SLA, one possible solution is to measure the SLA related performance parameters, and dynamically provision and optimize services based on the performance monitoring results. Performance monitoring in a large scale network could generate a huge amount of performance information. Therefore, the appropriate way to deliver the information in the client and network interfaces should be carefully considered.

The YANG models developed in this document describe two models: TE KPI Telemetry Model which provides the TE-Tunnel level of performance monitoring mechanism and scaling intent mechanism that allows scale in/out programming by the customer. (See & for details). VN KPI Telemetry Model which provides the VN level of the aggregated performance monitoring mechanism and scaling intent mechanism that allows scale in/out programming by the customer (See & for details).

This module describes performance telemetry for TE-tunnel model. The telemetry data is augmented to tunnel state. This module also allows autonomic traffic engineering scaling intent configuration mechanism on the TE-tunnel level. Various conditions can be set for auto-scaling based on the telemetry data (See for details) The TE KPI Telemetry Model augments the TE-Tunnel Model to enhance TE performance monitoring capability. This monitoring capability will facilitate proactive re-optimization and reconfiguration of TEs based on the performance monitoring data collected via the TE KPI Telemetry YANG model.

This module describes performance telemetry for VN model. The telemetry data is augmented both at the VN Level as well as individual VN member level. This module also allows autonomic traffic engineering scaling intent configuration mechanism on the VN level. Scale in/out criteria might be used for network autonomics in order the controller to react to a certain set of variations in monitored parameters (See for illustrations). Moreover, this module also provides mechanism to define aggregated telemetry parameters as a grouping of underlying VN level telemetry parameters. Grouping operation (such as maximum, mean) could be set at the time of configuration. For example, if maximum grouping operation is used for delay at the VN level, the VN telemetry data is reported as the maximum {delay_vn_member_1, delay_vn_member_2,.. delay_vn_member_N}. Thus, this telemetry abstraction mechanism allows the grouping of a certain common set of telemetry values under a grouping operation. This can be done at the VN-member level to suggest how the E2E telemetry be inferred from the per domain tunnel created and monitored by PNCs. One proposed example is the following:

The VN Telemetry Model augments the basic VN model to enhance VN monitoring capability. This monitoring capability will facilitate proactive re-optimization and reconfiguration of VNs based on the performance monitoring data collected via the VN Telemetry YANG model.

Scaling intent configuration mechanism allows the client to configure automatic scale-in and scale-out mechanisms on both the TE-tunnel and the VN level. Various conditions can be set for auto- scaling based on the PM telemetry data. There are a number of parameters involved in the mechanism: scale-out-intent or scale-in-intent: whether to scale-out or scale-in. performance-type: performance metric type (e.g., one-way-delay, one-way-delay-min, one-way-delay-max, two-way-delay, two-way- delay-min, two-way-delay-max, utilized bandwidth, etc.) threshold-value: the threshold value for a certain performance-type that triggers scale-in or scale-out. scaling-operation-type: in case where scaling condition can be set with one or more performance types, then scaling-operation-type (AND, OR, MIN, MAX, etc.) is applied to these selected performance types and its threshold values. Threshold-time: the duration for which the criteria MUST hold true. Cooldown-time: the duration after a scaling action has been triggered, for which there will be no further operation. The following tree is a part of ietf-te-kpi-telemetry tree whose model is presented in full detail in Sections 6 & 7.

Let say the client wants to set the scaling out operation based on two performance-types (e.g., two-way-delay and utilized-bandwidth for a te-tunnel), it can be done as follows: Set Threshold-time: x (sec) (duration for which the criteria must hold true) Set Cooldown-time: y (sec) (the duration after a scaling action has been triggered, for which there will be no further operation) Set AND for the scale-out-operation-type In the scaling condition's list, the following two components can be set: List 1: Scaling Condition for Two-way-delay performance type: Two-way-delay threshold-value: z milli-seconds List 2: Scaling Condition for Utilized bandwidth performance type: Utilized bandwidth threshold-value: w megabytes

This model does not define specific notifications. To enable notifications, the mechanism defined in and can be used. This mechanism currently allows the user to: Subscribe to notifications on a per client basis. Specify subtree filters or xpath filters so that only interested contents will be sent. Specify either periodic or on-demand notifications.

allows subscriber applications to request a continuous, customized stream of updates from a YANG datastore. Below example shows the way for a client to subscribe to the telemetry information for a particular tunnel (Tunnel1). The telemetry parameter that the client is interested in is one-way- delay.

Tunnel1

500 encode-xml ]]> This example shows the way for a client to subscribe to the telemetry information for all VNs. The telemetry parameter that the client is interested in is one-way-delay and one-way-utilized- bandwidth.

500 ]]>

/te:te/tunnels/tunnel/te-kpi:te-telemetry/id +--ro grouping-operation? grouping-operation ]]>

The YANG code is as follows:

file "ietf-te-kpi-telemetry@2021-02-19.yang" module ietf-te-kpi-telemetry { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-te-kpi-telemetry"; prefix te-tel; /* Import TE */ import ietf-te { prefix te; reference "I-D.ietf-teas-yang-te: A YANG Data Model for Traffic Engineering Tunnels and Interfaces"; } /* Import TE Common types */ import ietf-te-types { prefix te-types; reference "RFC 8776: Common YANG Data Types for Traffic Engineering"; } organization "IETF Traffic Engineering Architecture and Signaling (TEAS) Working Group"; contact "WG Web: WG List: Editor: Young Lee Dhruv Dhody "; description "This module describes YANG data model for performance monitoring telemetry for te tunnels. Copyright (c) 2021 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 XXXX; 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."; /* Note: The RFC Editor will replace XXXX with the number assigned to the RFC once draft-ietf-teas-pm-telemetry- autonomics becomes an RFC.*/ revision 2021-02-19 { description "Initial revision."; reference "RFC XXXX: YANG models for VN/TE Performance Monitoring Telemetry and Scaling Intent Autonomics"; } identity telemetry-param-type { description "Base identity for telemetry param types"; } identity one-way-delay { base telemetry-param-type; description "To specify average Delay in one (forward) direction. At the VN level, it is the max delay of the VN-members."; reference "RFC 7471: OSPF Traffic Engineering (TE) Metric Extensions. RFC 8570: IS-IS Traffic Engineering (TE) Metric Extensions. RFC 7823: Performance-Based Path Selection for Explicitly Routed Label Switched Paths (LSPs) Using TE Metric Extensions"; } identity two-way-delay { base telemetry-param-type; description "To specify average Delay in both (forward and reverse) directions. At the VN level, it is the max delay of the VN-members."; reference "RFC 7471: OSPF Traffic Engineering (TE) Metric Extensions. RFC 8570: IS-IS Traffic Engineering (TE) Metric Extensions. RFC 7823: Performance-Based Path Selection for Explicitly Routed Label Switched Paths (LSPs) Using TE Metric Extensions"; } identity one-way-delay-variation { base telemetry-param-type; description "To specify average Delay Variation in one (forward) direction. At the VN level, it is the max delay variation of the VN-members."; reference "RFC 7471: OSPF Traffic Engineering (TE) Metric Extensions. RFC 8570: IS-IS Traffic Engineering (TE) Metric Extensions. RFC 7823: Performance-Based Path Selection for Explicitly Routed Label Switched Paths (LSPs) Using TE Metric Extensions"; } identity two-way-delay-variation { base telemetry-param-type; description "To specify average Delay Variation in both (forward and reverse) directions. At the VN level, it is the max delay variation of the VN-members."; reference "RFC 7471: OSPF Traffic Engineering (TE) Metric Extensions. RFC 8570: IS-IS Traffic Engineering (TE) Metric Extensions. RFC 7823: Performance-Based Path Selection for Explicitly Routed Label Switched Paths (LSPs) Using TE Metric Extensions"; } identity utilized-bandwidth { base telemetry-param-type; description "To specify utilized bandwidth over the specified source and destination."; reference "RFC 7471: OSPF Traffic Engineering (TE) Metric Extensions. RFC 8570: IS-IS Traffic Engineering (TE) Metric Extensions. RFC 7823: Performance-Based Path Selection for Explicitly Routed Label Switched Paths (LSPs) Using TE Metric Extensions"; } identity utilized-percentage { base telemetry-param-type; description "To specify utilization percentage of the entity (e.g., tunnel, link, etc.)"; } identity scale-op { description "Base identity for scaling operation"; } identity scale-capacity-up { base scale-op; description "Scale up the bandwidth capacity"; } identity scale-capacity-down { base scale-op; description "Scale down the bandwidth capacity"; } /* Typedef */ typedef telemetry-id { type string; description "Identifier for the telemetry data."; } typedef scaling-criteria-operation { type enumeration { enum AND { description "AND operation"; } enum OR { description "OR operation"; } } description "Operations to analize list of scaling criterias"; } grouping scaling-duration { description "Base scaling criteria durations"; leaf threshold-time { type uint32; units "seconds"; description "The duration for which the criteria must hold true"; } leaf cooldown-time { type uint32; units "seconds"; description "The duration after a scaling-in/scaling-out action has been triggered, for which there will be no further operation"; } } grouping scaling-criteria { description "Grouping for scaling criteria"; leaf performance-type { type identityref { base telemetry-param-type; } description "Reference to the tunnel level telemetry type"; } leaf threshold-value { type string; description "Scaling threshold for the telemetry parameter type"; } } grouping scaling-in-intent { description "Basic scaling in intent"; uses scaling-duration; list scaling-condition { key "performance-type"; description "Scaling conditions"; uses scaling-criteria; leaf scale-in-operation-type { type scaling-criteria-operation; default "AND"; description "Operation to be applied to check between scaling criterias to check if the scale in threshold condition has been met. Defaults to AND"; } } leaf scale-in-op { type identityref { base scale-op; } default "scale-capacity-down"; description "The scaling operation to be performed when scaling condition is met"; } leaf scale { type string; description "Additional scaling-by information to be interpritted as per the scale-in-op."; } } grouping scaling-out-intent { description "Basic scaling out intent"; uses scaling-duration; list scaling-condition { key "performance-type"; description "Scaling conditions"; uses scaling-criteria; leaf scale-out-operation-type { type scaling-criteria-operation; default "OR"; description "Operation to be applied to check between scaling criterias to check if the scale out threshold condition has been met. Defauls to OR"; } } leaf scale-out-op { type identityref { base scale-op; } default "scale-capacity-up"; description "The scaling operation to be performed when scaling condition is met"; } leaf scale { type string; description "Additional scaling-by information to be interpritted as per the scale-out-op."; } } augment "/te:te/te:tunnels/te:tunnel" { description "Augmentation parameters for config scaling-criteria TE tunnel topologies. Scale in/out criteria might be used for network autonomics in order the controller to react to a certain set of monitored params."; container te-scaling-intent { description "The scaling intent"; container scale-in-intent { description "scale-in"; uses scaling-in-intent; } container scale-out-intent { description "scale-out"; uses scaling-out-intent; } } container te-telemetry { config false; description "Telemetry Data"; leaf id { type telemetry-id; description "ID of telemetry data used for easy reference"; } uses te-types:performance-metrics-attributes; } } }

]]>



	
   The YANG code is as follows:

	 file "ietf-vn-kpi-telemetry@2021-02-19.yang"
module ietf-vn-kpi-telemetry {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:ietf-vn-kpi-telemetry";
  prefix vn-kpi;

  /* Import VN */

  import ietf-vn {
    prefix vn;
    reference
      "I-D.ietf-teas-actn-vn-yang: A YANG Data Model for VN
       Operation";
  }

  /* Import TE */

  import ietf-te {
    prefix te;
    reference
      "I-D.ietf-teas-yang-te: A YANG Data Model for Traffic
       Engineering Tunnels and Interfaces";
  }

  /* Import TE Common types */

  import ietf-te-types {
    prefix te-types;
    reference
      "RFC 8776: Common YANG Data Types for Traffic Engineering";
  }

  /* Import TE KPI */

  import ietf-te-kpi-telemetry {
    prefix te-kpi;
    reference
      "RFC XXXX: YANG models for VN/TE Performance Monitoring
       Telemetry and Scaling Intent Autonomics";
  }

  /* Note: The RFC Editor will replace XXXX with the number
     assigned to this draft.*/

  organization
    "IETF Traffic Engineering Architecture and Signaling (TEAS)
     Working Group";
  contact
    "WG Web:  
     WG List: 
     Editor:  Young Lee 
              Dhruv Dhody ";
  description
    "This module describes YANG data models for performance
     monitoring telemetry for Virtual Network (VN).

     Copyright (c) 2021 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 XXXX; 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.";

  /* Note: The RFC Editor will replace XXXX with the number
     assigned to the RFC once draft-lee-teas-pm-telemetry-
     autonomics becomes an RFC.*/

  revision 2021-02-19 {
    description
      "Initial revision.";
    reference
      "RFC XXXX: YANG models for VN/TE Performance Monitoring
       Telemetry and Scaling Intent Autonomics";
  }

  typedef grouping-operation {
    type enumeration {
      enum MINIMUM {
        description
          "Select the minimum param";
      }
      enum MAXIMUM {
        description
          "Select the maximum param";
      }
      enum MEAN {
        description
          "Select the MEAN of the params";
      }
      enum STD_DEV {
        description
          "Select the standard deviation of the monitored params";
      }
      enum AND {
        description
          "Select the AND of the params";
      }
      enum OR {
        description
          "Select the OR of the params";
      }
    }
    description
      "Operations to analize list of monitored params";
  }

  grouping vn-telemetry-param {
    description
      "augment of te-kpi:telemetry-param for VN specific params";
    leaf-list te-grouped-params {
      type leafref {
        path
          "/te:te/te:tunnels/te:tunnel/te-kpi:te-telemetry/te-kpi:id";
      }
      description
        "Allows the definition of a vn-telemetry param
         as a grouping of underlying TE params";
    }
    leaf grouping-operation {
      type grouping-operation;
      description
        "describes the operation to apply to
         te-grouped-params";
    }
  }

  augment "/vn:vn/vn:vn" {
    description
      "Augmentation parameters for state TE VN topologies.";
    container vn-scaling-intent {
      description
        "scaling intent";
      container scale-in-intent {
        description
          "VN scale-in";
        uses te-kpi:scaling-in-intent;
      }
      container scale-out-intent {
        description
          "VN scale-out";
        uses te-kpi:scaling-out-intent;
      }
    }
    container vn-telemetry {
      config false;
      description
        "VN telemetry params";
      uses te-types:performance-metrics-attributes;
      leaf grouping-operation {
        type grouping-operation;
        description
          "describes the operation to apply to the VN-members";
      }
    }
  }

  augment "/vn:vn/vn:vn/vn:vn-member" {
    description
      "Augmentation parameters for state TE vn member topologies.";
    container vn-member-telemetry {
      config false;
      description
        "VN member telemetry params";
      uses te-types:performance-metrics-attributes;
      uses vn-telemetry-param;
    }
  }
}


]]>



	
   The YANG module specified in this document defines a schema for data
   that is designed to be accessed via network management protocols
   such as NETCONF  or RESTCONF . The lowest NETCONF
   layer is the secure transport layer, and the mandatory-to-implement
   secure transport is Secure Shell (SSH) . The lowest
   RESTCONF layer is HTTPS, and the mandatory-to-implement secure
   transport is TLS .

	
   The NETCONF access control model  provides the means to
   restrict access for particular NETCONF users to a preconfigured
   subset of all available NETCONF protocol operations and content. The
   NETCONF Protocol over Secure Shell (SSH)  describes a
   method for invoking and running NETCONF within a Secure Shell (SSH)
   session as an SSH subsystem. The Network Configuration Access
   Control Model (NACM)  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.

	
   A number of configuration data nodes defined in this document are
   writable/deletable (i.e., "config true"). These data nodes may be
   considered sensitive or vulnerable in some network environments.

	
   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:

	
	/te:te/te:tunnels/te:tunnel/te-scaling-intent/scale-in-intent
  /te:te/te:tunnels/te:tunnel/te-scaling-intent/scale-out-intent
	/vn:vn/vn:vn/vn-scaling-intent/scale-in-intent
  /vn:vn/vn:vn/vn-scaling-intent/scale-out-intent
  

	

	
   This document registers the following namespace URIs in the IETF XML
   registry :

	
	
	
   This document registers the following YANG modules in the YANG
   Module.

	
   Names registry :

	
	
	

	
   We thank Rakesh Gandhi, Tarek Saad, Igor Bryskin and Kenichi Ogaki for useful
   discussions and their suggestions for this work.