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A YANG Model for VPN Service Performance Monitoring
draft-www-bess-yang-vpn-service-pm-00

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Document Type
This is an older version of an Internet-Draft whose latest revision state is "Expired".
Authors Zitao Wang , Qin Wu , Roni Even , Bin Wen
Last updated 2018-09-27
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draft-www-bess-yang-vpn-service-pm-00
BESS Working Group                                               M. Wang
Internet-Draft                                                     Q. Wu
Intended status: Standards Track                                 R. Even
Expires: March 31, 2019                                           Huawei
                                                                  B. Wen
                                                                 Comcast
                                                      September 27, 2018

          A YANG Model for VPN Service Performance Monitoring
                 draft-www-bess-yang-vpn-service-pm-00

Abstract

   As specified in [RFC8345], the data model defined in
   [RFC8345]introduces vertical layering relationships between networks
   that can be augmented to cover network/service topologies.  This
   document defines a YANG Model for VPN Service Performance Monitoring
   that can be used to monitor and manage network Performance between
   VPN sites and it is an augmentation to the I2RS network topology YANG
   data model.

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 March 31, 2019.

Copyright Notice

   Copyright (c) 2018 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

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   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions used in this document . . . . . . . . . . . . . .   3
   3.  VPN Service Topology Overview . . . . . . . . . . . . . . . .   4
   4.  VPN service assurance model . . . . . . . . . . . . . . . . .   5
   5.  Model Usage Guideline . . . . . . . . . . . . . . . . . . . .   5
     5.1.  Performance Monitoring Data Source  . . . . . . . . . . .   5
     5.2.  Retrieval via I2RS Pub/Sub  . . . . . . . . . . . . . . .   5
     5.3.  On demand Retrieval via RPC model . . . . . . . . . . . .   6
   6.  Design of the Data Model  . . . . . . . . . . . . . . . . . .   6
     6.1.  Network Level . . . . . . . . . . . . . . . . . . . . . .   6
     6.2.  Node Level  . . . . . . . . . . . . . . . . . . . . . . .   6
     6.3.  Link and Termination Point Level  . . . . . . . . . . . .   7
   7.  Example of I2RS Pub/Sub Retrieval . . . . . . . . . . . . . .   8
   8.  Example of RPC model based Retrieval  . . . . . . . . . . . .   9
   9.  VPN Service Assurance YANG Module . . . . . . . . . . . . . .   9
   10. Security Considerations . . . . . . . . . . . . . . . . . . .  16
   11. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  17
   12. Normative References  . . . . . . . . . . . . . . . . . . . .  17
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  18

1.  Introduction

   [RFC8345] defines an abstract YANG data model for network/service
   topologies and inventories.  Service topology in [RFC8345] includes
   the a virtual topology for a service layer above the L1, L2, and L3
   layers.  This virtual topology has the generic topology elements of
   node,link, and terminating point.  One typical example of a service
   topology is described in figure 3 of [RFC8345],two VPN service
   topologies instantiated over a common L3 topology.  Each VPN service
   topology is mapped onto a subset of nodes from the common L3
   topology.

   In [RFC8299], the 3 types of VPN service topologies proposed for
   L3VPN service data model are any to any, hub and spoke, hub and spoke
   disjoint.  These VPN topology types can be used to describe how VPN
   sites are communicating with each other.

   This document defines a YANG Model for VPN Service Performance
   Monitoring that can be used to monitor and manage network Performance

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   between VPN sites and it is an augmentation to the I2RS network
   topology YANG data model.

2.  Conventions used in this document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].  In this
   document, these words will appear with that interpretation only when
   in ALL CAPS.  Lower case uses of these words are not to be
   interpreted as carrying [RFC2119] significance.

   The following notations are used within the data tree and carry the
   meaning as below.

   Each node is printed as:

    <status> <flags> <name> <opts> <type>

    <status> is one of:
         +  for current

    <flags> is one of:

        rw for configuration data
        ro for non-configuration data
        -x for rpcs
        -n for notifications
        -w for writable

    <name> is the name of the node

    If the node is augmented into the tree from another module, its name
    is printed as <prefix>:<name>.

    <opts> is one of:

         ?  for an optional leaf or choice
         !  for a presence container
         *  for a leaf-list or list
         [<keys>] for a list's keys
         (choice)/:(case) Parentheses enclose choice and case nodes,
         and case nodes are also marked with a colon (":")
         <type> is the name of the type for leafs and leaf-lists

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3.  VPN Service Topology Overview

   As specified in [RFC8345], the data model defined in [RFC8345] can
   describe vertical layering relationships between networks that can be
   augmented to cover network/service topologies.  The following figure
   describes relationships between L3VPN Service Topo and Underlying
   network:

                  VPN-1           VPN-2
                     /               \
      L3VPN-Service-topology 1  L3VPN-Service-topology-2
            /     |      \            /     |      \
       Site-1A site-1B site1-C    site-2A Site-2B Site-2C    Top-Down
         |          |       |       |         |     |      Service Topo
     ====|==========|=======|=======|=========|=====|===================
         +-------+  |        \    /           /     |
      Bottoms-up |  |         \ /           /       |
      Network    |  |         /\           /        |
      topology   |  |       /    \        |         |
                 |  |      |       |      |         |
             node1 node2 node3   node4   node5    node6
               PE   PE    PE       PE      PE       PE
               |     |     |        |       |        |
              CE    CE     CE      CE      CE       CE

     layering relationships between L3VPN Service Topo and Underlying
                                  network

   As shown in figure 1, the Site-1,A,B,C are mapped to node 1,2,3 while
   Site-2 A,B,C are mapped to node 4,5,6 in the underlying physical
   network.  In this figure, an L3SM has two VPN services topologies
   with each built on top of one common underlying physical network.

      VPN-svc 1: supporting hub-spoke communication for Customer 1 with
      connecting the customers access at 3 sites

      VPN-svc 2: supporting hub-spoke disjoint communication for
      Customer 2 with connecting the customers access at 3 sites

   L3VPN service topology 1 is hub and spoke topology while L3VPN
   service topology 2 is hub and spoke disjoint topology.  In L3VPN
   service topology1, Site-1 A plays the role of hub while Site-2 B and
   C plays the role of spoke.  In L3VPN service topoogy2, Site-2 A and B
   play the role of hub while Site-2 C plays the role of spoke.

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4.  VPN service assurance model

   This module describes VPN Service assurance that can be used to
   monitor and manage network Performance between VPN sites and it is a
   augmentation to the I2RS network topology YANG data model.  The
   performance monitoring data is augmented to service topology.

   +------------+          +---------------------+
   |I2RS Network|          |    VPN Service      |
   |Topo Model  |<---------|Peformance Monitoring|
   +------------+ augments |        Model        |
                           +---------------------+

5.  Model Usage Guideline

   An SP must be able to manage the capabilities and characteristics of
   their VPN services when VPN sites are setup to communicate with each
   other.  VPN service topology such as hub and spoke describes how
   these VPN sites are communicating with each other.

5.1.  Performance Monitoring Data Source

   As described in section 2, once the mapping between VPN Service
   topology and underlying physical network has been setup, the
   performance monitoring data per link in the underlying network can be
   collected using network performance measurement method such as MPLS
   Loss and Delay Measurement [RFC6374] and The performance monitoring
   information reflecting the quality of the VPN service such as end to
   end network performance data between VPN sites can be aggregated or
   calculated using PCEP solution [RFC5440] or LMAP solution [RFC8194]
   and fed into data source such as the management system or network
   devices.  The measurement interval and report interval associated
   with these performance data usually depends on configuration
   parameters.

5.2.  Retrieval via I2RS Pub/Sub

   For some applications such as service-assurance applications, which
   must maintain a continuous view of operational data and state, they
   can use subscription model [I-D.ietf-netconf-yang-push] to subscribe
   to their interested VPN service performance data in the data source.
   And then the data source can use VPN service assurance model and push
   model [I-D.ietf-netconf-yang-push] to publish specific telemetry data
   to target recipients.

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5.3.  On demand Retrieval via RPC model

   To obtain a snapshot of a large amount of performance data from the
   network element, service-assurance applications can also use polling
   based solution such as RPC model to fetch performance data on demand.

6.  Design of the Data Model

   This document defines the YANG module "ietf-vpn-svc-pm", which has
   the following structure

6.1.  Network Level

   module: ietf-vpn-svc-pm
     augment /nw:networks/nw:network/nw:network-types:
       +--rw svc-topo-type?   identityref
     augment /nw:networks/nw:network:
       +--rw svc-topo-attributes
          +--rw vpn-topo?   identityref

                   Network Level View of the hierarchies

   The VPN service performance monitoring model defines only the
   following minimal set of Network level service topology attributes:

   o  svc-topo-type: Indicate the network type is service topology type
      such as L3VPN service topology, L2VPN service topology.

   o  vpn-topo: The type of VPN service topology, Ourproposed model
      supports any-to-any, Hub and Spoke (where Hubs can exchange
      traffic), and "Hub and Spoke disjoint" (where Hubs cannot exchange
      traffic).

6.2.  Node Level

   augment /nw:networks/nw:network/nw:node:
       +--rw node-attributes
          +--rw node-type?   identityref
          +--rw site-id?     string
          +--rw site-role?   Identityref

                    Node Level View of the hierarchies

   The VPN service performance monitoring model defines only the
   following minimal set of Node level service topology attributes and
   constraints:

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   o  Node-type (Attribute): Indicate the type of the node, such as PE
      or ASBR.

   o  Site-id (Constraint): Uniquely identifies the site within the
      overall network infrastructure.

   o  Site-role (Constraint):Defines the role of the site in a
      particular VPN topology.

6.3.  Link and Termination Point Level

     augment /nw:networks/nw:network/nt:link:
       +--ro svc-telemetry-attributes
          +--ro loss-statistics
          |  +--ro direction                 identityref
          |  +--ro packet-loss-count?          uint32
          |  +--ro loss-ratio?                 percentage
          |  +--ro packet-reorder-count?       uint32
          |  +--ro packets-out-of-seq-count?   uint32
          |  +--ro packets-dup-count?          uint32
          +--ro delay-statistics
          |  +--ro direction?       identityref
          |  +--ro min-delay-value?       uint32
          |  +--ro max-delay-value?       uint32
          |  +--ro average-delay-value?   uint32
          +--ro jitter-statistics
             +--ro direction?             identityref
             +--ro min-jitter-value?       uint32
             +--ro max-jitter-value?       uint32
             +--ro average-jitter-value?   uint32

         Link and Termination point Level View of the hierarchies

   The VPN service performance monitoring model defines only the
   following minimal set of Link level service topology attributes:

      Loss Statistics: A set of loss statistics attributes that are used
      to measure end to end loss between VPN sites.

      Delay Statistics: A set of delay statistics attributes that are
      used to measure end to end latency between VPN sites.

      Jitter Statistics: A set of jitter statistics attributes that are
      used to measure end to end jitter between VPN sites.

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7.  Example of I2RS Pub/Sub Retrieval

   This example shows the way for a client to subscribe for the
   Performance monitoring information for VPN service between VPN sites.
   The performance monitoring parameter that the client is interested in
   is end to end loss attribute.

   <rpc netconf:message-id="101"
       xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
       <establish-subscription
          xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications">
          <stream-subtree-filter>
             <networks xmlns="urn:ietf:params:xml:ns:yang:ietf-network-topo">
                <network>
                 <network-id>vpn1</network-id>
                  <node>
                   <node-id>A</node-id>
                   <node-type xmlns="urn:ietf:params:xml:ns:yang:ietf-svc-topo">pe</node-type>
                  </node>
                  <node>
                   <node-id>B</node-id>
                   <node-type xmlns="urn:ietf:params:xml:ns:yang:ietf-svc-topo">pe</node-type>
                  </node>
                  <link xmlns="urn:ietf:params:xml:ns:yang:ietf-network-topology">
                   <link-id>A-B</link-id>
                   <source>
                    <source-node>A</source-node>
                   </source>
                   <destination>
                    <dest-node>B</dest-node>
                   </destination>
                    <svc-telemetry-attributes
                     xmlns="urn:ietf:params:xml:ns:yang:ietf-svc-topo">
                     <loss-statistics>
                      <packet-loss-count/>
                     </loss-statistics>
                    </svc-telemetry-attributes>
                   </link>
                </network>
             </networks>
          </stream-subtree-filter>
          <period xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-push:1.0">500</period>
       </establish-subscription>
    </rpc>

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8.  Example of RPC model based Retrieval

   This example shows the way for the client to use RPC model to fetch
   performance data on demand,e.g., the client requests packet-loss-
   count between PE1 in site 1 and PE2 in site 2 belonging to VPN1.

   <rpc xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"
        message-id="1">
     <report xmlns="urn:ietf:params:xml:ns:yang:example-service-pm-report">
      <networks xmlns="urn:ietf:params:xml:ns:yang:ietf-network-topo">
        <network>
          <network-id>vpn1</network-id>
          <node>
              <node-id>A</node-id>
              <node-type xmlns="urn:ietf:params:xml:ns:yang:ietf-svc-topo">pe</node-type>
         </node>
         <node>
            <node-id>B</node-id>
            <node-type xmlns="urn:ietf:params:xml:ns:yang:ietf-svc-topo">pe</node-type>
         </node>
         <link-id>A-B</link-id>
            <source>
            <source-node>A</source-node>
            </source>
            <destination>
            <dest-node>B</dest-node>
             </destination>
             <svc-telemetry-attributes xmlns="urn:ietf:params:xml:ns:yang:ietf-svc-topo">
             <loss-statistics>
               <packet-loss-count/>
               </loss-statistics>
             </svc-telemetry-attributes>
         </link>
     </report>
   </rpc>

9.  VPN Service Assurance YANG Module

<CODE BEGINS> file "ietf-vpn-svc-pm.yang"
module ietf-vpn-svc-pm {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:ietf-vpn-svc-pm";
  prefix svc-topo;
  import ietf-network {
    prefix nw;
  }
  import ietf-network-topology {
    prefix nt;

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  }
  import ietf-l3vpn-svc {
   prefix l3vpn-svc;
  }
  organization
    "IETF xxx Working Group";
  contact
    "Zitao Wang: wangzitao@huawei.com
     Qin Wu: bill.wu@huawei.com";
  description
    "This module defines a model for the service topology.";

  revision 2018-08-29 {
    description
      "Initial revision.";
    reference "foo";
  }

  identity service-type {
    description
      "Base type for service topology";
  }

  identity l3vpn-svc {
    base service-type;
    description
      "Indentity for layer3 vpn service";
  }

  identity l2vpn-svc {
    base service-type;
    description
      "Identity for layer2 vpn service";
  }

  identity node-type {
    description
      "Base identity for node type";
  }

  identity pe {
    base node-type;
    description
      "Identity for PE type";
  }

  identity ce {
    base node-type;

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    description
      "Identity for CE type";
  }

  identity asbr {
    base node-type;
    description
      "Identity for ASBR type";
  }

  identity p {
    base node-type;
    description
      "Identity for P type";
  }

  identity direction {
    description
      "Base Identity for measurement direction including
       one way measurement and two way measurement.";
  }

  identity oneway {
    base direction;
    description
      "Identity for one way measurement.";
  }

  identity twoway {
    base direction;
    description
      "Identity for two way measurement.";
  }

  typedef percentage {
    type decimal64 {
      fraction-digits 5;
      range "0..100";
    }
    description
      "Percentage.";
  }

  grouping link-error-statistics {
    description
      "Grouping for per link error statistics";
    container loss-statistics {
      description

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        "Per link loss statistics.";
       leaf direction {
        type identityref {
          base direction;
        }
        default "oneway";
        description
          "Define measurement direction including one way
           measurement and two way measurement.";
      }
      leaf packet-loss-count {
        type uint32 {
          range "0..4294967295";
        }
        default "0";
        description
          "Total received packet drops count.
           The value of count will be set to zero (0)
           on creation and will thereafter increase
           monotonically until it reaches a maximum value
           of 2^32-1 (4294967295 decimal), when it wraps
           around and starts increasing again from zero.";
      }
      leaf loss-ratio {
        type percentage;
        description
          "Loss ratio of the packets. Express as percentage
           of packets lost with respect to packets sent.";
      }
      leaf packet-reorder-count {
        type uint32 {
          range "0..4294967295";
        }
        default "0";
        description
          "Total received packet reordered count.
           The value of count will be set to zero (0)
           on creation and will thereafter increase
           monotonically until it reaches a maximum value
           of 2^32-1 (4294967295 decimal), when it wraps
           around and starts increasing again from zero.";
      }
      leaf packets-out-of-seq-count {
        type uint32 {
          range "0..4294967295";
        }
        description
          "Total received out of sequence count.

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           The value of count will be set to zero (0)
           on creation and will thereafter increase
           monotonically until it reaches a maximum value
           of 2^32-1 (4294967295 decimal), when it wraps
           around and starts increasing again from zero..";
      }
      leaf packets-dup-count {
        type uint32 {
          range "0..4294967295";
        }
        description
          "Total received packet duplicates count.
           The value of count will be set to zero (0)
           on creation and will thereafter increase
           monotonically until it reaches a maximum value
           of 2^32-1 (4294967295 decimal), when it wraps
           around and starts increasing again from zero.";
      }
    }
  }

  grouping link-delay-statistics {
    description
      "Grouping for per link delay statistics";
    container delay-statistics {
      description
        "Link delay summarised information. By default,
         one way measurement protocol (e.g., OWAMP) is used
         to measure delay.";
      leaf direction {
        type identityref {
          base direction;
        }
        default "oneway";
        description
          "Define measurement direction including one way
           measurement and two way measurement.";
      }
      leaf min-delay-value {
        type uint32;
        description
          "Minimum delay value observed.";
      }
      leaf max-delay-value {
        type uint32;
        description
          "Maximum delay value observed.";
      }

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      leaf average-delay-value {
        type uint32;
        description
          "Average delay value observed.";
      }
    }
  }

  grouping link-jitter-statistics {
    description
      "Grouping for per link jitter statistics";
    container jitter-statistics {
      description
        "Link jitter summarised information. By default,
         jitter is measured using IP Packet Delay Variation
         (IPDV) as defined in RFC3393.";
      leaf direction {
        type identityref {
          base direction;
        }
        default "oneway";
        description
          "Define measurement direction including one way
           measurement and two way measurement.";
      }
      leaf min-jitter-value {
        type uint32;
        description
          "Minimum jitter value observed.";
      }
      leaf max-jitter-value {
        type uint32;
        description
          "Maximum jitter value observed.";
      }
      leaf average-jitter-value {
        type uint32;
        description
          "Average jitter value observed.";
      }
    }
  }

  augment "/nw:networks/nw:network/nw:network-types" {
    description
      "Augment the network-types with service topologyies types";
    leaf svc-topo-type {
      type identityref {

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        base service-type;
      }
      description
        "Identify the topology type to be composited service topology";
    }
  }
  augment "/nw:networks/nw:network" {
    description
      "Augment the network with service topology attributes";
    container svc-topo-attributes {
      leaf vpn-topology {
        type identityref {
          base l3vpn-svc:vpn-topology;
        }
        description
          "VPN service topology, e.g. hub-spoke, any-to-any, hub-spoke-disjoint, etc";
      }
      description
        "Container for vpn services";
    }
  }
  augment "/nw:networks/nw:network/nw:node" {
    description
      "Augment the network node with serice attributes";
    container node-attributes {
      leaf node-type {
        type identityref {
          base node-type;
        }
        description
          "Node type, e.g. PE, P, ASBR, etc";
      }
      leaf site-id {
        type string;
        description
          "Asscoiated vpn site";
      }
      leaf site-role {
        type identityref {
          base l3vpn-svc:site-role;
        }
        default "l3vpn-svc:any-to-any-role";
        description
          "Role of the site in the IP VPN.";
      }
      description
        "Container for service topology attributes";
    }

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  }
  augment "/nw:networks/nw:network/nt:link" {
    description
      "Augment the network topology link with vpn service attributes";
    container svc-telemetry-attributes {
      config false;
      uses link-error-statistics;
      uses link-delay-statistics;
      uses link-jitter-statistics;
      description
        "Container for service telemetry attributes";
    }
  }
}
<CODE ENDS>

10.  Security Considerations

   The YANG modules defined in this document MAY be accessed via the
   RESTCONF protocol [RFC8040] or NETCONF protocol ([RFC6241]).  The
   lowest RESTCONF or NETCONF layer requires that the transport-layer
   protocol provides both data integrity and confidentiality, see
   Section 2 in [RFC8040] and [RFC6241].  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
   [RFC5246].

   The NETCONF access control model [RFC6536] 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:

   o  /ni:network-instances/ni:network-instance/svc-topo:svc-telemetry-
      attributes

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11.  IANA Considerations

   This document registers a URI in the IETF XML registry [RFC3688].
   Following the format in [RFC3688], the following registration is
   requested to be made:

   ---------------------------------------------------------------------
      URI: urn:ietf:params:xml:ns:yang:ietf-vpn-svc-pm

      Registrant Contact: The IESG.

      XML: N/A, the requested URI is an XML namespace.
   ---------------------------------------------------------------------

   This document registers a YANG module in the YANG Module Names
   registry [RFC6020].

   ---------------------------------------------------------------------
      Name:         ietf-vpn-svc-pm
      Namespace:    urn:ietf:params:xml:ns:yang:ietf-vpn-svc-pm
      Prefix:       vnrsc
      Reference:    RFC xxxx
   ---------------------------------------------------------------------

12.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", March 1997.

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

   [RFC5440]  Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
              Element (PCE) Communication Protocol (PCEP)", RFC 5440,
              DOI 10.17487/RFC5440, March 2009,
              <https://www.rfc-editor.org/info/rfc5440>.

   [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/info/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/info/rfc6241>.

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

   [RFC6370]  Bocci, M., Swallow, G., and E. Gray, "MPLS Transport
              Profile (MPLS-TP) Identifiers", RFC 6370,
              DOI 10.17487/RFC6370, September 2011,
              <https://www.rfc-editor.org/info/rfc6370>.

   [RFC6374]  Frost, D. and S. Bryant, "Packet Loss and Delay
              Measurement for MPLS Networks", RFC 6374,
              DOI 10.17487/RFC6374, September 2011,
              <https://www.rfc-editor.org/info/rfc6374>.

   [RFC6536]  Bierman, A. and M. Bjorklund, "Network Configuration
              Protocol (NETCONF) Access Control Model", RFC 6536,
              DOI 10.17487/RFC6536, March 2012,
              <https://www.rfc-editor.org/info/rfc6536>.

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

   [RFC7952]  Lhotka, L., "Defining and Using Metadata with YANG",
              RFC 7952, DOI 10.17487/RFC7952, August 2016,
              <https://www.rfc-editor.org/info/rfc7952>.

   [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/info/rfc8345>.

Authors' Addresses

   Michael Wang
   Huawei Technologies,Co.,Ltd
   101 Software Avenue, Yuhua District
   Nanjing  210012
   China

   Email: wangzitao@huawei.com

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   Qin Wu
   Huawei
   101 Software Avenue, Yuhua District
   Nanjing, Jiangsu  210012
   China

   Email: bill.wu@huawei.com

   Roni Even
   Huawei Technologies,Co.,Ltd
   Tel Aviv
   Israel

   Email: roni.even@huawei.com

   Bin Wen
   Comcast

   Email: bin_wen@comcast.com

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