Internet Engineering Task Force (IETF)                          D. Kumar
Request for Comments: 8533                                         Cisco
Category: Standards Track                                        M. Wang
ISSN: 2070-1721                                               Q. Wu, Ed.
                                                                  Huawei
                                                               R. Rahman
                                                             S. Raghavan
                                                                   Cisco
                                                              April 2019

     A YANG Data Model for Retrieval Methods for the Management of
      Operations, Administration, and Maintenance (OAM) Protocols
                 That Use Connectionless Communications

Abstract

   This document presents a retrieval method YANG data model for
   connectionless Operations, Administration, and Maintenance (OAM)
   protocols.  It provides technology-independent RPC operations for OAM
   protocols that use connectionless communication.  The retrieval
   methods model herein presented can be extended to include technology-
   specific details.  There are two key benefits of this approach:
   First, it leads to uniformity between OAM protocols.  Second, it
   supports both nested OAM workflows (i.e., performing OAM functions at
   different or the same levels through a unified interface) as well as
   interactive OAM workflows (i.e., performing OAM functions at the same
   levels through a unified interface).

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8533.

Copyright Notice

   Copyright (c) 2019 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 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.

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Conventions Used in This document . . . . . . . . . . . . . .   3
     2.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   4
     2.2.  Tree Diagrams . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Overview of the Connectionless OAM Retrieval Methods Model  .   4
     3.1.  RPC Operation Definitions . . . . . . . . . . . . . . . .   4
     3.2.  OAM Retrieval Methods Hierarchy . . . . . . . . . . . . .   7
   4.  OAM Retrieval Methods YANG Module . . . . . . . . . . . . . .  16
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  26
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  26
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  27
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  27
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  28
   Appendix A.  Extending Connectionless OAM Method Module Example .  29
     A.1.  Example of New Retrieval Procedures Model . . . . . . . .  29
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .  40
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  41

1. Introduction

   Operations, Administration, and Maintenance (OAM) are important
   networking functions that allow operators to:

   1.  monitor network communications (i.e., reachability verification
       and Continuity Check)

2. troubleshoot failures (i.e., fault verification and localization)

3. monitor service-level agreements and performance (i.e.,
performance management)

   An overview of OAM tools is presented in [RFC7276].

   Ping and Traceroute [RFC4443], as well as Bidirectional Forwarding
   Detection (BFD) [RFC5880], are well-known fault verification and
   isolation tools, respectively, for IP networks [RFC792].  Over the
   years, different technologies have developed similar toolsets for
   equivalent purposes.

   This document presents an on-demand retrieval method YANG data model
   for OAM protocols that use connectionless communication.  This model
   provides technology-independent RPC operations for OAM protocols that
   use connectionless communication (i.e., connectionless OAM).  It is
   separated from the generic YANG data model for connectionless OAM
   [RFC8532] and can avoid mixing the models for the retrieved data from
   the retrieval procedures.  It is expected that retrieval procedures
   will evolve faster than the data model [RFC8532] and will allow new
   procedures to be defined for retrieval of the same data defined by
   the generic YANG data model for connectionless OAM.

2.  Conventions Used in This document

   The following terms are defined in [RFC6241] and are used in this
   document:

   o  client

   o  configuration data

   o  server

   o  state data

   The following terms are defined in [RFC6020] and are used in this
   document:

   o  augment

   o  data model

   o  data node

   The terminology for describing YANG data models is found in
   [RFC6020].

2.1. Terminology

   TP - Test Point

   MAC - Media Access Control

   RPC - Remote Procedure Call

   RPC Operation - A specific Remote Procedure Call

2.2. Tree Diagrams

   Tree diagrams used in this document follow the notation defined in
   [RFC8340].

3.  Overview of the Connectionless OAM Retrieval Methods Model

   This document describes an on-demand retrieval method YANG data model
   for OAM protocols that use connectionless communication.  This model
   provides technology-independent retrieval procedures (RPC operations)
   for connectionless OAM protocols.  It provides a flexible way to
   retrieve the data that is defined by the "ietf-connectionless-
   oam.yang" module [RFC8532].

3.1. RPC Operation Definitions

   The RPC model facilitates issuing commands to a Network Configuration
   Protocol (NETCONF) server (in this case to the device that needs to
   execute the OAM command) and obtaining a response.

   Under the "connectionless-oam-methods" module, we summarize common
   OAM functions and define two generic RPC operations: 'continuity-
   check' and 'path-discovery'.  In practice, these RPC operations are
   activated on demand and are supported by corresponding technology-
   specific OAM tools [RFC7276].  For example, for the IP OAM model, the
   Continuity Check RPC corresponds to the IP Ping [RFC792] [RFC4443],

   while the path discovery RPC operation corresponds to IP Traceroute
   [RFC792] [RFC4443].

   Note that the RPC operation presented in this document is the base
   building block, which is used to derive a model for a technology-
   specific OAM (i.e., ICMP Ping [RFC792] [RFC4443] and Label Switched
   Path (LSP) Ping [RFC8029]).  This base building block should be
   extended with corresponding technology-specific parameters.  To
   facilitate this for future enhancements to data retrieval methods,
   the RPCs are captured under a separate module.

   The generic 'tp-address' grouping is used as data input from
   different RPCs described in this document.  The generic 'path-
   discovery-data' and 'continuity-check-data' groupings defined by the
   "ietf-connectionless-oam.yang" module [RFC8532] are used as data
   outputs from different RPCs described in this document.  Similar
   methods, including other RPCs, can retrieve the data using the same
   data model (i.e., the "ietf-connectionless-oam.yang" module).

        rpc continuity-check {
         if-feature cl-oam:continuity-check;
         description
           "Continuity Check RPC operation as per RFC 7276.";
         reference
           "RFC 7276: An Overview of Operations, Administration, and
            Maintenance (OAM) Tools";
         input {
         uses rpc-input-parameters;
         ....
         }
       output {
         container response-info {
           leaf protocol-id {
             type identityref {
               base protocol-id;
             }
             mandatory true;
             description
               "Protocol used in the Continuity Check. ";
           }
           leaf protocol-id-meta-data {
              type identityref {
               base protocol-id-meta-data;
               }
                description
                "An optional metadata related to the protocol ID.";
           }
           leaf status-code {

             type identityref{
            base status-code;
          }
             mandatory true;
             description
               "Status code for Continuity Check RPC operation.";
           }
           leaf status-sub-code {
             type identityref{
             base status-sub-code;
          }
             mandatory true;
             description
               "Status-sub-code for Continuity Check RPC operation.";
           }
           description
             "Status code and status-sub-code for Continuity Check RPC
              operation.";
         }
         uses cl-oam:continuity-check-data;
       }
     }

       rpc path-discovery {
         description
           "Path discovery RPC operation as per RFC 7276.";
         reference
           "RFC 7276: An Overview of Operations, Administration, and
            Maintenance (OAM) Tools";
         input {
         uses rpc-input-parameters;
         .....
         }
       output {
         list response-list {
           key "response-index";
           description
             "Path discovery response list.";
           leaf response-index {
             type uint32;
             mandatory true;
             description
               "Response index.";
           }
           leaf protocol-id {
             type identityref {
               base protocol-id;
             }

             mandatory true;
             description
               "Protocol used in path discovery. ";
           }
           leaf protocol-id-meta-data {
              type identityref {
               base protocol-id-meta-data;
               }
                description
                "An optional metadata related to the protocol ID.";
           }
           leaf status-code {
             type identityref{
             base status-code;
           }
             mandatory true;
             description
               "Status code for path discovery RPC operation. ";
           }
           leaf status-sub-code {
             type identityref{
             base status-sub-code;
          }
             mandatory true;
             description
               "Status-sub-code for path discovery RPC operation. ";
           }
         }
         uses cl-oam:path-discovery-data;
       }
     }

            Snippet of Data Hierarchy Related to RPC Operations

3.2. OAM Retrieval Methods Hierarchy

   The complete data hierarchy related to the Connectionless OAM
   Retrieval Methods YANG data model is presented below.

   module: ietf-connectionless-oam-methods

     rpcs:
       +---x continuity-check {cl-oam:continuity-check}?
       |  +---w input
       |  |  +---w destination-tp
       |  |  |  +---w tp-location-type    identityref
       |  |  |  +---w mac-address
       |  |  |  |  +---w mac-address    yang:mac-address

       |     +--ro hop-cnt?                     uint8
       |     +--ro session-packet-statistics
       |     |  +--ro rx-packet-count?    uint32
       |     |  +--ro tx-packet-count?    uint32
       |     |  +--ro rx-bad-packet?      uint32
       |     |  +--ro tx-packet-failed?   uint32
       |     +--ro session-error-statistics
       |     |  +--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 session-delay-statistics
       |     |  +--ro time-unit-value?       identityref
       |     |  +--ro min-delay-value?       uint32
       |     |  +--ro max-delay-value?       uint32
       |     |  +--ro average-delay-value?   uint32
       |     +--ro session-jitter-statistics
       |        +--ro unit-value?             identityref
       |        +--ro min-jitter-value?       uint32
       |        +--ro max-jitter-value?       uint32
       |        +--ro average-jitter-value?   uint32
       +---x path-discovery {cl-oam:path-discovery}?
          +---w input
          |  +---w destination-tp
          |  |  +---w tp-location-type    identityref
          |  |  +---w mac-address
          |  |  |  +---w mac-address    yang:mac-address
          |  |  +---w ipv4-address
          |  |  |  +---w ipv4-address    inet:ipv4-address
          |  |  +---w ipv6-address
          |  |  |  +---w ipv6-address    inet:ipv6-address
          |  |  +---w tp-attribute
          |  |  |  +---w tp-attribute-type?
          |  |  |  |       address-attribute-type
          |  |  |  +---w (tp-attribute-value)?
          |  |  |     +--:(ip-prefix)
          |  |  |     |  +---w ip-prefix?
          |  |  |     |          inet:ip-prefix
          |  |  |     +--:(bgp)
          |  |  |     |  +---w bgp?
          |  |  |     |          inet:ip-prefix
          |  |  |     +--:(tunnel)
          |  |  |     |  +---w tunnel-interface?         uint32
          |  |  |     +--:(pw)
          |  |  |     |  +---w remote-pe-address?
          |  |  |     |  |       inet:ip-address
          |  |  |     |  +---w pw-id?                    uint32

                   |           |          inet:ip-address
                   |           +--:(vpn)
                   |           |  +--ro as-number?
                   |           |          inet:as-number
                   |           +--:(global-id)
                   |              +--ro lsp-id?
                   |                      string
                   +--ro system-info
                   |  +--ro router-id?   rt:router-id
                   +--ro timestamp-type?         identityref
                   +--ro timestamp-64bit
                   |  +--ro timestamp-sec?       uint32
                   |  +--ro timestamp-nanosec?   uint32
                   +--ro timestamp-80bit {ptp-long-format}?
                   |  +--ro timestamp-sec?       uint64
                   |  +--ro timestamp-nanosec?   uint32
                   +--ro ntp-timestamp-32bit
                   |       {ntp-short-format}?
                   |  +--ro timestamp-sec?       uint16
                   |  +--ro timestamp-nanosec?   uint16
                   +--ro icmp-timestamp-32bit {icmp-timestamp}?
                   |  +--ro timestamp-millisec?   uint32
                   +--ro ingress-intf-name?
                   |       if:interface-ref
                   +--ro egress-intf-name?
                   |       if:interface-ref
                   +--ro queue-depth?            uint32
                   +--ro transit-delay?          uint32
                   +--ro app-meta-data?          uint64

                  Data Hierarchy of OAM Retrieval Methods

4. OAM Retrieval Methods YANG Module

   <CODE BEGINS> file
      "ietf-connectionless-oam-methods@2019-04-16.yang"

module ietf-connectionless-oam-methods {
  namespace
    "urn:ietf:params:xml:ns:yang:ietf-connectionless-oam-methods";
  prefix cloam-methods;

  import ietf-interfaces {
    prefix if;
  }
  import ietf-connectionless-oam {
    prefix cl-oam;
  }

  organization
    "IETF LIME Working Group";
  contact
    "WG Web:   <https://datatracker.ietf.org/wg/lime>
     WG List:  <mailto:lmap@ietf.org>

     Deepak Kumar <dekumar@cisco.com>
     Qin Wu <bill.wu@huawei.com>
     Srihari Raghavan <rihari@cisco.com>
     Michael Wang <wangzitao@huawei.com>
     Reshad Rahman <rrahman@cisco.com>";
  description
    "This YANG module defines the RPC operations for
     connectionless OAM to be used within the IETF
     in a protocol-independent manner.  It is
     assumed that each protocol maps corresponding
     abstracts to its native format.  Each protocol
     may extend the YANG data model defined here to
     include protocol-specific extensions.

     Copyright (c) 2019 IETF Trust and the persons identified as
     authors of the code.  All rights reserved.

     Redistribution and use in source and binary forms, with or
     without modification, is permitted pursuant to, and subject
     to the license terms contained in, the Simplified BSD License
     set forth in Section 4.c of the IETF Trust's Legal Provisions
     Relating to IETF Documents
     (http://trustee.ietf.org/license-info).

     This version of this YANG module is part of RFC 8533; see
     the RFC itself for full legal notices.";

  revision 2019-04-16 {
    description
      "Initial revision.";
    reference
      "RFC 8533: Retrieval Methods YANG Data Model for the Management
       of Operations, Administration, and Maintenance (OAM)
       Protocols That Use Connectionless Communications";
  }

  identity protocol-id {
    description
      "This is the base identity for a generic protocol
       ID.  The protocol registry can be found at
       https://www.iana.org/protocols.";
  }

  identity protocol-id-internet {
    base protocol-id;
    description
      "Identity for Internet Protocols.";
  }

  identity protocol-id-proprietary {
    base protocol-id;
    description
      "Identity for proprietary protocols (e.g.,
       IP SLA).";
  }

  identity protocol-id-sfc {
    base protocol-id;
    description
      "Identity for Service Function Chaining.";
  }

  identity protocol-id-mpls {
    base protocol-id;
    description
      "The MPLS protocol.";
  }

  identity protocol-id-mpls-tp {
    base protocol-id;
    description
      "The MPLS-TP protocol.";
  }

  identity protocol-id-twamp {
    base protocol-id;
    description
      "The Two-Way Active Measurement Protocol (TWAMP)
       protocol.";
  }

  identity protocol-id-bier {
    base protocol-id;
    description
      "The Bit Index Explicit Replication (BIER)
       protocol.";
  }

  identity status-code {
    description
      "This is base identity for a status code.";

  }

  identity success-reach {
    base status-code;
    description
      "Indicates that the destination being verified
       is reachable (see RFC 7276).";
    reference
      "RFC 7276: An Overview of Operations, Administration, and
       Maintenance (OAM) Tools";
  }

  identity fail-reach {
    base status-code;
    description
      "Indicates that the destination being verified
       is not reachable (see RFC 7276).";
    reference
      "RFC 7276: An Overview of Operations, Administration, and
       Maintenance (OAM) Tools";
  }

  identity success-path-verification {
    base status-code;
    description
      "Indicates that the path verification is performed
       successfully (see RFC 7276).";
    reference
      "RFC 7276: An Overview of Operations, Administration, and
       Maintenance (OAM) Tools";
  }

  identity fail-path-verification {
    base status-code;
    description
      "Indicates that the path verification fails
       (see RFC 7276).";
    reference
      "RFC 7276: An Overview of Operations, Administration, and
       Maintenance (OAM) Tools";
  }

  identity status-sub-code {
    description
      "IdentityBase status-sub-code.";
  }

  identity invalid-cc {

    base status-sub-code;
    description
      "Indicates that the Continuity Check message is invalid
       (see RFC 7276).";
    reference
      "RFC 7276: An Overview of Operations, Administration, and
       Maintenance (OAM) Tools";
  }

  identity invalid-pd {
    base status-sub-code;
    description
      "Indicates that the path discovery message is invalid
       (see RFC 7276).";
    reference
      "RFC 7276: An Overview of Operations, Administration, and
       Maintenance (OAM) Tools";
  }

  identity protocol-id-meta-data {
    description
      "This is the base identity for metadata that corresponds
       to the protocol ID.";
  }

  identity protocol-internet-number {
    base protocol-id-meta-data;
    description
      "Internet Protocol number for standard
       Internet Protocols (IANA-assigned Internet
       Protocol numbers) to help in protocol processing.
       The Protocol Numbers registry can be found at
       https://www.iana.org/assignments/protocol-numbers.";
  }

  grouping rpc-input-parameters {
    container destination-tp {
      uses cl-oam:tp-address;
      description
        "Destination test point.";
    }
    leaf source-interface {
      type if:interface-ref;
      mandatory true;
      description
        "Source interface.";
    }
    leaf outbound-interface {

      type if:interface-ref;
      mandatory true;
      description
        "Outbound interface.";
    }
    leaf vrf {
      type cl-oam:routing-instance-ref;
      description
        "Virtual Routing and Forwarding (VRF) instance.";
    }
    description
      "Grouping for RPC input parameters";
  }

  rpc continuity-check {
    if-feature "cl-oam:continuity-check";
    description
      "Continuity Check RPC operation as per RFC 7276.";
    reference
      "RFC 7276: An Overview of Operations, Administration, and
       Maintenance (OAM) Tools";
    input {
      uses rpc-input-parameters;
      uses cl-oam:session-type {
        description
          "If session-type is specified, then session-type
              must be set to on demand";
      }
      leaf count {
        type uint32 {
          range "0..4294967295" {
            description
              "The overall number of packets to be transmitted
               by the sender.  The value of the 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.";
          }
        }
        default "5";
        description
          "Specifies the number of
           packets that will be sent.  By
           default, the packet number is
           set to 5.";
      }
      leaf ttl {

        type uint8;
        default "255";
        description
          "Time to live (TTL) used to limit the lifetime
           of data packets transmitted in the network
           to prevent looping.  The TTL value is decremented
           for every hop that the packet traverses.  If the
           TTL is zero, the data packet will be discarded.";
      }
      leaf packet-size {
        type uint32 {
          range "64..10000";
        }
        default "64";
        description
          "Packet size of the Continuity Check message, in octets.
           By default, the packet size is set to 64 octets.";
      }
    }
    output {
      container response-info {
        leaf protocol-id {
          type identityref {
            base protocol-id;
          }
          mandatory true;
          description
            "Protocol used in the Continuity Check message.
             This could be a standard protocol (e.g.,
             TCP/IP protocols, MPLS, etc.) or a proprietary
             protocol as identified by this field.";
        }
        leaf protocol-id-meta-data {
          type identityref {
            base protocol-id-meta-data;
          }
          description
            "An optional metadata related to the protocol ID.
             For example, this could be the Internet Protocol
             number for standard Internet Protocols used for
             help with protocol processing.";
        }
        leaf status-code {
          type identityref {
            base status-code;
          }
          mandatory true;
          description

            "Status code for Continuity Check RPC operation.
             This could be a basic status code (e.g., destination
             is reachable or destination is not reachable; see RFC 7276)
             or some customized status code as identified by this
             field.";
          reference
            "RFC 7276: An Overview of Operations, Administration, and
             Maintenance (OAM) Tools";
        }
        leaf status-sub-code {
          type identityref {
            base status-sub-code;
          }
          mandatory true;
          description
            "An optional status-sub-code for Continuity Check
             RPC operation.  If the basic status code is destination
             reachable, this status-sub-code doesn't need to be
             specified.  If the basic status code is destination
             unreachable, the status-sub-code can be used to specify
             the detailed reasons.  This could be a basic
             sub-status-code (such as an invalid Continuity Check) or
             other error codes specific to the protocol under use for
             the Continuity Checks.  For example, if ICMP is the
             protocol under use, the error codes defined in RFC 4443
             can be used to specify the reasons specific to ICMP.
             This technology-specific status-sub-code can be
             defined in technology-specific models.";
          reference
            "RFC 4443: The IETF Administrative Oversight Committee
             (IAOC) Member Selection Guidelines and Process.";
        }
        description
          "Status code and status-sub-code for Continuity Check RPC
           operation.";
      }
      uses cl-oam:continuity-check-data;
    }
  }

  rpc path-discovery {
    if-feature "cl-oam:path-discovery";
    description
      "Path discovery RPC operation as per RFC 7276.";
    reference
      "RFC 7276: An Overview of Operations, Administration, and
       Maintenance (OAM) Tools";
    input {

      uses rpc-input-parameters;
      uses cl-oam:session-type {
        description
          "If session-type is specified, then session-type
            must be set to on demand";
      }
      leaf max-ttl {
        type uint8;
        default "255";
        description
          "Maximum TTL indicates the maximum number of hops that
           a packet is permitted to travel before being discarded
           by a router.  By default, the maximum TTL is set to
           255.";
      }
    }
    output {
      list response-list {
        key "response-index";
        description
          "Path discovery response list.";
        leaf response-index {
          type uint32;
          mandatory true;
          description
            "Response index.";
        }
        leaf protocol-id {
          type identityref {
            base protocol-id;
          }
          mandatory true;
          description
            "Protocol used in path discovery.  This could be a
             standard protocol (e.g., TCP/IP protocols, MPLS, etc.)
             or a proprietary protocol as identified by
             this field.";
        }
        leaf protocol-id-meta-data {
          type identityref {
            base protocol-id-meta-data;
          }
          description
            "An optional metadata related to the protocol ID.
             For example, this could be the Internet Protocol
             number for standard Internet Protocols used for
             help with protocol processing.";
        }

        leaf status-code {
          type identityref {
            base status-code;
          }
          mandatory true;
          description
            "Status code for Continuity Check RPC operation.
             This could be a basic status code (e.g., destination
             is reachable or destination is not reachable) or some
             customized status code as identified by this field.";
        }
        leaf status-sub-code {
          type identityref {
            base status-sub-code;
          }
          mandatory true;
          description
            "An optional status-sub-code for Continuity Check
             RPC operation.  If the basic status code is destination
             reachable, this status-sub-code doesn't need to be
             specified.  If the basic status code is destination
             unreachable, the status-sub-code can be used to specify
             the detailed reasons.  This could be a basic
             sub-status-code (such as an invalid Continuity Check) or
             other error codes specific to the protocol under use for
             Continuity Checks.  For example, if ICMP is the protocol
             under use, the error codes defined in RFC 4443
             can be used to specify the reasons specific to ICMP.
             This technology-specific status-sub-code can be defined
             in technology-specific models.";
          reference
            "RFC 4443: The IETF Administrative Oversight Committee
             (IAOC) Member Selection Guidelines and Process.";
        }
      }
      uses cl-oam:path-discovery-data;
    }
  }
}

<CODE ENDS>

5. Security Considerations

   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 [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.

   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:

   o  continuity-check: Generates Continuity Check.

   o  path-discovery: Generates path discovery.

   These operations are used to retrieve the data from the device that
   needs to execute the OAM command.  Unauthorized source access to some
   sensitive information in the above data may be used for network
   reconnaissance or lead to denial-of-service attacks on both the local
   device and the network.

6. IANA Considerations

   This document registers a URI in the "IETF XML Registry" [RFC3688].
   The following registration has been made:

   URI: urn:ietf:params:xml:ns:yang:ietf-connectionless-oam-methods
   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-connectionless-oam-methods
   namespace:
      urn:ietf:params:xml:ns:yang:ietf-connectionless-oam-methods
   prefix: cloam-methods
   reference: RFC 8533

7. References

7.1. Normative References

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

   [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>.

   [RFC7011]  Claise, B., Ed., Trammell, B., Ed., and P. Aitken,
              "Specification of the IP Flow Information Export (IPFIX)
              Protocol for the Exchange of Flow Information", STD 77,
              RFC 7011, DOI 10.17487/RFC7011, September 2013,
              <https://www.rfc-editor.org/info/rfc7011>.

   [RFC792]   Postel, J., "Internet Control Message Protocol", STD 5,
              RFC 792, DOI 10.17487/RFC0792, September 1981.

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

   [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/info/rfc8341>.

   [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/info/rfc8446>.

   [RFC8532]  Kumar, D., Wang, M., Wu, Q., Ed., Rahman, R., and
              S. Raghavan, "Generic YANG Data Model for the Management of
              Operations, Administration, and Maintenance (OAM)
              Protocols That Use Connectionless Communications",
              RFC 8532, DOI 10.17487/RFC8532, April 2019,
              <https://www.rfc-editor.org/info/rfc8532>.

7.2. Informative References

   [RFC4443]  Conta, A., Deering, S., and M. Gupta, Ed., "Internet
              Control Message Protocol (ICMPv6) for the Internet
              Protocol Version 6 (IPv6) Specification", STD 89,
              RFC 4443, DOI 10.17487/RFC4443, March 2006,
              <https://www.rfc-editor.org/info/rfc4443>.

   [RFC5880]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
              (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
              <https://www.rfc-editor.org/info/rfc5880>.

   [RFC7276]  Mizrahi, T., Sprecher, N., Bellagamba, E., and Y.
              Weingarten, "An Overview of Operations, Administration,
              and Maintenance (OAM) Tools", RFC 7276,
              DOI 10.17487/RFC7276, June 2014,
              <https://www.rfc-editor.org/info/rfc7276>.

   [RFC8029]  Kompella, K., Swallow, G., Pignataro, C., Ed., Kumar, N.,
              Aldrin, S., and M. Chen, "Detecting Multiprotocol Label
              Switched (MPLS) Data-Plane Failures", RFC 8029,
              DOI 10.17487/RFC8029, March 2017,
              <https://www.rfc-editor.org/info/rfc8029>.

   [RFC8340]  Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams", BCP 215,
              RFC 8340, DOI 10.17487/RFC8340, March 2018,
              <https://www.rfc-editor.org/info/rfc8340>.

   [RFC8407]  Bierman, A., "Guidelines for Authors and Reviewers of
              Documents Containing YANG Data Models", BCP 216, RFC 8407,
              DOI 10.17487/RFC8407, October 2018,
              <https://www.rfc-editor.org/info/rfc8407>.

   [YANG-Push]
              Clemm, A., Voit, E., Prieto, A., Tripathy, A., Nilsen-
              Nygaard, E., Bierman, A., and B. Lengyel, "Subscription to
              YANG Datastores", Work in Progress, draft-ietf-netconf-
              yang-push-22, February 2019.

Appendix A. Extending Connectionless OAM Method Module Example

   The following is an example of extensions possible to the
   "ietf-connectionless-oam-methods" YANG data model defined in this document.

   The snippet below depicts an example of augmenting the
   "ietf-connectionless-oam-methods" YANG data model with ICMP ping
   attributes:

   augment "/cloam-methods:continuity-check"
   +"/cloam-methods:output"{
     container session-rtt-statistics{
      leaf min-rtt{
       type uint32;
    description
    "This minimum ping round-trip-time (RTT) received.";
      }
      leaf max-rtt{
       type uint32;
    description
    "This maximum ping RTT received.";
      }
      leaf avg-rtt{
       type uint32;
    description
     "The current average ping RTT.";
      }
      description
      "This container presents the ping RTT statistics.";
     }
   }

A.1. Example of New Retrieval Procedures Model

   As discussed in the Introduction section of this document, the new
   retrieval procedures can be defined for retrieval of the same data
   defined by the base YANG data model for connectionless OAM protocols.
   This appendix demonstrates how the base connectionless OAM data model
   can be extended to support persistent data retrieval besides
   on-demand retrieval procedures defined in Section 3, i.e., first
   retrieve a persistent-id based on the destination test point location
   information, and then retrieve the export details based on
   persistent-id.  Internet Protocol Flow Information Export (IPFIX)
   [RFC7011] or YANG-Push [YANG-Push] are currently outlined here as
   data export options.  Additional export options can be added in the
   future.

   The YANG module "example-cl-oam-persistent-methods" shown below is
   intended as an illustration rather than a real definition of an RPC
   operation model for persistent data retrieval.  For the sake of
   brevity, this module does not obey all the guidelines specified in
   [RFC8407].

   module example-cl-oam-persistent-methods {
     namespace "http://example.com/cl-oam-persistent-methods";
     prefix pcloam-methods;

     import ietf-interfaces {
       prefix if;
     }
     import ietf-connectionless-oam {
       prefix cl-oam;
     }
     import ietf-yang-types {
       prefix yang;
     }

     identity export-method {
       description
         "Base identity to represent a conceptual
          export-method.";
     }

     identity ipfix-export {
       base export-method;
       description
         "IPFIX-based export.  Configuration provided
          separately.";
     }

     identity yang-push-export {
       base export-method;
       description
         "YANG-Push from draft-ietf-netconf-yang-push.";
     }

     identity protocol-id {
       description
         "A generic protocol identifier.";
     }

     identity status-code {
       description
         "Base status code.";
     }

     identity success-reach {
       base status-code;
       description
         "Indicates that the destination being verified
          is reachable.";
     }

     identity fail-reach {
       base status-code;
       description
         "Indicates that the destination being verified
          is not reachable";
     }

     identity success-path-verification {
       base status-code;
       description
         "Indicates that the path verification is performed
          successfully.";
     }

     identity fail-path-verification {
       base status-code;
       description
         "Indicates that the path verification fails.";
     }

     identity status-sub-code {
       description
         "Base status-sub-code.";
     }

     identity invalid-cc {
       base status-sub-code;
       description
         "Indicates that the Continuity Check message is
          invalid.";
     }

     identity invalid-pd {
       base status-sub-code;
       description
         "Indicates that the path discovery message is invalid.";
     }

     typedef export-method {
       type identityref {
         base export-method;

       }
       description
         "Export method type.";
     }

     typedef change-type {
       type enumeration {
         enum create {
           description
             "Change due to a create.";
         }
         enum delete {
           description
             "Change due to a delete.";
         }
         enum modify {
           description
             "Change due to an update.";
         }
       }
       description
         "Different types of changes that may occur.";
     }

     rpc cc-get-persistent-id {
       if-feature "cl-oam:continuity-check";
       description
         "Obtains Continuity Check persistent identification
          given mapping parameters as input.";
       input {
         container destination-tp {
           uses cl-oam:tp-address;
           description
             "Destination test point.";
         }
         uses cl-oam:session-type;
         leaf source-interface {
           type if:interface-ref;
           description
             "Source interface.";
         }
         leaf outbound-interface {
           type if:interface-ref;
           description
             "Outbound interface.";
         }
         leaf vrf {
           type cl-oam:routing-instance-ref;

           description
             "VRF instance.";
         }
       }
       output {
         container error-code {
           leaf protocol-id {
             type identityref {
               base protocol-id;
             }
             mandatory true;
             description
               "Protocol used.  This could be a standard
                protocol (e.g., TCP/IP protocols, MPLS, etc.)
                or a proprietary protocol as identified by
                this field.";
           }
           leaf protocol-id-meta-data {
             type uint64;
             description
               "An optional metadata related to the protocol ID.
                For example, this could be the Internet Protocol
                number for standard Internet Protocols used for
                help with protocol processing.";
           }
           leaf status-code {
             type identityref {
               base status-code;
             }
             mandatory true;
             description
               "Status code.";
           }
           leaf status-sub-code {
             type identityref {
               base status-sub-code;
             }
             mandatory true;
             description
               "Sub code for the Continuity Check.";
           }
           description
             "Status code and sub code.";
         }
         leaf cc-persistent-id {
           type string;
           description
             "Id to act as a cookie.";

         }
       }
     }

     rpc cc-persistent-get-export-details {
       if-feature "cl-oam:continuity-check";
       description
         "Given the persistent ID, gets the configuration
          options and details related to the configured data
          export.";
       input {
         leaf cc-persistent-id {
           type string;
           description
             "Persistent ID for use as a key in search.";
         }
       }
       output {
         container error-code {
           leaf protocol-id {
             type identityref {
               base protocol-id;
             }
             mandatory true;
             description
               "Protocol used.  This could be a standard
                protocol (e.g., TCP/IP protocols, MPLS, etc.)
                or a proprietary protocol as identified by
                this field.";
           }
           leaf protocol-id-meta-data {
             type uint64;
             description
               "An optional metadata related to the protocol ID.
                For example, this could be the Internet Protocol
                number for standard Internet Protocols used for
                help with protocol processing.";
           }
           leaf status-code {
             type identityref {
               base status-code;
             }
             mandatory true;
             description
               "Status code.";
           }
           leaf status-sub-code {
             type identityref {

               base status-sub-code;
             }
             mandatory true;
             description
               "Sub code for the Continuity Check.";
           }
           description
             "Status code and sub code.";
         }
         leaf data-export-method {
           type export-method;
           description
             "Type of export in use.";
         }
         choice cc-trigger {
           description
             "Necessary conditions for
              periodic or on-change trigger.";
           case periodic {
             description
               "Periodic reports.";
             leaf period {
               type yang:timeticks;
               description
                 "Time interval between reports.";
             }
             leaf start-time {
               type yang:date-and-time;
               description
                 "Timestamp from which reports were started.";
             }
           }
           case on-change {
             description
               "On-change trigger and not periodic.";
             leaf all-data-on-start {
               type boolean;
               description
                 "Full update done on start or not.";
             }
             leaf-list excluded-change {
               type change-type;
               description
                 "Changes that will not trigger an update.";
             }
           }
         }
       }

     }

     rpc pd-get-persistent-id {
       if-feature "cl-oam:path-discovery";
       description
         "Obtains persistent path discovery identification.";
       input {
         container destination-tp {
           uses cl-oam:tp-address;
           description
             "Destination test point.";
         }
         uses cl-oam:session-type;
         leaf source-interface {
           type if:interface-ref;
           description
             "Source interface.";
         }
         leaf outbound-interface {
           type if:interface-ref;
           description
             "Outbound interface.";
         }
         leaf vrf {
           type cl-oam:routing-instance-ref;
           description
             "VRF";
         }
       }
       output {
         list response-list {
           key "response-index";
           description
             "Path discovery response list.";
           leaf response-index {
             type uint32;
             mandatory true;
             description
               "Response index.";
           }
           leaf protocol-id {
             type identityref {
               base protocol-id;
             }
             mandatory true;
             description
               "Protocol used.  This could be a standard
                protocol (e.g., TCP/IP protocols, MPLS, etc.)

                or a proprietary protocol as identified by
                this field.";
           }
           leaf protocol-id-meta-data {
             type uint64;
             description
               "An optional metadata related to the protocol ID.
                For example, this could be the Internet Protocol
                number for standard Internet Protocols used for
                help with protocol processing.";
           }
           leaf status-code {
             type identityref {
               base status-code;
             }
             mandatory true;
             description
               "Status code for persistent path discovery
                information.";
           }
           leaf status-sub-code {
             type identityref {
               base status-sub-code;
             }
             mandatory true;
             description
               "Sub code for persistent path discovery
                information.";
           }
           leaf pd-persistent-id {
             type string;
             description
               "Id to act as a cookie.";
           }
         }
       }
     }

     rpc pd-persistent-get-export-details {
       if-feature "cl-oam:path-discovery";
       description
         "Given the persistent ID, gets the configuration
          options and details related to the configured data
          export.";
       input {
         leaf cc-persistent-id {
           type string;
           description

             "Persistent ID for use as a key in search.";
         }
       }
       output {
         list response-list {
           key "response-index";
           description
             "Path discovery response list.";
           leaf response-index {
             type uint32;
             mandatory true;
             description
               "Response index.";
           }
           leaf protocol-id {
             type identityref {
               base protocol-id;
             }
             mandatory true;
             description
               "Protocol used.  This could be a standard
                protocol (e.g., TCP/IP protocols, MPLS, etc.)
                or a proprietary protocol as identified by
                this field.";
           }
           leaf protocol-id-meta-data {
             type uint64;
             description
               "An optional metadata related to the protocol ID.
                For example, this could be the Internet Protocol
                number for standard Internet Protocols used for
                help with protocol processing.";
           }
           leaf status-code {
             type identityref {
               base status-code;
             }
             mandatory true;
             description
               "Status code for persistent path discovery
                creation.";
           }
           leaf status-sub-code {
             type identityref {
               base status-sub-code;
             }
             mandatory true;
             description

               "Sub code for persistent path discovery
                creation.";
           }
           leaf data-export-method {
             type export-method;
             description
               "Type of export.";
           }
           choice pd-trigger {
             description
               "Necessary conditions
                for periodic or on-change
                trigger.";
             case periodic {
               description
                 "Periodic reports.";
               leaf period {
                 type yang:timeticks;
                 description
                   "Time interval between reports.";
               }
               leaf start-time {
                 type yang:date-and-time;
                 description
                   "Timestamp from which reports are started.";
               }
             }
             case on-change {
               description
                 "On-change trigger and not periodic.";
               leaf all-data-on-start {
                 type boolean;
                 description
                   "Full update done on start or not.";
               }
               leaf-list excluded-change {
                 type change-type;
                 description
                   "Changes that will not trigger an update.";
               }
             }
           }
         }
       }
     }
   }

Acknowledgements

   The authors of this document would like to thank Elwyn Davies, Alia
   Atlas, Brian E. Carpenter, Greg Mirsky, Adam Roach, Alissa Cooper,
   Eric Rescorla, Ben Campbell, Benoit Claise, Kathleen Moriarty, Carlos
   Pignataro, Benjamin Kaduk, and others for their substantive review,
   comments, and proposals to improve the document.

Authors' Addresses

   Deepak Kumar
   CISCO Systems
   510 McCarthy Blvd.
   Milpitas, CA  95035
   United States of America

   Email: dekumar@cisco.com

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

   Email: wangzitao@huawei.com

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

   Email: bill.wu@huawei.com

   Reshad Rahman
   CISCO Systems
   2000 Innovation Drive
   Kanata, Ontario  K2K 3E8
   Canada

   Email: rrahman@cisco.com

   Srihari Raghavan
   CISCO Systems
   Tril Infopark Sez, Ramanujan IT City
   Neville Block, 2nd floor, Old Mahabalipuram Road
   Chennai, Tamil Nadu  600113
   India

   Email: srihari@cisco.com