Network Working Group                                           D. Kumar
Internet-Draft                                                     Cisco
Intended status: Standards Track                                 M. Wang
Expires: March 4, 19, 2018                                            Q. Wu
                                                                  Huawei
                                                               R. Rahman
                                                             S. Raghavan
                                                                   Cisco
                                                         August 31,
                                                      September 15, 2017

    Retrieval Methods YANG Data Model for Connectionless Operations,
             Administration, and Maintenance(OAM) protocols
           draft-ietf-lime-yang-connectionless-oam-methods-06
           draft-ietf-lime-yang-connectionless-oam-methods-07

Abstract

   This document presents a retrieval method YANG Data model for
   connectionless OAM protocols.  It provides technology-independent RPC
   operations for connectionless OAM protocols.  The retrieval methods
   model presented here can be extended to include technology specific
   details.  This is leading to uniformity between OAM protocols and
   support both nested OAM workflows (i.e., performing OAM functions at
   different levels through a unified interface) and interacting OAM
   workflows ( i.e., performing OAM functions at same levels through a
   unified interface).

Status of This Memo

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

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   Task Force (IETF).  Note that other groups may also distribute
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   Drafts is at http://datatracker.ietf.org/drafts/current/. 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 4, 19, 2018.

Copyright Notice

   Copyright (c) 2017 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
   (http://trustee.ietf.org/license-info)
   (https://trustee.ietf.org/license-info) in effect on the date of
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions used in this document . . . . . . . . . . . . . .   3
     2.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
     2.2.  Tree Diagrams . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Overview of the Connectionless OAM retrieval methods Model  .   4
     3.1.  RPC operation definitions . . . . . . . . . . . . . . . .   5
     3.2.  OAM Retrieval Methods Hierarchy . . . . . . . . . . . . .   8   7
   4.  OAM Retrieval Methods YANG Module . . . . . . . . . . . . . .  15  14
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  19
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  20  19
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  20
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  20
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  21
   Appendix A.  Appdendix A.1 Extending Connectionless OAM Method
                Module Example . . . . . . . . . . . . . . . . . . .  22  21
   Appendix B.  Appendix A.2 Example of new retrieval procedures
                Model  . . . . . . . . . . . . . . . . . . . .  22
     B.1.  OAM Retrieval Persistent Methods YANG Module  . . . . . .  23  22
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  33  30

1.  Introduction

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

   1.  Monitor reachability of destinations (Reachability Verification,
       Continuity Check).

   2.  Troubleshoot failures (Fault verification and localization).

   3.  Monitor Performance
   An overview of OAM tools is presented at [RFC7276].

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

   In this document, we present a an on-demand retrieval method YANG Data
   model for connectionless OAM protocols.  This module model provides technology-
   independent
   technology-independent RPC operations for connectionless OAM
   protocols.  It is separated from the generic YANG model for
   connectionless OAM [I-D.ietf-lime-yang-connectionless-oam] and can
   avoid mixing the models for the retrieved-data from the retrieval
   procedures.  It is expected that retrieval procedures would evolve
   faster than the data model [I-D.ietf-lime-yang-connectionless-oam]
   and will allow new procedures to be defined for retrieval of the same
   data defined by the base data model.

2.  Conventions used in this document

   The following terms are defined in [RFC6241] and are not redefined
   here:

   o  client

   o  configuration data

   o  server

   o  state data

   The following terms are defined in [RFC6020] and are not redefined
   here:

   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 - A Remote Procedure Call

   RPC operation - A specific Remote Procedure Call

2.2.  Tree Diagrams

   A simplified graphical representation of the data model is used in
   this document.  The meaning of the symbols in these diagrams is as
   follows:

   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

   <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

   <type> is the name of the type for leafs and leaf-lists

3.  Overview of the Connectionless OAM retrieval methods Model

   In this document, we present a an on-demand retrieval method YANG Data
   model for connectionless OAM protocols.  This module model provides technology-
   independent
   technology-independent retrieval procedures (RPC operations) for
   connectionless OAM protocols.  It provides a flexible way to retrieve
   the data which defined by the "ietf-connectionless-oam.yang"
   [I-D.ietf-lime-yang-connectionless-oam].

3.1.  RPC operation definitions

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

   Under '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 supported by corresponding technology-specific 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 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], LSP ping
   [RFC8029]), the 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 'path-discovery-data' and 'continuity-check-data'
   groupings 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.

        rpc continuity-check {
         if-feature coam:continuity-check;
         description
           "Generates continuity-check
           "Continuity-check RPC operation as per RFC7276.";
         input {
           container destination-tp {
             uses coam:tp-address;
                     description
                     "destination test point.";
           }
         uses coam:session-type;
           leaf source-interface {
             type if:interface-ref;
                     description
                     "source interface.";
           }
           leaf outbound-interface {
             type if:interface-ref;

                     description
                     "outbound interface.";
           }
           leaf count {
             type empty;
             description
               "Specifies the number of packets that will be sent.";
           }
           leaf vrf {
             type coam:routing-instance-ref;
             description
               "vrf instance.";
           }
           leaf ttl {
             type uint8;
             default "255";
             description
               "Time to live (TTL).";
           }
           leaf packet-size {
             type uint32 {
               range "64..10000";
             }
             default "64";
             description
               "Size of ping echo request packets, in octets";
           } rpc-input-parameters;
         ....
         }
       output {
           list error-code-list {
             key "response-index";
             leaf response-index
         container error-code {
               type uint32;
                       description
                       "response index.";
             }
           leaf status-code {
             type int32; identityref{
            base status-code;
          }
             mandatory true;
             description
                 "error
               "Error code is "; for CC.";
           }
           leaf status-sub-code {
             type uint8; identityref{
             base status-sub-code;
          }
             mandatory true;
             description
                       "sub code.";
               "Sub code for CC.";
           }
           description
                     "error
             "Error code list."; and Sub Code for CC.";
         }
         uses coam:continuity-check-data;
       }
     }

       rpc path-discovery {
         description
           "Generates path
           "path discovery RPC operation as per RFC7276.";
         input {
           container destination-tp {
         uses coam:tp-address;
                     description
                     "destination test point.";
           }
           uses coam: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 coam:routing-instance-ref;
             description
               "vrf";
           }
           leaf max-ttl {
             type uint8;
             default "255";
             description
               "max ttl.";
           } rpc-input-parameters;
         .....
         }
       output {
         list response-list {
           key "response-index";
           description
               "path
             "Path discovery response list.";
           leaf response-index {
             type uint32;
             mandatory true;
             description
                 "response
               "Response index.";
           }

           leaf status-code {
             type int32; identityref{
             base status-code;
           }
             mandatory true;
             description
                 "error
               "Error code is for Path Discovery. ";
           }
           leaf status-sub-code {
             type uint8; identityref{
             base status-sub-code;
          }
             mandatory true;
             description
                       "sub
               "Sub code is for Path Discovery. ";
           }

         }
         uses coam: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 model is presented below.

module: ietf-connectionless-oam-methods
rpcs:
   +---x continuity-check {coam:continuity-check}?
   |  +---w input
   |  |  +---w destination-tp
   |  |  |  +---w tp-location-type? tp-location-type    identityref
   |  |  |  +---w tp-address
   |  |  |     +---w mac-address
   |  |  |     |  +---w mac-address? mac-address    yang:mac-address
   |  |  |     +---w ipv4-address
   |  |  |     |  +---w ipv4-address? ipv4-address    inet:ipv4-address
   |  |  |     +---w ipv6-address
   |  |  |     |  +---w ipv6-address? 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
   |  |  |     |     +--:(vpls)
   |  |  |     |     |  +---w route-distinguisher?   uint64   rt:route-distinguisher
   |  |  |     |     |  +---w sender-ve-id?          uint16
   |  |  |     |     |  +---w receiver-ve-id?        uint16
   |  |  |     |     +--:(mpls-mldp)
   |  |  |     |        +---w (root-address)?
   |  |  |     |           +--:(ip-address)
   |  |  |     |           |  +---w source-address?        inet:ip-address
   |  |  |     |           |  +---w group-ip-address?      inet:ip-address
   |  |  |     |           +--:(vpn)
   |  |  |     |           |  +---w as-number?             inet:as-number
   |  |  |     |           +--:(global-id)
   |  |  |     |              +---w lsp-id?                string
   |  |  |     +---w system-info
   |  |  |        +---w system-id?   router-id
   |  |  +---w session-type?         enumeration   rt:router-id
   |  |  +---w source-interface? source-interface      if:interface-ref
   |  |  +---w outbound-interface? outbound-interface    if:interface-ref
   |  |  +---w count?                empty vrf?                  coam:routing-instance-ref
   |  |  +---w vrf?                  coam:routing-instance-ref count?                uint32
   |  |  +---w ttl?                  uint8
   |  |  +---w packet-size?          uint32
   |  +--ro output
   |     +--ro error-code-list* [response-index] error-code
   |     |  +--ro response-index     uint32
   |     |  +--ro status-code?       int32 status-code        identityref
   |     |  +--ro status-sub-code?   uint8 status-sub-code    identityref
   |     +--ro src-test-point
   |     |  +--ro ni?                 routing-instance-ref
   |     |  +--ro tp-location-type? tp-location-type    identityref
   |     |  +--ro tp-address
   |     |  |  +--ro mac-address
   |     |  |  |  +--ro mac-address? mac-address    yang:mac-address
   |     |  |  +--ro ipv4-address
   |     |  |  |  +--ro ipv4-address? ipv4-address    inet:ipv4-address
   |     |  |  +--ro ipv6-address
   |     |  |  |  +--ro ipv6-address? ipv6-address    inet:ipv6-address
   |     |  |  +--ro tp-attribute
   |     |  |  |  +--ro tp-attribute-type?     address-attribute-type
   |     |  |  |  +--ro (tp-attribute-value)?
   |     |  |  |     +--:(ip-prefix)
   |     |  |  |     |  +--ro ip-prefix?             inet:ip-prefix
   |     |  |  |     +--:(bgp)
   |     |  |  |     |  +--ro bgp?                   inet:ip-prefix
   |     |  |  |     +--:(tunnel)
   |     |  |  |     |  +--ro tunnel-interface?      uint32
   |     |  |  |     +--:(pw)
   |     |  |  |     |  +--ro remote-pe-address?     inet:ip-address
   |     |  |  |     |  +--ro pw-id?                 uint32
   |     |  |  |     +--:(vpls)
   |     |  |  |     |  +--ro route-distinguisher?   uint64   rt:route-distinguisher
   |     |  |  |     |  +--ro sender-ve-id?          uint16
   |     |  |  |     |  +--ro receiver-ve-id?        uint16
   |     |  |  |     +--:(mpls-mldp)
   |     |  |  |        +--ro (root-address)?
   |     |  |  |           +--:(ip-address)
   |     |  |  |           |  +--ro source-address?        inet:ip-address
   |     |  |  |           |  +--ro group-ip-address?      inet:ip-address
   |     |  |  |           +--:(vpn)
   |     |  |  |           |  +--ro as-number?             inet:as-number
   |     |  |  |           +--:(global-id)
   |     |  |  |              +--ro lsp-id?                string
   |     |  |  +--ro system-info
   |     |  |     +--ro system-id?   router-id   rt:router-id
   |     |  +--ro egress-intf-name?   if:interface-ref
   |     +--ro dest-test-point
   |     |  +--ro ni?                  routing-instance-ref
   |     |  +--ro tp-location-type? tp-location-type     identityref
   |     |  +--ro tp-address
   |     |  |  +--ro mac-address
   |     |  |  |  +--ro mac-address? mac-address    yang:mac-address
   |     |  |  +--ro ipv4-address
   |     |  |  |  +--ro ipv4-address? ipv4-address    inet:ipv4-address
   |     |  |  +--ro ipv6-address
   |     |  |  |  +--ro ipv6-address? ipv6-address    inet:ipv6-address
   |     |  |  +--ro tp-attribute
   |     |  |  |  +--ro tp-attribute-type?     address-attribute-type
   |     |  |  |  +--ro (tp-attribute-value)?
   |     |  |  |     +--:(ip-prefix)
   |     |  |  |     |  +--ro ip-prefix?             inet:ip-prefix
   |     |  |  |     +--:(bgp)
   |     |  |  |     |  +--ro bgp?                   inet:ip-prefix
   |     |  |  |     +--:(tunnel)
   |     |  |  |     |  +--ro tunnel-interface?      uint32
   |     |  |  |     +--:(pw)
   |     |  |  |     |  +--ro remote-pe-address?     inet:ip-address
   |     |  |  |     |  +--ro pw-id?                 uint32
   |     |  |  |     +--:(vpls)
   |     |  |  |     |  +--ro route-distinguisher?   uint64   rt:route-distinguisher
   |     |  |  |     |  +--ro sender-ve-id?          uint16
   |     |  |  |     |  +--ro receiver-ve-id?        uint16
   |     |  |  |     +--:(mpls-mldp)
   |     |  |  |        +--ro (root-address)?
   |     |  |  |           +--:(ip-address)
   |     |  |  |           |  +--ro source-address?        inet:ip-address
   |     |  |  |           |  +--ro group-ip-address?      inet:ip-address
   |     |  |  |           +--:(vpn)
   |     |  |  |           |  +--ro as-number?             inet:as-number
   |     |  |  |           +--:(global-id)
   |     |  |  |              +--ro lsp-id?                string
   |     |  |  +--ro system-info
   |     |  |     +--ro system-id?   router-id   rt:router-id
   |     |  +--ro ingress-intf-name?   if:interface-ref
   |     +--ro sequence-number?             uint64
   |     +--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-drops-count?         uint32
   |     |  +--ro packet-reorder-count?       uint32
   |     |  +--ro packets-out-of-seq-count?   uint32
   |     |  +--ro packets-dup-count?          uint32
   |     +--ro session-delay-statistics
   |     |  +--ro time-resolution-value?   identityref
   |     |  +--ro min-delay-value?         uint32
   |     |  +--ro max-delay-value?         uint32
   |     |  +--ro average-delay-value?     uint32
   |     +--ro session-jitter-statistics
   |        +--ro time-resolution-value?   identityref
   |        +--ro min-jitter-value?        uint32
   |        +--ro max-jitter-value?        uint32
   |        +--ro average-jitter-value?    uint32
   +---x path-discovery {coam:path-discovery}?
      +---w input
      |  +---w destination-tp
      |  |  +---w tp-location-type? tp-location-type    identityref
      |  |  +---w tp-address
      |  |     +---w mac-address
      |  |     |  +---w mac-address? mac-address    yang:mac-address
      |  |     +---w ipv4-address
      |  |     |  +---w ipv4-address? ipv4-address    inet:ipv4-address
      |  |     +---w ipv6-address
      |  |     |  +---w ipv6-address? 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
      |  |     |     +--:(vpls)
      |  |     |     |  +---w route-distinguisher?   uint64   rt:route-distinguisher
      |  |     |     |  +---w sender-ve-id?          uint16
      |  |     |     |  +---w receiver-ve-id?        uint16
      |  |     |     +--:(mpls-mldp)
      |  |     |        +---w (root-address)?
      |  |     |           +--:(ip-address)
      |  |     |           |  +---w source-address?        inet:ip-address
      |  |     |           |  +---w group-ip-address?      inet:ip-address
      |  |     |           +--:(vpn)
      |  |     |           |  +---w as-number?             inet:as-number
      |  |     |           +--:(global-id)
      |  |     |              +---w lsp-id?                string
      |  |     +---w system-info
      |  |        +---w system-id?   router-id
      |  +---w session-type?         enumeration   rt:router-id
      |  +---w source-interface? source-interface      if:interface-ref
      |  +---w outbound-interface? outbound-interface    if:interface-ref
      |  +---w vrf?                  coam:routing-instance-ref
      |  +---w max-ttl?              uint8
      +--ro output
         +--ro response-list* [response-index]
         |  +--ro response-index     uint32
         |  +--ro status-code?       int32 status-code        identityref
         |  +--ro status-sub-code?   uint8 status-sub-code    identityref
         +--ro src-test-point
         |  +--ro ni?                 routing-instance-ref
         |  +--ro tp-location-type? tp-location-type    identityref
         |  +--ro tp-address
         |     +--ro mac-address
         |     |  +--ro mac-address? mac-address    yang:mac-address
         |     +--ro ipv4-address
         |     |  +--ro ipv4-address? ipv4-address    inet:ipv4-address
         |     +--ro ipv6-address
         |     |  +--ro ipv6-address? ipv6-address    inet:ipv6-address
         |     +--ro tp-attribute
         |     |  +--ro tp-attribute-type?     address-attribute-type
         |     |  +--ro (tp-attribute-value)?
         |     |     +--:(ip-prefix)
         |     |     |  +--ro ip-prefix?             inet:ip-prefix
         |     |     +--:(bgp)
         |     |     |  +--ro bgp?                   inet:ip-prefix
         |     |     +--:(tunnel)
         |     |     |  +--ro tunnel-interface?      uint32
         |     |     +--:(pw)
         |     |     |  +--ro remote-pe-address?     inet:ip-address
         |     |     |  +--ro pw-id?                 uint32
         |     |     +--:(vpls)
         |     |     |  +--ro route-distinguisher?   uint64   rt:route-distinguisher
         |     |     |  +--ro sender-ve-id?          uint16
         |     |     |  +--ro receiver-ve-id?        uint16
         |     |     +--:(mpls-mldp)
         |     |        +--ro (root-address)?
         |     |           +--:(ip-address)
         |     |           |  +--ro source-address?        inet:ip-address
         |     |           |  +--ro group-ip-address?      inet:ip-address
         |     |           +--:(vpn)
         |     |           |  +--ro as-number?             inet:as-number
         |     |           +--:(global-id)
         |     |              +--ro lsp-id?                string
         |     +--ro system-info
         |        +--ro system-id?   router-id   rt:router-id
         +--ro dest-test-point
         |  +--ro ni?                 routing-instance-ref
         |  +--ro tp-location-type? tp-location-type    identityref
         |  +--ro tp-address
         |     +--ro mac-address
         |     |  +--ro mac-address? mac-address    yang:mac-address
         |     +--ro ipv4-address
         |     |  +--ro ipv4-address? ipv4-address    inet:ipv4-address
         |     +--ro ipv6-address
         |     |  +--ro ipv6-address? ipv6-address    inet:ipv6-address
         |     +--ro tp-attribute
         |     |  +--ro tp-attribute-type?     address-attribute-type
         |     |  +--ro (tp-attribute-value)?
         |     |     +--:(ip-prefix)
         |     |     |  +--ro ip-prefix?             inet:ip-prefix
         |     |     +--:(bgp)
         |     |     |  +--ro bgp?                   inet:ip-prefix
         |     |     +--:(tunnel)
         |     |     |  +--ro tunnel-interface?      uint32
         |     |     +--:(pw)
         |     |     |  +--ro remote-pe-address?     inet:ip-address
         |     |     |  +--ro pw-id?                 uint32
         |     |     +--:(vpls)
         |     |     |  +--ro route-distinguisher?   uint64   rt:route-distinguisher
         |     |     |  +--ro sender-ve-id?          uint16
         |     |     |  +--ro receiver-ve-id?        uint16
         |     |     +--:(mpls-mldp)
         |     |        +--ro (root-address)?
         |     |           +--:(ip-address)
         |     |           |  +--ro source-address?        inet:ip-address
         |     |           |  +--ro group-ip-address?      inet:ip-address
         |     |           +--:(vpn)
         |     |           |  +--ro as-number?             inet:as-number
         |     |           +--:(global-id)
         |     |              +--ro lsp-id?                string
         |     +--ro system-info
         |        +--ro system-id?   router-id   rt:router-id
         +--ro sequence-number?             uint64
         +--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-drops-count?         uint32
         |  +--ro packet-reorder-count?       uint32
         |  +--ro packets-out-of-seq-count?   uint32
         |  +--ro packets-dup-count?          uint32
         +--ro session-delay-statistics
         |  +--ro time-resolution-value?   identityref
         |  +--ro min-delay-value?         uint32
         |  +--ro max-delay-value?         uint32
         |  +--ro average-delay-value?     uint32
         +--ro session-jitter-statistics
         |  +--ro time-resolution-value?   identityref
         |  +--ro min-jitter-value?        uint32
         |  +--ro max-jitter-value?        uint32
         |  +--ro average-jitter-value?    uint32
         +--ro path-verification
         |  +--ro flow-info?                              string
         |  +--ro session-path-verification-statistics
         |     +--ro verified-count?   uint32
         |     +--ro failed-count?     uint32
         +--ro path-trace-info
            +--ro path-trace-info-list* [index]
               +--ro index                uint32
               +--ro ni?                  routing-instance-ref
               +--ro tp-location-type? tp-location-type     identityref
               +--ro tp-address
               |  +--ro mac-address
               |  |  +--ro mac-address? mac-address    yang:mac-address
               |  +--ro ipv4-address
               |  |  +--ro ipv4-address? ipv4-address    inet:ipv4-address
               |  +--ro ipv6-address
               |  |  +--ro ipv6-address? ipv6-address    inet:ipv6-address
               |  +--ro tp-attribute
               |  |  +--ro tp-attribute-type?     address-attribute-type
               |  |  +--ro (tp-attribute-value)?
               |  |     +--:(ip-prefix)
               |  |     |  +--ro ip-prefix?             inet:ip-prefix
               |  |     +--:(bgp)
               |  |     |  +--ro bgp?                   inet:ip-prefix
               |  |     +--:(tunnel)
               |  |     |  +--ro tunnel-interface?      uint32
               |  |     +--:(pw)
               |  |     |  +--ro remote-pe-address?     inet:ip-address
               |  |     |  +--ro pw-id?                 uint32
               |  |     +--:(vpls)
               |  |     |  +--ro route-distinguisher?   uint64   rt:route-distinguisher
               |  |     |  +--ro sender-ve-id?          uint16
               |  |     |  +--ro receiver-ve-id?        uint16
               |  |     +--:(mpls-mldp)
               |  |        +--ro (root-address)?
               |  |           +--:(ip-address)
               |  |           |  +--ro source-address?        inet:ip-address
               |  |           |  +--ro group-ip-address?      inet:ip-address
               |  |           +--:(vpn)
               |  |           |  +--ro as-number?             inet:as-number
               |  |           +--:(global-id)
               |  |              +--ro lsp-id?                string
               |  +--ro system-info
               |     +--ro system-id?   router-id   rt:router-id
               +--ro timestamp-type?      uint32
               +--ro timestamp-sec?       uint32
               +--ro timestamp-nanosec?   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@2017-08-30.yang" "ietf-connectionless-oam-methods@2017-09-06.yang"

module ietf-connectionless-oam-methods {
namespace "urn:ietf:params:xml:ns:yang:ietf-connectionless-oam-methods";
 prefix coam-methods;
 import ietf-interfaces {
  prefix if;
 }
 import ietf-connectionless-oam {
  prefix coam;
 }
  organization
    "IETF LIME Working Group";
  contact
    "Deepak Kumar dekumar@cisco.com
     Qin Wu bill.wu@huawei.com
     S Raghavan srihari@cisco.com
     Zitao Wang wangzitao@huawei.com
     R Rahman rrahman@cisco.com";
  description
    "This YANG module defines the RPCs RPC operations for
     connectionless OAM to be used within IETF
     in a protocol Independent manner.
     Functional level abstraction is indendent with
     YANG modeling.
     It is assumed that each protocol maps
     corresponding abstracts to its native format.
     Each protocol may extend the YANG model defined
     here to include protocol specific extensions";

  revision 2017-08-30 { 2017-09-06{
    description
      "02
      "08 version";
    reference "draft-ietf-lime-yang-connectionless-oam-methods";
  }

  rpc continuity-check

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

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

  identity invalid-pd {
    if-feature "coam:continuity-check";
   base status-code;
   description
      "Generates continuity-check as per RFC7276.";
    input
   "Indicates that the path discovery message is invalid";
  }

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

  grouping rpc-input-parameters {
        container destination-tp {
        uses coam:tp-address;
        description
          "Destination test point.";
       }
      uses coam:session-type;
       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 coam:routing-instance-ref;
        description
          "VRF instance.";
      }
    description
   "Grouping for RPC input parameters";
  }
  rpc continuity-check {
    if-feature "coam:continuity-check";
    description
      "Continuity-check RPC operation as per RFC7276.";
    input {
        uses rpc-input-parameters;
        uses coam:session-type {
        description "If session-type is specified, then session-type
        must be set to on-demand";
       }
        leaf count {
        type empty; uint32;
        default "5";
        description
          "Specifies the number of
           packets that will be sent.";
      }
      leaf vrf {
        type coam:routing-instance-ref;
        description
          "VRF instance."; sent. By
          default, the packet number is
          set to 5.";
       }
        leaf ttl {
        type uint8;
        default "255";
        description
          "Time to live (TTL)."; (TTL) used to limit lifetime
          of data packet transmitted in the network
          and prevent looping. The TTL value is decremented
          for every hop which 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
          "Size
          "Packet size of ping echo request
           packets, continuity-check message, in octets"; octets.
          By default, the packet size is set to 64 octets.";
      }

    }
    output {
      list error-code-list {
        key "response-index";
        leaf response-index
      container error-code {
          type uint32;
          description
            "Response index.";
        }
        leaf status-code {
          type int32; identityref{
         base status-code;
       }
        mandatory true;
        description
         "Error code is "; for continuity-check message. For example, Error code in
         ICMPv6 message includes
         1-Destination Unreachable
         2- Packet Too Big
         3- Time Exceeded
         4- Parameter Problem [RFC4443].";
        }
        leaf status-sub-code {
          type uint8; identityref{
          base status-sub-code;
          }
        mandatory true;
        description
         "Sub code."; code for continuity-check message. For example Sub code in
         ICMPv6 Parameter Problem Message includes:
         1-Erroneous header field encountered
         2-Unrecognized Next Header type encountered
         3-Unrecognized IPv6 option encountered.";
        }
        description
          "Error code list."; and Sub Code for continuity-check message.";
      }
      uses coam:continuity-check-data;
    }
  }

  rpc path-discovery {
    if-feature "coam:path-discovery";
    description
      "Generates path
      "Path discovery RPC operation as per RFC7276.";
    input {
      container destination-tp {
      uses coam:tp-address;
        description
          "Destination test point.";
      } rpc-input-parameters;
        uses coam:session-type;
      leaf source-interface coam:session-type {
        type if:interface-ref;
        description
          "Source interface.";
      }
      leaf outbound-interface {
        type if:interface-ref;
        description
          "Outbound interface.";
      }
      leaf vrf {
        type coam:routing-instance-ref;
        description
          "VRF"; "If session-type is specified, then session-type
        must be set to on-demand";
    }
      leaf max-ttl {
        type uint8;
        default "255";
        description
          "Max ttl.";
          "Maximum TTL indicates the maixmum number of hops that
          a packet is permitted to travel before being discarded
          by a router. By default, the maximimum 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 status-code {
          type int32; identityref{
          base status-code;
        }
          mandatory true;
          description
            "Error code is for Path Discovery message.
            For example, Error code in ICMPv6 message includes
            1-Destination Unreachable
            2- Packet Too Big
            3- Time Exceeded
            4- Parameter Problem [RFC4443]. ";
        }
        leaf status-sub-code {
          type uint8; identityref{
          base status-sub-code;
       }
          mandatory true;
          description
            "Sub code is for Path Discovery message. For example Sub code in
            ICMPv6 Parameter Problem Message includes:
            1-Erroneous header field encountered
            2-Unrecognized Next Header type encountered
            3-Unrecognized IPv6 option encountered ";
        }
        description
          "List of Error code and Sub Code for Path Discovery.";
      }
      uses coam:path-discovery-data;
    }
  }
}
   <CODE ENDS>

5.  Security Considerations

   The YANG module defined in this document 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 [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.

   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.

   which may lead to Denial-of-Service attack on both the local device
   and the network or unauthorized source access to some sensitive
   information.

6.  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-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: coam-methods

   reference: RFC XXXX

7.  References

7.1.  Normative References

   [I-D.ietf-lime-yang-connectionless-oam]
              Kumar, D., Wang, Z., Wu, Q., Rahman, R., and S. Raghavan,
              "Generic YANG Data Model for Connectionless Operations,
              Administration, and Maintenance(OAM) protocols", draft-
              ietf-lime-yang-connectionless-oam-08
              ietf-lime-yang-connectionless-oam-09 (work in progress),
              August 2017.

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

   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
              (TLS) Protocol Version 1.2", RFC 5246,
              DOI 10.17487/RFC5246, August 2008, <https://www.rfc-
              editor.org/info/rfc5246>.
              <https://www.rfc-editor.org/info/rfc5246>.

   [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>.
              <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>.

   [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>.
              <https://www.rfc-editor.org/info/rfc6536>.

   [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", RFC 792,
              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>.

7.2.  Informative References

   [I-D.ietf-netconf-yang-push]
              Clemm, A., Voit, E., Prieto, A., Tripathy, A., Nilsen-
              Nygaard, E., Bierman, A., and B. Lengyel, "Subscribing to
              YANG datastore push updates", draft-ietf-netconf-yang-
              push-08 (work in progress), August 2017.

   [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>.

   [RFC6087]  Bierman, A., "Guidelines for Authors and Reviewers of YANG
              Data Model Documents", RFC 6087, DOI 10.17487/RFC6087,
              January 2011, <https://www.rfc-editor.org/info/rfc6087>.

   [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>.
              <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>.
              <https://www.rfc-editor.org/info/rfc8029>.

Appendix A.  Appdendix A.1 Extending Connectionless OAM Method Module
             Example

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

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

   augment "/coam-methods:continutiy-check"
   +"/coam-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 round-trip-time(RTT) received.";
      }
      leaf avg-rtt{
       type uint32;
    description
     "The current average ping round-trip-time(RTT)";
      }
      description
      "This container presents the ping round-trip-time statistics.";
     }
   }

Appendix B.  Appendix A.2

   The following is an example related to the YANG model defined Example of new retrieval procedures Model

   As discussed in introduction section of this
   document.  The example discusses persistent methods.

   The persistent RPC operations are commands to trigger persistent
   continuity check or path discovery OAM while specifying document, the options new
   retrieval procedures can be defined for data-export from retrieval of the same data
   defined by base YANG Data model for connectionless OAM protocols.
   This appendix demonstrates how the device. 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
   persistent-id based on destination test point location information
   and then retrieve export details based on persistent-id.  Internet
   Protocol Flow Information Export (IPFIX) [RFC7011] or YANG-push
   [I-D.ietf-netconf-yang-push]. are currently outlined here as data
   export options and more can be added in future.  It should be noted that the persistent methods are
   used to trigger create, modify and delete the persistent state
   associated with the data export options.

   The YANG module "example-cl-oam-persistent-methods" shown below is
   intended as an illustration rather than a real definition of a RPC
   operation model for persistent data export specific
   configurations are beyond retrieval.  For the scope sake of
   brevity, this document.

B.1.  OAM Retrieval Persistent Methods YANG Module module does not obey all the guidelines specified in
   [RFC6087].

  module example-cl-oam-persistent-methods {
  namespace "http://example.com/cl-oam-persistent-methods";
   prefix pcoam-methods;
   import ietf-interfaces {
    prefix if;
   }
   import ietf-connectionless-oam {
    prefix coam;
   }
   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";
    }
    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-persistent-create cc-get-persistent-id {
      if-feature "coam:continuity-check";
      description
         "Generates
        "Obtains continuity-check persistent continuity-check."; identification given mapping
         parameters as input.";
      input {
        container destination-tp {
          uses coam:tp-address;
          description
            "Destination test point.";
        }
        uses coam: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 coam:routing-instance-ref;
          description
            "VRF instance.";
        }
         leaf ttl {
           type uint8;
           default "255";
           description
             "Time to live (TTL).";
         }
         leaf data-export-method {
           type export-method;
           description
             "Type of export.";
         }
         choice cc-trigger {
           description
             "Defines 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 needed on start or not.";
             }
             leaf-list excluded-change {
               type change-type;
               description
                 "Restrict which changes trigger an update.";
             }
           }
         }
      }
      output {
         list error-code-list {
           key "response-index";
           leaf response-index
        container error-code {
             type uint32;
             description
               "Response index.";
           }
          leaf status-code {
            type int32; identityref{
              base status-code;
            }
            mandatory true;
            description
              "Error code.";
          }
          leaf status-sub-code {
            type uint8; identityref{
              base status-sub-code;
            }
            mandatory true;
            description
              "Sub code."; code for CC.";
          }
          description
            "Error code list."; and Sub Code.";
        }

        leaf cc-persistent-id {
          type string;
          description
            "Id to act as a cookie.";
        }
      }
    }

    rpc cc-persistent-modify cc-persistent-get-export-details {
      if-feature "coam:continuity-check";
      description
         "Modifies
        "Given the persistent continuity-check
          as per RFC7276."; id, gets the configuration
         options, details related to the configured data
         export.";
      input {
        leaf cc-persistent-id {
          type string;
          description
             "Cookie
            "Persistent Id to be used for modifications."; use as a key in search.";
        }
      }
      output {
        container error-code {
          leaf status-code {
            type identityref{
              base status-code;
            }
            mandatory true;
            description
              "Error code.";
          }
          leaf status-sub-code {
            type identityref{
              base status-sub-code;
            }
            mandatory true;
            description
              "Sub code for CC.";
          }
          description
            "Error code and Sub Code.";
        }

        leaf data-export-method {
          type export-method;
          description
            "Type of export to in use.";
        }

        choice cc-trigger {
          description
             "Defines necessary
            "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 were started.";
            }
          }
          case on-change {
            description
              "On-change trigger and not periodic.";
            leaf all-data-on-start {
              type boolean;
              description
                "Full update needed done on start or not.";
            }
            leaf-list excluded-change {
              type change-type;
              description
                 "Restrict which changes
                "Changes that will not trigger an update.";
            }
          }
        }
      }
       output {
         list error-code-list {
           key "response-index";
           leaf response-index {
             type uint32;
             description
               "Response index.";
           }
           leaf status-code {
             type int32;
             description
               "Error code";
           }
           leaf status-sub-code {
             type uint8;
             description
               "Sub code.";
           }
           description
             "Error code list.";
         }
         leaf cc-persistent-id {
           type string;
           description
             "Id to represent a cookie.";
         }
       }
    }

   rpc cc-persistent-delete pd-get-persistent-id {
      if-feature "coam:continuity-check";
       description
         "Deletes persistent continuity-check as per RFC7276.";
       input {
         leaf cc-persistent-id {
           type string;
           description
             "Cookie Id to be used in deletion.";
         }
       }
       output {
         list error-code-list {
           key "response-index";
           leaf response-index {
             type uint32;
             description
               "Response index.";
           }
           leaf status-code {
             type int32;
             description
               "Error code.";
           }
           leaf status-sub-code {
             type uint8;
             description
               "Sub code.";
           }
           description
             "Error code list.";
         }
       }
     }

    rpc pd-persistent-create { "coam:path-discovery";
      description
         "Generates
        "Obtains persistent path discovery."; discovery identification.";

      input {
        container destination-tp {
          uses coam:tp-address;
          description
            "Destination test point.";
        }
        uses coam: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 coam:routing-instance-ref;
          description
            "VRF";
        }
         leaf max-ttl {
           type uint8;
           default "255";
           description
             "Max ttl.";
         }
         leaf data-export-method {
           type export-method;
           description
             "Type of export.";
         }
         choice pd-trigger {
           description
             "Defines 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 needed on start or not.";
             }
             leaf-list excluded-change {
               type change-type;
               description
                 "Restrict which changes trigger an update.";
             }
           }
         }
      }
      output {
        list response-list {
          key "response-index";
          description
            "Path discovery response list.";
          leaf response-index {
            type uint32;
            mandatory true;
            description
              "Response index.";
          }
          leaf status-code {
            type int32; identityref {
              base status-code;
            }
            mandatory true;
            description
              "Error code is for Persistent Path Discovery Information. ";
          }
          leaf status-sub-code {
            type uint8; identityref{
              base status-sub-code;
            }
            mandatory true;
            description
              "Sub code is for Persistent Path Discovery Information. ";
          }
          leaf pd-persistent-id {
            type string;
            description
              "Id to act as a cookie.";
          }
        }
      }
   }

  rpc pd-persistent-modify pd-persistent-get-export-details {
     if-feature "coam:path-discovery";
     description
         "Modifies
       "Given the persistent path discovery."; id, gets the configuration
        options, details related to the configured data
        export.";
     input {
       leaf pd-persistent-id cc-persistent-id {
         type string;
         description
             "Cookie
           "Persistent Id to be used for modifications."; 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 status-code {
           type identityref{
             base status-code;
           }
           mandatory true;
           description
             "Error 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
             "Defines necessary
             "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 needed done on start or not.";
             }
             leaf-list excluded-change {
               type change-type;
               description
                 "Restrict which changes
                 "Changes that will not trigger an update.";
             }
           }
         }
       }
       output {
         list response-list {
           key "response-index";
           description
             "path discovery response list.";
           leaf response-index {
             type uint32;
             description
               "response index.";
           }
           leaf status-code {
             type int32;
             description
               "error code is ";
           }
           leaf status-sub-code {
             type uint8;
             description
               "sub code is ";
           }
           leaf pd-persistent-id {
             type string;
             description
               "Id to act as a cookie.";
           }
         }
       }
     }
     rpc pd-persistent-delete {
       description
         "Deletes persistent path discovery.";
       input {
         leaf pd-persistent-id {
           type string;
           description
             "Cookie Id to be used in deletion.";
         }
       }
       output {
         list response-list {
           key "response-index";
           description
             "path discovery response list.";
           leaf response-index {
             type uint32;
             description
               "response index.";
           }
           leaf status-code {
             type int32;
             description
               "error code is ";
           }
           leaf status-sub-code {
             type uint8;
             description
               "sub code is ";
         }
       }
     }
   }
 }

Authors' Addresses

   Deepak Kumar
   CISCO Systems
   510 McCarthy Blvd
   Milpitas, CA  95035
   USA

   Email: dekumar@cisco.com

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

   Email: wangzitao@huawei.com

   Qin Wu
   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