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A Yang Data Model for OAM and Management of ALTO Protocol
draft-ietf-alto-oam-yang-02

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This is an older version of an Internet-Draft whose latest revision state is "Active".
Authors Jingxuan Zhang , Dhruv Dhody , Kai Gao , Roland Schott
Last updated 2022-10-24
Replaces draft-zhang-alto-oam-yang
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draft-ietf-alto-oam-yang-02
ALTO WG                                                         J. Zhang
Internet-Draft                                         Tongji University
Intended status: Standards Track                                D. Dhody
Expires: 27 April 2023                               Huawei Technologies
                                                                  K. Gao
                                                      Sichuan University
                                                               R. Schott
                                                        Deutsche Telekom
                                                         24 October 2022

       A Yang Data Model for OAM and Management of ALTO Protocol
                      draft-ietf-alto-oam-yang-02

Abstract

   This document defines a YANG data model for Operations,
   Administration, and Maintenance (OAM) & Management of Application-
   Layer Traffic Optimization (ALTO) Protocol.  The operator can use the
   data model to create and update ALTO information resources, manage
   the access control, configure server-to-server communication and
   server discovery, and collect statistical data.

Discussion Venues

   This note is to be removed before publishing as an RFC.

   Discussion of this document takes place on the ALTO Working Group
   mailing list (alto@ietf.org), which is archived at
   https://mailarchive.ietf.org/arch/browse/alto/.

   Source for this draft and an issue tracker can be found at
   https://github.com/ietf-wg-alto/draft-alto-oam-yang.

Status of This Memo

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

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

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

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   This Internet-Draft will expire on 27 April 2023.

Copyright Notice

   Copyright (c) 2022 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   3
   3.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
     3.1.  Tree Diagrams . . . . . . . . . . . . . . . . . . . . . .   4
     3.2.  Prefixes in Data Node Names . . . . . . . . . . . . . . .   4
   4.  Design Scope and Requirements . . . . . . . . . . . . . . . .   4
     4.1.  Scope of Data Model for ALTO O&M  . . . . . . . . . . . .   4
     4.2.  Basic Requirements  . . . . . . . . . . . . . . . . . . .   5
     4.3.  Additional Requirements for Extensibility . . . . . . . .   6
     4.4.  Overview of ALTO O&M Data Model for Reference ALTO
           Architecture  . . . . . . . . . . . . . . . . . . . . . .   7
   5.  Design of ALTO O&M Data Model . . . . . . . . . . . . . . . .   7
     5.1.  Overview of ALTO O&M Data Model . . . . . . . . . . . . .   7
     5.2.  Data Model for Server-level Operation and Management  . .   9
       5.2.1.  Data Model for ALTO Server Setup  . . . . . . . . . .  10
       5.2.2.  Data Model for Logging Management . . . . . . . . . .  11
       5.2.3.  Data Model for ALTO-related Management  . . . . . . .  12
       5.2.4.  Data Model for Security Management  . . . . . . . . .  12
     5.3.  Data Model for ALTO Server Configuration Management . . .  12
       5.3.1.  Data Source Configuration Management  . . . . . . . .  12
       5.3.2.  ALTO Information Resources Configuration
               Management  . . . . . . . . . . . . . . . . . . . . .  13
   6.  Design of ALTO O&M Statistics Data Model  . . . . . . . . . .  16
     6.1.  Model for ALTO-specific Performance Monitoring  . . . . .  17
   7.  ALTO OAM YANG Module  . . . . . . . . . . . . . . . . . . . .  18
     7.1.  The ietf-alto Module  . . . . . . . . . . . . . . . . . .  18
     7.2.  The ietf-alto-stats Module  . . . . . . . . . . . . . . .  36
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  41
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  41
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  41

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     10.1.  Normative References . . . . . . . . . . . . . . . . . .  41
     10.2.  Informative References . . . . . . . . . . . . . . . . .  43
   Appendix A.  Example: Extending the ALTO O&M Data Model . . . . .  44
     A.1.  Example Module for Extended Data Sources  . . . . . . . .  45
     A.2.  Example Module for Information Resource Creation
           Algorithm . . . . . . . . . . . . . . . . . . . . . . . .  47
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .  48
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  48

1.  Introduction

   This document defines a YANG data model for the Operations,
   Administration, and Maintenance (OAM) & Management of Application-
   Layer Traffic Optimization (ALTO) Protocol.  The basic purpose of
   this YANG data model is discussed in Section 16 of [RFC7285].  The
   operator can use the data model to create and update ALTO information
   resources, manage the access control, configure server-to-server
   communication and server discovery, and collect statistical data.

   The basic structure of this YANG data model is guided by Section 16
   of [RFC7285] and [RFC7971].  Although the scope of the YANG data
   model in this document mainly focuses on the support of the base ALTO
   protocol [RFC7285] and the existing ALTO standard extensions
   (including [RFC8189], [RFC8895], [RFC8896], [RFC9240], [RFC9241], and
   {RFC9275}), the design will also be extensible for future standard
   extensions (e.g., [I-D.ietf-alto-performance-metrics]).

2.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.  When the words appear in lower case, they
   are to be interpreted with their natural language meanings.

3.  Terminology

   This document uses the following acronyms:

   *  OAM - Operations, Administration, and Maintainance

   *  O&M - OAM and Management

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3.1.  Tree Diagrams

   A simplified graphical representation of the data model is used in
   this document.  The meaning of the symbols in these diagrams is
   defined in [RFC8340].

3.2.  Prefixes in Data Node Names

   In this document, names of data nodes and other data model objects
   are often used without a prefix, as long as it is clear from the
   context in which YANG module each name is defined.  Otherwise, names
   are prefixed using the standard prefix associated with the
   corresponding YANG module, as shown in Table 1.

   +=========+=================+=======================================+
   |Prefix   |YANG module      | Reference                             |
   +=========+=================+=======================================+
   |yang     |ietf-yang-types  | [RFC6991]                             |
   +---------+-----------------+---------------------------------------+
   |inet     |ietf-inet-types  | [RFC6991]                             |
   +---------+-----------------+---------------------------------------+
   |key-chain|ietf-key-chain   | [RFC8177]                             |
   +---------+-----------------+---------------------------------------+
   |tcp      |ietf-tcp-server  | [I-D.ietf-netconf-tcp-client-server]  |
   +---------+-----------------+---------------------------------------+
   |tls      |ietf-tls-server  | [I-D.ietf-netconf-tls-client-server]  |
   +---------+-----------------+---------------------------------------+
   |http     |ietf-http-server | [I-D.ietf-netconf-http-client-server] |
   +---------+-----------------+---------------------------------------+

              Table 1: Prefixes and corresponding YANG modules

4.  Design Scope and Requirements

4.1.  Scope of Data Model for ALTO O&M

   What is in the scope of this document?

   *  Data model for deploy an ALTO server/client.

   *  Data model for operate and manage a running ALTO server/client.

   *  Data model for functionality/capability configuration for ALTO
      services.

   *  Data model for monitoring ALTO-related performance metrics.

   What is not in the scope of this document?

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   This document does not define any data model related to specific
   implementation, including:

   *  Data structures for how to store/deliver ALTO information
      resources (e.g., database schema to store a network map).

   *  Data structures for how to store information collected from data
      sources. (e.g., database schema to store topology collected from
      an Interface to the Routing System (I2RS) client [RFC7921])

4.2.  Basic Requirements

   Based on discussions and recommendations in [RFC7285] and [RFC7971],
   the data model provided by this document satisfies basic requirements
   listed in Table 2.

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     +======================================+========================+
     | Requirement                          | Reference              |
     +======================================+========================+
     | R1: The data model should support    | Section 16.1 of        |
     | configuration for ALTO server setup. | [RFC7285]              |
     +--------------------------------------+------------------------+
     | R2: The data model should provide    | Section 16.2.1 of      |
     | logging management.                  | [RFC7285]              |
     +--------------------------------------+------------------------+
     | R3: The data model should provide    | Section 16.2.2 of      |
     | ALTO-related management information. | [RFC7285]              |
     +--------------------------------------+------------------------+
     | R4: The data model should support    | Section 16.2.6 of      |
     | configuration for security policy    | [RFC7285]              |
     | management.                          |                        |
     +--------------------------------------+------------------------+
     | R5-1: The data model should support  | Section 16.2.4 of      |
     | configuration for different data     | [RFC7285], Section 3.2 |
     | sources.                             | of [RFC7971]           |
     +--------------------------------------+------------------------+
     | R5-2: The data model should support  | Section 16.2.4 of      |
     | configuration for information        | [RFC7285]              |
     | resource generation algorithms.      |                        |
     +--------------------------------------+------------------------+
     | R5-3: The data model should support  | Section 16.2.4 of      |
     | configuration for access control at  | [RFC7285]              |
     | information resource level.          |                        |
     +--------------------------------------+------------------------+
     | R6: The data model should provide    | Section 16.2.3 of      |
     | metrics for server failures.         | [RFC7285], Section 3.3 |
     |                                      | of [RFC7971]           |
     +--------------------------------------+------------------------+
     | R7: The data model should provide    | Section 16.2.5 of      |
     | performance monitoring for ALTO-     | [RFC7285], Section 3.4 |
     | specific metrics.                    | of [RFC7971]           |
     +--------------------------------------+------------------------+

          Table 2: Basic Requirements of Data Model for ALTO O&M.

4.3.  Additional Requirements for Extensibility

   R8: As the ALTO protocol is extensible, the data model for ALTO O&M
   should allow for augmentation to support potential future extensions.

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4.4.  Overview of ALTO O&M Data Model for Reference ALTO Architecture

   Figure 1 shows a reference architecture for ALTO server
   implementation and YANG modules that server components implement.
   The server manager, information resource manager and data source
   listeners need to implement ietf-alto.yang (see Section 5).  The
   performance monitor and logging and fault manager need to implement
   ietf-alto-stats.yang (see Section 6).

   The data broker and algorithm plugins are not in the scope of the
   data model defined in this document.  But user specified YANG modules
   can be applied to different algorithm plugins by augmenting the data
   model defined in this document (see Appendix A).

     +----------------------+      +-----------------+
     | Performance Monitor: |<-----| Server Manager: |
     | ietf-alto-stats.yang |<-+ +-| ietf-alto.yang  |
     +----------------------+  | | +-----------------+
                             report
     +----------------------+  | | +-------------------+
     | Logging and Fault    |  +---| Information       |
     | Manager:             |<---+ | Resource Manager: |
     | ietf-alto-stats.yang |<-----| ietf-alto.yang    |
     +----------------------+      +-------------------+
                                            ^|
                                            || callback
                                            |v
        .............          ..............................
       /             \ ------> . Algorithm Plugin:          .
       . Data Broker .  read   . example-ietf-alto-alg.yang .
       ...............         ..............................
              ^
              | write
     +----------------+  Southbound  ++=============++
     | Data Source    |     API      ||             ||
     | Listener:      | <==========> || Data Source ||
     | ietf-alto.yang |              ||             ||
     +----------------+              ++=============++

      Figure 1: A Reference ALTO Server Architecture and YANG Modules

5.  Design of ALTO O&M Data Model

5.1.  Overview of ALTO O&M Data Model

   The ietf-alto module defined in this document provide all the basic
   ALTO O&M data models fitting the requirements listed in Section 4.

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   The container "alto-server" in the ietf-alto module contains all the
   configured and operational parameters of the adminstrated ALTO server
   instance.

   module: ietf-alto
     +--rw alto-server
        +--rw listen
        |  +---u alto-server-listen-stack-grouping
        +--rw server-discovery
        |  +---u alto-server-discovery-grouping
        +--rw logging-system
        |  +---u alto-logging-system-grouping
        +--rw cost-type* [cost-type-name]
        |  +--rw cost-type-name    string
        |  +--rw cost-mode         identityref
        |  +--rw cost-metric       identityref
        +--rw meta* [meta-key]
        |  +--rw meta-key      string
        |  +--rw meta-value    string
        +--rw data-source* [source-id]
        |  +--rw source-id              string
        |  +--rw source-type            identityref
        |  +--rw (update-policy)
        |  |  +--:(reactive)
        |  |  |  +--rw reactive         boolean
        |  |  +--:(proactive)
        |  |     +--rw poll-interval    uint32
        |  +--rw (source-params)?
        +--rw resource* [resource-id]
           +--rw resource-id                       resource-id
           +--rw resource-type                     identityref
           +--rw description?                      string
           +--rw accepted-group*                   string
           +--rw dependency*
           |       -> /alto-server/resource/resource-id
           +--rw auth
           |  +--rw (auth-type-selection)?
           |     +--:(auth-key-chain)
           |     |  +--rw key-chain?   key-chain:key-chain-ref
           |     +--:(auth-key)
           |     +--:(auth-tls)
           +--rw (resource-params)?
              +--:(ird)
              |  +--rw alto-ird-params
              |     +--rw delegation    inet:uri
              +--:(networkmap)
              |  +--rw alto-networkmap-params
              |     +--rw is-default?   boolean

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              |     +--rw filtered?     boolean
              |     +---u algorithm
              +--:(costmap)
              |  +--rw alto-costmap-params
              |     +--rw filtered?             boolean
              |     +---u filter-costmap-cap
              |     +---u algorithm
              +--:(endpointcost)
              |  +--rw alto-endpointcost-params
              |     +---u endpoint-cost-cap
              |     +---u algorithm
              +--:(endpointprop)
              |  +--rw alto-endpointprop-params
              |     +--rw prop-types*   string
              |     +---u algorithm
              +--:(propmap) {propmap}?
              |  +--rw alto-propmap-params
              |     +---u algorithm
              +--:(cdni) {cdni}?
              |  +--rw alto-cdni-params
              |     +---u algorithm
              +--:(update) {incr-update}?
                 +--rw alto-update-params
                    +---u algorithm

5.2.  Data Model for Server-level Operation and Management

   The ALTO server instance contains the following configuration
   parameters for server-level operation and management for ALTO, which
   satisfies R1 - R4 in Section 4.2.

   module: ietf-alto
     +--rw alto-server
        +--rw listen
        |  +---u alto-server-listen-stack-grouping
        +--rw server-discovery
        |  +---u alto-server-discovery-grouping
        +--rw logging-system
        |  +---u alto-logging-system-grouping
        +--rw cost-type* [cost-type-name]
        |  +--rw cost-type-name    string
        |  +--rw cost-mode         identityref
        |  +--rw cost-metric       identityref
        +--rw meta* [meta-key]
        |  +--rw meta-key      string
        |  +--rw meta-value    string
        ...

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5.2.1.  Data Model for ALTO Server Setup

   To satisfy R1 in Section 4.2, the ALTO server instance contains the
   following basic configurations for the server setup.

5.2.1.1.  ALTO Server Listen Stack

   The "listen" contains all the configurations for the whole server
   listen stack across HTTP layer, TLS layer and TCP layer.

     grouping alto-server-grouping:
       +-- base-uri?   inet:uri
     grouping alto-server-listen-stack-grouping
       +-- (transport)
          +--:(http) {http-listen}?
          |  +-- http
          |     +-- tcp-server-parameters
          |     |  +---u tcp:tcp-server-grouping
          |     +-- http-server-parameters
          |     |  +---u http:http-server-grouping
          |     +-- alto-server-parameters
          +--:(https)
             +-- https
                +-- tcp-server-parameters
                   +---u tcp:tcp-server-grouping
                   +-- tls-server-parameters
                   |  +---u tls:tls-server-grouping
                   +-- http-server-parameters
                   |  +---u http:http-server-grouping
                   +-- alto-server-parameters

5.2.1.2.  ALTO Server Discovery Setup

   In practice, multiple ALTO servers can be deployed for scalability.
   That may require communication among different ALTO servers.

   The YANG module defined in this document does not contain any
   configuration for the communication between two ALTO servers.
   Instead, it provides the configuration for how an ALTO server can be
   discovered by another ALTO server on demand.

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     grouping alto-server-discovery-grouping:
       +-- (server-discovery-manner)?
          +--:(reverse-dns)
          |  +-- rdns-naptr-records
          |     +-- static-prefix*           inet:ip-prefix
          |     +-- dynamic-prefix-source*
          |             -> /alto-server/data-source/source-id
          +--:(internet-routing-registry)
          |  +-- irr-params
          |     +-- aut-num?   inet:as-number
          +--:(peeringdb)
             +-- peeringdb-params
                +-- org-id?   uint32

   The server-discovery node provides configuration for ALTO server
   discovery using different mechanisms.

   *  The reverse-dns case is used to configure DNS NAPTR records for
      ALTO server discovery, which is suugested by [RFC7286] and
      [RFC8686].  It configures a set of endpoints in the scope of the
      network domain serving this ALTO server.  The node contains two
      leaf lists.  The static list contains a list of manual configured
      endpoints.  The dynamic list points to a list of data sources to
      retrieve the endpoints dynamically.  As suggested by [RFC7286] and
      [RFC8686], the IP prefixes in the scope will be translated into
      DNS NAPTR resource records for server discovery.

   *  The internet-routing-registry case is used to configure objects in
      an Internet Routing Registry (IRR) database.  Other ALTO servers/
      clients can query an IRR database using the Routing Policy
      Specification Language (RPSL) [RFC2622] to get the corresponding
      ALTO server to a given Autonomous System (AS).

   *  The peeringdb case is used to configure organization records in
      PeeringDB.  Other ALTO servers/clients can directly query the
      PeeringDB to get the corresponding ALTO server to a given network.

5.2.2.  Data Model for Logging Management

   To satisfy R2 in Section 4.2, the ALTO server instance contains the
   following configuration parameters for the logging management.

   The logging-system node provides configuration to select a logging
   system to capture log messages generated by the ALTO server.

   By default, syslog is the only supported logging system.  When
   selecting syslog, the related configuration is delegated to the
   configuration file of the syslog server.

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     grouping alto-logging-system-grouping:
       +-- (logging-system)?
          +--:(syslog)
             +-- syslog-params
                +-- config-file?   inet:uri

   A specific server implementation can extend the logging-system node
   to add other logging systems.

5.2.3.  Data Model for ALTO-related Management

   To satisfy R3 in Section 4.2, the data model contains the following
   ALTO-related management information.

   *  The "cost-type" list is the registry for the cost types that can
      be used in the ALTO server.

   *  The "meta" list contains the customized meta data of the ALTO
      server.  It will be populated into the meta field of the default
      Information Resource Directory (IRD).

5.2.4.  Data Model for Security Management

   To satisfy R4 in Section 4.2, the data model leverages HTTP and TLS
   to provide basic security management for an ALTO server.  All the
   related configurations are covered by the server listen stack.

5.3.  Data Model for ALTO Server Configuration Management

5.3.1.  Data Source Configuration Management

   To satisfy R5-1 in Section 4.2, the ALTO server instance contains a
   list of data-source entries to subscribe the data sources from which
   ALTO information resources are derived (See Section 16.2.4 of
   [RFC7285]).

   A data-source entry MUST include:

   *  a unique source-id for resource creation algorithms to reference,

   *  the source-type attribute to declare the type of the data source,

   *  the update-policy to specify how to get the data update from the
      data source,

   *  the source-params to specify where and how to query the data.

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   The update policy can be either reactive or proactive.  For the
   reactive update, the ALTO server gets the update as soon as the data
   source changes.  For the proactive update, the ALTO server has to
   proactively fetch the data source periodically.

   To use the reactive update, the reactive attribute MUST be set true.
   To use the proactive update, the poll-interval attribute MUST be
   greater than zero.  The value of poll-interval specifies the interval
   of fetching the data in milliseconds.  If reactive is false or poll-
   interval is zero, the ALTO server will not update the data source.

   The data-source/source-params node can be augmented for different
   types of data sources.

   module: ietf-alto
     +--rw alto-server
        ...
        +--rw data-source* [source-id]
        |  +--rw source-id              string
        |  +--rw source-type            identityref
        |  +--rw (update-policy)
        |  |  +--:(reactive)
        |  |  |  +--rw reactive         boolean
        |  |  +--:(proactive)
        |  |     +--rw poll-interval    uint32
        |  +--rw (source-params)?
        ...

   This data model only includes common configuration parameters for an
   ALTO server to correctly interact with a data source.  The
   implementation-specific parameters of any certain data source can be
   augmented in another module.  An example is included in Appendix A.1.

5.3.2.  ALTO Information Resources Configuration Management

   To satisfy R5-2 and R-3, the ALTO server instance contains a list of
   resource entries.  Each resource entry contains the configurations of
   an ALTO information resource (See Section 8.1 of [RFC7285]).  The
   operator of the ALTO server can use this model to create, update, and
   remove the ALTO information resource.

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   Each resoruce entry provides configurations defining how to create or
   update an ALTO information resource.  Adding a new resource entry
   notifies the ALTO server to create a new ALTO information resource.
   Updating an existing resource entry notifies the ALTO server to
   update the generation parameters (e.g., capabilities and the creation
   algorithm) of an existing ALTO information resource.  Removing an
   existing resource entry will remove the corresponding ALTO
   information resource.

   A resource entry MUST include a unique resource-id and a resource-
   type.

   It can also include an accepted-group node containing a list of user-
   groups that can access this ALTO information resource.  As section
   15.5.2 of [RFC7285] suggests, the module also defines authentication
   related configuration to employ access control at information
   resource level.  The ALTO server returns the IRD to the ALTO client
   based on its authentication information.

   For some resource-type, the resource entry MUST also include the a
   dependency node containing the resource-id of the dependent ALTO
   information resources (See Section 9.1.5 of [RFC7285]).

   For each type of ALTO information resource, the resource entry MAY
   also need type-specific parameters.  These type-specific parameters
   include two categories:

   1.  One categories of the type-specific parameters are common for the
       same type of ALTO information resource.  They declare the
       Capabilities of the ALTO information resource (See Section 9.1.3
       of [RFC7285]).

   2.  The other categories of the type-specific parameters are
       algorithm-specific.  The developer of the ALTO server can
       implement their own creation altorithms and augment the algorithm
       node to declare algorithm-specific input parameters.

   Except for the ird resource, all the other types of resource entries
   have augmented algorithm node.  The augmented algorithm node can
   reference data sources subscribed by the data-source entries (See
   Section 5.3.1).  An example of extending algorithm node for a
   specific type of resource is included in Appendix A.2.

   The developer cannot customize the creation algorithm of the ird
   resource.  The default ird resource will be created automatically
   based on all the added resource entries.  The delegated ird resource
   will be created as a static ALTO information resource (See
   Section 9.2.4 of [RFC7285]).

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   module: ietf-alto
     +--rw alto-server
        ...
        +--rw resource* [resource-id]
           +--rw resource-id                       resource-id
           +--rw resource-type                     identityref
           +--rw description?                      string
           +--rw accepted-group*                   string
           +--rw dependency*
           |       -> /alto-server/resource/resource-id
           +--rw auth
           |  +--rw (auth-type-selection)?
           |     +--:(auth-key-chain)
           |     |  +--rw key-chain?   key-chain:key-chain-ref
           |     +--:(auth-key)
           |     +--:(auth-tls)
           +--rw (resource-params)?
              +--:(ird)
              |  +--rw alto-ird-params
              |     +--rw delegation    inet:uri
              +--:(networkmap)
              |  +--rw alto-networkmap-params
              |     +--rw is-default?   boolean
              |     +--rw filtered?     boolean
              |     +---u algorithm
              +--:(costmap)
              |  +--rw alto-costmap-params
              |     +--rw filtered?             boolean
              |     +---u filter-costmap-cap
              |     +---u algorithm
              +--:(endpointcost)
              |  +--rw alto-endpointcost-params
              |     +---u endpoint-cost-cap
              |     +---u algorithm
              +--:(endpointprop)
              |  +--rw alto-endpointprop-params
              |     +--rw prop-types*   string
              |     +---u algorithm
              +--:(propmap) {propmap}?
              |  +--rw alto-propmap-params
              |     +---u algorithm
              +--:(cdni) {cdni}?
              |  +--rw alto-cdni-params
              |     +---u algorithm
              +--:(update) {incr-update}?
                 +--rw alto-update-params
                    +---u algorithm

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     grouping filter-costmap-cap:
       +-- cost-type-names*            string
       +-- cost-constraints?           boolean
       +-- max-cost-types?             uint32 {multi-cost}?
       +-- testable-cost-type-names*   string {multi-cost}?
       +-- calendar-attributes {cost-calendar}?
          +-- cost-type-names*       string
          +-- time-interval-size     decimal64
          +-- number-of-intervals    uint32
     grouping endpoint-cost-cap:
       +---u filter-costmap-cap
     grouping algorithm:
       +-- (algorithm)

6.  Design of ALTO O&M Statistics Data Model

   The module, "ietf-alto-stats", augments the ietf-alto module to
   include statistics at the ALTO server and information resource level.

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   module: ietf-alto-stats

     augment /alto:alto-server:
       +--ro num-total-req?         yang:counter32
       +--ro num-total-succ?        yang:counter32
       +--ro num-total-fail?        yang:counter32
       +--ro num-total-last-req?    yang:counter32
       +--ro num-total-last-succ?   yang:counter32
       +--ro num-total-last-fail?   yang:counter32
     augment /alto:alto-server/alto:resource:
       +--ro num-res-upd?    yang:counter32
       +--ro res-mem-size?   yang:counter32
       +--ro res-enc-size?   yang:counter32
       +--ro num-res-req?    yang:counter32
       +--ro num-res-succ?   yang:counter32
       +--ro num-res-fail?   yang:counter32
     augment /alto:alto-server/alto:resource/alto:resource-params
               /alto:networkmap/alto:alto-networkmap-params:
       +--ro num-map-pid?   yang:counter32
     augment /alto:alto-server/alto:resource/alto:resource-params
               /alto:propmap/alto:alto-propmap-params:
       +--ro num-map-entry?   yang:counter32
     augment /alto:alto-server/alto:resource/alto:resource-params
               /alto:cdni/alto:alto-cdni-params:
       +--ro num-base-obj?   yang:counter32
     augment /alto:alto-server/alto:resource/alto:resource-params
               /alto:update/alto:alto-update-params:
       +--ro num-upd-sess?      yang:counter32
       +--ro num-event-total?   yang:counter32
       +--ro num-event-max?     yang:counter32
       +--ro num-event-min?     yang:counter32
       +--ro num-event-avg?     yang:counter32

   ## Model for ALTO Server Failure Monitoring

   To satisfy R6 in Section 4.2, the YANG data module defined in this
   document contains statistics that indicates server failures.

   More specifically, num-total-* and num-total-last-* provides server-
   level failure counters; num-res-* provides information resource-level
   failure counters.

6.1.  Model for ALTO-specific Performance Monitoring

   To satisfy R7 in Section 4.2, the YANG data module defined in this
   document also contains statistics for ALTO-specific performance
   metrics.

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   More specifically, this data model contains the following measurement
   information suggested by [RFC7971]:

   *  Measurement of impact

      -  Total amount and distribution of traffic

      -  Application performance

   *  System and service performance

      -  Requests and responses for each information resource

      -  CPU and memory utilization

      -  ALTO map updates

      -  Number of PIDs

      -  ALTO map sizes

   Besides the measurement information suggested by [RFC7971], this data
   model also contains useful measurement information for other ALTO
   extensions:

   *  num-map-entry and num-base-obj provides measurement for number of
      generic ALTO entities (for [RFC9240] and [RFC9241])

   *  num-upd-sess and num-event-* provides statistics for update
      sessions and events (for [RFC8189])

7.  ALTO OAM YANG Module

7.1.  The ietf-alto Module

   <CODE BEGINS> file "ietf-alto@2022-07-11.yang"
   module ietf-alto {
     yang-version 1.1;
     namespace
       "urn:ietf:params:xml:ns:yang:ietf-alto";
     prefix "alto";

     import ietf-inet-types {
       prefix "inet";
       reference
         "RFC 6991: Common YANG Data Types";
     }

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     import ietf-key-chain {
       prefix key-chain;
       reference
         "RFC 8177: YANG Data Model for Key Chains";
     }

     import ietf-tcp-server {
       prefix tcp;
       reference
         "RFC DDDD: YANG Groupings for TCP Clients and TCP Servers";
     }

     import ietf-tls-server {
       prefix tls;
       reference
         "RFC FFFF: YANG Groupings for TLS Clients and TLS Servers";
     }

     import ietf-http-server {
       prefix http;
       reference
         "RFC GGGG: YANG Groupings for HTTP Clients and HTTP Servers";
     }

     organization
       "IETF ALTO Working Group";

     contact
       "WG Web:   <https://datatracker.ietf.org/wg/alto/about/>
        WG List:  <alto@ietf.org>";

     description
       "This YANG module defines all the configured and operational
        parameters of the administrated ALTO server instance.

        Copyright (c) 2022 IETF Trust and the persons identified as
        authors of the code.  All rights reserved.

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

        This version of this YANG module is part of RFC XXXX
        (https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself
        for full legal notices.

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        The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL
        NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'NOT RECOMMENDED',
        'MAY', and 'OPTIONAL' in this document are to be interpreted as
        described in BCP 14 (RFC 2119) (RFC 8174) when, and only when,
        they appear in all capitals, as shown here.";

     revision "2022-10-24" {
       description
         "Initial Version.";
       reference
         "RFC XXXX: A YANG Data Model for OAM and Management of ALTO
          Protocol.";
     }

     typedef resource-id {
       type string {
         length "1..64";
         pattern "[0-9a-zA-Z\\-:@_]*";
       }
       description
         "Format of Resource ID";
       reference
         "Section 9.1.1 of RFC 7285.";
     }

     // Base identities

     identity resource-type {
       description
         "Base identity for type of information resource.";
     }

     identity source-type {
       description
         "Base identity for type of data source.";
     }

     identity cost-mode {
       description
         "The cost mode attribute indicates how costs should be
          interpreted. Specifically, the cost mode attribute indicates
          whether returned costs should be interpreted as numerical
          values or ordinal rankings.";
       reference
         "Section 6.1.2 of RFC 7285.";
     }

     identity cost-metric {

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       description
         "The cost metric attribute indicates what the cost
          represents.";
       reference
         "Section 6.1.1 of RFC 7285.";
     }

     // Identities for ALTO information resources

     identity network-map {
       base resource-type;
       description
         "Identity for network map.";
     }

     identity cost-map {
       base resource-type;
       description
         "Identity for cost map.";
     }

     identity property-map {
       base resource-type;
       description
         "Identity for property map.";
     }

     // Identities for cost mode

     identity numerical {
       base cost-mode;
       description
         "This mode indicates that it is safe to perform numerical
          operations";
     }

     identity ordinal {
       base cost-mode;
       description
         "This mode indicates that the cost values in a cost map
          represent ranking";
     }

     identity array {
       if-feature "path-vector";
       base cost-mode;
       description
         "This mode indicates that every cost value in the response body

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          of a (Filtered) Cost Map or an Endpoint Cost Service MUST be
          interpreted as a JSON array.";
     }

     // Identities for cost metrics

     identity routingcost {
       base cost-metric;
       description
         "This metric conveys a generic measure for the cost of routing
          traffic from a source to a destination.";
     }

     identity ane-path {
       if-feature "path-vector";
       base cost-metric;
       description
         "This metric indicates that the value of such a cost type
          conveys an array of Abstract Network Element (ANE) names,
          where each ANE name uniquely represents an ANE traversed by
          traffic from a source to a destination.";
     }

     identity delay-ow {
       if-feature "performance-metrics";
       base cost-metric;
       description
         "Section 4.1 of RFC XXXX";
     }

     identity delay-rt {
       if-feature "performance-metrics";
       base cost-metric;
       description
         "Section 4.2 of RFC XXXX";
     }

     identity delay-variation {
       if-feature "performance-metrics";
       base cost-metric;
       description
         "Section 4.3 of RFC XXXX";
     }

     identity lossrate {
       if-feature "performance-metrics";
       base cost-metric;
       description

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         "Section 4.4 of RFC XXXX";
     }

     identity hopcount {
       if-feature "performance-metrics";
       base cost-metric;
       description
         "Section 4.5 of RFC XXXX";
     }

     identity tput {
       if-feature "performance-metrics";
       base cost-metric;
       description
         "Section 5.1 of RFC XXXX";
     }

     identity bw-residual {
       if-feature "performance-metrics";
       base cost-metric;
       description
         "Section 5.2 of RFC XXXX";
     }

     identity bw-available {
       if-feature "performance-metrics";
       base cost-metric;
       description
         "Section 5.3 of RFC XXXX";
     }

     // Features

     feature http-listen {
       description
         "The 'http-listen' feature is only used for test depolyment.
          According to Sec 8.3.5 of RFC 7285, it shouldn't be used in
          the production depolyment.";
     }

     feature multi-cost {
       description
         "Support multi-cost extension.";
       reference
         "RFC 8189: Multi-Cost Application-Layer Traffic Optimization
          (ALTO)";
     }

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     feature incr-update {
       description
         "Support incremental update extension.";
       reference
         "RFC 8895: Application-Layer Traffic Optimization (ALTO)
          Incremental Updates Using Server-Sent Events (SSE)";
     }

     feature cost-calendar {
       description
         "Support cost calendar extension.";
       reference
         "RFC 8896: Application-Layer Traffic Optimization (ALTO) Cost
          Calendar";
     }

     feature propmap {
       description
         "Support entity property map extension.";
       reference
         "RFC 9240: An ALTO Extension: Entity Property Maps";
     }

     feature cdni {
       description
         "Support CDNi extension.";
       reference
         "RFC 9241: Content Delivery Network Interconnection (CDNI)
          Request Routing: CDNI Footprint and Capabilities
          Advertisement using ALTO";
     }

     feature path-vector {
       description
         "Support path vector extension.";
       reference
         "RFC XXXX: An ALTO Extension: Path Vector";
     }

     feature performance-metrics {
       description
         "Support performance metrics extension.";
       reference
         "RFC XXXX: ALTO Performance Cost Metrics";
     }

     // Groupings

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     grouping filter-costmap-cap {
       description
         "This grouping defines data model for
          FilteredCostMapCapabilities.";
       reference
         "Sec 11.3.2.4 of RFC 7285.";
       leaf-list cost-type-names {
         type string;
         min-elements 1;
         description
           "Supported cost types";
       }
       leaf cost-constraints {
         type boolean;
         description
           "If true, then the ALTO server allows cost
            constraints to be included in requests to the
            corresponding URI. If not present, this field MUST
            be interpreted as if it specified false.";
       }
       leaf max-cost-types {
         if-feature "multi-cost";
         type uint32;
         default 0;
         description
           "If present with value N greater than 0, this resource
            understands the multi-cost extensions in this document and
            can return a multi-cost map with any combination of N or
            fewer cost types in the 'cost-type-names' list. If omitted,
            the default value is 0.";
       }
       leaf-list testable-cost-type-names {
         if-feature "multi-cost";
         type string;
         description
           "If present, the resource allows constraint tests, but only
            on the cost type names in this array.";
       }
       container calendar-attributes {
         if-feature "cost-calendar";
         leaf-list cost-type-names {
           type string;
           min-elements 1;
           description
             "An array of one or more elements indicating the cost type
              names in the IRD entry to which the values of
              'time-interval-size' and 'number-of-intervals' apply.";
         }

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         leaf time-interval-size {
           type decimal64 {
             fraction-digits 4;
           }
           mandatory true;
           description
             "The duration of an ALTO Calendar time interval in a unit
              of seconds.";
         }
         leaf number-of-intervals {
           type uint32 {
             range "1..max";
           }
           mandatory true;
           description
             "A strictly positive integer (greater or equal to 1) that
              indicates the number of values of the Cost Calendar
              array.";
         }
         description
           "Configuration for CalendarAttributes.";
         reference
           "Section 4.1 of RFC 8896.";
       }
     }

     grouping endpoint-cost-cap {
       uses filter-costmap-cap;
       description
         "This grouping defines EndpointCostCapabilities as the same as
          FilteredCostMapCapabilities defined by the grouping
          filter-costmap-cap.";
       reference
         "Section 11.5.1.4 of RFC 7285";
     }

     grouping algorithm {
       choice algorithm {
         mandatory true;
         description
           "Information resource creation algorithm to be augmented.";
       }
       description
         "This grouping defines base data model for information
          resource creation algorithm.";
     }

     grouping alto-server-grouping {

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       description
         "A reuseable grouping for configuring an ALTO server without
          any consideration for how underlying transport sessions are
          established.";
       leaf base-uri {
         type inet:uri;
         description
           "The base URI for the ALTO server.";
       }
     }

     grouping alto-server-listen-stack-grouping {
       description
         "A reuseable grouping for configuring an ALTO server
          'listen' protocol stack for a single connection.";
       choice transport {
         mandatory true;
         description
           "Selects between available transports.";
         case http {
           if-feature "http-listen";
           container http {
             description
               "Configures ALTO server stack assuming that
                TLS-termination is handled externally.";
             container tcp-server-parameters {
               description
                 "A wrapper around the TCP server parameters
                  to avoid name collisions.";
               uses tcp:tcp-server-grouping {
                 refine "local-port" {
                   default "80";
                   description
                     "The RESTCONF server will listen on the IANA-
                      assigned well-known port value for 'http'
                      (80) if no value is specified.";
                 }
               }
             }
             container http-server-parameters {
               description
                 "A wrapper around the HTTP server parameters
                  to avoid name collisions.";
               uses http:http-server-grouping;
             }
             container alto-server-parameters {
               description
                 "A wrapper around the ALTO server parameters

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                  to avoid name collisiions.";
               uses alto-server-grouping;
             }
           }
         }
         case https {
           container https {
             description
               "Configures ALTO server stack assuming that
                TLS-termination is handled internally.";
             container tcp-server-parameters {
               description
                 "A wrapper around the TCP server parameters
                  to avoid name collisions.";
               uses tcp:tcp-server-grouping {
                 refine "local-port" {
                   default "443";
                   description
                     "The ALTO server will listen on the IANA-
                      assigned well-known port value for 'https'
                      (443) if no value is specified.";
                 }
               }
               container tls-server-parameters {
                 description
                   "A wrapper around the TLS server parameters
                    to avoid name collisions.";
                 uses tls:tls-server-grouping;
               }
               container http-server-parameters {
                 description
                   "A wrapper around the HTTP server parameters
                    to avoid name collisions.";
                 uses http:http-server-grouping;
               }
               container alto-server-parameters {
                 description
                   "A wrapper around the ALTO server parameters
                    to avoid name collisions.";
                 uses alto-server-grouping;
               }
             }
           }
         }
       }
     }

     grouping alto-server-discovery-grouping {

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       description
         "Configure how to set up server discovery for clients or other
          ALTO servers to discovery the URI of this ALTO server.";
       choice server-discovery-manner {
         description
           "Selects among available server discovery manners";
         case reverse-dns {
           description
             "Configure DNS NAPTR records for cross-domain ALTO server
              discovery using reverse DNS lookup.";
           container rdns-naptr-records {
             description
               "Configuration parameters for DNS NAPTR records.";
             leaf-list static-prefix {
               type inet:ip-prefix;
               description
                 "Static IP prefixes in the scope.";
             }
             leaf-list dynamic-prefix-source {
               type leafref {
                 path "/alto:alto-server/alto:data-source/alto:source-id";
               }
               description
                 "Dynamic IP prefixes collected from data sources.";
             }
           }
           reference
             "RFC 8686: Application-Layer Traffic Optimization (ALTO)
              Cross-Domain Server Discovery.";
         }
         case internet-routing-registry {
           description
             "Update descr attributes of a aut-num class in a Internet
              Routing Registry (IRR) database for ALTO server discovery
              using RPSL.";
           reference
             "RFC 2622: Routing Policy Specification Language (RPSL).";
           container irr-params {
             description
               "Configuration parameters for IRR database.";
             leaf aut-num {
               type inet:as-number;
               description
                 "The autonomous system (AS) to be updated.";
             }
           }
         }
         case peeringdb {

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           description
             "Update metadata of a network record in PeeringDB database
              for ALTO server discovery using PeeringDB lookup.";
           container peeringdb-params {
             description
               "Configuration parameters for PeeringDB database.";
             leaf org-id {
               type uint32;
               description
                 "The ID referring to the org object of the
                  organization record in PeeringDB.";
             }
           }
         }
       }
     }

     grouping alto-logging-system-grouping {
       description
         "Grouping for configuration of logging system used by the ALTO
          server.";
       choice logging-system {
         description
           "Selects among available logging systems";
         case syslog {
           description
             "Use syslog as logging system.";
           container syslog-params {
             description
               "Configuration parameters for syslog.";
             leaf config-file {
               type inet:uri {
                 pattern 'file:.*';
               }
               description
                 "The file location of the syslog configuration.";
             }
           }
         }
       }
     }

     // Top-level container

     container alto-server {
       description
         "The ALTO server instance.";
       container listen {

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         description
           "Configure the ALTO server to listen for ALTO clients.";
         uses alto-server-listen-stack-grouping;
       }
       container server-discovery {
         description
           "Configure how the ALTO server to be discovered by others.";
         uses alto-server-discovery-grouping;
       }
       container logging-system {
         description
           "Configure logging system to capture log messages generated
            by the ALTO server.";
         uses alto-logging-system-grouping;
       }
       list cost-type {
         key "cost-type-name";
         leaf cost-type-name {
           type string;
           description
             "The name to reference cost type";
         }
         leaf cost-mode {
           type identityref {
             base cost-mode;
           }
           mandatory true;
           description
             "The referenced cost mode";
         }
         leaf cost-metric {
           type identityref {
             base cost-metric;
           }
           mandatory true;
           description
             "The referenced cost metric";
         }
         description
           "Mapping between name and referenced cost type";
       }
       list meta {
         key "meta-key";
         leaf meta-key {
           type string;
           description
             "Custom meta key";
         }

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         leaf meta-value {
           type string;
           mandatory true;
           description
             "Custom meta value";
         }
         description
           "Mapping of custom meta information";
         reference
           "Section 8.4.1 of RFC 7285.";
       }
       list data-source {
         key "source-id";
         leaf source-id {
           type string;
           description
             "Data source id that can be referenced by information
              resource creation algorithms.";
         }
         leaf source-type {
           type identityref {
             base source-type;
           }
           mandatory true;
           description
             "Identify the type of the data source.";
         }
         choice update-policy {
           mandatory true;
           case reactive {
             leaf reactive {
               type boolean;
               mandatory true;
               description
                 "Reactive mode.";
             }
           }
           case proactive {
             leaf poll-interval {
               type uint32;
               mandatory true;
               description
                 "Polling interval in seconds for proactive mode.";
             }
           }
           description
             "Policy to get updates from data sources.";
         }

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         choice source-params {
           description
             "Data source specific configuration.";
         }
         description
           "List of subscribed data sources.";
       }
       list resource {
         key "resource-id";
         leaf resource-id {
           type resource-id;
           description
             "resource-id to be defined.";
         }
         leaf resource-type {
           type identityref {
             base resource-type;
           }
           mandatory true;
           description
             "identityref to be defined.";
         }
         leaf description {
           type string;
           description
             "The optional description for this information resource.";
         }
         leaf-list accepted-group {
           type string;
           description
             "Access list for authenticated clients.";
         }
         leaf-list dependency {
           type leafref {
             path "/alto:alto-server/alto:resource/alto:resource-id";
           }
           description
             "A list of dependent information resources.";
         }
         container auth {
           description
             "The authentication options";
           choice auth-type-selection {
             description
               "Options for expressing authentication
                setting.";
             case auth-key-chain {
               leaf key-chain {

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                 type key-chain:key-chain-ref;
                 description
                   "key-chain name.";
               }
             }
             case auth-key {
             }
             case auth-tls {
             }
           }
         }
         choice resource-params {
           description
             "Resource-specific configuration.";
           case ird {
             container alto-ird-params {
               leaf delegation {
                 type inet:uri;
                 mandatory true;
                 description
                   "Upstream IRD to be delegated.";
               }
               description
                 "IRD-specific configuration.";
             }
           }
           case networkmap {
             container alto-networkmap-params {
               description
                 "(Filtered) Network Map specific configuration.";
               reference
                 "Section 11.2.1 and Section 11.3.1 of RFC 7285.";
               leaf is-default {
                 type boolean;
                 description
                   "Set whether this is the default network map.";
               }
               leaf filtered {
                 type boolean;
                 default false;
                 description
                   "Configure whether filtered network map is
                    supported.";
               }
               uses algorithm;
             }
           }
           case costmap {

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             container alto-costmap-params {
               description
                 "(Filtered) Cost Map specific configuration.";
               reference
                 "Section 11.2.2 and Section 11.3.2 of RFC 7285.";
               leaf filtered {
                 type boolean;
                 description
                   "Configure whether filtered cost map is supported.";
               }
               uses filter-costmap-cap;
               uses algorithm;
             }
           }
           case endpointcost {
             container alto-endpointcost-params {
               description
                 "Endpoint Cost Service specific configuration.";
               reference
                 "Section 11.5 of RFC 7285.";
               uses endpoint-cost-cap;
               uses algorithm;
             }
           }
           case endpointprop {
             container alto-endpointprop-params {
               description
                 "Endpoint Cost Service specific configuration.";
               reference
                 "Section 11.5 of RFC 7285.";
               leaf-list prop-types {
                 type string;
                 min-elements 1;
                 description
                   "Supported endpoint properties.";
               }
               uses algorithm;
             }
           }
           case propmap {
             if-feature "propmap";
             container alto-propmap-params {
               uses algorithm;
               description
                 "(Filtered) Entity Property Map specific
                  configuration.";
             }
           }

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           case cdni {
             if-feature "cdni";
             container alto-cdni-params {
               uses algorithm;
               description
                 "CDNi specific configuration";
             }
           }
           case update {
             if-feature "incr-update";
             container alto-update-params {
               uses algorithm;
               description
                 "Incremental Updates specific configuration";
             }
           }
         }
         description
           "ALTO information resources to be defined";
       }
     }
   }
   <CODE ENDS>

7.2.  The ietf-alto-stats Module

   <CODE BEGINS> file "ietf-alto-stats@2022-07-11.yang"
   module ietf-alto-stats {
     yang-version 1.1;
     namespace
       "urn:ietf:params:xml:ns:yang:ietf-alto-stats";
     prefix "alto-stats";

     import ietf-yang-types {
       prefix "yang";
       reference
         "RFC 6991: Common YANG Data Types";
     }

     import ietf-alto {
       prefix alto;
       reference
         "RFC XXXX: A YANG Data Model for OAM and Management of ALTO
          Protocol.";
     }

     organization
       "IETF ALTO Working Group";

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     contact
       "WG Web:   <https://datatracker.ietf.org/wg/alto/about/>
        WG List:  <alto@ietf.org>";

     description
       "This YANG module defines all the configured and operational
        parameters of the administrated ALTO server instance.

        Copyright (c) 2022 IETF Trust and the persons identified as
        authors of the code.  All rights reserved.

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

        This version of this YANG module is part of RFC XXXX
        (https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself
        for full legal notices.";

     revision "2022-07-11" {
       description
         "Initial Version.";
       reference
         "RFC XXXX: A YANG Data Model for Operations, Administration,
          and Maintenance of ALTO Protocol.";
     }

     augment "/alto:alto-server" {
       description
         "Top-level statistics for the whole ALTO server.";
       leaf num-total-req {
         type yang:counter32;
         config false;
         description
           "The total number of ALTO requests received by this ALTO
            server.";
       }
       leaf num-total-succ {
         type yang:counter32;
         config false;
         description
           "The total number of successful responses sent by this ALTO
            server.";
       }
       leaf num-total-fail {

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         type yang:counter32;
         config false;
         description
           "The total number of failed responses sent by this ALTO
            server.";
       }
       leaf num-total-last-req {
         type yang:counter32;
         config false;
         description
           "The total number of ALTO requests received within the last
            5 minutes.";
       }
       leaf num-total-last-succ {
         type yang:counter32;
         config false;
         description
           "The total number of successful responses sent by this ALTO
            server within the last 5 minutes.";
       }
       leaf num-total-last-fail {
         type yang:counter32;
         config false;
         description
           "The total number of failed responses sent by this ALTO
            server within the last 5 minutes.";
       }
     }

     augment "/alto:alto-server/alto:resource" {
       description
         "Common statistics for each information resource.";
       leaf num-res-upd {
         type yang:counter32;
         config false;
         description
           "The number of version updates since the information resource
            was created.";
       }
       leaf res-mem-size {
         type yang:counter32;
         config false;
         description
           "Memory size (Bytes) utilized by the information resource.";
       }
       leaf res-enc-size {
         type yang:counter32;
         config false;

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         description
           "Size (Bytes) of JSON encoded data of the information
            resource.";
       }
       leaf num-res-req {
         type yang:counter32;
         config false;
         description
           "The number of ALTO requests to this information resource.";
       }
       leaf num-res-succ {
         type yang:counter32;
         config false;
         description
           "The number of successful responses for requests to this
            information resource.";
       }
       leaf num-res-fail {
         type yang:counter32;
         config false;
         description
           "The total number of failed responses for requests to this
            information resource.";
       }
     }

     augment "/alto:alto-server/alto:resource/alto:resource-params"
           + "/alto:networkmap/alto:alto-networkmap-params" {
       description
         "Augmented statistics for network maps only.";
       leaf num-map-pid {
         type yang:counter32;
         config false;
         description
           "Number of PIDs contained by the network map.";
       }
     }

     augment "/alto:alto-server/alto:resource/alto:resource-params"
           + "/alto:propmap/alto:alto-propmap-params" {
       description
         "Augmented statistics for property maps only.";
       leaf num-map-entry {
         type yang:counter32;
         config false;
         description
           "Number of ALTO entities contained by the property map.";
       }

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     }

     augment "/alto:alto-server/alto:resource/alto:resource-params"
           + "/alto:cdni/alto:alto-cdni-params" {
       description
         "Augmented statistics for CDNi resources only.";
       leaf num-base-obj {
         type yang:counter32;
         config false;
         description
           "Number of base CDNi advertisement objects contained by the
            CDNi resource.";
       }
     }

     augment "/alto:alto-server/alto:resource/alto:resource-params"
           + "/alto:update/alto:alto-update-params" {
       description
         "Augmented statistics for incremental updates only.";
       leaf num-upd-sess {
         type yang:counter32;
         config false;
         description
           "Number of sessions connected to the incremental update
            service.";
       }
       leaf num-event-total {
         type yang:counter32;
         config false;
         description
           "Total number of update events sent to all the connected
            clients.";
       }
       leaf num-event-max {
         type yang:counter32;
         config false;
         description
           "The maximum number of update events sent to the connected
            clients.";
       }
       leaf num-event-min {
         type yang:counter32;
         config false;
         description
           "The minimum number of update events sent to the connected
            clients.";
       }
       leaf num-event-avg {

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         type yang:counter32;
         config false;
         description
           "The average number of update events sent to the connected
            clients.";
       }
     }
   }
   <CODE ENDS>

8.  Security Considerations

   TBD.

9.  IANA Considerations

   This document registers two URIs in the "IETF XML Registry"
   [RFC3688].  Following the format in RFC 3688, the following
   registrations are requested.

     URI: urn:ietf:params:xml:ns:yang:ietf-alto
     Registrant Contact: The IESG.
     XML: N/A; the requested URI is an XML namespace.

     URI: urn:ietf:params:xml:ns:yang:ietf-alto-stats
     Registrant Contact: The IESG.
     XML: N/A; the requested URI is an XML namespace.

   This document registers two YANG modules in the "YANG Module Names"
   registry [RFC6020].

     Name: ietf-alto
     Namespace: urn:ietf:params:xml:ns:yang:ietf-alto
     Prefix: alto
     Reference: [RFCthis]

     Name: ietf-alto-stats
     Namespace: urn:ietf:params:xml:ns:yang:ietf-alto-stats
     Prefix: alto
     Reference: [RFCthis]

   [RFC Editor: Please replace RFCthis with the published RFC number for
   this document.]

10.  References

10.1.  Normative References

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

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

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

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

   [RFC7285]  Alimi, R., Ed., Penno, R., Ed., Yang, Y., Ed., Kiesel, S.,
              Previdi, S., Roome, W., Shalunov, S., and R. Woundy,
              "Application-Layer Traffic Optimization (ALTO) Protocol",
              RFC 7285, DOI 10.17487/RFC7285, September 2014,
              <https://www.rfc-editor.org/rfc/rfc7285>.

   [RFC7286]  Kiesel, S., Stiemerling, M., Schwan, N., Scharf, M., and
              H. Song, "Application-Layer Traffic Optimization (ALTO)
              Server Discovery", RFC 7286, DOI 10.17487/RFC7286,
              November 2014, <https://www.rfc-editor.org/rfc/rfc7286>.

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

   [RFC8177]  Lindem, A., Ed., Qu, Y., Yeung, D., Chen, I., and J.
              Zhang, "YANG Data Model for Key Chains", RFC 8177,
              DOI 10.17487/RFC8177, June 2017,
              <https://www.rfc-editor.org/rfc/rfc8177>.

   [RFC8189]  Randriamasy, S., Roome, W., and N. Schwan, "Multi-Cost
              Application-Layer Traffic Optimization (ALTO)", RFC 8189,
              DOI 10.17487/RFC8189, October 2017,
              <https://www.rfc-editor.org/rfc/rfc8189>.

   [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/rfc/rfc8340>.

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   [RFC8686]  Kiesel, S. and M. Stiemerling, "Application-Layer Traffic
              Optimization (ALTO) Cross-Domain Server Discovery",
              RFC 8686, DOI 10.17487/RFC8686, February 2020,
              <https://www.rfc-editor.org/rfc/rfc8686>.

   [RFC8895]  Roome, W. and Y. Yang, "Application-Layer Traffic
              Optimization (ALTO) Incremental Updates Using Server-Sent
              Events (SSE)", RFC 8895, DOI 10.17487/RFC8895, November
              2020, <https://www.rfc-editor.org/rfc/rfc8895>.

   [RFC8896]  Randriamasy, S., Yang, R., Wu, Q., Deng, L., and N.
              Schwan, "Application-Layer Traffic Optimization (ALTO)
              Cost Calendar", RFC 8896, DOI 10.17487/RFC8896, November
              2020, <https://www.rfc-editor.org/rfc/rfc8896>.

10.2.  Informative References

   [I-D.ietf-alto-performance-metrics]
              Wu, Q., Yang, Y. R., Lee, Y., Dhody, D., Randriamasy, S.,
              and L. M. Contreras, "ALTO Performance Cost Metrics", Work
              in Progress, Internet-Draft, draft-ietf-alto-performance-
              metrics-28, 21 March 2022,
              <https://datatracker.ietf.org/doc/html/draft-ietf-alto-
              performance-metrics-28>.

   [I-D.ietf-netconf-http-client-server]
              Watsen, K., "YANG Groupings for HTTP Clients and HTTP
              Servers", Work in Progress, Internet-Draft, draft-ietf-
              netconf-http-client-server-11, 19 October 2022,
              <https://datatracker.ietf.org/doc/html/draft-ietf-netconf-
              http-client-server-11>.

   [I-D.ietf-netconf-tcp-client-server]
              Watsen, K. and M. Scharf, "YANG Groupings for TCP Clients
              and TCP Servers", Work in Progress, Internet-Draft, draft-
              ietf-netconf-tcp-client-server-14, 19 October 2022,
              <https://datatracker.ietf.org/doc/html/draft-ietf-netconf-
              tcp-client-server-14>.

   [I-D.ietf-netconf-tls-client-server]
              Watsen, K., "YANG Groupings for TLS Clients and TLS
              Servers", Work in Progress, Internet-Draft, draft-ietf-
              netconf-tls-client-server-31, 19 October 2022,
              <https://datatracker.ietf.org/doc/html/draft-ietf-netconf-
              tls-client-server-31>.

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   [RFC2622]  Alaettinoglu, C., Villamizar, C., Gerich, E., Kessens, D.,
              Meyer, D., Bates, T., Karrenberg, D., and M. Terpstra,
              "Routing Policy Specification Language (RPSL)", RFC 2622,
              DOI 10.17487/RFC2622, June 1999,
              <https://www.rfc-editor.org/rfc/rfc2622>.

   [RFC7921]  Atlas, A., Halpern, J., Hares, S., Ward, D., and T.
              Nadeau, "An Architecture for the Interface to the Routing
              System", RFC 7921, DOI 10.17487/RFC7921, June 2016,
              <https://www.rfc-editor.org/rfc/rfc7921>.

   [RFC7971]  Stiemerling, M., Kiesel, S., Scharf, M., Seidel, H., and
              S. Previdi, "Application-Layer Traffic Optimization (ALTO)
              Deployment Considerations", RFC 7971,
              DOI 10.17487/RFC7971, October 2016,
              <https://www.rfc-editor.org/rfc/rfc7971>.

   [RFC8346]  Clemm, A., Medved, J., Varga, R., Liu, X.,
              Ananthakrishnan, H., and N. Bahadur, "A YANG Data Model
              for Layer 3 Topologies", RFC 8346, DOI 10.17487/RFC8346,
              March 2018, <https://www.rfc-editor.org/rfc/rfc8346>.

   [RFC9240]  Roome, W., Randriamasy, S., Yang, Y., Zhang, J., and K.
              Gao, "An Extension for Application-Layer Traffic
              Optimization (ALTO): Entity Property Maps", RFC 9240,
              DOI 10.17487/RFC9240, July 2022,
              <https://www.rfc-editor.org/rfc/rfc9240>.

   [RFC9241]  Seedorf, J., Yang, Y., Ma, K., Peterson, J., and J. Zhang,
              "Content Delivery Network Interconnection (CDNI) Footprint
              and Capabilities Advertisement Using Application-Layer
              Traffic Optimization (ALTO)", RFC 9241,
              DOI 10.17487/RFC9241, July 2022,
              <https://www.rfc-editor.org/rfc/rfc9241>.

   [RFC9275]  Gao, K., Lee, Y., Randriamasy, S., Yang, Y., and J. Zhang,
              "An Extension for Application-Layer Traffic Optimization
              (ALTO): Path Vector", RFC 9275, DOI 10.17487/RFC9275,
              September 2022, <https://www.rfc-editor.org/rfc/rfc9275>.

Appendix A.  Example: Extending the ALTO O&M Data Model

   Developers and operators can also extend this ALTO O&M data model to
   align with their own implementations.  Specifically, the following
   nodes of the data model can be augmented:

   *  The data-source choice.

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   *  The algorithm choice of the resource-params of each resource.

A.1.  Example Module for Extended Data Sources

   The base data model defined by ietf-alto.yang does not include any
   choice cases for specific data sources.  The following example module
   demonstrates how a implementation-specific data source can be
   augmented into the base data model.

   The yang-datastore case is used to import the YANG data from a YANG
   model-driven data store.

   It supports two types of endpoints: local and remote.

   *  For a local endpoint, the YANG data is located the data from the
      same YANG model-driven data store supplying the current ALTO O&M
      data model.  Therefore, the ALTO data source listener retrieves
      the data using the internal API provided by the data store.

   *  For a remote endpoint, the ALTO data source listener establishes
      an HTTP connection to the remote RESTCONF server, and retrieve the
      data using the RESTCONF API.

   The source-path is used to specify the XPath of the data source node.

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   module example-ietf-alto-data-source {

     namespace "urn:example:ietf-alto-data-source";
     prefix "alto-ds";

     import ietf-alto {
       prefix alto;
     }

     identity yang-datastore {
       base source-type;
       description
         "Identity for data source of YANG-based datastore.";
     }

     augment "/alto:alto-server/alto:data-source/alto:source-params" {
       case yang-datastore {
         when 'derived-from-or-self(source-type, "alto:yang-datastore"';
         container yang-datastore-source-params {
           leaf source-path {
             type yang:xpath1.0;
             mandatory true;
             description
               "XPath to subscribed YANG datastore node.";
           }
           description
             "YANG datastore specific configuration.";
           choice restconf-endpoint {
             case local {
               // Use local API to access YANG datastore
             }
             case remote {
               container restconf-endpoint-params {
                 uses rcc:restconf-client-listen-stack-grouping;
               }
             }
           }
         }
       }
     }

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A.2.  Example Module for Information Resource Creation Algorithm

   The base data model defined by ietf-alto.yang does not include any
   choice cases for information resource creation algorithms.  But
   developers may augment the ietf-alto.yang data model with definitions
   for any custom creation algorithms for different information
   resources.  The following example module demonstrates the parameters
   of a network map creation algorithm that translates an IETF layer 3
   unicast topology into a network map.

   module: example-ietf-alto-alg

     augment /alto:alto-server/alto:resource/alto:resource-params
               /alto:networkmap/alto:alto-networkmap-params
               /alto:algorithm:
       +--:(l3-unicast-cluster)
          +--rw l3-unicast-cluster-algorithm
             +--rw l3-unicast-topo
             |       -> /alto:alto-server/data-source/source-id
             +--rw depth?             uint32

   This example defines a creation algorithm called l3-unicast-cluster-
   algorithm for the network map resource.  It takes two algorithm-
   specific parameters:

   l3-unicast-topo  This parameter refers to the source id of a data
      source node subscribed in the data-source list (See
      Section 5.3.1).  The corresponding data source is assumed to be a
      yang-datastore data source (See Appendix A.1) for an IETF layer 3
      unicast topology defined in [RFC8346].  The algorithm uses the
      topology data from this data source to compute the ALTO network
      map resource.

   depth  This optional parameter sets the depth of the clustering
      algorithm.  For example, if the depth sets to 1, the algorithm
      will generate PID for every l3-node in the topology.

   The creation algorithm can be reactively called once the referenced
   data source updates.  Therefore, the ALTO network map resource can be
   updated dynamically.  The update of the reference data source depends
   on the used update-policy (See Section 5.3.1).

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   module example-ietf-alto-alg {

     namespace "urn:example:ietf-alto-alg";
     prefix "alto-alg";

     import ietf-alto {
       prefix "alto";
     }

     augment "/alto:alto-server/alto:resource/alto:resource-params"
           + "/alto:networkmap/alto:alto-networkmap-params"
           + "/alto:algorithm" {
       case l3-unicast-cluster {
         container l3-unicast-cluster-algorithm {
           leaf l3-unicast-topo {
             type leafref {
               path "/alto:alto-server/data-source/source-id";
             }
             mandatory true;
             description
               "The data source to an IETF layer 3 unicast topology.";
           }
           leaf depth {
             type uint32;
             description
               "The depth of the clustering.";
           }
         }
       }
     }
   }

Acknowledgements

   The authors thank Qiufang Ma and Qin Wu for their help with drafting
   the initial version of the YANG modules.  Thanks also to Adrian
   Farrel, Qiao Xiang, Qin Wu, and Qiufang Ma for their reviews and
   valuable feedback.

Authors' Addresses

   Jingxuan Jensen Zhang
   Tongji University
   4800 Cao'An Hwy
   Shanghai
   201804
   China
   Email: jingxuan.n.zhang@gmail.com

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Internet-Draft                ALTO O&M YANG                 October 2022

   Dhruv Dhody
   Huawei Technologies
   Divyashree Techno Park, Whitefield
   Bangalore 560066
   Karnataka
   India
   Email: dhruv.ietf@gmail.com

   Kai Gao
   Sichuan University
   No.24 South Section 1, Yihuan Road
   Chengdu
   610000
   China
   Email: kaigao@scu.edu.cn

   Roland Schott
   Deutsche Telekom
   Heinrich-Hertz-Strasse 3-7
   64295 Darmstadt
   Germany
   Email: Roland.Schott@telekom.de

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