Internet-Draft YANG Notification Transport Capabilities October 2024
Wu, et al. Expires 20 April 2025 [Page]
Workgroup:
NETCONF Working Group
Internet-Draft:
draft-netana-netconf-yp-transport-capabilities-00
Published:
Intended Status:
Standards Track
Expires:
Authors:
Q. Wu
Huawei
Q. Ma
Huawei
A. Huang Feng
INSA-Lyon
T. Graf
Swisscom

YANG Notification Transport Capabilities

Abstract

This document proposes a YANG module for YANG notifications transport capabilities which augments "ietf-system-capabilities" YANG module defined in [RFC9196] and provides transport, encoding and encryption system capabilities for transport specific notification. This YANG module can be used by the client to learn capability information from the server at runtime or at implementation time, by making use of the YANG instance data file format.

Status of This Memo

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

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

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

This Internet-Draft will expire on 20 April 2025.

1. Introduction

Notification capabilities model defined in [RFC9196] allows a client to discover a set of capabilities supported by the server (e.g., basic system capabilities and YANG-Push related capabilities) both at implementation time and at runtime. These capabilities allow the client to adjust its behavior to take advantage of the features exposed by the server.

However the client and the server may still support various different transport specific parameters (e.g., transport protocol, encoding format, encryption). As described in Section 3.1 of [RFC8641], a simple negotiation (i.e., inserting hints into error responses to a failed RPC request) between subscribers and publishers for subscription parameters increases the likelihood of success for subsequent RPC requests, but not guaranteed, which may cause unexpected failure or additional message exchange between client and server.

This document defines a corresponding solution by proposing a YANG module for YANG notifications transport capabilities that is built on top of [RFC9196]. The module can be used by the client to discover capability information from the server at runtime or at implementation time, by making use of the YANG instance data file format.

1.1. Terminology

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.

2. Capabilities for Systems and Datastore Update Notifications

The YANG module "ietf-notification-capabilities" defined in [RFC9196] specifies the following server capabilities related to YANG Push:

  • Supported (reporting) periods for "periodic" subscriptions

  • Maximum number of objects that can be sent in an update

  • The set of datastores or data nodes for which "periodic" or "on-change" notification is supported

  • Supported dampening periods for "on-change" subscriptions

These server capabilities are transport independent, session level capabilities. They can be provided either at the implementation time or reported at runtime.

This document augments System Capabilities model and provides additional transport related attributes associated with system capabilities:

  • Specification of transport protocols the client can request to establish a HTTPS-based [I-D.ietf-netconf-https-notif] or UDP-based [I-D.ietf-netconf-udp-notif] configured transport connection;

  • Specification of transport encoding, such as JSON or XML as defined in [RFC8040] or CBOR as defined in [RFC9254] the client can request to encode YANG notifications;

  • Specification of secure transport mechanisms that are needed by the client to communicate with the server such as DTLS as defined in [RFC9147] TLS as defined in [RFC8446] or SSH as defined in [RFC4254];

2.1. Tree Diagram

The following tree diagram [RFC8340] provides an overview of the data model.

module: ietf-notification-transport-capabilities

  augment /sysc:system-capabilities/notc:subscription-capabilities:
    +--ro transport-capabilities
       +--ro transport-capability* [transport-protocol]
          +--ro transport-protocol    identityref
          +--ro security-protocol?    identityref
          +--ro encoding-format*      identityref

3. YANG Module

<CODE BEGINS> file "ietf-notification-transport-capabilities@2024-10-14.yang"

module ietf-notification-transport-capabilities {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:ietf-notification-transport-capabilities";
  prefix ntc;

  import ietf-subscribed-notifications {
    prefix sn;
    reference
      "RFC 8639: Subscription to YANG Notifications";
  }
  import ietf-system-capabilities {
    prefix sysc;
    reference
      "RFC 9196: YANG Modules Describing Capabilities for
       Systems and Datastore Update Notifications";
  }
  import ietf-notification-capabilities {
    prefix notc;
    reference
      "RFC 9196: YANG Modules Describing Capabilities for
       Systems and Datastore Update Notifications";
  }

  organization "IETF NETCONF (Network Configuration) Working Group";
  contact
    "WG Web:   <https://datatracker.ietf.org/group/netconf/>
     WG List:  <mailto:netconf@ietf.org>

     Authors:  Qin Wu
               <mailto:bill.wu@huawei.com>
               Qiufang Ma
               <mailto:maqiufang1@huawei.com>
               Alex Huang Feng
               <mailto:alex.huang-feng@insa-lyon.fr>
               Thomas Graf
               <mailto:thomas.graf@swisscom.com>";

  description
    "This module defines an extension to System Capability and YANG Push
     Notification Capabilities model and provides additional
     transport specific capabilities for YANG notifications.

     Copyright (c) 2024 IETF Trust and the persons identified as
     authors of the code.  All rights reserved.

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

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

  revision 2024-10-14 {
    description
      "Initial revision.";
    reference
      "RFC XXXX: YANG Notifications Transport Capabilities";
  }

  identity security-protocol {
    description
      "Identity for security protocols.";
  }

  identity tls {
    base security-protocol;
    description
      "Identity for TLS security protocol.";
  }

  identity dtls12 {
    base security-protocol;
    description
      "Identity for DTLS 1.2 security protocol.";
  }

  identity dtls13 {
    base security-protocol;
    description
      "Identity for DTLS 1.3 security protocol.";
  }

  identity ssh {
    base security-protocol;
    description
      "Identity for ssh transport protocol.";
  }

  augment "/sysc:system-capabilities/notc:subscription-capabilities" {
    description
      "Add system level capability.";
    container transport-capabilities {
      description
        "Capabilities related to YANG-Push transports.";
      list transport-capability {
        key "transport-protocol";
        description
          "Capability list related to notification transport capabilities.";
        leaf transport-protocol {
          type identityref {
            base sn:transport;
          }
          description
            "Supported transport protocol for YANG-Push.";
        }
        leaf security-protocol {
          type identityref {
            base security-protocol;
          }
          description
            "Type of secure transport.";
        }
        leaf-list encoding-format {
          type identityref {
            base sn:encoding;
          }
          description
            "Supported encoding formats.";
        }
      }
    }
  }
}

<CODE ENDS>

4. IANA Considerations

4.1. Updates to the IETF XML Registry

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

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

4.2. Updates to the YANG Module Names Registry

This document registers one YANG module in the "YANG Module Names" registry [RFC6020]. Following the format in [RFC6020], the following registration has been made:

   name:
      ietf-notification-transport-capabilities
   namespace:
      urn:ietf:params:xml:ns:yang:ietf-notification-transport-capabilities
   prefix:
      ntc
   reference:
      RFC XXXX (RFC Ed.: replace XXX with actual RFC number and remove
      this note.)

5. Security Considerations

This section is modeled after the template described in Section 3.7 of [I-D.ietf-netmod-rfc8407bis]

The "ietf-notification-transport-capabilities" YANG module defines a data model that is designed to be accessed via YANG-based management protocols, such as NETCONF [RFC6241] and RESTCONF [RFC8040]. These protocols have to use a secure transport layer (e.g., SSH [RFC4252], TLS [RFC8446], and QUIC [RFC9000]) and have to use mutual authentication.

The Network Configuration Access Control Model (NACM) [RFC8341] provides the means to restrict access for particular NETCONF or RESTCONF users to a preconfigured subset of all available NETCONF or RESTCONF protocol operations and content.

All protocol-accessible data nodes are read-only and cannot be modified. The data in the module is not security sensitive. It inherits all the security considerations of [RFC9196].

6. Contributors

   Ran Tao
   Huawei
   101 Software Avenue, Yuhua District
   Nanjing, Jiangsu 210012
   China
   Email: taoran20@huawei.com

   Liang Geng
   China Mobile
   32 Xuanwumen West St, Xicheng District
   Beijing 10053
   China
   Email: gengliang@chinamobile.com

   Peng Liu
   China Mobile
   Beiqijia Town, Changping District
   Beijing 10053
   China
   Email: liupengyjy@chinamobile.com

   Wei Wang
   China Telecom
   32 Xuanwumen West St, Xicheng District
   Beijing 102209
   China
   Email: wangw36@chinatelecom.cn

7. References

7.1. Normative References

[RFC2119]
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <https://www.rfc-editor.org/info/rfc2119>.
[RFC4254]
Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH) Connection Protocol", RFC 4254, DOI 10.17487/RFC4254, , <https://www.rfc-editor.org/info/rfc4254>.
[RFC6241]
Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., and A. Bierman, Ed., "Network Configuration Protocol (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, , <https://www.rfc-editor.org/info/rfc6241>.
[RFC6242]
Wasserman, M., "Using the NETCONF Protocol over Secure Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, , <https://www.rfc-editor.org/info/rfc6242>.
[RFC8040]
Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, , <https://www.rfc-editor.org/info/rfc8040>.
[RFC8174]
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <https://www.rfc-editor.org/info/rfc8174>.
[RFC8341]
Bierman, A. and M. Bjorklund, "Network Configuration Access Control Model", STD 91, RFC 8341, DOI 10.17487/RFC8341, , <https://www.rfc-editor.org/info/rfc8341>.
[RFC8446]
Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, , <https://www.rfc-editor.org/info/rfc8446>.
[RFC8641]
Clemm, A. and E. Voit, "Subscription to YANG Notifications for Datastore Updates", RFC 8641, DOI 10.17487/RFC8641, , <https://www.rfc-editor.org/info/rfc8641>.
[RFC9147]
Rescorla, E., Tschofenig, H., and N. Modadugu, "The Datagram Transport Layer Security (DTLS) Protocol Version 1.3", RFC 9147, DOI 10.17487/RFC9147, , <https://www.rfc-editor.org/info/rfc9147>.
[RFC9196]
Lengyel, B., Clemm, A., and B. Claise, "YANG Modules Describing Capabilities for Systems and Datastore Update Notifications", RFC 9196, DOI 10.17487/RFC9196, , <https://www.rfc-editor.org/info/rfc9196>.
[RFC9254]
Veillette, M., Ed., Petrov, I., Ed., Pelov, A., Bormann, C., and M. Richardson, "Encoding of Data Modeled with YANG in the Concise Binary Object Representation (CBOR)", RFC 9254, DOI 10.17487/RFC9254, , <https://www.rfc-editor.org/info/rfc9254>.

7.2. Informative References

[I-D.ietf-netconf-https-notif]
Jethanandani, M. and K. Watsen, "An HTTPS-based Transport for YANG Notifications", Work in Progress, Internet-Draft, draft-ietf-netconf-https-notif-15, , <https://datatracker.ietf.org/doc/html/draft-ietf-netconf-https-notif-15>.
[I-D.ietf-netconf-udp-notif]
Zheng, G., Zhou, T., Graf, T., Francois, P., Feng, A. H., and P. Lucente, "UDP-based Transport for Configured Subscriptions", Work in Progress, Internet-Draft, draft-ietf-netconf-udp-notif-14, , <https://datatracker.ietf.org/doc/html/draft-ietf-netconf-udp-notif-14>.
[I-D.ietf-netmod-rfc8407bis]
Bierman, A., Boucadair, M., and Q. Wu, "Guidelines for Authors and Reviewers of Documents Containing YANG Data Models", Work in Progress, Internet-Draft, draft-ietf-netmod-rfc8407bis-18, , <https://datatracker.ietf.org/doc/html/draft-ietf-netmod-rfc8407bis-18>.
[RFC3688]
Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, , <https://www.rfc-editor.org/info/rfc3688>.
[RFC4252]
Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH) Authentication Protocol", RFC 4252, DOI 10.17487/RFC4252, , <https://www.rfc-editor.org/info/rfc4252>.
[RFC6020]
Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, , <https://www.rfc-editor.org/info/rfc6020>.
[RFC8340]
Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams", BCP 215, RFC 8340, DOI 10.17487/RFC8340, , <https://www.rfc-editor.org/info/rfc8340>.
[RFC9000]
Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based Multiplexed and Secure Transport", RFC 9000, DOI 10.17487/RFC9000, , <https://www.rfc-editor.org/info/rfc9000>.

Appendix A. Usage Example of interaction with UDP-Notif and HTTPS-Notif for Configured Subscription

The following instance-data example describes the notification transport capabilities of a hypothetical "acme-router".

<?xml version="1.0" encoding="UTF-8"?>
<instance-data-set xmlns=
"urn:ietf:params:xml:ns:yang:ietf-yang-instance-data">
  <name>acme-router-notification-capabilities</name>
  <content-schema>
    <module>ietf-system-capabilities@2020-03-23</module>
    <module>ietf-notification-capabilities@2020-03-23</module>
    <module>ietf-notification-transport-capabilities@2024-10-14</module>
  </content-schema>
  <!-- revision date, contact, etc. -->
  <description>Server Capability Discovery</description>
  <content-data>
    <system-capabilities xmlns="urn:ietf:params:xml:ns:yang:ietf-system\
      -capabilities">
      <subscription-capabilities xmlns="urn:ietf:params:xml:ns:yang:iet\
        f-notification-capabilities">
        <transport-capabilities xmlns="urn:ietf:params:xml:ns:yang:ietf\
          -notification-transport-capabilities">
          <transport-capability>
            <transport-protocol xmlns:hnt="urn:ietf:params:xml:ns:yang:\
            ietf-https-notif-transport">hnt:https</transport-protocol>
            <encoding-format xmlns:sn="urn:ietf:params:xml:ns:yang:ietf\
              -subscribed-notifications">sn:encode-xml</encoding-format>
            <encoding-format xmlns:sn="urn:ietf:params:xml:ns:yang:ietf\
             -subscribed-notifications">sn:encode-json</encoding-format>
          </transport-capability>
          <transport-capability>
            <transport-protocol xmlns:unt="urn:ietf:params:xml:ns:yang:\
            ietf-udp-notif-transport">unt:udp-notif</transport-protocol>
            <encoding-format xmlns:unt="urn:ietf:params:xml:ns:yang:iet\
              f-udp-notif-transport">unt:encode-cbor</encoding-format>
          </transport-capability>
        </transport-capabilities>
      </subscription-capabilities>
    </system-capabilities>
  </content-data>
</instance-data-set>

In addition, the client could also query notification transport capabilities from the server. For example, the client sends <get> request message to the the server to query from the server.

 <rpc message-id="101" xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
   <get>
     <filter type="subtree">
     <system-capabilities xmlns="urn:ietf:params:xml:ns:yang:ietf-syste\
       m-capabilities">
       <subscription-capabilities xmlns="urn:ietf:params:xml:ns:yang:ie\
         tf-notification-capabilities">
       <transport-capabilities/>
       </subscription-capabilities>
     </system-capabilities>
    </filter>
   </get>
 </rpc>

The server returns server data export capability using <rpc-reply> as follows:

<rpc-reply xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"
  message-id="101">
  <data>
    <system-capabilities xmlns="urn:ietf:params:xml:ns:yang:ietf-system\
      -capabilities">
      <subscription-capabilities xmlns="urn:ietf:params:xml:ns:yang:iet\
        f-notification-capabilities">
        <transport-capabilities xmlns="urn:ietf:params:xml:ns:yang:ietf\
          -notification-transport-capabilities">
          <transport-capability>
            <transport-protocol xmlns:hnt="urn:ietf:params:xml:ns:yang:\
            ietf-https-notif-transport">hnt:https</transport-protocol>
            <encoding-format xmlns:sn="urn:ietf:params:xml:ns:yang:ietf\
            -subscribed-notifications">sn:encode-xml</encoding-format>
            <encoding-format xmlns:sn="urn:ietf:params:xml:ns:yang:ietf\
             -subscribed-notifications">sn:encode-json</encoding-format>
          </transport-capability>
          <transport-capability>
            <transport-protocol xmlns:unt="urn:ietf:params:xml:ns:yang:\
            ietf-udp-notif-transport">unt:udp-notif</transport-protocol>
            <encoding-format xmlns:unt="urn:ietf:params:xml:ns:yang:iet\
              f-udp-notif-transport">unt:encode-cbor</encoding-format>
          </transport-capability>
        </transport-capabilities>
      </subscription-capabilities>
    </system-capabilities>
  </data>
</rpc-reply>

Authors' Addresses

Qin Wu
Huawei
101 Software Avenue, Yuhua District
Nanjing
Jiangsu, 210012
China
Qiufang Ma
Huawei
101 Software Avenue, Yuhua District
Nanjing
Jiangsu, 210012
China
Alex Huang Feng
INSA-Lyon
Lyon
France
Thomas Graf
Swisscom
Binzring 17
CH-8045 Zurich
Switzerland