Internet-Draft YANG Notifications Observation Time July 2023
Graf, et al. Expires 7 January 2024 [Page]
Workgroup:
Network Working Group
Internet-Draft:
draft-netconf-tgraf-yang-push-observation-time-00
Published:
Intended Status:
Standards Track
Expires:
Authors:
T. Graf
Swisscom
B. Claise
Huawei
A. Huang Feng
INSA-Lyon

Support of Network Observation Timestamping in YANG Notifications

Abstract

This document extends the YANG Notification header with the YANG objects observation timestamping, both for the "push-update" and "push-change-update" notifications.

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 7 January 2024.

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Table of Contents

1. Introduction

To correlate network data among different Network Telemetry planes as described in Section 3.1 of [RFC9232] or among different YANG push subscription types defined in Section 3.1 of [RFC8641], network observation timestamping describes when the state change was observed or from when to when the data was accounted. This is essential for understanding the timely relationship among these different planes and YANG push subscription types.

With [I-D.tgraf-netconf-notif-sequencing] the delay between the YANG Notification export and the arrival at the downstream system storing the data can be measured. With network observation timestamping described in this document, the delay between the network observation and the data export of the YANG push publisher process can be measured as well, extending the delay measurement scope from the time the network observation and storing the data.

By extending the YANG Notification header with the YANG objects observation-time for periodical and state-changed-observation-time for on-change subscriptions these use cases can be addressed accordingly.

2. Terminologies

The following terms are defined in [RFC8639] and are not redefined here:

Publisher

Receiver

Subscription

In addition, this document defines the following terms:

Observation-time: Describes the measurement observation time for the "push-update" notification in a "periodical" subscription.

State-changed-observation-time: Describes the time when the network state change was observed.

3. Extend the Streaming Update Notifications

Besides the Subscription ID as described in Section 3.7 of [RFC8641], the following network observation time metadata objects are part of "push-update" and "push-change-update" notifications.

observation-time:
Describes the measurement observation time for the "push-update" notification in a "periodical" subscription. By comparing the "observation-time" of two "push-update" notifications, the collector can deduce the actual cadence of the measurements, and compare it with the configured one.
state-changed-observation-time:
Describes in the "push-change-update" notification in a "on-change" subscription the time when the network state change was observed after the subscription was initially established. In case of an "on-change sync on start" subscription it describes the time when the network state change was observed before the subscription was established.

Figure 1 provides an example of a JSON encoded, [RFC8259], "push-change-update" notification message over HTTPS-based [I-D.ietf-netconf-https-notif] or UDP-based [I-D.ietf-netconf-udp-notif] transport for the same subscription.

{
   "ietf-notification:notification": {
      "eventTime": "2023-02-04T16:30:11.22Z",
      "sysName": "example-router",
      "sequenceNumber": 187653,
      "ietf-yang-push:push-update": {
         "id": 1011,
         "observation-time": "2023-02-04T16:30:09.44Z",
         "datastore-xpath-filter": "ietf-interfaces:interfaces",
         "datastore-contents": {
            "ietf-interfaces:interface": {
               "name": {
                  "eth0": {
                     "oper-status": "up"
                  }
               }
            }
         }
      }
   }
}
Figure 1: JSON Push Example for a subscription-modified notification message

4. The "ietf-yang-push-netobs-timestamping" YANG Module

This YANG module augments the "ietf-yang-push" module with the observation-time in the "push-update" and "push-change-update" streaming update notifications.

4.1. Data Model Overview

4.1.1. Tree View

The following is the YANG tree diagram [RFC8340] for the ietf-yang-push-netobs-timestamping YANG module

module: ietf-yang-push-netobs-timestamping

  augment /yp:push-update:
    +--ro observation-time?   yang:date-and-time
  augment /yp:push-change-update:
    +--ro state-changed-observation-time?   yang:date-and-time

4.1.2. Full Tree View

The following is the YANG tree diagram [RFC8340] for the ietf-yang-push-netobs-timestamping augmentation within the ietf-subscribed-notifications, including the RPCs and notifications.

module: ietf-yang-push

  augment /sn:establish-subscription/sn:input:
    +---w (update-trigger)?
       +--:(periodic)
       |  +---w periodic!
       |     +---w period         centiseconds
       |     +---w anchor-time?   yang:date-and-time
       +--:(on-change) {on-change}?
          +---w on-change!
             +---w dampening-period?   centiseconds
             +---w sync-on-start?      boolean
             +---w excluded-change*    change-type
  augment /sn:establish-subscription/sn:input/sn:target:
    +--:(datastore)
       +-- datastore                               identityref
       +-- (selection-filter)?
          +--:(by-reference)
          |  +-- selection-filter-ref
          |          selection-filter-ref
          +--:(within-subscription)
             +-- (filter-spec)?
                +--:(datastore-subtree-filter)
                |  +-- datastore-subtree-filter?   <anydata>
                |          {sn:subtree}?
                +--:(datastore-xpath-filter)
                   +-- datastore-xpath-filter?     yang:xpath1.0
                           {sn:xpath}?
  augment /sn:modify-subscription/sn:input:
    +---w (update-trigger)?
       +--:(periodic)
       |  +---w periodic!
       |     +---w period         centiseconds
       |     +---w anchor-time?   yang:date-and-time
       +--:(on-change) {on-change}?
          +---w on-change!
             +---w dampening-period?   centiseconds
  augment /sn:modify-subscription/sn:input/sn:target:
    +--:(datastore)
       +-- datastore                               identityref
       +-- (selection-filter)?
          +--:(by-reference)
          |  +-- selection-filter-ref
          |          selection-filter-ref
          +--:(within-subscription)
             +-- (filter-spec)?
                +--:(datastore-subtree-filter)
                |  +-- datastore-subtree-filter?   <anydata>
                |          {sn:subtree}?
                +--:(datastore-xpath-filter)
                   +-- datastore-xpath-filter?     yang:xpath1.0
                           {sn:xpath}?
  augment /sn:subscription-started:
    +--ro (update-trigger)?
       +--:(periodic)
       |  +--ro periodic!
       |     +--ro period         centiseconds
       |     +--ro anchor-time?   yang:date-and-time
       +--:(on-change) {on-change}?
          +--ro on-change!
             +--ro dampening-period?   centiseconds
             +--ro sync-on-start?      boolean
             +--ro excluded-change*    change-type
  augment /sn:subscription-started/sn:target:
    +--:(datastore)
       +-- datastore                               identityref
       +-- (selection-filter)?
          +--:(by-reference)
          |  +-- selection-filter-ref
          |          selection-filter-ref
          +--:(within-subscription)
             +-- (filter-spec)?
                +--:(datastore-subtree-filter)
                |  +-- datastore-subtree-filter?   <anydata>
                |          {sn:subtree}?
                +--:(datastore-xpath-filter)
                   +-- datastore-xpath-filter?     yang:xpath1.0
                           {sn:xpath}?
  augment /sn:subscription-modified:
    +--ro (update-trigger)?
       +--:(periodic)
       |  +--ro periodic!
       |     +--ro period         centiseconds
       |     +--ro anchor-time?   yang:date-and-time
       +--:(on-change) {on-change}?
          +--ro on-change!
             +--ro dampening-period?   centiseconds
             +--ro sync-on-start?      boolean
             +--ro excluded-change*    change-type
  augment /sn:subscription-modified/sn:target:
    +--:(datastore)
       +-- datastore                               identityref
       +-- (selection-filter)?
          +--:(by-reference)
          |  +-- selection-filter-ref
          |          selection-filter-ref
          +--:(within-subscription)
             +-- (filter-spec)?
                +--:(datastore-subtree-filter)
                |  +-- datastore-subtree-filter?   <anydata>
                |          {sn:subtree}?
                +--:(datastore-xpath-filter)
                   +-- datastore-xpath-filter?     yang:xpath1.0
                           {sn:xpath}?
  augment /sn:filters:
    +--rw selection-filter* [filter-id]
       +--rw filter-id                         string
       +--rw (filter-spec)?
          +--:(datastore-subtree-filter)
          |  +--rw datastore-subtree-filter?   <anydata>
          |          {sn:subtree}?
          +--:(datastore-xpath-filter)
             +--rw datastore-xpath-filter?     yang:xpath1.0
                     {sn:xpath}?
  augment /sn:subscriptions/sn:subscription:
    +--rw (update-trigger)?
       +--:(periodic)
       |  +--rw periodic!
       |     +--rw period         centiseconds
       |     +--rw anchor-time?   yang:date-and-time
       +--:(on-change) {on-change}?
          +--rw on-change!
             +--rw dampening-period?   centiseconds
             +--rw sync-on-start?      boolean
             +--rw excluded-change*    change-type
  augment /sn:subscriptions/sn:subscription/sn:target:
    +--:(datastore)
       +--rw datastore                               identityref
       +--rw (selection-filter)?
          +--:(by-reference)
          |  +--rw selection-filter-ref
          |          selection-filter-ref
          +--:(within-subscription)
             +--rw (filter-spec)?
                +--:(datastore-subtree-filter)
                |  +--rw datastore-subtree-filter?   <anydata>
                |          {sn:subtree}?
                +--:(datastore-xpath-filter)
                   +--rw datastore-xpath-filter?
                           yang:xpath1.0 {sn:xpath}?

  rpcs:
    +---x resync-subscription {on-change}?
       +---w input
          +---w id    sn:subscription-id

  notifications:
    +---n push-update
    |  +--ro id?                      sn:subscription-id
    |  +--ro datastore-contents?      <anydata>
    |  +--ro incomplete-update?       empty
    |  +--ro ypnt:observation-time?   yang:date-and-time
    +---n push-change-update {on-change}?
       +--ro id?
       |       sn:subscription-id
       +--ro datastore-changes
       |  +--ro yang-patch
       |     +--ro patch-id    string
       |     +--ro comment?    string
       |     +--ro edit* [edit-id]
       |        +--ro edit-id      string
       |        +--ro operation    enumeration
       |        +--ro target       target-resource-offset
       |        +--ro point?       target-resource-offset
       |        +--ro where?       enumeration
       |        +--ro value?       <anydata>
       +--ro incomplete-update?                     empty
       +--ro ypnt:state-changed-observation-time?
               yang:date-and-time

4.2. YANG Module

The YANG module has one leave augmenting the model of Subscription to YANG Notifications [RFC8639].

<CODE BEGINS> file "ietf-yang-push-netobs-timestamping@2023-03-06.yang"

module ietf-yang-push-netobs-timestamping {
  yang-version 1.1;
  namespace
    "urn:ietf:params:xml:ns:yang:ietf-yang-push-netobs-timestamping";
  prefix ypnt;
  import ietf-yang-types {
    prefix yang;
    reference
      "RFC 6991: Common YANG Data Types";
  }
  import ietf-yang-push {
    prefix yp;
    reference
      "RFC 8641: Subscription to YANG Notifications for Datastore Updates";
  }
  organization "IETF NETCONF (Network Configuration) Working Group";
  contact
    "WG Web:   <http:/tools.ietf.org/wg/netconf/>
     WG List:  <mailto:netconf@ietf.org>

     Authors:  Thomas Graf
               <mailto:thomas.graf@swisscom.com>
               Benoit Claise
               <mailto:benoit.claise@huawei.com>
               Alex Huang Feng
               <mailto:alex.huang-feng@insa-lyon.fr>";

  description
    "Defines YANG push event notification header with the observation
    time in push-update and push-change-update notifications.

    Copyright (c) 2023 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; see the RFC
    itself for full legal notices.";

  revision 2023-03-06 {
    description
      "First revision";
    reference
      "RFC XXXX: Support of YANG Notifications Observation Time";
  }

  feature yang-push-change-update-obs-timestamp {
    description
      "This feature indicates the YANG-push Notifications support
      the observation timestamps in the push-change-update notifications.";
  }

  feature yang-push-update-obs-timestamp {
    description
      "This feature indicates the YANG-push Notifications support
      the observation timestamps in the push-update notifications.";
  }

  grouping yang-push-update-obs-timestamp {
    description
      "This grouping adds the start timestamp and the end timestamp of the
      observed metrics.";
    leaf observation-time {
      type yang:date-and-time;
      description
        "This is the time when metrics started counting.";
    }
  }

  grouping yang-push-change-update-obs-timestamp {
    description
      "This grouping adds the timestamp of the recorded event.";
    leaf state-changed-observation-time {
      type yang:date-and-time;
      description
        "This is the time when event happened.";
    }
  }

  // Event notifications
  augment "/yp:push-update" {
    description
      "This augmentation adds the start timestamp of the counted metrics
      in the push-update notification.";
    uses ypnt:yang-push-update-obs-timestamp;
  }

  augment "/yp:push-change-update" {
    description
      "This augmentation adds the timestamp of the event in the push-change-update
      notification.";
      uses ypnt:yang-push-change-update-obs-timestamp;
  }
}

<CODE ENDS>

5. Security Considerations

The security considerations for the YANG notifications subscription mechanism are described in [RFC8641]. This document adds no additional security considerations.

6. IANA Considerations

This document describes the URI used for the IETF XML Registry and registers a new YANG module name.

6.1. URI

IANA is requested to add this document as a reference in the following URI in the IETF XML Registry [RFC3688].

URI:
urn:ietf:params:xml:ns:yang:ietf-yang-push-netobs-timestamping
Registrant Contact:
The IESG.
XML:
N/A; the requested URI is an XML namespace.
Reference:
RFC5277; RFC-to-be

6.2. YANG module name

This document registers the following YANG module in the YANG Module Names Registry [RFC6020], within the "YANG Parameters" registry:

name:
ietf-yang-push-netobs-timestamping
namespace:
urn:ietf:params:xml:ns:yang:ietf-yang-push-netobs-timestamping
prefix:
ypnt
Reference:
RFC-to-be

7. Operational Considerations

7.1. On Change Sync On Start

For "on-change sync on start" subscriptions, if the timestamp for the network state change was observed before the subscription was established and is not recorded in the YANG datastore, then no timestamp should be populated to state-changed-observation-time.

8. Acknowledgements

The authors would like to thank Rob Wilton, Nick Corran, Pierre Francois Ahmed Elhassany and Jean Quilbeuf for their review and valuable comments.

9. References

9.1. Normative References

[I-D.tgraf-netconf-notif-sequencing]
Graf, T., Quilbeuf, J., and A. Huang Feng, "Support of Hostname and Sequencing in YANG Notifications", Work in Progress, Internet-Draft, draft-tgraf-netconf-notif-sequencing-00, , <https://datatracker.ietf.org/doc/html/draft-tgraf-netconf-notif-sequencing-00>.
[RFC3688]
Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, , <https://www.rfc-editor.org/info/rfc3688>.
[RFC6020]
Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, , <https://www.rfc-editor.org/info/rfc6020>.
[RFC8639]
Voit, E., Clemm, A., Gonzalez Prieto, A., Nilsen-Nygaard, E., and A. Tripathy, "Subscription to YANG Notifications", RFC 8639, DOI 10.17487/RFC8639, , <https://www.rfc-editor.org/info/rfc8639>.
[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>.

9.2. 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-13, , <https://datatracker.ietf.org/doc/html/draft-ietf-netconf-https-notif-13>.
[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-09, , <https://datatracker.ietf.org/doc/html/draft-ietf-netconf-udp-notif-09>.
[RFC8259]
Bray, T., Ed., "The JavaScript Object Notation (JSON) Data Interchange Format", STD 90, RFC 8259, DOI 10.17487/RFC8259, , <https://www.rfc-editor.org/info/rfc8259>.
[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>.
[RFC9232]
Song, H., Qin, F., Martinez-Julia, P., Ciavaglia, L., and A. Wang, "Network Telemetry Framework", RFC 9232, DOI 10.17487/RFC9232, , <https://www.rfc-editor.org/info/rfc9232>.

Authors' Addresses

Thomas Graf
Swisscom
Binzring 17
CH-8045 Zurich
Switzerland
Benoit Claise
Huawei
Alex Huang Feng
INSA-Lyon
Lyon
France