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Versions: 00

NETCONF Working Group                                            Z. Wang
Internet-Draft                                                     Q. Wu
Intended status: Standards Track                                 W. Song
Expires: September 4, 2020                                        Huawei
                                                                 L. Geng
                                                                  P. Liu
                                                            China Mobile
                                                           March 3, 2020


               Adaptive Subscription to YANG Notification
              draft-wang-netconf-adaptive-subscription-00

Abstract

   This document defines a YANG data model and associated mechanism
   enabling subscriber's adaptive subscriptions to a publisher's event
   streams.  Applying these elements allows a subscriber to
   automatically adjust the volume of telemetry traffic sent from
   publisher to the receivers.

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 September 4, 2020.

Copyright Notice

   Copyright (c) 2020 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



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   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Model Overview  . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Bulk Subscription YANG Module . . . . . . . . . . . . . . . .   4
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
     4.1.  Updates to the IETF XML Registry  . . . . . . . . . . . .   7
     4.2.  Updates to the YANG Module Names Registry . . . . . . . .   8
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   9
     6.2.  Informative References  . . . . . . . . . . . . . . . . .  10
   Appendix A.  Adaptive Subscription Example  . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  13

1.  Introduction

   YANG-Push subscriptions [RFC8641] allow client applications to
   subscribe to continuous datastore updates without needing to poll.
   It defines a mechanism (i.e.,update trigger) to determine when an
   update record needs to be generated.  Two type of subscriptions are
   introduced in [RFC8641], distinguished by how updates are triggered:
   periodic and on-change.

   o  Periodic subscription allows subscribed data to be streamed to the
      destination at a configured fixed periodic interval

   o  On-change subscription allows update to be triggered when whenever
      a change in the subscribed information is detected.  The periodic
      interval is set to zero value in the on-change subscription case.

   However in some cases (e.g., wireless channel contention and
   interference causes the WLAN throughput and per-packet delays to vary
   over time), both collectors and publishers are configured with
   multiple periodic intervals and the subscribed data set can be
   streamed out to the destination at adaptive sampling or export rate,
   e.g., when wireless signal strength drops below a certain threshold,
   more data should be collected at high frequency.

   This document defines a YANG data model and associated mechanism
   enabling subscriber's adaptive subscriptions to a publisher's event
   streams.  Applying these elements allows a subscriber to



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   automatically adjust the volume of telemetry traffic sent from
   publisher to the receivers.

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.

   This document uses the following terms:

   Event:  Something that happens which may be of interest or trigger
      the invocation of the rule.  A fault, an alarm, a change in
      network state, network security threat, hardware malfunction,
      buffer untilization crossing a threshold, network connection
      setup, an external input to the system, for example [RFC3877].

   Client:  Defined in [RFC8342].

   Configuration:   Defined in [RFC8342].

   Configured subscription:  Defined in [RFC8639]

   Configuration datastore:    Defined in [RFC8342].

   Notification message:   Information intended for a receiver
      indicating that one or more events have occurred [RFC8639].

   Publisher:  An entity responsible for streaming notification messages
      per the terms of a subscription [RFC8639].

   Receiver:  A target to which a publisher pushes subscribed event
      records.  For dynamic subscriptions, the receiver and subscriber
      are the same entity [RFC8639].

   Subscriber:   A client able to request and negotiate a contract for
      the generation and push of event records from a publisher.  For
      dynamic subscriptions, the receiver and subscriber are the same
      entity [RFC8639].

   Subscription:  A contract with a publisher, stipulating the
      information that one or more receivers wish to have pushed from
      the publisher without the need for further solicitation [RFC8639].






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   On-change subscription:  A datastore subscription with updates that
      are triggered when changes in subscribed datastore nodes are
      detected.

   Periodic subscription:  A datastore subscription with updates that
      are triggered periodically according to some time interval.

2.  Model Overview

   The YANG data model for the "Adaptive Subscription to YANG
   Notification" augments the "update-trigger" in the YANG Push model to
   add a "adaptive-period" case.  Under the "adaptive-period" case, a
   "adaptive-period" list is defined.  The "adaptive-period" list uses
   the key "id" for indexing.  Within the "adaptive-period" list, an
   "interval" leaf and the corresponding trigger conditions are defined.
   When the trigger condition is satisfied, e.g., "op-field" exceeds the
   "op-value" and the change of "op-field" is monotonically increasing,
   the update interval will be changed into the value of "interval" leaf
   and the objects being filtered will be exported every interval
   specified by the value of "interval" leaf.  The "anchor-time" is used
   to indciate at which points in time periodic updates need to be
   assembled and sent.

   The following tree diagrams [RFC8340] provide an overview of the data
   model for "ietf-adaptive-subscription.yang" module.

   module: ietf-adaptive-subscription
     augment /sn:subscriptions/sn:subscription/yp:update-trigger:
       +--:(adaptive-subscription)
          +--rw adaptive-subsciptions
             +--rw adaptive-period* [id]
             |   +--rw id              string
             |   +--rw op-field?       yang:xpath1.0
             |   +--rw op-value?       string
             |   +--rw operator?       operator
             |   +--rw interval          centiseconds
             |   +--rw anchor-time       yang:date-time

3.  Bulk Subscription YANG Module

  <CODE BEGINS> file "ietf-adaptive-subscription@2020-02-14.yang"
  module ietf-adaptive-subscription {
    yang-version 1.1;
    namespace "urn:ietf:params:xml:ns:yang:ietf-adaptive-subscription";
    prefix as;
    import ietf-subscribed-notifications {
      prefix sn;
    }



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    import ietf-yang-push {
      prefix yp;
    }
    import ietf-yang-types {
      prefix yang;
    }
    organization
      "IETF NETCONF (Network Configuration) Working Group";
    contact
      "";
    description
      "NETCONF Protocol Data Types and Protocol Operations.
       Copyright (c) 2020 IETF Trust and the persons identified as
       the document authors.  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 2019-12-15 {
      description
        "Initial revision";
      reference
        "RFCxxx Adaptive subscription to YANG notification.";
    }

    typedef centiseconds {
         type uint32;
         description
           "A period of time, measured in units of 0.01 seconds.";
       }
    typedef operator {
      type enumeration {
        enum unequal {
          description
            "Indicates that the comparision type is unequal to.";
        }
        enum equal {
          description
            "Indicates that the comparision type is equal to.";
        }
        enum less {



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          description
            "Indicates that the comparision type is less than.";
        }
        enum less-or-equal {
          description
            "Indicates that the comparision type is less than
             or equal to.";
        }
        enum greater {
          description
            "Indicates that the comparision type is greater than.";
        }
        enum greater-or-equal {
          description
            "Indicates that the comparision type is greater than
             or equal to.";
        }
      }
      description
        "definition of the operator";
    }
    augment "/sn:subscriptions/sn:subscription/yp:update-trigger" {
           description
           "This augmentation adds additional subscription parameters
            that apply specifically to adaptive subscription.";
      case adaptive-period {
        container adaptive-periods {
          list adaptive-period {
            key "id";
            leaf id {
              type string;
              description
                "identifier";
            }
            leaf op-field {
              type yang:xpath1.0;
              description
                "targeted objects";
            }
            leaf op-value {
              type string;
              description
                "Compartion value which is static threshold value.";
            }
            leaf operator {
              type operator;
              description
                "Comparison type.";



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            }
           leaf interval {
              type centiseconds;
              mandatory true;
              description
                "Duration of time that should occur between periodic
                 push updates, in units of 0.01 seconds.";
          }
          leaf anchor-time {
               type yang:date-and-time;
               description
                 "Designates a timestamp before or after which a series
                  of periodic push updates are determined.  The next
                 update will take place at a point in time that is a
                 multiple of a period from the 'anchor-time'.
                 If an anchor-time is not provided, then the anchor-time
                 MUST be set with the creation time of the initial
                 update record. ";
               }
          description
            "List for adaptive periods";
        }
            description
               "Container for adaptive periods.";
      }
    }
   }
  }
  <CODE ENDS>

4.  IANA Considerations

4.1.  Updates to the IETF XML Registry

   This document registers two URIs in the IETF XML registry [RFC3688].
   Following the format in [RFC3688], the following registrations are
   requested to be made:

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








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4.2.  Updates to the YANG Module Names Registry

   This document registers two YANG modules in the YANG Module Names
   registry [RFC7950]. . Following the format in [RFC6020], the
   following registration has been made:

   ---------------------------------------------------------------------
      Name:         ietf-adaptive-subscription
      Namespace:    urn:ietf:params:xml:ns:yang:ietf-adaptive-subscription
      Prefix:       as
      Reference:    RFC xxxx
   ---------------------------------------------------------------------

5.  Security Considerations

   The YANG module specified in this document defines a schema for data
   that is designed to be accessed via network management protocols such
   as NETCONF [RFC6241] or RESTCONF [RFC8040].  The lowest NETCONF layer
   is the secure transport layer, and the mandatory-to-implement secure
   transport is Secure Shell (SSH) [RFC6242].  The lowest RESTCONF layer
   is HTTPS, and the mandatory-to-implement secure transport is TLS
   [RFC8446].

   The NETCONF 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.

   There are a number of data nodes defined in this YANG module that are
   writable/creatable/deletable (i.e., config true, which is the
   default).  These data nodes may be considered sensitive in some
   network environments.  Write operations (e.g., edit-config) to these
   data nodes without proper protection can have a negative effect on
   network operations.  These are the subtrees and data nodes and their
   sensitivity/vulnerability:

   o  /sn:subscriptions/sn:subscription/yp:update-trigger/adaptive-
      periods/adaptive-period/id

   o  /sn:subscriptions/sn:subscription/yp:update-trigger/adaptive-
      periods/adaptive-period/interval

6.  References








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6.1.  Normative References

   [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/info/rfc2119>.

   [RFC6241]  Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
              and A. Bierman, Ed., "Network Configuration Protocol
              (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
              <https://www.rfc-editor.org/info/rfc6241>.

   [RFC6242]  Wasserman, M., "Using the NETCONF Protocol over Secure
              Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
              <https://www.rfc-editor.org/info/rfc6242>.

   [RFC7950]  Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
              RFC 7950, DOI 10.17487/RFC7950, August 2016,
              <https://www.rfc-editor.org/info/rfc7950>.

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

   [RFC8126]  Cotton, M., Leiba, B., and T. Narten, "Guidelines for
              Writing an IANA Considerations Section in RFCs", BCP 26,
              RFC 8126, DOI 10.17487/RFC8126, June 2017,
              <https://www.rfc-editor.org/info/rfc8126>.

   [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/info/rfc8174>.

   [RFC8341]  Bierman, A. and M. Bjorklund, "Network Configuration
              Access Control Model", STD 91, RFC 8341,
              DOI 10.17487/RFC8341, March 2018,
              <https://www.rfc-editor.org/info/rfc8341>.

   [RFC8342]  Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K.,
              and R. Wilton, "Network Management Datastore Architecture
              (NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018,
              <https://www.rfc-editor.org/info/rfc8342>.

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




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   [RFC8446]  Rescorla, E., "The Transport Layer Security (TLS) Protocol
              Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
              <https://www.rfc-editor.org/info/rfc8446>.

   [RFC8641]  Clemm, A. and E. Voit, "Subscription to YANG Notifications
              for Datastore Updates", RFC 8641, DOI 10.17487/RFC8641,
              September 2019, <https://www.rfc-editor.org/info/rfc8641>.

6.2.  Informative References

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

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

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

Appendix A.  Adaptive Subscription Example

   The example YANG module used in this document represents performance
   data telemetry on a simple optical device.  The collector can control
   the rate of telemtry data to be streamed to the destination by
   switching to different time interval for the update to be sent.

   YANG tree diagram for the "example-opticalbox-telemetry" module:




















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          module example-opticalbox-telemetry {
              namespace "tag:ietf:example:opticalbox";
              prefix "optibox";
              container opticalstat {
                  leaf transmit-power {
                      description "Transmit optical power reading";
                      type int;
                      config false;
                  }
                  leaf receiving-power {
                      description " Receiving optical power reading";
                      type int;
                      config false;
                  }
                  leaf power-threhold {
                      description "Optical Power Threshold";
                      type int;
                  }
                  leaf high-voltage {
                      description "High voltage threshold";
                      type int;
                  }
                  leaf low-voltage {
                      description "Low voltage threshold";
                      type int;
                  }
                  leaf voltage {
                      description "current voltage reading";
                      type int;
                    config false;
                  }
                  leaf current-temperature {
                      description "Current temperature reading";
                      type int;
                      config false;
                  }
                  leaf cup-usage {
                    type uint32;
                    config false;
               }
              }
          }

   The adaptive subscription model can be used to keep track of
   performance data change such as temperature, voltage, power,cup
   usage.  In addition, it can adjust update period based on performance
   data change, e.g., when the current receiving power is higher than
   the pre-configured threshold, the notification for the optical



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   performance data from publisher can be sent at a low frequency.  When
   the current receiving power is lower than the pre-configured
   threshold, the notification for the optical performance data can be
   sent at a high frequency.

<netconf:rpc message-id="101"
     xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
   <establish-subscription
       xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications"
       xmlns:yp="urn:ietf:params:xml:ns:yang:ietf-yang-push">
     <yp:datastore
          xmlns:ds="urn:ietf:params:xml:ns:yang:ietf-datastores">
       ds:operational
     </yp:datastore>
     <yp:datastore-xpath-filter
         xmlns:ex="https://example.com/sample-data/1.0">
       /ex:foo
     </yp:datastore-xpath-filter>
     <as:adaptive-periods>
       <as:adaptive-period>
        <as:id>01</as:id>
        <as:op-field>/opticalstat/current-voltage</as:op-field>
        <as:op-value>60</as:op-value>
        <as:operator>greater</as:operator>
        <as:period>500</as:period>
       </as:adaptive-period>
       <as:adaptive-period>
        <as:id>02</as:id>
        <as:op-field>/opticalstat/current-voltage</as:op-field>
        <as:op-value>60</as:op-value>
        <as:operator>less-or-equal</as:operator>
        <as:period>100</as:period>
       </as:adaptive-period>
     </yp:adaptive-periods>
   </establish-subscription>
 </netconf:rpc>

   In another example, when the time interval for update to be sent is
   set to 5 seconds and specific performance data,e.g., 5 receiving
   power values
   (0.48dB&#12289;0.57dB&#12289;0.61dB&#12289;0.69dB&#12289;0.70dB) can
   be sampled per second and collected during this time interval
   changes.  When power changes exceed the preconfigured threhold
   (e.g.,0.20dB), all these 5 receiving power values falling within
   detection time window or update time interval should be published to
   the destinations for data analysis.





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Authors' Addresses

   Michael Wang
   Huawei
   101 Software Avenue, Yuhua District
   Nanjing, Jiangsu  210012
   China

   Email: wangzitao@huawei.com


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

   Email: bill.wu@huawei.com


   Wei Song
   Huawei
   101 Software Avenue, Yuhua District
   Nanjing, Jiangsu  210012
   China

   Email: songwei80@huawei.com


   Liang Geng
   China Mobile
   32 Xuanwumen West St, Xicheng District
   Beijing  10053

   Email: gengliang@chinamobile.com


   Peng Liu
   China Mobile
   32 Xuanwumen West St, Xicheng District
   Beijing  10053

   Email: liupengyjy@chinamobile.com








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