[Docs] [txt|pdf|xml|html] [Tracker] [WG] [Email] [Diff1] [Diff2] [Nits]

Versions: (draft-lengyel-netconf-notification-capabilities) 00 01 02 03 04 05 06 07

Netconf                                                       B. Lengyel
Internet-Draft                                                  Ericsson
Intended status: Standards Track                                A. Clemm
Expires: September 2, 2019                                    Huawei USA
                                                           March 1, 2019


                   YangPush Notification Capabilities
            draft-ietf-netconf-notification-capabilities-01

Abstract

   This document proposes a YANG module that allows a YANG server to
   specify server capabilities related to "Subscription to YANG
   Datastores" (YangPush).  It proposes to use YANG Instance Data to
   document this information already in implementation time.

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 2, 2019.

Copyright Notice

   Copyright (c) 2019 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 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.



Lengyel & Clemm         Expires September 2, 2019               [Page 1]


Internet-Draft     YangPush Notification Capabilities         March 2019


Table of Contents

   1.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Notification Capability Model . . . . . . . . . . . . . . . .   4
     3.1.  Tree Diagram  . . . . . . . . . . . . . . . . . . . . . .   5
     3.2.  YANG Module . . . . . . . . . . . . . . . . . . . . . . .   6
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
     5.1.  The IETF XML Registry . . . . . . . . . . . . . . . . . .   9
     5.2.  The YANG Module Names Registry  . . . . . . . . . . . . .   9
   6.  Open Issues . . . . . . . . . . . . . . . . . . . . . . . . .   9
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  10
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  10
   Appendix A.  Changes between revisions  . . . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

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.

   The terms Yang-Push, On-change subscription and Periodic subscription
   are used as defined in [I-D.ietf-netconf-yang-push]

   On-change Notification Capability: The capability of the YANG server
   to support On-change subscriptions.

   Implementation-time information: Information about the YANG server's
   behavior that is made available during the implementation of the
   server, available from a source other then a running Yang server.

   Rutime-information: Information about the YANG server's behavior that
   is available from the running YANG server via a protocol like
   NETCONF, RESTCONF or HTTPS.

2.  Introduction

   As defined in [I-D.ietf-netconf-yang-push] a YANG server may allow
   clients to subscribe to updates from a datastore and subsequently
   push such update notifications to the client.  Notifications may be
   sent periodically or on-change (more or less immediately after each
   change).




Lengyel & Clemm         Expires September 2, 2019               [Page 2]


Internet-Draft     YangPush Notification Capabilities         March 2019


   A YANG server supporting YANG-Push has a number of capabilities that
   are determined during the implementation of the server.  These
   include:

   o  Supported dampening periods for on-change subscriptions

   o  Supported (reporting) periods for periodic subscriptions

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

   o  The set of data nodes for which on-change notification is
      supported

   Servers MAY have limitations in how many update notifications and how
   many datastore node updates they can send out in a certain time-
   period.

   In some cases, a publisher supporting on-change notifications will
   not be able to push updates for some object types on-change.  Reasons
   for this might be that the value of the datastore node changes
   frequently (e.g. in-octets counter), that small object changes are
   frequent and meaningless (e.g., a temperature gauge changing 0.1
   degrees), or that the implementation is not capable of on-change
   notification for a particular object.  In those cases, it will be
   important for client applications to have a way to identify for which
   objects on-change notifications are supported and for which ones not.

   Faced with the reality that support for on-change notification does
   not mean that such notifications will be sent for any specific data
   node, client/management applications can not rely on the on-change
   functionality unless the client has some means to identify for which
   objects on-change notifications are supported.  YANG models are meant
   to be used as an interface contract.  Without identification of data
   nodes supporting on-change, this contract would only state the YANG
   server may (or may not) send on-change notifications for a data node
   specified in a YANG module.

   This document proposes a YANG module that allows a client to discover
   YANG-Push related capabilities.

   YANG-Push related capability information will be needed both in
   implementation-time and run-time.

   Implementation time information is needed by Network Management
   System (NMS) implementers.  During NMS implementation for any
   functionality that depends on the notifications the information about
   on change notification capability is needed.  If the information is
   not available early in some document, but only as instance data from



Lengyel & Clemm         Expires September 2, 2019               [Page 3]


Internet-Draft     YangPush Notification Capabilities         March 2019


   the network node, the NMS implementation will be delayed, because it
   has to wait for the network node to be ready.  Also assuming that all
   NMS implementers will have a correctly configured network node
   available to retrieve data from, is an expensive proposition.  (An
   NMS may handle dozens of network node types.)  Often a fully
   functional NMS is a requirement for introducing a new network node
   type into a network, so delaying the NMS effectively delays the
   availability of the network node as well.

   Implementation time information is needed by system integrators.
   When introducing a network node type into their network, operators
   often need to integrate the node type into their own management
   system.  The NMS may have management functions that depend on on-
   change notifications.  The network operator needs to plan his
   management practices and NMS implementation before he even decides to
   buy the specific network node type.  Moreover the decision to buy the
   node type sometimes depends on these management possibilities.

   Run-time information is needed

   o  for any "purely model driven" client, e.g. a NETCONF-browser.  As
      long as it has a valid model to read the capability information,
      it does not care which data nodes send notification, it will just
      handle what is available.

   o  in case the capability might change during run-time e.g. due to
      licensing, HW constraints etc.

   o  to check that early, implementation time capability information
      about the capabilities is indeed what the server implements (is
      the supplied documentation correct?)

3.  Notification Capability Model

   It is a goal to provide YangPush notification capability information
   in a format that is

   o  vendor independent (standard)

   o  formal (no freeform English text please)

   o  the same both in implementation-time and run-time

   The YANG module ietf-notification-capabilities is defined to provide
   the information.  It contains

      a set of capabilities related to the amount of notifications the
      server can send out



Lengyel & Clemm         Expires September 2, 2019               [Page 4]


Internet-Draft     YangPush Notification Capabilities         March 2019


      a default on-change notification capability separately for config
      false and config true data nodes

      an on-change-notification-capability list containing a potentially
      different true/false notification capability for a few data nodes
      in the schema tree.  Unless a node is in this list with a specific
      capability value, it inherits its on-change-notification-
      capability from its parent in the data tree, or from the relevant
      default values.  It is assumed that only a small number of nodes
      will be included in this list: special cases where the default
      behavior is not followed.  For a detailed description of the usage
      of this list see the description in the YANG module.

   The information SHALL be provided in two ways both following the
   ietf-notification-capabilities module:

   o  It SHALL be provided by the implementer as YANG instance data file
      complying to the [I-D.lengyel-netmod-yang-instance-data].  The
      file SHALL be available already in implementation time retrievable
      in a way that does not depend on a live network node.  E.g.
      download from product Website.

   o  It SHALL be available via NETCONF or RESTCONF from the live YANG
      server during runtime.

3.1.  Tree Diagram

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

 module: ietf-notification-capabilities
   +--ro yangpush-notification-capabilities
      +--ro minimum-dampening-period?               uint32
      +--ro (update-period)?
      |  +--:(minimum-update-period)
      |  |  +--ro minimum-update-period?                  uint32
      |  +--:(supported-update-period)
      |     +--ro supported-update-period*                uint32
      +--ro max-objects-per-update?                 uint32
      +--ro notification-sent-for-config-default?   boolean
      +--ro notification-sent-for-state-default?    boolean
      +--ro on-change-notification-capability* [node-selector]
         +--ro node-selector               nacm:node-instance-identifier
         +--ro on-change-notification-sent    boolean







Lengyel & Clemm         Expires September 2, 2019               [Page 5]


Internet-Draft     YangPush Notification Capabilities         March 2019


3.2.  YANG Module

   <CODE BEGINS> file "ietf-notification-capabilities.yang"

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

   import ietf-netconf-acm { prefix nacm; }

   organization
     "IETF NETCONF (Network Configuration) Working Group";

   contact
     "WG Web:   <https://datatracker.ietf.org/wg/netconf/>
      WG List:  <mailto:netconf@ietf.org>

      WG Chair: Kent Watsen
                <mailto:kwatsen@juniper.net>

      WG Chair: Mahesh Jethanandani
                <mailto:mjethanandani@gmail.com>

      Editor:   Balazs Lengyel
                <mailto:balazs.lengyel@ericsson.com>";


   description "This module specifies YANG-Push related server
     capabilities. It contains
     - capabilities related to the amount of notifications the
     server can send out
     - default and schema node specific information specifying
     the set of data nodes for which the YANG server is capable
     of sending on-change notifications.

     On-change notification capability is marked as true or false.
     This marking is inherited from the parent down the data tree
     unless explicitly marked otherwise.

     On-change notifications SHALL be sent for a config=true
     data node if one of the following is true:
     - if it is a top level data-node and is not specified in the
     on-change-notification-capability list and the
     notification-sent-for-config-default is true; or
     - notifications are sent for its parent data node and it is
     not specified in the on-change-notification-capability list; or



Lengyel & Clemm         Expires September 2, 2019               [Page 6]


Internet-Draft     YangPush Notification Capabilities         March 2019


     - it is specified in the on-change-notification-capability
     list and has a on-change-notification-sent value true.

     On-change notifications SHALL be sent for a config=false
     data node if one of the following is true:
     - if it is a top level data-node or has a config=true parent
     data node and is not specified in the
     on-change-notification-capability list and the
     notification-sent-for-state-default is true; or
     - notifications are sent for its parent data node
     which is also config=false and it is
     not specified in the on-change-notification-capability list; or
     - it is specified in the on-change-notification-capability
     list and has an on-change-notification-sent value true or
     ";

   revision 2019-02-28 {
     description "Initial version";
     reference
       "RFC XXX: YangPush Notification Capabilities";
   }

   container yangpush-notification-capabilities {
     config false;
     description "YANG-Push related server capabilities";

     leaf minimum-dampening-period {
       type uint32;
       units msec;
       description "The minimum dampening period supported for on-change
         subscriptions.";
     }

     choice update-period {
       description "Supported period values.";
       leaf minimum-update-period {
         type uint32;
         units centiseconds;
         description "Minimum update period supported for a
           periodic subscription.";
       }

       leaf-list supported-update-period {
         type uint32;
         units centiseconds;
         description "Specific supported update period values
           for a periodic subscription";
       }



Lengyel & Clemm         Expires September 2, 2019               [Page 7]


Internet-Draft     YangPush Notification Capabilities         March 2019


     }

     leaf max-objects-per-update {
       type uint32;
       description "Maximum number of objects that can be sent
         in an update";
     }

     leaf notification-sent-for-config-default {
       type boolean;
       default true;
       description "Specifies the default value for
         top level configuration data nodes for the
         on-change-notification-sent capability.";
     }

     leaf notification-sent-for-state-default {
       type boolean;
       default false;
       description "Specifies the default value
         top level state data nodes for the
         on-change-notification-sent capability.";
     }

     list on-change-notification-capability {
       key node-selector ;
       description "A list of data nodes that have the
          on-change-notification-capability specifically defined.

          Should be used when specific data nodes support
          on-change notification in a module/subtree that
          generally does not support it or when some data nodes
          do not support the notification in a module/subtree
          that generally supports on-change notifications.";

       leaf node-selector {
         type nacm:node-instance-identifier;
         description "Selects the data nodes for which
             on-change capability is specified.";
       }

       leaf on-change-notification-sent {
         type boolean;
         mandatory true;
         description "Specifies whether the YANG server will
           send on-change notifications for the selected
           data nodes.";
       }



Lengyel & Clemm         Expires September 2, 2019               [Page 8]


Internet-Draft     YangPush Notification Capabilities         March 2019


     }
   }
 }

   <CODE ENDS>

4.  Security Considerations

   The YANG module defined in this document is designed to be accessed
   via YANG based management protocols, such as NETCONF and RESTCONF.
   Both of these protocols have mandatory-to- implement secure transport
   layers (e.g., SSH, TLS) with mutual authentication.

   The NETCONF access control model (NACM) provides the means to
   restrict access for particular users to a pre-configured subset of
   all available protocol operations and content.

   The data in this module is not security sensitive.

5.  IANA Considerations

5.1.  The IETF XML Registry

   This document registers one URI in the IETF XML registry [RFC3688].
   Following the format in [RFC3688], the following registrations are
   requested:

      URI: urn:ietf:params:xml:ns:yang:ietf-notification-capabilities
      Registrant Contact: The NETCONF WG of the IETF.
      XML: N/A, the requested URI is an XML namespace.

5.2.  The YANG Module Names Registry

   This document registers one YANG module in the YANG Module Names
   registry [RFC7950].  Following the format in [RFC7950], the the
   following registrations are requested:

  name:       ietf-notification-capabilities
  namespace:  urn:ietf:params:xml:ns:yang:ietf-notification-capabilities
  prefix:     inc
  reference:  RFC XXXX

6.  Open Issues

      Do we need separate defaults/individual lists for every datastore?
      Proposal: no, it would be an overkill.





Lengyel & Clemm         Expires September 2, 2019               [Page 9]


Internet-Draft     YangPush Notification Capabilities         March 2019


      Should type nacm:node-instance-identifier be moved to yang-types?
      It is useful for more then just nacm.

7.  References

7.1.  Normative References

   [I-D.ietf-netconf-yang-push]
              Clemm, A., Voit, E., Prieto, A., Tripathy, A., Nilsen-
              Nygaard, E., Bierman, A., and B. Lengyel, "Subscription to
              YANG Datastores", draft-ietf-netconf-yang-push-22 (work in
              progress), February 2019.

   [I-D.lengyel-netmod-yang-instance-data]
              Lengyel, B. and B. Claise, "YANG Based Instance Data Files
              Format", draft-lengyel-netmod-yang-instance-data-05 (work
              in progress), October 2018.

   [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>.

7.2.  Informative 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>.

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

   [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>.

   [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.  Changes between revisions

   v00 - v01

   o  Add more capabilities: minimum period, supported period max-number
      of objects, min dampening period, dampening supported




Lengyel & Clemm         Expires September 2, 2019              [Page 10]


Internet-Draft     YangPush Notification Capabilities         March 2019


Authors' Addresses

   Balazs Lengyel
   Ericsson
   Magyar Tudosok korutja 11
   1117 Budapest
   Hungary

   Email: balazs.lengyel@ericsson.com


   Alexander Clemm
   Huawei USA
   2330 Central Expressway
   Santa Clara, CA 95050
   USA

   Email: ludwig@clemm.org

































Lengyel & Clemm         Expires September 2, 2019              [Page 11]


Html markup produced by rfcmarkup 1.129d, available from https://tools.ietf.org/tools/rfcmarkup/