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Network Working Group                                       M. Bjorklund
Internet-Draft                                            Tail-f Systems
Updates: 8040 (if approved)                             J. Schoenwaelder
Intended status: Standards Track                       Jacobs University
Expires: September 2, 2018                                     P. Shafer
                                                               K. Watsen
                                                        Juniper Networks
                                                               R. Wilton
                                                           Cisco Systems
                                                           March 1, 2018


    RESTCONF Extensions to Support the Network Management Datastore
                              Architecture
                  draft-ietf-netconf-nmda-restconf-03

Abstract

   This document extends the RESTCONF protocol defined in RFC 8040 in
   order to support the Network Management Datastore Architecture
   defined in I-D.ietf-netmod-revised-datastores.

   This document updates RFC 8040 by introducing new datastore
   resources, adding a new query parameter, and requiring the usage of
   I-D.ietf-netconf-rfc7895bis by RESTCONF servers implementing the
   Network Management Datastore Architecture.

   REF Editor: please replace "I-D.ietf-netmod-revised-datastores" and
   "I-D.ietf-netconf-rfc7895bis" above with their final RFC assignments.

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 http://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, 2018.





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Copyright Notice

   Copyright (c) 2018 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
   (http://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.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Datastore and YANG Library Requirements . . . . . . . . . . .   3
   3.  RESTCONF Extensions . . . . . . . . . . . . . . . . . . . . .   3
     3.1.  New Datastore Resources . . . . . . . . . . . . . . . . .   3
     3.2.  Protocol Operations . . . . . . . . . . . . . . . . . . .   4
       3.2.1.  With-defaults query parameter on the operational
               state datastore . . . . . . . . . . . . . . . . . . .   5
       3.2.2.  New "with-origin" Query Parameter . . . . . . . . . .   5
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   6.  Normative References  . . . . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   This document extends the RESTCONF protocol defined in [RFC8040] in
   order to support the Network Management Datastore Architecture (NMDA)
   defined in [I-D.ietf-netmod-revised-datastores].

   This document updates [RFC8040] in order to enable RESTCONF clients
   to discover which datastores are supported by the RESTCONF server, as
   well as determine which modules are supported in each datastore and,
   finally, to interact with all the datastores supported by the NMDA.
   Specifically, the update introduces new datastore resources, adds a
   new query parameter, and requires the usage of
   [I-D.ietf-netconf-rfc7895bis] by RESTCONF servers implementing the
   NMDA.






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   The solution presented in this document is backwards compatible with
   [RFC8040].  This is achieved by only adding new resources and leaving
   the semantics of the existing resources unchanged.

1.1.  Terminology

   This document uses the terminology defined by the NMDA
   [I-D.ietf-netmod-revised-datastores].

   The keywords "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.  Datastore and YANG Library Requirements

   RFC Ed.: Update 201X-XX-XX below with correct date.

   An NMDA-compliant RESTCONF server MUST support the operational state
   datastore and it MUST implement at least revision 201X-XX-XX of the
   "ietf-yang-library" module defined in [I-D.ietf-netconf-rfc7895bis].

   Such a server identifies that it supports the NMDA both by
   implementing the {+restconf}/ds/ietf-datastores:operational resource,
   and by implementing at least revision 201X-XX-XX of the
   "ietf-yang-library" module.

   A RESTCONF client can test if a server supports the NMDA by using
   either the HEAD or GET methods on {+restconf}/ds/ietf-
   datastores:operational.

3.  RESTCONF Extensions

   This section describes the RESTCONF extensions needed to support the
   NMDA.

3.1.  New Datastore Resources

   This document defines a set of new resources representing datastores
   as defined in [I-D.ietf-netmod-revised-datastores].  These resources
   are available using the following resource path template:

     {+restconf}/ds/<datastore>

   The <datastore> path component is encoded as an "identity" according
   to the JSON encoding rules for identities, defined in Section 4 of
   [RFC7951].  Such an identity MUST be derived from the "datastore"



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   identity defined in the "ietf-datastores" YANG module
   [I-D.ietf-netmod-revised-datastores].

   Specifically:

   o  The resource {+restconf}/ds/ietf-datastores:operational refers to
      the operational state datastore.

   o  The resource {+restconf}/ds/ietf-datastores:running refers to the
      running configuration datastore.

   o  The resource {+restconf}/ds/ietf-datastores:intended refers to the
      intended configuration datastore.

   An NMDA-compliant server MUST implement {+restconf}/ds/ietf-
   datastores:operational.  Other datastore resources are optional to
   implement.

   YANG actions can only be invoked in {+restconf}/ds/ietf-
   datastores:operational.

   If a server implements the example datastore "ds-ephemeral" in the
   module "example-ds-ephemeral", it would implement the resource
   {+restconf}/ds/example-ds-ephemeral:ds-ephemeral.

3.2.  Protocol Operations

   The protocol operations available for the new datastore resources
   (Section 3.1) are the same as the protocol operations defined in
   [RFC8040] for the {+restconf}/data resource with the following
   exceptions:

   o  Dynamic configuration datastores are excluded, as each dynamic
      configuration datastore definition needs to be reviewed for what
      protocol operations it supports.

   o  Some datastores are read-only by nature (e.g., <intended>), and
      hence any attempt to modify these datastores will fail.  A server
      MUST return a response with a "405 Method Not Allowed" status-
      line, and error-tag value "operation-not-supported".

   o  The semantics of the "with-defaults" query parameter ([RFC8040],
      Section 4.8.9) differs when interacting with the operational state
      datastore.  The semantics are described below, in Section 3.2.1.

   o  [RFC8040], Section 3.5.4, paragraph 3 does not apply when
      interacting with any resource under {+restconf}/ds.




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3.2.1.  With-defaults query parameter on the operational state datastore

   The "with-defaults" query parameter ([RFC8040], Section 4.8.9) is
   optional to support when interacting with {+restconf}/ds/ietf-
   datastores:operational.  The associated capability to indicate a
   server's support is identified with the URI:

     urn:ietf:params:restconf:capability:with-operational-defaults:1.0

   For servers that support it, the behavior of the "with-defaults"
   query parameter on the operational state datastore is defined as
   follows:

   o  If no "with-defaults" query parameter is specified, or if it is
      set to "explicit", "report-all", or "report-all-tagged", then the
      "in use" values, as defined in
      [I-D.ietf-netmod-revised-datastores] section 5.3, are returned
      from the operational state datastore, even if a node happens to
      have a default statement in the YANG module, and this default
      value is being used by the server.  If the "with-defaults"
      parameter is set to "report-all-tagged", any values that match the
      schema default are tagged with additional metadata, as described
      in [RFC8040], Section 4.8.9.

   o  If the "with-defaults" query parameter is set to "trim", all "in
      use" values are returned, except that the output is filtered to
      exclude any values that match the default defined in the YANG
      schema.

   Servers are not required to support all values in the "with-defaults"
   query parameter on the operational state datastore.  If a request is
   made using a value that is not supported, then the error handling
   behavior is as described in ([RFC8040], Section 4.8.9).

3.2.2.  New "with-origin" Query Parameter

   A new query parameter named "with-origin" is added to the GET
   operation.  If present, it requests that the server includes "origin"
   metadata annotations in its response, as detailed in the NMDA.  This
   parameter is only valid when querying {+restconf}/ds/ietf-
   datastores:operational or any datastores with identities derived from
   the "operational" identity.  Otherwise, if an invalid datastore is
   specified then the server MUST return a response with a "400 Bad
   Request" status-line, using an error-tag value of "invalid-value".
   "origin" metadata annotations are not included unless a client
   explicitly requests them.





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   Data in the operational state datatstore can come from multiple
   sources.  The server should return the most accurate value for the
   "origin" metadata annotation as possible, indicating the source of
   the operational value, as specified in Section 5.3.4 of
   [I-D.ietf-netmod-revised-datastores].

   When encoding the origin metadata annotation for a hierarchy of
   returned nodes, the annotation can be omitted for a child node when
   the value matches that of the parent node, as described in
   "ietf-origin" YANG module [I-D.ietf-netmod-revised-datastores].

   The "with-origin" query parameter is optional to support.  It is
   identified with the URI:

     urn:ietf:params:restconf:capability:with-origin:1.0

4.  IANA Considerations

   This document defines two capability identifier URNs in the "RESTCONF
   Capability URNs" registry defined in [RFC8040]:

     Index
     Capability Identifier
     ---------------------

     :with-origin
     urn:ietf:params:restconf:capability:with-origin:1.0

     :with-operational-defaults
     urn:ietf:params:restconf:capability:with-operational-defaults:1.0

5.  Security Considerations

   This documents extends the RESTCONF protocol by introducing new
   datastore resources.  The lowest RESTCONF layer is HTTPS, and the
   mandatory-to-implement secure transport is TLS [RFC5246].  The
   RESTCONF protocol uses the network configuration access control model
   [I-D.ietf-netconf-rfc6536bis], which provides the means to restrict
   access for particular RESTCONF users to a preconfigured subset of all
   available RESTCONF protocol operations and content.

   The security constraints for the base RESTCONF protocol (see
   Section 12 of [RFC8040] apply to the new RESTCONF datastore resources
   defined in this document.







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6.  Normative References

   [I-D.ietf-netconf-rfc6536bis]
              Bierman, A. and M. Bjorklund, "Network Configuration
              Access Control Module", draft-ietf-netconf-rfc6536bis-09
              (work in progress), December 2017.

   [I-D.ietf-netconf-rfc7895bis]
              Bierman, A., Bjorklund, M., Schoenwaelder, J., Watsen, K.,
              and R. Wilton, "YANG Library", draft-ietf-netconf-
              rfc7895bis-05 (work in progress), February 2018.

   [I-D.ietf-netmod-revised-datastores]
              Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K.,
              and R. Wilton, "Network Management Datastore
              Architecture", draft-ietf-netmod-revised-datastores-10
              (work in progress), January 2018.

   [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>.

   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
              (TLS) Protocol Version 1.2", RFC 5246, DOI 10.17487/
              RFC5246, August 2008, <https://www.rfc-editor.org/info/
              rfc5246>.

   [RFC7951]  Lhotka, L., "JSON Encoding of Data Modeled with YANG", RFC
              7951, DOI 10.17487/RFC7951, August 2016, <https://www.rfc-
              editor.org/info/rfc7951>.

   [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>.

   [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>.

Authors' Addresses

   Martin Bjorklund
   Tail-f Systems

   Email: mbj@tail-f.com





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   Juergen Schoenwaelder
   Jacobs University

   Email: j.schoenwaelder@jacobs-university.de


   Phil Shafer
   Juniper Networks

   Email: phil@juniper.net


   Kent Watsen
   Juniper Networks

   Email: kwatsen@juniper.net


   Robert Wilton
   Cisco Systems

   Email: rwilton@cisco.com





























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