NETMOD Working Group                                           K. Watsen
Internet-Draft                                          Juniper Networks
Intended status: Informational                                 T. Nadeau
Expires: April 21, June 17, 2016                                  Brocade Networks
                                                        October 19,
                                                       December 15, 2015

                 NETMOD Operational State Requirements
                   draft-ietf-netmod-opstate-reqs-00
                   draft-ietf-netmod-opstate-reqs-01

Abstract

   This document defines requirements for servers enabling better
   visibility and control over the server's operational state.  To
   achieve this end, this document also defines terminology describing a
   conceptual model enabling the requirements to be expressed.

Status of This Memo

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Table of Contents

   1.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements  . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     6.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Appendix A.  Relation to Terms Defined in Other Drafts  . . . . .   7
   Appendix B.  Relation to Requirements in Other Drafts . . . . . .   7
   Appendix C.  Open Issues  . . . . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

   The term "server" is used throughout this document to refer to what
   is many times known as the "device", "system", or "network element".
   This definition is intended to be consistent with the term "server"
   defined in [RFC6241], Section 1.1, but free of any association to a
   particular protocol.

   This document defines the following terms:

   Applied Configuration:  This data represents the configuration state
       that the server is actually in.  That is, the configuration state
       which is currently being used by server components (e.g., control
       plane daemons, operating system kernels, line cards).

          NOTE: The server's ability to report applied configuration
          accurately may be limited in some cases, such as when the
          configuration goes through an intermediate layer without an
          ability to inspect the lower layer.

   Asynchronous Configuration Operation:  A configuration request to
       update the running configuration of a server that is applied
       asynchronously with respect to the client request.  The server
       MUST update its intended configuration (see term) before replying
       to the client indicating whether the request will be processed.
       This reply to the client only indicates whether there are any
       errors in the original request.  The server's applied
       configuration state (see term) is updated after the configuration
       change has been fully effected to all impacted components in the
       server.  Once applied, there MUST be a mechanism for the client
       to determine when the request has completed processing and
       whether the intended config is now fully effective or there are
       any errors from applying the configuration change, which could be
       from an asynchronous notification or via a client operation.

   Continue On Error:  Continue to process configuration data on error;
       error is recorded, and negative response is generated if any
       errors occur.

   Derived State:  This data represents information which is generated
       as part of the server's own interactions.  For example, derived
       state may consist of the results of protocol interactions (the
       negotiated duplex state of an Ethernet link), statistics (such as
       message queue depth), or counters (such as packet input or output
       bytes).

   Intended Configuration:  This data represents the configuration state
       that the network operator intends the server to be in, and that
       has been accepted by the server as valid configuration.

   Operational State:  Operational State is the current state of the
       system as known to the various components of the system (e.g.,
       control plane daemons, operating system kernels, line cards).
       The operational state includes both applied configuration and
       derived state.

   Rollback On Error:  If an error condition occurs such that part of
       applying the configuration fails, the server will stop processing
       the configuration operation and restore the specified
       configuration to its complete state at the start of this
       configuration operation.

   Synchronous Configuration Operation:  A configuration request to
       update the running configuration of a server that is applied
       synchronously with respect to the client request (i.e. a blocking
       call).  The server MUST fully attempt to apply the configuration
       change to all impacted components in the server, updating both
       the server's intended and applied configuration (see terms),
       before replying to the client.  The reply to the client indicates
       whether there are any errors in the request or errors from
       applying the configuration change.

2.  Requirements

   1.  Ability to interact with both intended and applied configuration
       A.  The ability to ask the operational components of a server
           (e.g., line cards) for the configuration that they are
           currently using.  This is the applied configuration (see
           term).

       B.  Applied configuration is read-only

       C.  The data model for the applied configuration is the same as
           the data model for the intended configuration (same leaves)

       D.  When a configuration change for any intended configuration
           node has been successfully applied to the server (e.g. not
           failed, nor deferred due to absent hardware) then the
           existence and value of the corresponding applied
           configuration node must match the intended configuration
           node.

   2.  Applied configuration as part of operational state

       A.  The ability to retrieve the applied configuration and derived
           state nodes in a single protocol operation.

   3.  Support for both synchronous and asynchronous configuration
       operations (see terms)

       A.  A server may support only synchronous configuration
           operations, or only asynchronous configuration operations, or
           both synchronous and asynchronous configuration operations on
           a client-specified per-operation basis.

       B.  Servers that support asynchronous configuration operations
           MAY also provide a verify operation that a client can request
           from the server to return information regarding the
           difference between the intended and applied configurations.

       C.  The configuration protocol MUST specify how configuration
           errors are handled.  Errors may be handled by "stop on
           error", "continue on error" or "rollback on error" semantics
           (see terms).  Support for "rollback on error" SHOULD be
           provided.

   4.

   3.  Separation of the applied configuration and operational derived state data; aspects
       of operational state; ability to retrieve them and independently and
       together

       A.  Be able to retrieve only the derived state applied configuration aspects of
           operational state

       B.  Be able to retrieve only the non-derived derived state aspects of
           operational state

       C.  Be able to retrieve both the derived applied configuration and non-derived
           derived state aspects of operational state together

   5.  Ability to retrieve operational state corresponding only to
       derived values, statistics, etc.

          // this is a duplicate of # 4-a

   6.

   4.  Ability to relate configuration with its corresponding
       operational state

       A.  Ability to map intended config nodes to corresponding applied
           config nodes

       B.  Ability to map intended config nodes to associated derived
           state nodes

       C.  The mappings needs to be programmatically consumable

   7.

   5.  Ability for distinct modules to leverage a common model-structure

       A.  Focus on the IETF-defined modules, and ideally provides
           guidance to other SDOs

       B.  Multiple domain-specific model-structure trees are okay

       C.  Model-structures may be defined in multiple modules with
           distinct namespaces

3.  Security Considerations

   None

4.  IANA Considerations

   None

5.  Acknowledgements

   The authors would like to thank the following for contributing to
   this document (in alphabetic order): Acee Lindem, Andy Bierman, Anees
   Shaikh, Benoit Claise, Carl Moberg, Dan Romascanu, Dean Bogdanovic,
   Gert Grammel, Jonathan Hansford, Juergen Schoenwaelder, Lou Berger,
   Mahesh Jethanandani, Martin Bjorklund, Phil Shafer, Randy Presuhn,
   Rob Shakir, Robert Wilton, Sterne, Jason.

6.  References

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, 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

6.2.  Informative References

   [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,
              <http://www.rfc-editor.org/info/rfc6241>.

   [draft-openconfig-netmod-model-structure-00]
              Shaikh, A., Shakir, R., D'Souza, K., and L. Fang,
              "Operational Structure and Organization of YANG Models",
              draft-openconfig-netmod-model-structure-00 (work in
              progress), 2015, <https://tools.ietf.org/html/draft-
              openconfig-netmod-model-structure-00>.

   [draft-openconfig-netmod-opstate-01]
              Shakir, R., Shaikh, A., and M. Hines, "Consistent Modeling
              of Operational State Data in YANG", draft-openconfig-
              netmod-opstate-01 (work in progress), 2015,
              <https://tools.ietf.org/html/draft-openconfig-netmod-
              opstate-01>.

   [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,
              <http://www.rfc-editor.org/info/rfc6241>.

Appendix A.  Relation to Terms Defined in Other Drafts

   The following terms were originally defined in [RFC6241], but since
   modified by the NETMOD WG:

   o  continue-on-error

   o  stop-on-error

   o  rollback-on-error

   The following terms were originally defined in
   [draft-openconfig-netmod-opstate-01], but since modified by the
   NETMOD WG:

   o  Intended Configuration

   o  Applied Configuration

   o  Derived State

Appendix B.  Relation to Requirements in Other Drafts

   The requirements in this document roughly map onto the requirements
   listed in [draft-openconfig-netmod-opstate-01] and
   [draft-openconfig-netmod-model-structure-00] as list below.  Some
   liberty was taken to adjust the requirements based on what looked
   liked consensus from on list discussions:

   1.  draft-openconfig-netmod-opstate-01, Section 3

   2.  draft-openconfig-netmod-opstate-01, Section 4.1

   3.  draft-openconfig-netmod-opstate-01, Section 4.2

   4.

   3.  draft-openconfig-netmod-opstate-01, Section 4.3

   5.  draft-openconfig-netmod-opstate-01, Section 4.4

   6.

   4.  draft-openconfig-netmod-opstate-01, Section 4.5

   7.

   5.  draft-openconfig-netmod-model-structure-00 (no section)

Appendix C.  Open Issues

   All issues with this draft are tracked using GitHub issues.  Please
   see: https://github.com/netmod-wg/opstate-reqs/issues to see
   currently opened issues.

Authors' Addresses

   Kent Watsen
   Juniper Networks

   EMail: kwatsen@juniper.net

   Thomas Nadeau
   Brocade Networks

   EMail: tnadeau@lucidvision.com