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Versions: 00

NETCONF WG                                               M. Jethanandani
Internet-Draft
Intended status: Standards Track                                  J. Lam
Expires: August 27, 2018                                        A. Leung
                                                     Cisco Systems, Inc.
                                                       February 23, 2018


                      Binary Encoding for NETCONF
                draft-mahesh-netconf-binary-encoding-00

Abstract

   This document describes a method by which a NETCONF [RFC6241] client
   and server can negotiate an alternate form of encoding.

   This document updates RFC 6241.

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 August 27, 2018.

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
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   publication of this document.  Please review these documents
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   include Simplified BSD License text as described in Section 4.e of




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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Definitions and Acronyms  . . . . . . . . . . . . . . . .   2
   2.  Protocol Negotiation  . . . . . . . . . . . . . . . . . . . .   2
     2.1.  Encoding  . . . . . . . . . . . . . . . . . . . . . . . .   3
       2.1.1.  Overview  . . . . . . . . . . . . . . . . . . . . . .   3
       2.1.2.  Dependencies  . . . . . . . . . . . . . . . . . . . .   3
       2.1.3.  Capability Identifier . . . . . . . . . . . . . . . .   3
       2.1.4.  New Operation . . . . . . . . . . . . . . . . . . . .   3
   3.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
     4.1.  NETCONF Capability URNs . . . . . . . . . . . . . . . . .   5
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     6.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   NETCONF [RFC6241], by default, supports XML encoding for its payload.
   However, XML can be very verbose, specially for operational data.
   That combined with parsing of tags leads to slow processing of the
   data.  This document proposes a mechanism by which clients and
   servers can negotiate an alternate form of encoding, e.g.  binary
   encoding, and use that to exchange data.  Binary encoding can reduce
   the physical size of the data exchanged, in some cases by as much as
   66%, and improve the time that is required to process the data, while
   preserving the original data.

   Several binary encoding mechanisms have been proposed, including CBOR
   [RFC7049].  This document does not advocate any particular binary
   encoding format.  Instead, it leaves it up to the negotiation between
   client and server to decide the form of encoding.  For an example of
   how to encode YANG in CBOR format, see CBOR Encoding of Data Modeled
   with YANG [I-D.ietf-core-yang-cbor].

1.1.  Definitions and Acronyms

2.  Protocol Negotiation

   NETCONF clients and servers exchange a hello as part of establishing
   a connection.  As part of the hello exchange, each of them advertises




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   their set of capabilities.  This draft suggests advertisement of the
   following additional capability.

2.1.  Encoding

2.1.1.  Overview

   The :encoding capability indicates what encoding format each side is
   willing to support.  If the client and server are capable of
   supporting multiple forms of encoding, they can list each of them.
   There is no need to include xml in the list, as that is supported by
   default.

2.1.2.  Dependencies

   When using this capability, any binardy encoding needs the underlying
   transport to be 8-bit clean, and which preserves message boundaries
   when dealing with arbitrary binary data.  This requires use of
   Chunked Framing mechanism as described in NETCONF over SSH [RFC6242].

2.1.3.  Capability Identifier

   The :encoding capability is identfied by the following capability
   string:

   urn:ietf:params:netconf:capability:encoding:1.0?format={name, ...}

   The :encoding capability URI MUST contain a "format" argument
   assigned a comma-separated list of formats supported by the device.
   For example:

   urn:ietf:params:netconf:capability:encoding:1.0?format=cbor,gpb,thrif
   t

2.1.4.  New Operation

2.1.4.1.  <activate>

   Description:

   After each side has exchanged capabilities, a client can initiate a
   request to switch to a new encoding format using the <activate>
   operation.

   Parameters:

   encoding:




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   The <activate> operation instructs the server to switch to the new
   binary format.  If the server does not support the new binary format
   or is unable to switch to the new binary format for any reason, it
   MUST fail with the <error-tag> value of "not-supported" and keep the
   existing encoding format it is using.

   If the system does not have the :encoding capability, the <activate>
   operation is not available.  If there is a desire to fall back to
   default encoding of XML, the client needs to terminate the existing
   connection and establish a new connection.

   Positive Response:

   If the device is able to satisfy the requests, an <rpc-reply> is sent
   that contains an <ok> element.

   Negative Response:

   An <rpc-error> element is included in the <rpc-reply> with the <type>
   element set to "not-supported".  The <error-tag> element must be set
   to "server-error".

   Example:

   <rpc message-id="101"
       xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
     <activate>
       <encoding>cbor</encoding>
     </activate>
   </rpc>

   <rpc-reply message-id="101"
       xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
       <ok/>
   </rpc-reply>

3.  Security Considerations

4.  IANA Considerations

   This document registers a URI in the IETF XML registry [RFC3688].
   Following the format in RFC 3688, the following registration is
   requested to be made:








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4.1.  NETCONF Capability URNs

   IANA registry "Network Configuration Protocol (NETCONF) Capability
   URNs" needs to be updated to include the following capability.

   Index
       Capability Identifier
   -------------------------
   :encoding
       urn:ietf:params:netconf:capability:encoding:1.0

5.  Acknowledgements

6.  References

6.1.  Normative 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>.

   [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>.

   [RFC7049]  Bormann, C. and P. Hoffman, "Concise Binary Object
              Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049,
              October 2013, <https://www.rfc-editor.org/info/rfc7049>.

6.2.  Informative References

   [I-D.ietf-core-yang-cbor]
              Veillette, M., Pelov, A., Somaraju, A., Turner, R., and A.
              Minaburo, "CBOR Encoding of Data Modeled with YANG",
              draft-ietf-core-yang-cbor-06 (work in progress), February
              2018.

Authors' Addresses

   Mahesh Jethanandani

   Email: mjethanandani@gmail.com




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   Jason Lam
   Cisco Systems, Inc.

   Email: lamj@cisco.com


   Alfred Leung
   Cisco Systems, Inc.

   Email: alfleung@cisco.com









































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