Binary Encoding for NETCONF
draft-mahesh-netconf-binary-encoding-00
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| Authors | Mahesh Jethanandani , Jason Lam , Alfred Leung | ||
| Last updated | 2018-02-21 | ||
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draft-mahesh-netconf-binary-encoding-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
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provisions of BCP 78 and BCP 79.
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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.
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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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