NETCONF

NETCONF is a network management protocol developed in the IETF by the Netconf working group. It was published as RFC 4741.

The NETCONF protocol provides mechanisms to install, manipulate, and delete the configuration of network devices. It also can perform some monitoring functions. It uses an Extensible Markup Language (XML) based data encoding for the configuration data as well as the protocol messages. The NETCONF protocol operations are realized on top of a simple Remote Procedure Call (RPC) layer. This in turn is realized on top of the transport protocol.

NETCONF can be conceptually partitioned into four layers:

       Layer                            Example
   +-------------+      +-------------------------------------------+
   |   Content   |      |     Configuration data                    |
   +-------------+      +-------------------------------------------+
             |                           |
   +-------------+      +-------------------------------------------+
   | Operations  |      |<get-config>, <edit-config>, <notification>|
   +-------------+      +-------------------------------------------+
             |                           |                    |
   +-------------+      +-----------------------------+       |
   |     RPC     |      |    <rpc>, <rpc-reply>       |       |
   +-------------+      +-----------------------------+       |
             |                           |                    |
   +-------------+      +-------------------------------------------+
   |  Transport  |      |   BEEP, SSH, SSL, console                 |
   |  Protocol   |      |                                           |
   +-------------+      +-------------------------------------------+

Operations

Basic Operations

The base protocol includes the following protocol operations: <get>, <get-config>, <edit-config>, <copy-config>, <delete-config>, <lock>, <unlock>, <close-session>, <kill-session>.

Capabilities

Basic NETCONF functionality can be extended by the definition of NETCONF capabilities. The set of additional protocol features an implementation supports is communicated between the server and the client during the capability exchange portion of session setup. Mandatory protocol features are not included in the capability exchange since they are assumed. RFC 4741 defines a number of optional capabilities including :xpath and :validate.

A capability to support subscribing and receiving asynchronous event notifications is published in RFC 5277. It defines the <create-subscription> operation, which enables creating real-time and replay subscriptions. Notifications are then sent asynchronously using the <notification> construct. The RFC also defines the :interleave capability, which when supported with the basic :notification capability facilitates the processing of other NETCONF operations while the subscription is active.

The working group is currently working on a partial locking capability.

Transport Protocol

Netconf defines three transport mappings

SSH (RFC 4742), which is mandatory to implement
SOAP (RFC 4743)
BEEP (RFC 4744)

The working group is currently working on a Transport Layer Security(TLS) mapping.

History

The IETF developed SNMP in the late 1980s and it proved to be a very popular network management protocol. In the early part of the 21st century it became apparent that in spite of what was originally intended, SNMP was not being used to configure network equipment, but was mainly being used for network monitoring. In 2002, the Internet Architecture Board and key members of the IETF's network management community got together with network operators to discuss the situation. The results of this meeting are documented in RFC 3535. It turned out that operators were primarily using proprietary Command Line Interfaces (CLI) to configure their boxes. This had a number of features that the operators liked, including the fact that it was text-based, as opposed to the BER-encoded SNMP. In addition, many equipment vendors did not provide the option to completely configure their devices via SNMP. As operators generally liked to write scripts to help manage their boxes, they did find the CLI lacking in a number of ways. Most notably was the unpredictable nature of the output. The content and formatting of output was prone to change in unpredictable ways.

Around this same time, Juniper Networks had been using an XML-based network management approach. This was brought to the IETF and shared with the broader community.

Collectively, these two events led the IETF to the creation of a protocol which it hopes will better align with the needs of network operators and equipment vendors.

Not to be Confused with

netconf is also the (working) name of a network configuration tool, which is currently in development. It remains to be decided whether the tool name ought to be changed to avoid confusion.

External links

Network Configuration (netconf) Charter