.. _netconf-user-guide:

.. |ss| raw:: html

   <strike>

.. |se| raw:: html

   </strike>

NETCONF User Guide
==================

Overview
--------

NETCONF is an XML-based protocol used for configuration and monitoring
devices in the network. The base NETCONF protocol is described in
`RFC-6241 <http://tools.ietf.org/html/rfc6241>`__.

**NETCONF in OpenDaylight:.**

OpenDaylight supports the NETCONF protocol as a northbound server as
well as a southbound plugin. It also includes a set of test tools for
simulating NETCONF devices and clients.

Southbound (netconf-connector)
------------------------------

The NETCONF southbound plugin is capable of connecting to remote NETCONF
devices and exposing their configuration/operational datastores, RPCs
and notifications as MD-SAL mount points. These mount points allow
applications and remote users (over RESTCONF) to interact with the
mounted devices.

In terms of RFCs, the connector supports:

-  `RFC-6241 <http://tools.ietf.org/html/rfc6241>`__

-  `RFC-5277 <https://tools.ietf.org/html/rfc5277>`__

-  `RFC-6022 <https://tools.ietf.org/html/rfc6022>`__

-  `draft-ietf-netconf-yang-library-06 <https://tools.ietf.org/html/draft-ietf-netconf-yang-library-06>`__

**Netconf-connector is fully model-driven (utilizing the YANG modeling
language) so in addition to the above RFCs, it supports any
data/RPC/notifications described by a YANG model that is implemented by
the device.**

.. tip::

    NETCONF southbound can be activated by installing
    ``odl-netconf-connector-all`` Karaf feature.

Netconf-connector configuration
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

There are 2 ways for configuring netconf-connector: NETCONF or RESTCONF.
This guide focuses on using RESTCONF.

.. important::

    There are 2 different endpoints related to RESTCONF protocols:

    - | ``http://localhost:8181/restconf`` is related to `draft-bierman-netconf-restconf-02 <https://tools.ietf.org/html/draft-bierman-netconf-restconf-02>`__,
      | can be activated by installing ``odl-restconf-nb-bierman02``
       Karaf feature.
      | This user guide uses this approach.

    - | ``http://localhost:8181/rests`` is related to `RFC-8040 <https://tools.ietf.org/html/rfc8040>`__,
      | can be activated by installing ``odl-restconf-nb-rfc8040``
       Karaf feature.

    | In case of `RFC-8040 <https://tools.ietf.org/html/rfc8040>`__
     resources for configuration and operational datastores start
     ``/rests/data/``,
    | e. g. GET
     http://localhost:8181/rests/data/network-topology:network-topology
     with response of both datastores. It's allowed to use query
     parameters to distinguish between them.
    | e. g. GET
     http://localhost:8181/rests/data/network-topology:network-topology?content=config
     for configuration datastore
    | and GET
     http://localhost:8181/rests/data/network-topology:network-topology?content=nonconfig
     for operational datastore.

    | Also in case of `RFC-8040 <https://tools.ietf.org/html/rfc8040>`__,
     if a data node in the path expression is a YANG leaf-list or list
     node, the path segment has to be constructed by having leaf-list or
     list node name, followed by an "=" character, then followed by the
     leaf-list or list value. Any reserved characters must be
     percent-encoded.
    | e. g. GET
     http://localhost:8181/rests/data/network-topology:network-topology/topology=topology-netconf?content=config
     for retrieving data from configuration datastore for
     topology-netconf value of topology list is equivalent to the deprecated request
    | |ss| GET |se|
     http://localhost:8181/restconf/config/network-topology:network-topology/topology/topology-netconf,
     which is related to `draft-bierman-netconf-restconf-02
     <https://tools.ietf.org/html/draft-bierman-netconf-restconf-02>`__.

    Examples in the `Spawning new NETCONF connectors`_ section include both bierman02 and rfc8040
    formats


Default configuration
^^^^^^^^^^^^^^^^^^^^^

The default configuration contains all the necessary dependencies (file:
01-netconf.xml) and a single instance of netconf-connector (file:
99-netconf-connector.xml) called **controller-config** which connects
itself to the NETCONF northbound in OpenDaylight in a loopback fashion.
The connector mounts the NETCONF server for config-subsystem in order to
enable RESTCONF protocol for config-subsystem. This RESTCONF still goes
via NETCONF, but using RESTCONF is much more user friendly than using
NETCONF.

Spawning additional netconf-connectors while the controller is running
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Preconditions:

1. OpenDaylight is running

2. In Karaf, you must have the netconf-connector installed (at the Karaf
   prompt, type: ``feature:install odl-netconf-connector-all``); the
   loopback NETCONF mountpoint will be automatically configured and
   activated

3. Wait until log displays following entry:
   RemoteDevice{controller-config}: NETCONF connector initialized
   successfully

To configure a new netconf-connector you need to send following request
to RESTCONF:

POST
http://localhost:8181/restconf/config/network-topology:network-topology/topology/topology-netconf/node/controller-config/yang-ext:mount/config:modules

Headers:

-  Accept application/xml

-  Content-Type application/xml

::

    <module xmlns="urn:opendaylight:params:xml:ns:yang:controller:config">
      <type xmlns:prefix="urn:opendaylight:params:xml:ns:yang:controller:md:sal:connector:netconf">prefix:sal-netconf-connector</type>
      <name>new-netconf-device</name>
      <address xmlns="urn:opendaylight:params:xml:ns:yang:controller:md:sal:connector:netconf">127.0.0.1</address>
      <port xmlns="urn:opendaylight:params:xml:ns:yang:controller:md:sal:connector:netconf">830</port>
      <username xmlns="urn:opendaylight:params:xml:ns:yang:controller:md:sal:connector:netconf">admin</username>
      <password xmlns="urn:opendaylight:params:xml:ns:yang:controller:md:sal:connector:netconf">admin</password>
      <tcp-only xmlns="urn:opendaylight:params:xml:ns:yang:controller:md:sal:connector:netconf">false</tcp-only>
      <event-executor xmlns="urn:opendaylight:params:xml:ns:yang:controller:md:sal:connector:netconf">
        <type xmlns:prefix="urn:opendaylight:params:xml:ns:yang:controller:netty">prefix:netty-event-executor</type>
        <name>global-event-executor</name>
      </event-executor>
      <binding-registry xmlns="urn:opendaylight:params:xml:ns:yang:controller:md:sal:connector:netconf">
        <type xmlns:prefix="urn:opendaylight:params:xml:ns:yang:controller:md:sal:binding">prefix:binding-broker-osgi-registry</type>
        <name>binding-osgi-broker</name>
      </binding-registry>
      <dom-registry xmlns="urn:opendaylight:params:xml:ns:yang:controller:md:sal:connector:netconf">
        <type xmlns:prefix="urn:opendaylight:params:xml:ns:yang:controller:md:sal:dom">prefix:dom-broker-osgi-registry</type>
        <name>dom-broker</name>
      </dom-registry>
      <client-dispatcher xmlns="urn:opendaylight:params:xml:ns:yang:controller:md:sal:connector:netconf">
        <type xmlns:prefix="urn:opendaylight:params:xml:ns:yang:controller:config:netconf">prefix:netconf-client-dispatcher</type>
        <name>global-netconf-dispatcher</name>
      </client-dispatcher>
      <processing-executor xmlns="urn:opendaylight:params:xml:ns:yang:controller:md:sal:connector:netconf">
        <type xmlns:prefix="urn:opendaylight:params:xml:ns:yang:controller:threadpool">prefix:threadpool</type>
        <name>global-netconf-processing-executor</name>
      </processing-executor>
      <keepalive-executor xmlns="urn:opendaylight:params:xml:ns:yang:controller:md:sal:connector:netconf">
        <type xmlns:prefix="urn:opendaylight:params:xml:ns:yang:controller:threadpool">prefix:scheduled-threadpool</type>
        <name>global-netconf-ssh-scheduled-executor</name>
      </keepalive-executor>
    </module>

This spawns a new netconf-connector which tries to connect to (or mount)
a NETCONF device at 127.0.0.1 and port 830. You can check the
configuration of config-subsystem’s configuration datastore. The new
netconf-connector will now be present there. Just invoke:

GET
http://localhost:8181/restconf/config/network-topology:network-topology/topology/topology-netconf/node/controller-config/yang-ext:mount/config:modules

The response will contain the module for new-netconf-device.

Right after the new netconf-connector is created, it writes some useful
metadata into the datastore of MD-SAL under the network-topology
subtree. This metadata can be found at:

GET
http://localhost:8181/restconf/operational/network-topology:network-topology/

Information about connection status, device capabilities, etc. can be
found there.

Connecting to a device not supporting NETCONF monitoring
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The netconf-connector in OpenDaylight relies on ietf-netconf-monitoring
support when connecting to remote NETCONF device. The
ietf-netconf-monitoring support allows netconf-connector to list and
download all YANG schemas that are used by the device. NETCONF connector
can only communicate with a device if it knows the set of used schemas
(or at least a subset). However, some devices use YANG models internally
but do not support NETCONF monitoring. Netconf-connector can also
communicate with these devices, but you have to side load the necessary
yang models into OpenDaylight’s YANG model cache for netconf-connector.
In general there are 2 situations you might encounter:

**1. NETCONF device does not support ietf-netconf-monitoring but it does
list all its YANG models as capabilities in HELLO message**

This could be a device that internally uses only ietf-inet-types YANG
model with revision 2010-09-24. In the HELLO message that is sent from
this device there is this capability reported:

::

    urn:ietf:params:xml:ns:yang:ietf-inet-types?module=ietf-inet-types&revision=2010-09-24

**For such devices you only need to put the schema into folder
cache/schema inside your Karaf distribution.**

.. important::

    The file with YANG schema for ietf-inet-types has to be called
    ietf-inet-types@2010-09-24.yang. It is the required naming format of
    the cache.

**2. NETCONF device does not support ietf-netconf-monitoring and it does
NOT list its YANG models as capabilities in HELLO message**

Compared to device that lists its YANG models in HELLO message, in this
case there would be no capability with ietf-inet-types in the HELLO
message. This type of device basically provides no information about the
YANG schemas it uses so its up to the user of OpenDaylight to properly
configure netconf-connector for this device.

Netconf-connector has an optional configuration attribute called
yang-module-capabilities and this attribute can contain a list of "YANG
module based" capabilities. So by setting this configuration attribute,
it is possible to override the "yang-module-based" capabilities reported
in HELLO message of the device. To do this, we need to modify the
configuration of netconf-connector by adding this XML (It needs to be
added next to the address, port, username etc. configuration elements):

::

    <yang-module-capabilities xmlns="urn:opendaylight:params:xml:ns:yang:controller:md:sal:connector:netconf">
      <capability xmlns="urn:opendaylight:params:xml:ns:yang:controller:md:sal:connector:netconf">
        urn:ietf:params:xml:ns:yang:ietf-inet-types?module=ietf-inet-types&amp;revision=2010-09-24
      </capability>
    </yang-module-capabilities>

**Remember to also put the YANG schemas into the cache folder.**

.. note::

    For putting multiple capabilities, you just need to replicate the
    capability xml element inside yang-module-capability element.
    Capability element is modeled as a leaf-list. With this
    configuration, we would make the remote device report usage of
    ietf-inet-types in the eyes of netconf-connector.

Reconfiguring Netconf-Connector While the Controller is Running
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

It is possible to change the configuration of a running module while the
whole controller is running. This example will continue where the last
left off and will change the configuration for the brand new
netconf-connector after it was spawned. Using one RESTCONF request, we
will change both username and password for the netconf-connector.

To update an existing netconf-connector you need to send following
request to RESTCONF:

PUT
http://localhost:8181/restconf/config/network-topology:network-topology/topology/topology-netconf/node/controller-config/yang-ext:mount/config:modules/module/odl-sal-netconf-connector-cfg:sal-netconf-connector/new-netconf-device

::

    <module xmlns="urn:opendaylight:params:xml:ns:yang:controller:config">
      <type xmlns:prefix="urn:opendaylight:params:xml:ns:yang:controller:md:sal:connector:netconf">prefix:sal-netconf-connector</type>
      <name>new-netconf-device</name>
      <username xmlns="urn:opendaylight:params:xml:ns:yang:controller:md:sal:connector:netconf">bob</username>
      <password xmlns="urn:opendaylight:params:xml:ns:yang:controller:md:sal:connector:netconf">passwd</password>
      <tcp-only xmlns="urn:opendaylight:params:xml:ns:yang:controller:md:sal:connector:netconf">false</tcp-only>
      <event-executor xmlns="urn:opendaylight:params:xml:ns:yang:controller:md:sal:connector:netconf">
        <type xmlns:prefix="urn:opendaylight:params:xml:ns:yang:controller:netty">prefix:netty-event-executor</type>
        <name>global-event-executor</name>
      </event-executor>
      <binding-registry xmlns="urn:opendaylight:params:xml:ns:yang:controller:md:sal:connector:netconf">
        <type xmlns:prefix="urn:opendaylight:params:xml:ns:yang:controller:md:sal:binding">prefix:binding-broker-osgi-registry</type>
        <name>binding-osgi-broker</name>
      </binding-registry>
      <dom-registry xmlns="urn:opendaylight:params:xml:ns:yang:controller:md:sal:connector:netconf">
        <type xmlns:prefix="urn:opendaylight:params:xml:ns:yang:controller:md:sal:dom">prefix:dom-broker-osgi-registry</type>
        <name>dom-broker</name>
      </dom-registry>
      <client-dispatcher xmlns="urn:opendaylight:params:xml:ns:yang:controller:md:sal:connector:netconf">
        <type xmlns:prefix="urn:opendaylight:params:xml:ns:yang:controller:config:netconf">prefix:netconf-client-dispatcher</type>
        <name>global-netconf-dispatcher</name>
      </client-dispatcher>
      <processing-executor xmlns="urn:opendaylight:params:xml:ns:yang:controller:md:sal:connector:netconf">
        <type xmlns:prefix="urn:opendaylight:params:xml:ns:yang:controller:threadpool">prefix:threadpool</type>
        <name>global-netconf-processing-executor</name>
      </processing-executor>
      <keepalive-executor xmlns="urn:opendaylight:params:xml:ns:yang:controller:md:sal:connector:netconf">
        <type xmlns:prefix="urn:opendaylight:params:xml:ns:yang:controller:threadpool">prefix:scheduled-threadpool</type>
        <name>global-netconf-ssh-scheduled-executor</name>
      </keepalive-executor>
    </module>

Since a PUT is a replace operation, the whole configuration must be
specified along with the new values for username and password. This
should result in a 2xx response and the instance of netconf-connector
called new-netconf-device will be reconfigured to use username bob and
password passwd. New configuration can be verified by executing:

GET
http://localhost:8181/restconf/config/network-topology:network-topology/topology/topology-netconf/node/controller-config/yang-ext:mount/config:modules/module/odl-sal-netconf-connector-cfg:sal-netconf-connector/new-netconf-device

With new configuration, the old connection will be closed and a new one
established.

Destroying Netconf-Connector While the Controller is Running
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Using RESTCONF one can also destroy an instance of a module. In case of
netconf-connector, the module will be destroyed, NETCONF connection
dropped and all resources will be cleaned. To do this, simply issue a
request to following URL:

DELETE
http://localhost:8181/restconf/config/network-topology:network-topology/topology/topology-netconf/node/controller-config/yang-ext:mount/config:modules/module/odl-sal-netconf-connector-cfg:sal-netconf-connector/new-netconf-device

The last element of the URL is the name of the instance and its
predecessor is the type of that module (In our case the type is
**sal-netconf-connector** and name **new-netconf-device**). The type and
name are actually the keys of the module list.

Netconf-connector configuration with MD-SAL
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

It is also possible to configure new NETCONF connectors directly through
MD-SAL with the usage of the network-topology model. You can configure
new NETCONF connectors both through the NETCONF server for MD-SAL (port
2830) or RESTCONF. This guide focuses on RESTCONF.

.. tip::

    To enable NETCONF connector configuration through MD-SAL install
    either the ``odl-netconf-topology`` or
    ``odl-netconf-clustered-topology`` feature. We will explain the
    difference between these features later.

Preconditions
^^^^^^^^^^^^^

1. OpenDaylight is running

2. In Karaf, you must have the ``odl-netconf-topology`` or
   ``odl-netconf-clustered-topology`` feature installed.

3. Feature ``odl-restconf`` must be installed

4. Wait until log displays following entry:

   ::

       Successfully pushed configuration snapshot 02-netconf-topology.xml(odl-netconf-topology,odl-netconf-topology)

   or until

   ::

       GET http://localhost:8181/restconf/operational/network-topology:network-topology/topology/topology-netconf/

   returns a non-empty response, for example:

   ::

       <topology xmlns="urn:TBD:params:xml:ns:yang:network-topology">
         <topology-id>topology-netconf</topology-id>
       </topology>

Spawning new NETCONF connectors
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

To create a new NETCONF connector you need to send the following PUT request
to RESTCONF:

.. list-table::
   :widths: 1 5

   * - bierman02
     - http://localhost:8181/restconf/config/network-topology:network-topology/topology/topology-netconf/node/new-netconf-device
   * - rfc8040
     - http://localhost:8181/rests/data/network-topology:network-topology/topology=topology-netconf/node=new-netconf-device

You could use the same body to create the new  NETCONF connector with a POST
without specifying the node in the URL:

.. list-table::
   :widths: 1 5

   * - bierman02
     - http://localhost:8181/restconf/config/network-topology:network-topology/topology/topology-netconf
   * - rfc8040
     - http://localhost:8181/rests/data/network-topology:network-topology/topology=topology-netconf

Headers:

-  Accept: application/xml

-  Content-Type: application/xml

Payload:

::

    <node xmlns="urn:TBD:params:xml:ns:yang:network-topology">
      <node-id>new-netconf-device</node-id>
      <host xmlns="urn:opendaylight:netconf-node-topology">127.0.0.1</host>
      <port xmlns="urn:opendaylight:netconf-node-topology">17830</port>
      <username xmlns="urn:opendaylight:netconf-node-topology">admin</username>
      <password xmlns="urn:opendaylight:netconf-node-topology">admin</password>
      <tcp-only xmlns="urn:opendaylight:netconf-node-topology">false</tcp-only>
      <!-- non-mandatory fields with default values, you can safely remove these if you do not wish to override any of these values-->
      <reconnect-on-changed-schema xmlns="urn:opendaylight:netconf-node-topology">false</reconnect-on-changed-schema>
      <connection-timeout-millis xmlns="urn:opendaylight:netconf-node-topology">20000</connection-timeout-millis>
      <max-connection-attempts xmlns="urn:opendaylight:netconf-node-topology">0</max-connection-attempts>
      <between-attempts-timeout-millis xmlns="urn:opendaylight:netconf-node-topology">2000</between-attempts-timeout-millis>
      <sleep-factor xmlns="urn:opendaylight:netconf-node-topology">1.5</sleep-factor>
      <!-- keepalive-delay set to 0 turns off keepalives-->
      <keepalive-delay xmlns="urn:opendaylight:netconf-node-topology">120</keepalive-delay>
    </node>

Note that the device name in <node-id> element must match the last
element of the restconf URL.

Reconfiguring an existing connector
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The steps to reconfigure an existing connector are exactly the same as
when spawning a new connector. The old connection will be disconnected
and a new connector with the new configuration will be created. This needs
to be done with a PUT request because the node already exists. A POST
request will fail for that reason.

Additionally, a PATCH request can be used to modify an existing
configuration. Currently, only yang-patch (`RFC-8072 <https://tools.ietf.org/html/rfc8072>`__)
is supported. The URL would be the same as the above PUT examples.
Using JSON for the body, the headers needed for the request would
be:

Headers:

-  Accept: application/yang.patch-status+json

-  Content-Type: application/yang.patch+json

Example JSON payload to modify the password entry:

::

    {
      "ietf-restconf:yang-patch" : {
        "patch-id" : "0",
        "edit" : [
          {
            "edit-id" : "edit1",
            "operation" : "merge",
            "target" : "",
            "value" : {
             "node": [
                {
                 "node-id": "new-netconf-device",
                 "netconf-node-topology:password" : "newpassword"
                }
             ]
            }
         }
        ]
      }
    }


Deleting an existing connector
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

To remove an already configured NETCONF connector you need to send a
DELETE request to the same PUT request URL that was used to create the
device:

.. list-table::
   :widths: 1 5

   * - bierman02
     - http://localhost:8181/restconf/config/network-topology:network-topology/topology/topology-netconf/node/new-netconf-device
   * - rfc8040
     - http://localhost:8181/rests/data/network-topology:network-topology/topology=topology-netconf/node=new-netconf-device

.. note::

    No body is needed to delete the node/device

Connecting to a device supporting only NETCONF 1.0
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

OpenDaylight is schema-based distribution and heavily depends on YANG
models. However some legacy NETCONF devices are not schema-based and
implement just RFC 4741. This type of device does not utilize YANG
models internally and OpenDaylight does not know how to communicate
with such devices, how to validate data, or what the semantics of data
are.

NETCONF connector can communicate also with these devices, but the
trade-offs are worsened possibilities in utilization of NETCONF
mountpoints. Using RESTCONF with such devices is not suported. Also
communicating with schemaless devices from application code is slightly
different.

To connect to schemaless device, there is a optional configuration option
in netconf-node-topology model called schemaless. You have to set this
option to true.

Clustered NETCONF connector
~~~~~~~~~~~~~~~~~~~~~~~~~~~

To spawn NETCONF connectors that are cluster-aware you need to install
the ``odl-netconf-clustered-topology`` karaf feature.

.. warning::

    The ``odl-netconf-topology`` and ``odl-netconf-clustered-topology``
    features are considered **INCOMPATIBLE**. They both manage the same
    space in the datastore and would issue conflicting writes if
    installed together.

Configuration of clustered NETCONF connectors works the same as the
configuration through the topology model in the previous section.

When a new clustered connector is configured the configuration gets
distributed among the member nodes and a NETCONF connector is spawned on
each node. From these nodes a master is chosen which handles the schema
download from the device and all the communication with the device. You
will be able to read/write to/from the device from all slave nodes due
to the proxy data brokers implemented.

You can use the ``odl-netconf-clustered-topology`` feature in a single
node scenario as well but the code that uses akka will be used, so for a
scenario where only a single node is used, ``odl-netconf-topology``
might be preferred.

Netconf-connector utilization
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Once the connector is up and running, users can utilize the new mount
point instance. By using RESTCONF or from their application code. This
chapter deals with using RESTCONF and more information for app
developers can be found in the developers guide or in the official
tutorial application **ncmount** that can be found in the coretutorials
project:

-  https://github.com/opendaylight/coretutorials/tree/master/ncmount

Reading data from the device
^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Just invoke (no body needed):

GET
http://localhost:8080/restconf/operational/network-topology:network-topology/topology/topology-netconf/node/new-netconf-device/yang-ext:mount/

This will return the entire content of operation datastore from the
device. To view just the configuration datastore, change **operational**
in this URL to **config**.

Writing configuration data to the device
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

In general, you cannot simply write any data you want to the device. The
data have to conform to the YANG models implemented by the device. In
this example we are adding a new interface-configuration to the mounted
device (assuming the device supports Cisco-IOS-XR-ifmgr-cfg YANG model).
In fact this request comes from the tutorial dedicated to the
**ncmount** tutorial app.

POST
http://localhost:8181/restconf/config/network-topology:network-topology/topology/topology-netconf/node/new-netconf-device/yang-ext:mount/Cisco-IOS-XR-ifmgr-cfg:interface-configurations

::

    <interface-configuration xmlns="http://cisco.com/ns/yang/Cisco-IOS-XR-ifmgr-cfg">
        <active>act</active>
        <interface-name>mpls</interface-name>
        <description>Interface description</description>
        <bandwidth>32</bandwidth>
        <link-status></link-status>
    </interface-configuration>

Should return 200 response code with no body.

.. tip::

    This call is transformed into a couple of NETCONF RPCs. Resulting
    NETCONF RPCs that go directly to the device can be found in the
    OpenDaylight logs after invoking ``log:set TRACE
    org.opendaylight.controller.sal.connect.netconf`` in the Karaf
    shell. Seeing the NETCONF RPCs might help with debugging.

This request is very similar to the one where we spawned a new netconf
device. That’s because we used the loopback netconf-connector to write
configuration data into config-subsystem datastore and config-subsystem
picked it up from there.

Invoking custom RPC
^^^^^^^^^^^^^^^^^^^

Devices can implement any additional RPC and as long as it provides YANG
models for it, it can be invoked from OpenDaylight. Following example
shows how to invoke the get-schema RPC (get-schema is quite common among
netconf devices). Invoke:

POST
http://localhost:8181/restconf/operations/network-topology:network-topology/topology/topology-netconf/node/new-netconf-device/yang-ext:mount/ietf-netconf-monitoring:get-schema

::

    <input xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-monitoring">
      <identifier>ietf-yang-types</identifier>
      <version>2013-07-15</version>
    </input>

This call should fetch the source for ietf-yang-types YANG model from
the mounted device.

Netconf-connector + Netopeer
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

`Netopeer <https://github.com/cesnet/netopeer>`__ (an open-source
NETCONF server) can be used for testing/exploring NETCONF southbound in
OpenDaylight.

Netopeer installation
^^^^^^^^^^^^^^^^^^^^^

A `Docker <https://www.docker.com/>`__ container with netopeer will be
used in this guide. To install Docker and start the `netopeer
image <https://index.docker.io/u/dockeruser/netopeer/>`__ perform
following steps:

1. Install docker http://docs.docker.com/linux/step_one/

2. Start the netopeer image:

   ::

       docker run --rm -t -p 1831:830 dockeruser/netopeer

3. Verify netopeer is running by invoking (netopeer should send its
   HELLO message right away:

   ::

       ssh root@localhost -p 1831 -s netconf
       (password root)

Mounting netopeer NETCONF server
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Preconditions:

-  OpenDaylight is started with features ``odl-restconf-all`` and
   ``odl-netconf-connector-all``.

-  Netopeer is up and running in docker

Now just follow the section: `Spawning new NETCONF connectors`_.
In the payload change the:

-  name, e.g., to netopeer

-  username/password to your system credentials

-  ip to localhost

-  port to 1831.

After netopeer is mounted successfully, its configuration can be read
using RESTCONF by invoking:

GET
http://localhost:8181/restconf/config/network-topology:network-topology/topology/topology-netconf/node/netopeer/yang-ext:mount/

Northbound (NETCONF servers)
----------------------------

OpenDaylight provides 2 types of NETCONF servers:

-  **NETCONF server for config-subsystem (listening by default on port
   1830)**

   -  Serves as a default interface for config-subsystem and allows
      users to spawn/reconfigure/destroy modules (or applications) in
      OpenDaylight

-  **NETCONF server for MD-SAL (listening by default on port 2830)**

   -  Serves as an alternative interface for MD-SAL (besides RESTCONF)
      and allows users to read/write data from MD-SAL’s datastore and to
      invoke its rpcs (NETCONF notifications are not available in the
      Boron release of OpenDaylight)

.. note::

    The reason for having 2 NETCONF servers is that config-subsystem and
    MD-SAL are 2 different components of OpenDaylight and require
    different approach for NETCONF message handling and data
    translation. These 2 components will probably merge in the future.

.. note::

    Since Nitrogen release, there is performance regression in NETCONF
    servers accepting SSH connections. While opening a connection takes
    less than 10 seconds on Carbon, on Nitrogen time can increase up to
    60 seconds. Please see https://bugs.opendaylight.org/show_bug.cgi?id=9020

NETCONF server for config-subsystem
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This NETCONF server is the primary interface for config-subsystem. It
allows the users to interact with config-subsystem in a standardized
NETCONF manner.

In terms of RFCs, these are supported:

-  `RFC-6241 <http://tools.ietf.org/html/rfc6241>`__

-  `RFC-5277 <https://tools.ietf.org/html/rfc5277>`__

-  `RFC-6470 <https://tools.ietf.org/html/rfc6470>`__

   -  (partially, only the schema-change notification is available in
      Boron release)

-  `RFC-6022 <https://tools.ietf.org/html/rfc6022>`__

For regular users it is recommended to use RESTCONF + the
controller-config loopback mountpoint instead of using pure NETCONF. How
to do that is spesific for each component/module/application in
OpenDaylight and can be found in their dedicated user guides.

NETCONF server for MD-SAL
~~~~~~~~~~~~~~~~~~~~~~~~~

This NETCONF server is just a generic interface to MD-SAL in
OpenDaylight. It uses the stadard MD-SAL APIs and serves as an
alternative to RESTCONF. It is fully model driven and supports any data
and rpcs that are supported by MD-SAL.

In terms of RFCs, these are supported:

-  `RFC-6241 <http://tools.ietf.org/html/rfc6241>`__

-  `RFC-6022 <https://tools.ietf.org/html/rfc6022>`__

-  `draft-ietf-netconf-yang-library-06 <https://tools.ietf.org/html/draft-ietf-netconf-yang-library-06>`__

Notifications over NETCONF are not supported in the Boron release.

.. tip::

    Install NETCONF northbound for MD-SAL by installing feature:
    ``odl-netconf-mdsal`` in karaf. Default binding port is **2830**.

Configuration
^^^^^^^^^^^^^

The default configuration can be found in file: *08-netconf-mdsal.xml*.
The file contains the configuration for all necessary dependencies and a
single SSH endpoint starting on port 2830. There is also a (by default
disabled) TCP endpoint. It is possible to start multiple endpoints at
the same time either in the initial configuration file or while
OpenDaylight is running.

The credentials for SSH endpoint can also be configured here, the
defaults are admin/admin. Credentials in the SSH endpoint are not yet
managed by the centralized AAA component and have to be configured
separately.

Verifying MD-SAL’s NETCONF server
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

After the NETCONF server is available it can be examined by a command
line ssh tool:

::

    ssh admin@localhost -p 2830 -s netconf

The server will respond by sending its HELLO message and can be used as
a regular NETCONF server from then on.

Mounting the MD-SAL’s NETCONF server
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

To perform this operation, just spawn a new netconf-connector as
described in `Spawning new NETCONF connectors`_. Just change the ip to
"127.0.0.1" port to "2830" and its name to "controller-mdsal".

Now the MD-SAL’s datastore can be read over RESTCONF via NETCONF by
invoking:

GET
http://localhost:8181/restconf/operational/network-topology:network-topology/topology/topology-netconf/node/controller-mdsal/yang-ext:mount

.. note::

    This might not seem very useful, since MD-SAL can be accessed
    directly from RESTCONF or from Application code, but the same method
    can be used to mount and control other OpenDaylight instances by the
    "master OpenDaylight".

NETCONF stress/performance measuring tool
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This is basically a NETCONF client that puts NETCONF servers under heavy
load of NETCONF RPCs and measures the time until a configurable amount
of them is processed.

RESTCONF stress-performance measuring tool
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Very similar to NETCONF stress tool with the difference of using
RESTCONF protocol instead of NETCONF.

YANGLIB remote repository
-------------------------

There are scenarios in NETCONF deployment, that require for a centralized
YANG models repository. YANGLIB plugin provides such remote repository.

To start this plugin, you have to install odl-yanglib feature. Then you
have to configure YANGLIB either through RESTCONF or NETCONF. We will
show how to configure YANGLIB through RESTCONF.

YANGLIB configuration through RESTCONF
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

You have to specify what local YANG modules directory you want to provide.
Then you have to specify address and port whre you want to provide YANG
sources. For example, we want to serve yang sources from folder /sources
on localhost:5000 adress. The configuration for this scenario will be
as follows:

::

    PUT  http://localhost:8181/restconf/config/network-topology:network-topology/topology/topology-netconf/node/controller-config/yang-ext:mount/config:modules/module/yanglib:yanglib/example

Headers:

-  Accept: application/xml

-  Content-Type: application/xml

Payload:

::

   <module xmlns="urn:opendaylight:params:xml:ns:yang:controller:config">
     <name>example</name>
     <type xmlns:prefix="urn:opendaylight:params:xml:ns:yang:controller:yanglib:impl">prefix:yanglib</type>
     <broker xmlns="urn:opendaylight:params:xml:ns:yang:controller:yanglib:impl">
       <type xmlns:prefix="urn:opendaylight:params:xml:ns:yang:controller:md:sal:binding">prefix:binding-broker-osgi-registry</type>
       <name>binding-osgi-broker</name>
     </broker>
     <cache-folder xmlns="urn:opendaylight:params:xml:ns:yang:controller:yanglib:impl">/sources</cache-folder>
     <binding-addr xmlns="urn:opendaylight:params:xml:ns:yang:controller:yanglib:impl">localhost</binding-addr>
     <binding-port xmlns="urn:opendaylight:params:xml:ns:yang:controller:yanglib:impl">5000</binding-port>
   </module>

This should result in a 2xx response and new YANGLIB instance should be
created. This YANGLIB takes all YANG sources from /sources folder and
for each generates URL in form:

::

    http://localhost:5000/schemas/{modelName}/{revision}

On this URL will be hosted YANG source for particular module.

YANGLIB instance also write this URL along with source identifier to
ietf-netconf-yang-library/modules-state/module list.

Netconf-connector with YANG library as fallback
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

There is an optional configuration in netconf-connector called
yang-library. You can specify YANG library to be plugged as additional
source provider into the mount's schema repository. Since YANGLIB
plugin is advertising provided modules through yang-library model, we
can use it in mount point's configuration as YANG library.  To do this,
we need to modify the configuration of netconf-connector by adding this
XML

::

    <yang-library xmlns="urn:opendaylight:netconf-node-topology">
      <yang-library-url xmlns="urn:opendaylight:netconf-node-topology">http://localhost:8181/restconf/operational/ietf-yang-library:modules-state</yang-library-url>
      <username xmlns="urn:opendaylight:netconf-node-topology">admin</username>
      <password xmlns="urn:opendaylight:netconf-node-topology">admin</password>
    </yang-library>

This will register YANGLIB provided sources as a fallback schemas for
particular mount point.

NETCONF Call Home
-----------------

.. important::

    The call home feature is experimental and will change in a future
    release. In particular, the Yang models will change to those specified
    in the `RFC 8071 <https://tools.ietf.org/html/rfc8071>`__

Call Home Installation
~~~~~~~~~~~~~~~~~~~~~~

ODL Call-Home server is installed in Karaf by installing karaf feature
``odl-netconf-callhome-ssh``. RESTCONF feature is recommended for
configuring Call Home & testing its functionality.

::

  feature:install odl-netconf-callhome-ssh


.. note::

    In order to test Call Home functionality we recommend Netopeer.
    See `Netopeer Call Home <https://github.com/CESNET/netopeer/wiki/CallHome>`__ to learn how to enable call-home on Netopeer.

Northbound Call-Home API
~~~~~~~~~~~~~~~~~~~~~~~~

The northbound Call Home API is used for administering the Call-Home Server. The
following describes this configuration.

Global Configuration
^^^^^^^^^^^^^^^^^^^^

Configuring global credentials
''''''''''''''''''''''''''''''

ODL Call-Home server allows user to configure global credentials, which
will be used for devices which does not have device-specific credentials
configured.

This is done by creating
``/odl-netconf-callhome-server:netconf-callhome-server/global/credentials``
with username and passwords specified.

*Configuring global username & passwords to try*

.. code-block:: none

    PUT
    /restconf/config/odl-netconf-callhome-server:netconf-callhome-server/global/credentials HTTP/1.1
    Content-Type: application/json
    Accept: application/json

.. code-block:: json

    {
      "credentials":
      {
        "username": "example",
        "passwords": [ "first-password-to-try", "second-password-to-try" ]
      }
    }

Configuring to accept any ssh server key using global credentials
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''

By default Netconf Call-Home Server accepts only incoming connections
from allowed devices
``/odl-netconf-callhome-server:netconf-callhome-server/allowed-devices``,
if user desire to allow all incoming connections, it is possible to set
``accept-all-ssh-keys`` to ``true`` in
``/odl-netconf-callhome-server:netconf-callhome-server/global``.

The name of this devices in ``netconf-topology`` will be in format
``ip-address:port``. For naming devices see Device-Specific
Configuration.

*Allowing unknown devices to connect*

This is a debug feature and should not be used in production. Besides being an obvious
security issue, this also causes the Call-Home Server to drastically increase its output
to the log.

.. code-block:: none

    POST
    /restconf/config/odl-netconf-callhome-server:netconf-callhome-server/global HTTP/1.1
    Content-Type: application/json
    Accept: application/json

.. code-block:: json

    {
      "global": {
        "accept-all-ssh-keys": "true"
      }
    }

Device-Specific Configuration
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Allowing Device & Configuring Name
''''''''''''''''''''''''''''''''''

Netconf Call Home Server uses device provided SSH server key (host key)
to identify device. The pairing of name and server key is configured in
``/odl-netconf-callhome-server:netconf-callhome-server/allowed-devices``.
This list is colloquially called a whitelist.

If the Call-Home Server finds the SSH host key in the whitelist, it continues
to negotiate a NETCONF connection over an SSH session. If the SSH host key is
not found, the connection between the Call Home server and the device is dropped
immediately. In either case, the device that connects to the Call home server
leaves a record of its presence in the operational store.

*Example of configuring device*

.. code-block:: none

    PUT
    /restconf/config/odl-netconf-callhome-server:netconf-callhome-server/allowed-devices/device/example HTTP/1.1
    Content-Type: application/json
    Accept: application/json

.. code-block:: json

    {
      "device": {
        "unique-id": "example",
        "ssh-host-key": "AAAAB3NzaC1yc2EAAAADAQABAAABAQDHoH1jMjltOJnCt999uaSfc48ySutaD3ISJ9fSECe1Spdq9o9mxj0kBTTTq+2V8hPspuW75DNgN+V/rgJeoUewWwCAasRx9X4eTcRrJrwOQKzb5Fk+UKgQmenZ5uhLAefi2qXX/agFCtZi99vw+jHXZStfHm9TZCAf2zi+HIBzoVksSNJD0VvPo66EAvLn5qKWQD4AdpQQbKqXRf5/W8diPySbYdvOP2/7HFhDukW8yV/7ZtcywFUIu3gdXsrzwMnTqnATSLPPuckoi0V2jd8dQvEcu1DY+rRqmqu0tEkFBurlRZDf1yhNzq5xWY3OXcjgDGN+RxwuWQK3cRimcosH"
      }
    }

Configuring Device with Device-specific Credentials
'''''''''''''''''''''''''''''''''''''''''''''''''''

Call Home Server also allows to configure credentials per device basis,
this is done by introducing ``credentials`` container into
device-specific configuration. Format is same as in global credentials.

*Configuring Device with Credentials*

.. code-block:: none

    PUT
    /restconf/config/odl-netconf-callhome-server:netconf-callhome-server/allowed-devices/device/example HTTP/1.1
    Content-Type: application/json
    Accept: application/json

.. code-block:: json

    {
      "device": {
        "unique-id": "example",
        "credentials": {
          "username": "example",
          "passwords": [ "password" ]
        },
        "ssh-host-key": "AAAAB3NzaC1yc2EAAAADAQABAAABAQDHoH1jMjltOJnCt999uaSfc48ySutaD3ISJ9fSECe1Spdq9o9mxj0kBTTTq+2V8hPspuW75DNgN+V/rgJeoUewWwCAasRx9X4eTcRrJrwOQKzb5Fk+UKgQmenZ5uhLAefi2qXX/agFCtZi99vw+jHXZStfHm9TZCAf2zi+HIBzoVksSNJD0VvPo66EAvLn5qKWQD4AdpQQbKqXRf5/W8diPySbYdvOP2/7HFhDukW8yV/7ZtcywFUIu3gdXsrzwMnTqnATSLPPuckoi0V2jd8dQvEcu1DY+rRqmqu0tEkFBurlRZDf1yhNzq5xWY3OXcjgDGN+RxwuWQK3cRimcosH"
      }
    }

Operational Status
^^^^^^^^^^^^^^^^^^

Once an entry is made into the config side of "allowed-devices", the Call-Home Server will
populate an corresponding operational device that is the same as the config device but
has an additional status. By default, this status is *DISCONNECTED*. Once a device calls
home, this status will change to one of:

*CONNECTED* — The device is currently connected and the NETCONF mount is available for network
management.

*FAILED_AUTH_FAILURE* — The last attempted connection was unsuccessful because the Call-Home
Server was unable to provide the acceptable credentials of the device. The device is also
disconnected and not available for network management.

*FAILED_NOT_ALLOWED* — The last attempted connection was unsuccessful because the device was
not recognized as an acceptable device. The device is also disconnected and not available for
network management.

*FAILED* — The last attempted connection was unsuccessful for a reason other than not
allowed to connect or incorrect client credentials. The device is also disconnected and not
available for network management.

*DISCONNECTED* — The device is currently disconnected.

Rogue Devices
'''''''''''''

Devices which are not on the whitelist might try to connect to the Call-Home Server. In
these cases, the server will keep a record by instantiating an operational device. There
will be no corresponding config device for these rogues. They can be identified readily
because their device id, rather than being user-supplied, will be of the form
"address:port". Note that if a device calls back multiple times, there will only be
a single operatinal entry (even if the port changes); these devices are recognized by
their unique host key.

Southbound Call-Home API
~~~~~~~~~~~~~~~~~~~~~~~~

The Call-Home Server listens for incoming TCP connections and assumes that the other side of
the connection is a device calling home via a NETCONF connection with SSH for
management. The server uses port 6666 by default and this can be configured via a
blueprint configuration file.

The device **must** initiate the connection and the server will not try to re-establish the
connection in case of a drop. By requirement, the server cannot assume it has connectivity
to the device due to NAT or firewalls among others.

RESTCONF Event Notifications
----------------------------

RESTCONF Northbound supports YANG-defined event notifications as defined in the specification `Subscription
to YANG Notifications <https://tools.ietf.org/html/rfc8639>`_.

Subscription to notification event streams is done via SSE (Server-sent-events) when using HTTP/1.1 or via
HTTP/2 streams when using HTTP/2 protocol.

Clients can subscribe to and receive content from notification streams that are supported by the RESTCONF server.
This mechanism is through the use of a subscription. Currently, only the dynamic subscription mechanism is supported.
Subscriptions are created, modified or deleted using the subscription RPC operations defined within
the "ietf-subscribed-notifications" YANG module (and augmented from "ietf-yang-push" YANG module).
These RPCs are described in more detail further below.

Establishing a subscription
~~~~~~~~~~~~~~~~~~~~~~~~~~~

Before subscribing to a notifications stream, the client needs to create a stream subscription. This is done via
the "establish-subscription" RPC operation.

Here is an example of a POST request for invocation of such operation:

.. code-block:: none

    POST
    /restconf/operations/ietf-subscribed-notifications:establish-subscription
    Content-Type: application/json
    Accept: application/json

.. code-block:: json

    {
      "ietf-subscribed-notifications:input" : {
        "stream": "toaster:toasterRestocked",
        "encoding": "encode-json"
      }
    }

The server returns a reply with the RPC output containing the subscription-result and the identifier of the
created subscription. In case the subscription could not be created, a negative subscription-result is returned
within the RPC output.

.. code-block:: json

    {
      "output" : {
        "subscription-result": "ietf-subscribed-notifications:ok",
        "identifier": 123
      }
    }

The identifier is then used by the client to subscribe to the specified event stream and start receiving
notifications. In order to do this, the client issues the following request using the GET method for HTTP/1.1 or
POST method for HTTP/2 connections:

.. code-block:: none

    POST
    /restconf/notification/toaster:toasterRestocked/123
    Content-Type: application/json
    Accept: application/json

The server will now start sending event notifications back to the client within a SSE event stream if HTTP/1.1
was used for the request or within a HTTP/2 stream in case the request was made with HTTP/2.

Notification with JSON encoding:

.. code-block:: json

    {
      "ietf-restconf:notification": {
        "toaster:toasterRestocked": {
          "amountOfBread":100
        }
      },
      "event-time": "2018-03-07T13:33:06.141+01:00"
    }

Notification with XML encoding:

.. code-block:: xml

    <notification xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
      <eventTime>2018-03-07T14:05:06.119+01:00</eventTime>
      <toasterRestocked xmlns="http://netconfcentral.org/ns/toaster">
          <amountOfBread>100</amountOfBread>
      </toasterRestocked>
    </notification>

The "establish-subscription" RPC requires at least the input parameter "stream" to be present in the request
message-body. This parameter specifies for which notification stream is the subscription established. The value of
the parameter must consist of a YANG module name and a name of the notification in that module separated by a colon.
Each subscription belongs to exactly one notification stream.
Other input parameters that are supported for this RPC are encoding, replay-start-time, stop-time and period.
They are described further below.

The data encoding of notifications can be specified with the "establish-subscription" input parameter "encoding".
Notifications can be streamed in either XML or JSON encoding (supported parameter values are "encode-xml" or
"encode-json"). If the "encoding" parameter is not present in the RPC input or an unsupported value is used,
the server will default to "encode-xml" format.

If the client wants to receive notifications in periodic intervals, "period" parameter must be present in
the "establish-subscription" RPC input. This parameter is augmented into the RPC from the "ietf-yang-push" YANG module,
so the module name prefix has to be prepended to the parameter name. Value of "period" must be a uint32 number.

Here is an example of request message-body for establishing a periodic subscription:

.. code-block:: json

    {
      "ietf-subscribed-notifications:input" : {
        "stream": "toaster:toasterRestocked",
        "encoding": "encode-json",
        "ietf-yang-push:period": 3
      }
    }

In this case, notifications will be sent to the client every three seconds.

Another parameter which may be specified in "establish-subscription" RPC input is the "replay-start-time".
The inclusion of this parameter within an "establish-subscription" RPC indicates a replay request.
A subscription established through such request is also capable of passing along recently generated event records.
In other words, as the subscription initializes itself, it sends any previously generated content from within target
event stream which meets the time frame criteria. These historical event records are then followed by event records
generated after the subscription has been established. All event records are delivered in the order generated.

Here is an example of request message-body for establishing a replay request:

.. code-block:: json

    {
      "ietf-subscribed-notifications:input" : {
        "stream": "toaster:toasterRestocked",
        "encoding": "encode-json",
        "replay-start-time": "2018-03-07T14:05:00.00Z"
      }
    }

The client will receive all notifications which have been generated for the target event stream since the date and
time specified in the "replay-start-time" value up to the present, followed by a "replay-completed" notification.
The date and time value is in UTC format.

.. code-block:: json

    {
      "ietf-restconf:notification": {
        "toaster:toasterRestocked": {
          "amountOfBread":100
        }
      },
      "event-time":"2018-03-07T14:05:06.096+01:00"
    }
    {
      "ietf-restconf:notification": {
        "toaster:toasterRestocked": {
          "amountOfBread":100
        }
      },
      "event-time":"2018-03-07T14:13:00.777+01:00"
    }
    {
      "ietf-restconf:notification": {
        "ietf-subscribed-notifications: replay-completed": {
          "identifier": 123
          }
        },
      "event-time":"2018-03-07T14:23:05.856+01:00"
    }

Active subscriptions can also be scheduled to stop using the "stop-time" parameter. The value of this parameter is
a date and time in UTC format.

Here is an example of request message-body for establishing a subscription that is scheduled to stop:

.. code-block:: json

    {
      "ietf-subscribed-notifications:input" : {
        "stream": "toaster:toasterRestocked",
        "encoding": "encode-json",
        "stop-time": "2018-01-24T08:55:00.00Z"
      }
    }

The subscription will cease to exist once the specified date and time is reached. A "subscription-completed"
notification is sent back to the client afterwards.

.. code-block:: json

    {
      "ietf-restconf:notification": {
        "ietf-subscribed-notifications: subscription-completed": {
          "identifier": 123
          }
        },
      "event-time":"2018-03-07T15:13:05.347+01:00"
    }

The value of "stop-time" parameter must be for a future time, otherwise it will be ignored. However, if combined with
"replay-start-time", it can point to the past, but it must be later than the "replay-start-time". The combination of
these two parameters will result into a replay of notifications from within the time frame specified with
"replay-start-time" and "stop-time".

Modifying a subscription
~~~~~~~~~~~~~~~~~~~~~~~~

Once a subscription has been established, the client can modify some of its properties using the "modify-subscription"
RPC. The identifier of the subscription must be specified in the RPC input. This operation can only be performed using
the same transport session as the one that was used for establishing the subscription. RESTCONF Northbound
currently supports modification of "period" and "stop-time" parameters.

Here is an example of a request payload for changing the terms of an existing subscription:

.. code-block:: json

    {
      "ietf-subscribed-notifications:input" : {
        "identifier": 123,
        "ietf-yang-push:period": 5,
        "stop-time": "2018-01-24T08:55:00.00Z"
      }
    }

The server will respond with a corresponding RPC output specifying whether the operation was successful or not.

.. code-block:: json

    {
      "output" : {
        "subscription-result": "ietf-subscribed-notifications:ok"
      }
    }

Deleting a subscription
~~~~~~~~~~~~~~~~~~~~~~~

Once a subscription has been established, the client can remove it using the "delete-subscription" RPC operation.
The identifier of the subscription must be specified in the RPC input.

Here is an example of a request which cancels an existing subscription with the specified identifier:

.. code-block:: none

    POST
    /restconf/operations/ietf-subscribed-notifications:delete-subscription
    Content-Type: application/json
    Accept: application/json

.. code-block:: json

    {
      "ietf-subscribed-notifications:input" : {
        "identifier": 123
      }
    }

After a successful deletion request, no more notifications will be sent for the subscription.

However, a subscription can only be deleted using the same transport session as the one that was used for subscription
establishment.

Killing a subscription
~~~~~~~~~~~~~~~~~~~~~~

Once a subscription has been established, the client can remove it using the "kill-subscription" RPC operation.
The identifier of the subscription must be specified in the RPC input.

Here is an example of a request which terminates an existing subscription with the specified identifier:

.. code-block:: none

    POST
    /restconf/operations/ietf-subscribed-notifications:kill-subscription
    Content-Type: application/json
    Accept: application/json

.. code-block:: json

    {
      "ietf-subscribed-notifications:input" : {
        "identifier": 123
      }
    }

If the operation is successful, a "subscription-terminated" notification is sent back to the client.

.. code-block:: json

    {
      "ietf-restconf:notification": {
        "ietf-subscribed-notifications:subscription-terminated": {
          "identifier":123
        }
      },
      "event-time":"2018-03-07T14:13:53.895+01:00"
    }

Unlike the "delete-subscription" RPC, "kill-subscription" can cancel any subscription even when the transport session
being used is not the same as the one that was used for subscription creation.


Retrieving information about all active subscriptions
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Information about active notification stream subscriptions can be obtained using the following GET request on
subscriptions container:

.. code-block:: none

    GET
    /restconf/data/ietf-subscribed-notifications:subscriptions
    Content-Type: application/json
    Accept: application/json

Subscriptions are removed from the list once they expire (reaching stop-time) or when they are terminated by
a "kill-subscription" or "delete-subscription" operation.