Internet DRAFT - draft-ietf-netconf-rfc5277bis
draft-ietf-netconf-rfc5277bis
NETCONF A. Clemm
Internet-Draft Sympotech
Intended status: Standards Track A. Gonzalez Prieto
Expires: April 30, 2017 E. Voit
E. Nilsen-Nygaard
A. Tripathy
Cisco Systems
S. Chisholm
Ciena
H. Trevino
Cisco Systems
October 27, 2016
Subscribing to Event Notifications
draft-ietf-netconf-rfc5277bis-01
Abstract
This document defines capabilities and operations for subscribing to
content and providing asynchronous notification message delivery on
that content. Notification delivery can occur over a variety of
protocols used commonly in conjunction with YANG, such as NETCONF and
RESTCONF. The capabilities and operations defined in this document
when using in conjunction with draft-ietf-netconf-netconf-event-
notifications are intended to replace RFC 5277.
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 http://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 April 30, 2017.
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Copyright Notice
Copyright (c) 2016 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
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
1.3. Solution Overview . . . . . . . . . . . . . . . . . . . . 5
2. Solution . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.1. Event Streams . . . . . . . . . . . . . . . . . . . . . . 6
2.2. Event Stream Discovery . . . . . . . . . . . . . . . . . 7
2.3. Filters . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.4. Subscription State Model at the Publisher . . . . . . . . 7
3. Data Model Trees for Event Notifications . . . . . . . . . . 8
4. Dynamic Subscriptions . . . . . . . . . . . . . . . . . . . . 12
4.1. Establishing a Subscription . . . . . . . . . . . . . . . 12
4.2. Modifying a Subscription . . . . . . . . . . . . . . . . 13
4.3. Deleting a Subscription . . . . . . . . . . . . . . . . . 13
5. Configured Subscriptions . . . . . . . . . . . . . . . . . . 14
5.1. Establishing a Configured Subscription . . . . . . . . . 14
5.2. Modifying a Configured Subscription . . . . . . . . . . . 16
5.3. Deleting a Configured Subscription . . . . . . . . . . . 16
6. Event (Data Plane) Notifications . . . . . . . . . . . . . . 17
7. Control Plane Notifications . . . . . . . . . . . . . . . . . 18
7.1. replayComplete . . . . . . . . . . . . . . . . . . . . . 19
7.2. notificationComplete . . . . . . . . . . . . . . . . . . 19
7.3. subscription-started . . . . . . . . . . . . . . . . . . 19
7.4. subscription-modified . . . . . . . . . . . . . . . . . . 19
7.5. subscription-terminated . . . . . . . . . . . . . . . . . 19
7.6. subscription-suspended . . . . . . . . . . . . . . . . . 20
7.7. subscription-resumed . . . . . . . . . . . . . . . . . . 20
8. Data Model for Event Notifications . . . . . . . . . . . . . 20
9. Backwards Compatibility . . . . . . . . . . . . . . . . . . . 40
10. Security Considerations . . . . . . . . . . . . . . . . . . . 41
11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 42
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12. References . . . . . . . . . . . . . . . . . . . . . . . . . 42
12.1. Normative References . . . . . . . . . . . . . . . . . . 42
12.2. Informative References . . . . . . . . . . . . . . . . . 42
Appendix A. Issues that are currently being worked and resolved 43
A.1. Unresolved and yet-to-be addressed issues . . . . . . . . 43
A.2. Agreement in principal . . . . . . . . . . . . . . . . . 43
A.3. Resolved Issues . . . . . . . . . . . . . . . . . . . . . 44
Appendix B. Changes between revisions . . . . . . . . . . . . . 44
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 45
1. Introduction
This document defines mechanisms that provide an asynchronous message
notification delivery service in a protocol-agnostic manner. This
document defines capabilities and operations for providing
asynchronous message notification delivery for notifications
including those necessary to establish, monitor, and support
subscriptions to notification delivery.
Notification delivery can occur over a variety of protocols used
commonly in conjunction with YANG, such as NETCONF [RFC6241] (defined
in [I-D.ietf-netconf-netconf-event-notif]) and Restconf
[I-D.ietf-netconf-restconf] (defined in
[I-D.ietf-netconf-restconf-notif]). The capabilities and operations
defined in this document are intended to replace RFC 5277, along with
their mapping onto NETCONF transport.
1.1. Motivation
The motivation for this work is to enable the sending of transport
agnostic asynchronous notification messages driven by a YANG
Subscription that are consistent with the data model (content) and
security model. Predating this work was used within a NETCONF
implementation. [RFC5277] which defined a limited defines a
notification mechanism for for NETCONF. However, there are various
[RFC5277] has limitations:, many of which have been exposed in
[RFC7923].
The scope of the work aims at meeting the operational needs of
network subscriptions:
o Ability to dynamically or statically subscribe to event
notifications available on a publisher.
o Ability to negotiate acceptable dynamic subscription parameters.
o Ability to filter the subset of notifications to be pushed with
stream-specific semantics.
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o Ability for the notification payload to be interpreted
independently of the transport protocol. (In other words, the
encoded notification fully describes itself.)
o Mechanism to communicate the notifications.
o Ability to replay locally logged notifications.
1.2. 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].
Configured subscription: A subscription installed via a configuration
interface which persists across reboots.
Dynamic subscription: A subscription agreed between subscriber and
publisher via create, establish, modify, and delete RPC control plane
signaling messages.
Event: An occurrence of something that may be of interest. (e.g., a
configuration change, a fault, a change in status, crossing a
threshold, or an external input to the system.)
Event notification: A set of information intended for a Receiver
indicating that one or more Event(s) have occurred. Details of the
Event(s) may be included within the Notification.
Filter: Evaluation criteria, which may be applied against a targeted
set of objects/events in a subscription. Information traverses the
filter only if specified filter criteria are met.
NACM: NETCONF Access Control Model.
OAM: Operations, Administration, Maintenance.
Publisher: An entity responsible for streaming Event Notifications
per the terms of a Subscriptions
Receiver: A target to which a publisher pushes event notifications.
For dynamic subscriptions, the receiver and subscriber will often be
the same entity.
RPC: Remote Procedure Call.
Stream (also referred to as "event stream"): A continuous ordered set
of events grouped under an explicit criteria.
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Subscriber: An entity able to request and negotiate a contract for
the receipt of event notifications from a publisher.
Subscription: A contract with a publisher, stipulating which
information receiver(s) wishes to have pushed from the publisher
without the need for further solicitation.
1.3. Solution Overview
This document describes mechanisms for subscribing and receiving
event notifications from an event server publisher. This document
builds on top of the capabilities defined in [RFC5277], extending
them, and generalizing them to be protocol-agnostic.
Some enhancements over RFC 5277 include the ability to have multiple
subscriptions on a single transport session, to terminate a single
subscriptions without terminating the transport session, and to
modify existing subscriptions.
These enhancements do not affect existing RFC 5277 subscribers that
do not support these particular subscription requirements.
The solution supports subscribing to event notifications using two
mechanisms:
1. Dynamic subscriptions, where a subscriber initiates a
subscription negotiation with a publisher via RPC. A subscriber
initiates a negotiation by issuing a subscription request. If
the publisher wants to serve this request, it will accept it, and
then start pushing event notifications as negotiated. If the
publisher does not wish to serve it as requested, it may respond
with subscription parameters which it would have accepted.
2. Configured subscriptions, which is an optional mechanism that
enables managing subscriptions via a configuration interface so
that a publisher can send event notifications to configured
receiver(s).
Some key characteristics of configured and dynamic subscriptions
include:
o The lifetime of a dynamic subscription is limited by the lifetime
of the subscriber session used to establish it. Typically loss of
the transport session tears down any dependent dynamic
subscriptions.
o The lifetime of a configured subscription is driven by
configuration being present on the running configuration. This
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implies configured subscriptions persist across reboots, and
persists even when transport is unavailable. This also means
configured subscriptions do not support negotiation.
o Subscriptions can be modified or terminated at any point of their
lifetime. configured subscriptions can be modified by any
configuration client with write rights on the configuration of the
subscription.
Note that there is no mixing-and-matching of dynamic and configured
subscriptions. Specifically, a configured subscription cannot be
modified or deleted using RPC. Similarly, a subscription created via
RPC cannot be modified through configuration operations.
The publisher may decide to terminate a dynamic subscription at any
time. Similarly, it may decide to temporarily suspend the sending of
event notifications for either configured or dynamic subscriptions.
Such termination or suspension may be driven by the publisher running
out of resources to serve the subscription, or by internal errors on
the publisher.
2. Solution
2.1. Event Streams
An event stream is a set of events available for subscription from a
publisher. It is out of the scope of this document to identify a)
how streams are defined, b) how events are defined/generated, and c)
how events are assigned to streams.
That said, some event streams will be standardized whereas others may
be vendor specific. One standardized event stream is the "NETCONF"
notification event stream. The NETCONF event stream contains all
NETCONF XML event notifications supported by the publisher, except
for those belonging only to streams that explicitly indicate that
they must be excluded from the NETCONF stream, such as notifications
that serve OAM and signaling purposes.
The following is a high-level description of the flow of a
notification. Note that it does not mandate and/or preclude an
implementation. As events are raised, they are assigned to streams.
An event may be assigned to multiple streams. The event is
distributed to subscribers and receivers based on the current
subscriptions and access control. Access control is needed because
if any receiver of that subscription does not have permission to
receive an event, then it never makes it into a notification, and
processing of the event is completed for that subscription.
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2.2. Event Stream Discovery
A publisher maintains a list of available event streams as
operational data. This list contains both standardized and vendor-
specific event streams. A client can retrieve this list like any
other YANG-defined data, for example using the <get> operation when
using NETCONF.
2.3. Filters
a publisher implementation SHOULD support the ability to perform
filtering of notification records per RFC 5277. (TODO: since 5277 is
to be obsoleted, we should describe the filter here.)
2.4. Subscription State Model at the Publisher
Below is the state machine of a subscription for the publisher. It
is important to note that a subscription doesn't exist at the
publisher until it is accepted and made active. The mere request by
a subscriber to establish a subscription is insufficient for that
asserted subscription to be externally visible via this state
machine.
.-------.
| start |
'-------'
|
establish
|
| .----------modify--------------.
v v '
.-----------. .-----------.
.--------. | |------>suspend------->| |
modify '| active | | suspended |
'--------->| |<----resume----<------| |
'-----------' '-----------'
| |
delete delete
| |
v |
.-------. |
| end |<-----------------------------'
'-------'
Figure 1: Subscription states at publisher
Of interest in this state machine are the following:
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o Successful <establish-subscription> or <modify-subscription>
requests put the subscription into an active state.
o Failed <modify-subscription> requests will leave the subscription
in its previous state, with no visible change to any streaming
updates.
o A <delete-subscription> request will delete the entire
subscription.
3. Data Model Trees for Event Notifications
The YANG data model for event notifications is depicted in this
section.
module: ietf-event-notifications
+--ro streams
| +--ro stream* stream
+--rw filters
| +--rw filter* [filter-id]
| +--rw filter-id filter-id
| +--rw (filter-type)?
| +--:(rfc5277)
| +--rw filter?
+--rw subscription-config {configured-subscriptions}?
| +--rw subscription* [subscription-id]
| +--rw subscription-id subscription-id
| +--rw stream? stream
| +--rw encoding? encoding
| +--rw (filter-type)?
| | +--:(rfc5277)
| | | +--rw filter?
| | +--:(by-reference)
| | +--rw filter-ref? filter-ref
| +--rw startTime? yang:date-and-time
| +--rw stopTime? yang:date-and-time
| +--rw receivers
| | +--rw receiver* [address]
| | +--rw address inet:host
| | +--rw port inet:port-number
| | +--rw protocol? transport-protocol
| +--rw (push-source)?
| +--:(interface-originated)
| | +--rw source-interface? if:interface-ref
| +--:(address-originated)
| +--rw source-vrf? uint32
| +--rw source-address inet:ip-address-no-zone
+--ro subscriptions
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+--ro subscription* [subscription-id]
+--ro subscription-id subscription-id
+--ro configured-subscription?
| empty {configured-subscriptions}?
+--ro subscription-status? subscription-status
+--ro stream? stream
+--ro encoding? encoding
+--ro (filter-type)?
| +--:(rfc5277)
| | +--ro filter?
| +--:(by-reference)
| +--ro filter-ref? filter-ref
+--ro startTime? yang:date-and-time
+--ro stopTime? yang:date-and-time
+--ro receivers
| +--ro receiver* [address]
| +--ro address inet:host
| +--ro port inet:port-number
| +--ro protocol? transport-protocol
+--ro (push-source)?
+--:(interface-originated)
| +--ro source-interface? if:interface-ref
+--:(address-originated)
+--ro source-vrf? uint32
+--ro source-address inet:ip-address-no-zone
rpcs:
+---x establish-subscription
| +---w input
| | +---w stream? stream
| | +---w encoding? encoding
| | +---w (filter-type)?
| | | +--:(rfc5277)
| | | | +---w filter?
| | | +--:(by-reference)
| | | +---w filter-ref? filter-ref
| | +---w startTime? yang:date-and-time
| | +---w stopTime? yang:date-and-time
| +--ro output
| +--ro subscription-result subscription-result
| +--ro (result)?
| +--:(success)
| | +--ro subscription-id subscription-id
| +--:(no-success)
| +--ro stream? stream
| +--ro encoding? encoding
| +--ro (filter-type)?
| | +--:(rfc5277)
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| | | +--ro filter?
| | +--:(by-reference)
| | +--ro filter-ref? filter-ref
| +--ro startTime? yang:date-and-time
| +--ro stopTime? yang:date-and-time
+---x create-subscription
| +---w input
| +---w stream? stream
| +---w encoding? encoding
| +---w (filter-type)?
| | +--:(rfc5277)
| | +---w filter?
| +---w startTime? yang:date-and-time
| +---w stopTime? yang:date-and-time
+---x modify-subscription
| +---w input
| | +---w subscription-id? subscription-id
| | +---w (filter-type)?
| | | +--:(rfc5277)
| | | | +---w filter?
| | | +--:(by-reference)
| | | +---w filter-ref? filter-ref
| | +---w startTime? yang:date-and-time
| | +---w stopTime? yang:date-and-time
| +--ro output
| +--ro subscription-result subscription-result
| +--ro (result)?
| +--:(success)
| | +--ro subscription-id subscription-id
| +--:(no-success)
| +--ro stream? stream
| +--ro encoding? encoding
| +--ro (filter-type)?
| | +--:(rfc5277)
| | | +--ro filter?
| | +--:(by-reference)
| | +--ro filter-ref? filter-ref
| +--ro startTime? yang:date-and-time
| +--ro stopTime? yang:date-and-time
+---x delete-subscription
+---w input
| +---w subscription-id subscription-id
+--ro output
+--ro subscription-result subscription-result
notifications:
+---n replay-complete
| +--ro subscription-id subscription-id
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+---n notification-complete
| +--ro subscription-id subscription-id
+---n subscription-started
| +--ro subscription-id subscription-id
| +--ro stream? stream
| +--ro encoding? encoding
| +--ro (filter-type)?
| | +--:(rfc5277)
| | | +--ro filter?
| | +--:(by-reference)
| | +--ro filter-ref? filter-ref
| +--ro startTime? yang:date-and-time
| +--ro stopTime? yang:date-and-time
+---n subscription-suspended
| +--ro subscription-id subscription-id
| +--ro reason? subscription-susp-reason
+---n subscription-resumed
| +--ro subscription-id subscription-id
+---n subscription-modified
| +--ro subscription-id subscription-id
| +--ro stream? stream
| +--ro encoding? encoding
| +--ro (filter-type)?
| | +--:(rfc5277)
| | | +--ro filter?
| | +--:(by-reference)
| | +--ro filter-ref? filter-ref
| +--ro startTime? yang:date-and-time
| +--ro stopTime? yang:date-and-time
+---n subscription-terminated
+--ro subscription-id subscription-id
+--ro reason? subscription-term-reason
The data model is structured as follows:
o "Streams" contains a list of event streams that are supported by
the publisher and that can be subscribed to.
o "Filters" contains a configurable list of filters that can be
applied to a subscription. This allows users to reference an
existing filter definition as an alternative to defining a filter
inline for each subscription.
o "Subscription-config" contains the configuration of configured
subscriptions. The parameters of each configured subscription are
a superset of the parameters of a dynamic subscription and use the
same groupings. In addition, the configured subscriptions must
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also specify intended receivers and may specify the push source
from which to send the stream of notification messages.
o "Subscriptions" contains a list of all subscriptions on a
publisher, both configured and dynamic. It can be used to
retrieve information about the subscriptions which an publisher is
serving.
The data model also contains a number of notifications that allow a
publisher to signal information about a subscription. Finally, the
data model contains a number of RPC definitions that are used to
manage dynamic subscriptions.
4. Dynamic Subscriptions
Dynamic subscriptions are managed via RPC.
4.1. Establishing a Subscription
This operation includes and extends the "create-subscription"
operation defined in RFC 5277. It allows a subscriber to request the
creation of a subscription both via RPC and configuration operations.
When invoking the RPC, establish-subscription permits negotiating the
subscription terms, changing them dynamically.
The input parameters of the operation are those of create
subscription plus:
o filter-ref: filters that have been previously (and separately)
configured can be referenced by a subscription. This mechanism
enables the reuse of filters.
o encoding: by default, updates are encoded using XML. Other
encodings may be supported, such as JSON.
If the publisher cannot satisfy the request, it sends a negative
<subscription-result> element.
If the subscriber has no authorization to establish the subscription,
the <subscription-result> indicates an authorization error. If the
request is rejected because the publisher is not able to serve it,
the publisher SHOULD include in the returned error what subscription
parameters would have been accepted for the request when it was
processed. However, they is no guarantee that subsequent requests
with those parameters for this subscriber or others will be accepted.
For instance, consider a subscription from
[I-D.ietf-netconf-yang-push], which augments the establish-
subscription with some additional parameters, including "period".
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Subscription requests will fail if a filter with invalid syntax is
provided or if the name of a non-existent stream is provided.
4.2. Modifying a Subscription
This operation permits modifying the terms of a dynamic subscription
previously established. Subscriptions created by configuration
cannot be modified. Dynamic subscriptions can be modified one or
multiple times. If the publisher accepts the request, it immediately
starts sending events based on the new terms, completely ignoring the
previous ones. If the publisher rejects the request, the
subscription remains as prior to the request. That is, the request
has no impact whatsoever. The contents of negative responses to
modify-subscription requests are the subset of the establish
subscription request parameters which are allowed to be dynamically
modified.
Dynamic subscriptions established via RPC can only be modified (or
deleted) via RPC using the same transport session used to establish
that subscription.
Configured subscriptions cannot be modified (or deleted) using RPCs.
Instead, configured subscriptions are modified (or deleted) as part
of regular configuration operations. Publishers MUST reject any
attempts to modify (or delete) configured subscriptions via RPC.
4.3. Deleting a Subscription
This operation permits canceling a subscription previously
established. If the publisher accepts the request, it immediately
stops sending events for the subscription. If the publisher rejects
the request, all subscriptions remain as prior to the request. That
is, the request has no impact whatsoever.
Subscriptions created via RPC can only be deleted via RPC using the
same transport session used for subscription establishment.
Configured subscriptions cannot be deleted using RPCs. Instead,
configured subscriptions are deleted as part of regular configuration
operations. Publishers MUST reject any RPC attempt to delete
configured subscriptions.
The only parameter to delete-subscription is the identifier of the
subscription to delete.
If the publisher can satisfy the request, it sends an OK element.
If the publisher cannot satisfy the request, it sends an error-rpc
element.
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5. Configured Subscriptions
A configured subscription is a subscription installed via a
configuration interface.
Configured subscriptions persist across reboots, and persist even
when transport is unavailable. This also means configured
subscriptions do not support negotiation.
Configured subscriptions can be modified by any configuration client
with write permissions for the configuration of the subscription.
Subscriptions can be modified or terminated at any point of their
lifetime.
Supporting configured subscriptions is optional and advertised using
the "configured-subscriptions" feature.
In addition to subscription parameters that apply to dynamic
subscriptions, the following additional parameters apply to
configured subscriptions:
o One or more receiver IP addresses (and corresponding ports)
intended as the destination for push updates for each
subscription. In addition, the transport protocol for each
destination may be defined.
o Optional parameters to identify an egress interface or IP address
/ VRF where a subscription updates should be pushed from the
publisher.
5.1. Establishing a Configured Subscription
Configured subscriptions are established using configuration
operations against the top-level subtree subscription-config. There
are two key differences between RPC and configuration operations for
subscription establishment. Firstly, configuration operations do not
support negotiation while RPCs do. Secondly, while RPCs mandate that
the subscriber establishing the subscription is the only receiver of
the notifications, configuration operations permit specifying
receivers independent of any tracked subscriber. Immediately after a
subscription is successfully established, the publisher sends to its
receivers a control-plane notification stating the subscription has
been established (subscription-started).
Because there is no explicit association with an existing transport
session, configured configuration operations require additional
parameters to indicate the receivers of the notifications and
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possibly the source of the notifications such as a specific egress
interface.
For example at subscription establishment, a client may send:
<rpc message-id="101"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"
xmlns:nc="urn:ietf:params:xml:ns:netconf:base:1.0">
<edit-config>
<target>
<running/>
</target>
<subscription-config
xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
<subscription>
<subscription-id>
1922
</subscription-id>
<stream>
foo
</stream>
<receiver>
<address>
1.2.3.4
</address>
<port>
1234
</port>
</receiver>
</subscription>
</subscription-config>
</edit-config>
</rpc>
Figure 2: Establish configured subscription
if the request is accepted, the publisher would reply:
<rpc-reply message-id="101"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<ok/>
</rpc-reply>
Figure 3: Response to a successful configured subscription
establishment
if the request is not accepted because the publisher cannot serve it,
the publisher may reply:
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<rpc-reply xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<rpc-error>
<error-type>application</error-type>
<error-tag>resource-denied</error-tag>
<error-severity>error</error-severity>
<error-message xml:lang="en">
Temporarily the publisher cannot serve this
subscription due to the current workload.
</error-message>
</rpc-error>
</rpc-reply>
Figure 4: Response to a failed configured subscription establishment
5.2. Modifying a Configured Subscription
Configured subscriptions can be modified using configuration
operations against the top-level subtree subscription-config.
Immediately after a subscription is successfully modified, the
publisher sends to the existing receivers a control-plane
notification stating the subscription has been modified (i.e.,
subscription-modified).
If the modification involved adding and/or removing receivers, those
modified receivers are sent control-plane notifications, indicating
they have been added (i.e, subscription-started to a specific
receiver) or removed (i.e., subscription-terminated to a specific
receiver.)
5.3. Deleting a Configured Subscription
Subscriptions can be deleted using configuration operations against
the top-level subtree subscription-config. For example, in RESTCONF:
DELETE /subscription-config/subscription=1922 HTTP/1.1
Host: example.com
HTTP/1.1 204 No Content
Date: Sun, 24 Jul 2016 11:23:40 GMT
Server: example-server
Figure 5: Deleting a configured subscription
Immediately after a subscription is successfully deleted, the
publisher sends to all receivers a control-plane notification stating
the subscription has been terminated (subscription-terminated).
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6. Event (Data Plane) Notifications
Once a subscription has been set up, the publisher streams
(asynchronously) the event notifications per the terms of the
subscription. We refer to these as data plane notifications. For
dynamic subscriptions set up via RPC operations, event notifications
are sent over the session used to create or establish the
subscription. For configured subscriptions, event notifications are
sent over the specified connections.
An event notification is sent to the receiver(s) when an event of
interest (i.e., meeting the specified filtering criteria) has
occurred. An event notification is a complete and well-formed XML
document. Note that <notification> is not a Remote Procedure Call
(RPC) method but rather the top-level element identifying the one-way
message as a notification. Note that event notifications never
trigger responses.
The event notification always includes an <eventTime> element. It is
the time the event was generated by the event source. This parameter
is of type dateTime and compliant to [RFC3339]. Implementations must
support time zones.
The event notifications must also include the subscription-id if the
establish-subscription was used in its establishment, or if it was
configured via an operational interface.
The event notification also contains notification-specific tagged
content, if any.
The following is an example of an event notification from [RFC7950]:
notification link-failure {
description "A link failure has been detected";
leaf if-name {
type leafref {
path "/interface/name";
}
}
leaf if-admin-status {
type admin-status;
}
leaf if-oper-status {
type oper-status;
}
}
Figure 6: Definition of a data plane notification
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<notification
xmlns=" urn:ietf:params:xml:ns:netconf:notification:1.0">
<eventTime>2007-09-01T10:00:00Z</eventTime>
<link-failure xmlns="http://acme.example.com/system">
<if-name>so-1/2/3.0</if-name>
<if-admin-status>up</if-admin-status>
<if-oper-status>down</if-oper-status>
</link-failure>
</notification>
Figure 7: Data plane notification
The equivalent using json encoding would be
<notification
xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
<eventTime>2007-09-01T10:00:00Z</eventTime>
<notification-contents-json>
{
"acme-system:link-failure": {
"if-name": "so-1/2/3.0",
"if-admin-status": "up",
"if-oper-status": "down "
}
}
</notification-contents-json>
</notification>
Figure 8: Data plane notification using JSON encoding
7. Control Plane Notifications
In addition to data plane notifications, a publisher may send control
plane notifications to indicate to receivers that an event related to
the subscription management has occurred.
Control plane notifications are unlike other notifications in that
they are not general-purpose notifications. They cannot be filtered
out, and they are delivered only to the receiver of a subscription.
The definition of control plane notifications is distinct from other
notifications by making use of a YANG extension tagging them as
control plane notification.
Control plane notifications include indications that a replay of
notifications has been completed, that a subscription is done sending
notifications because an end time has been reached, and that a
subscription has started, been modified, been terminated, or been
suspended. They are described in the following subsections.
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7.1. replayComplete
This notification is originally defined in [RFC5277]. It is sent to
indicate that all of the replay notifications have been sent. This
notification must not be sent for any other reason.
In the case of a subscription without a stop time or a stop time
which has not been reached, after the <replayComplete> notification
has been sent, it can be expected that any notifications generated
since the start of the subscription creation will be sent, followed
by notifications in sequence as they arise naturally within the
system.
7.2. notificationComplete
This notification is originally defined in [RFC5277]. It is sent to
indicate that a subscription, which includes a stop time, has
finished passing events.
7.3. subscription-started
This notification indicates that a configured subscription has
started and data updates are beginning to be sent. This notification
includes the parameters of the subscription, except for the
receiver(s) addressing information and push-source information. Note
that for RPC-based subscriptions, no such notifications are sent.
7.4. subscription-modified
This notification indicates that a configured subscription has been
modified successfully. This notification includes the parameters of
the subscription, except for the receiver(s) addressing information
and push-source information. Note that for RPC-based subscriptions,
no such notifications are sent.
7.5. subscription-terminated
This notification indicates that a subscription has been terminated
by the publisher. The notification includes the reason for the
termination. The publisher may decide to terminate a subscription
when it is running out of resources for serving it, an internal error
occurs, etc. Publisher-driven terminations are notified to all
receivers. The management plane can also terminate configured
subscriptions using configuration operations.
Subscribers can terminate via RPC subscriptions established via RPC.
In such cases, no subscription-terminated notifications are sent.
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7.6. subscription-suspended
This notification indicates that a publisher has suspended a
subscription. The notification includes the reason for the
suspension. A possible reason is the lack of resources to serve it.
No further data plane notifications will be sent until the
subscription resumes. Suspensions are notified to the subscriber (in
the case of dynamic subscriptions) and all receivers (in the case of
configured subscriptions).
7.7. subscription-resumed
This notification indicates that a previously suspended dubscription
has been resumed. Data plane notifications generated in the future
will be sent after the subscription terms. Resumptions are notified
to the subscriber (in the case of dynamic subscriptions) and all
receivers (in the case of configured subscriptions).
8. Data Model for Event Notifications
<CODE BEGINS> file "ietf-event-notifications@2016-10-27.yang"
module ietf-event-notifications {
namespace
"urn:ietf:params:xml:ns:yang:ietf-event-notifications";
prefix notif-bis;
import ietf-yang-types {
prefix yang;
}
import ietf-inet-types {
prefix inet;
}
import ietf-interfaces {
prefix if;
}
organization "IETF";
contact
"WG Web: <http://tools.ietf.org/wg/netconf/>
WG List: <mailto:netconf@ietf.org>
WG Chair: Mahesh Jethanandani
<mailto:mjethanandani@gmail.com>
WG Chair: Mehmet Ersue
<mailto:mehmet.ersue@nokia.com>
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Editor: Alexander Clemm
<mailto:alex@sympotech.com>
Editor: Alberto Gonzalez Prieto
<mailto:albertgo@cisco.com>
Editor: Eric Voit
<mailto:evoit@cisco.com>
Editor: Einar Nilsen-Nygaard
<mailto:einarnn@cisco.com>
Editor: Ambika Prasad Tripathy
<mailto:ambtripa@cisco.com>
Editor: Sharon Chisholm
<mailto:schishol@ciena.com>
Editor: Hector Trevino
<mailto:htrevino@cisco.com";
description
"This module contains conceptual YANG specifications
for NETCONF Event Notifications.";
revision 2016-10-27 {
description
"Tweaks to remove two notifications,
RPC for create subscription refined with stream default,
new grouping to eliminate some dymanically modifiable
parameters in modifiy subscription RPC";
reference
"draft-ietf-netconf-rfc5277bis-01";
}
/*
* FEATURES
*/
feature json {
description
"This feature indicates that JSON encoding of notifications
is supported.";
}
feature configured-subscriptions {
description
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"This feature indicates that management plane configuration
of subscription is supported.";
}
/*
* EXTENSIONS
*/
extension control-plane-notif {
description
"This statement applies only to notifications.
It indicates that the notification is a control-plane
notification (aka OAM notification). Therefore it does
not participate in a regular event stream and does not
need to be specifically subscribed to.";
}
/*
* IDENTITIES
*/
/* Identities for streams */
identity stream {
description
"Base identity to represent a generic stream of event
notifications.";
}
identity NETCONF {
base stream;
description
"Default NETCONF event stream, containing events based on
notifications defined as YANG modules that are supported
by the system.";
}
/* Identities for subscription results */
identity subscription-result {
description
"Base identity for RPC responses to requests surrounding
management (e.g. creation, modification, deletion) of
subscriptions.";
}
identity ok {
base subscription-result;
description
"OK - RPC was successful and was performed as requested.";
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}
identity error {
base subscription-result;
description
"RPC was not successful.
Base identity for error return codes.";
}
identity error-no-such-subscription {
base error;
description
"A subscription with the requested subscription ID
does not exist.";
}
identity error-no-such-option {
base error;
description
"A requested parameter setting is not supported.";
}
identity error-insufficient-resources {
base error;
description
"The publisher has insufficient resources to support the
subscription as requested.";
}
identity error-configured-subscription {
base error;
description
"Cannot apply RPC to a configured subscription, i.e.
to a subscription that was not established via RPC.";
}
identity error-other {
base error;
description
"An unspecified error has occurred (catch all).";
}
/* Identities for subscription stream status */
identity subscription-stream-status {
description
"Base identity for the status of subscriptions and
datastreams.";
}
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identity active {
base subscription-stream-status;
description
"Status is active and healthy.";
}
identity inactive {
base subscription-stream-status;
description
"Status is inactive, for example outside the
interval between start time and stop time.";
}
identity suspended {
base subscription-stream-status;
description
"The status is suspended, meaning that the publisher
is currently unable to provide the negotiated updates
for the subscription.";
}
identity in-error {
base subscription-stream-status;
description
"The status is in error or degraded, meaning that
stream and/or subscription is currently unable to provide
the negotiated notifications.";
}
/* Identities for subscription errors */
identity subscription-errors {
description
"Base identity for subscription error status.
This identity is not to be confused with error return
codes for RPCs";
}
identity internal-error {
base subscription-errors;
description
"Subscription failures caused by server internal error.";
}
identity no-resources {
base subscription-errors;
description
"Lack of resources, e.g. CPU, memory, bandwidth";
}
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identity subscription-deleted {
base subscription-errors;
description
"The subscription was terminated because the subscription
was deleted.";
}
identity other {
base subscription-errors;
description
"Fallback reason - any other reason";
}
/* Identities for encodings */
identity encodings {
description
"Base identity to represent data encodings";
}
identity encode-xml {
base encodings;
description
"Encode data using XML";
}
identity encode-json {
base encodings;
description
"Encode data using JSON";
}
/* Identities for transports */
identity transport {
description
"An identity that represents a transport protocol for
event notifications";
}
identity netconf {
base transport;
description
"Netconf notifications as a transport.";
}
/*
* TYPEDEFs
*/
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typedef subscription-id {
type uint32;
description
"A type for subscription identifiers.";
}
typedef filter-id {
type uint32;
description
"A type to identify filters which can be associated with a
subscription.";
}
typedef subscription-result {
type identityref {
base subscription-result;
}
description
"The result of a subscription operation";
}
typedef subscription-term-reason {
type identityref {
base subscription-errors;
}
description
"Reason for a publisher to terminate a subscription.";
}
typedef subscription-susp-reason {
type identityref {
base subscription-errors;
}
description
"Reason for a publisher to suspend a subscription.";
}
typedef encoding {
type identityref {
base encodings;
}
description
"Specifies a data encoding, e.g. for a data subscription.";
}
typedef subscription-status {
type identityref {
base subscription-stream-status;
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}
description
"Specifies the status of a subscription or datastream.";
}
typedef transport-protocol {
type identityref {
base transport;
}
description
"Specifies transport protocol used to send notifications to a
receiver.";
}
typedef push-source {
type enumeration {
enum "interface-originated" {
description
"Notifications will be sent from a specific interface on
a publisher";
}
enum "address-originated" {
description
"Notifications will be sent from a specific address on a
publisher";
}
}
description
"Specifies from where notifications will be sourced when
being sent by the publisher.";
}
typedef stream {
type identityref {
base stream;
}
description
"Specifies a system-provided datastream.";
}
typedef filter-ref {
type leafref {
path "/notif-bis:filters/notif-bis:filter/notif-bis:filter-id";
}
description
"This type is used to reference a filter.";
}
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/*
* GROUPINGS
*/
grouping base-filter {
description
"This grouping defines the base for filters for
notification events.
It includes the filter defined in 5277 and
it enables extending filtering to other
types of filters";
choice filter-type {
description
"A filter needs to be a single filter of a given type.
Mixing and matching of multiple filters does not occur
at the level of this grouping.";
case rfc5277 {
anyxml filter {
description
"Filter per RFC 5277. Notification filter.
If a filter element is specified to look for data of a
particular value, and the data item is not present
within a particular event notification for its value to
be checked against, the notification will be filtered
out. For example, if one were to check for
'severity=critical' in a configuration event
notification where this field was not supported, then
the notification would be filtered out. For subtree
filtering, a non-empty node set means that the filter
matches. For XPath filtering, the mechanisms defined
in [XPATH] should be used to convert the returned
value to boolean.";
}
}
}
}
grouping subscription-info-basic-non-modifiable {
description
"This grouping describes the information in a basic
subscription request.";
leaf stream {
type stream;
description
"Indicates which stream of events is of interest.
If not present, events in the default NETCONF stream
will be sent.";
}
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leaf encoding {
type encoding;
default "encode-xml";
description
"The type of encoding for the subscribed data.
Default is XML";
}
}
grouping subscription-info-basic-modifiable {
description
"This grouping describes some objects which may be changed
in a subscription via an RPC.";
uses base-filter;
leaf startTime {
type yang:date-and-time;
description
"Used to trigger the replay feature
and indicate that the replay should start at the time
specified. If <startTime> is not present, this is not a
replay subscription. It is not valid to specify start
times that are later than the current time. If the
<startTime> specified is earlier than the log can support,
the replay will begin with the earliest available
notification. This parameter is of type dateTime and
compliant to [RFC3339]. Implementations must
support time zones.";
}
leaf stopTime {
type yang:date-and-time;
must "current() > ../startTime" {
description
"stopTime must be used with and be later than <startTime>";
}
description
"Used with the optional replay feature to indicate the
newest notifications of interest. If <stopTime> is
not present, the notifications will continue until the
subscription is terminated. Must be used with and be
later than <startTime>. Values of <stopTime> in the
future are valid. This parameter is of type dateTime and
compliant to [RFC3339]. Implementations must support time
zones.";
}
}
grouping subscription-info-all-modifiable {
description
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"This grouping describes all rpc modifiable objects in a
subscription.";
uses subscription-info-basic-modifiable {
augment "filter-type" {
description
"Post-5277 subscriptions allow references to existing
filters";
case by-reference {
description
"Incorporate a filter that has been configured
separately.";
leaf filter-ref {
type filter-ref;
description
"References filter which is associated with the
subscription.";
}
}
}
}
}
grouping subscription-info {
description
"This grouping describes information concerning a
subscription.";
uses subscription-info-basic-non-modifiable;
uses subscription-info-all-modifiable;
}
grouping push-source-info {
description
"Defines the sender source from which notifications
for a configured subscription are sent.";
choice push-source {
description
"Identifies the egress interface on the Publisher from
which notifications will or are being sent.";
case interface-originated {
description
"When the push source is out of an interface on the
Publisher established via static configuration.";
leaf source-interface {
type if:interface-ref;
description
"References the interface for notifications.";
}
}
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case address-originated {
description
"When the push source is out of an IP address on the
Publisher established via static configuration.";
leaf source-vrf {
type uint32 {
range "16..1048574";
}
description
"Label of the vrf.";
}
leaf source-address {
type inet:ip-address-no-zone;
mandatory true;
description
"The source address for the notifications.";
}
}
}
}
grouping receiver-info {
description
"Defines where and how to deliver notifications for a
configured subscription. This includes
specifying the receiver, as well as defining
any network and transport aspects when sending of
notifications occurs outside of Netconf.";
container receivers {
description
"Set of receivers in a subscription.";
list receiver {
key "address";
min-elements 1;
description
"A single host or multipoint address intended as a target
for the notifications for a subscription.";
leaf address {
type inet:host;
mandatory true;
description
"Specifies the address for the traffic to reach a
remote host. One of the following must be
specified: an ipv4 address, an ipv6 address,
or a host name.";
}
leaf port {
type inet:port-number;
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mandatory true;
description
"This leaf specifies the port number to use for
messages destined for a receiver.";
}
leaf protocol {
type transport-protocol;
default "netconf";
description
"This leaf specifies the transport protocol used
to deliver messages destined for the receiver.";
}
}
}
}
grouping subscription-response {
description
"Defines the output to the rpc's establish-subscription
and modify-subscription.";
leaf subscription-result {
type subscription-result;
mandatory true;
description
"Indicates whether subscription is operational,
or if a problem was encountered.";
}
choice result {
description
"Depending on the subscription result, different
data is returned.";
case success {
description
"This case is used when the subscription request
was successful and a subscription was created/modified
as a result";
leaf subscription-id {
type subscription-id;
mandatory true;
description
"Identifier used for this subscription.";
}
}
case no-success {
description
"This case applies when a subscription request
was not successful and no subscription was
created (or modified) as a result. In this case,
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information MAY be returned that indicates
suggested parameter settings that would have a
high likelihood of succeeding in a subsequent
establish-subscription or modify-subscription
request.";
uses subscription-info;
}
}
}
/*
* RPCs
*/
rpc establish-subscription {
description
"This RPC allows a subscriber to create
(and possibly negotiate) a subscription on its own behalf.
If successful, the subscription
remains in effect for the duration of the subscriber's
association with the publisher, or until the subscription
is terminated by virtue of a delete-subscription request.
In case an error (as indicated by subscription-result)
is returned, the subscription is
not created. In that case, the RPC output
MAY include suggested parameter settings
that would have a high likelihood of succeeding in a
subsequent establish-subscription request.";
input {
uses subscription-info;
}
output {
uses subscription-response;
}
}
rpc create-subscription {
description
"This operation initiates an event notification subscription
that will send asynchronous event notifications to the
initiator of the command until the association terminates.
It is not possible to modify or delete a subscription
that was created using this operation. It is included for
reasons of backward compatibility with RFC 5277
implementations.";
input {
uses subscription-info-basic-non-modifiable{
refine "stream" {
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default "NETCONF";
}
}
uses subscription-info-basic-modifiable;
}
}
rpc modify-subscription {
description
"This RPC allows a subscriber to modify a subscription
that was previously created using establish-subscription.
If successful, the subscription
remains in effect for the duration of the subscriber's
association with the publisher, or until the subscription
is terminated by virtue of a delete-subscription request.
In case an error is returned (as indicated by
subscription-result), the subscription is
not modified and the original subscription parameters
remain in effect. In that case, the rpc error response
MAY include suggested parameter settings
that would have a high likelihood of succeeding in a
subsequent modify-subscription request.";
input {
leaf subscription-id {
type subscription-id;
description
"Identifier to use for this subscription.";
}
uses subscription-info-all-modifiable;
}
output {
uses subscription-response;
}
}
rpc delete-subscription {
description
"This RPC allows a subscriber to delete a subscription that
was previously created using establish-subscription.";
input {
leaf subscription-id {
type subscription-id;
mandatory true;
description
"Identifier of the subscription that is to be deleted.
Only subscriptions that were created using
establish-subscription can be deleted via this RPC.";
}
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}
output {
leaf subscription-result {
type subscription-result;
mandatory true;
description
"Indicates whether subscription is operational,
or if a problem was encountered.";
}
}
}
/*
* NOTIFICATIONS
*/
notification replay-complete {
notif-bis:control-plane-notif;
description
"This notification is sent to indicate that all of the
replay notifications have been sent. It must not be
sent for any other reason.";
leaf subscription-id {
type subscription-id;
mandatory true;
description
"This references the affected subscription.";
}
}
notification notification-complete {
notif-bis:control-plane-notif;
description
"This notification is sent to indicate that a
subscription, which includes a stop time, has
finished passing events.";
leaf subscription-id {
type subscription-id;
mandatory true;
description
"This references the affected subscription.";
}
}
notification subscription-started {
notif-bis:control-plane-notif;
description
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"This notification indicates that a subscription has
started and notifications are beginning to be sent.
This notification shall only be sent to receivers
of a subscription; it does not constitute a general-purpose
notification.";
leaf subscription-id {
type subscription-id;
mandatory true;
description
"This references the affected subscription.";
}
uses subscription-info;
}
notification subscription-suspended {
notif-bis:control-plane-notif;
description
"This notification indicates that a suspension of the
subscription by the publisher has occurred. No further
notifications will be sent until subscription
resumes.
This notification shall only be sent to receivers
of a subscription; it does not constitute a general-purpose
notification.";
leaf subscription-id {
type subscription-id;
mandatory true;
description
"This references the affected subscription.";
}
leaf reason {
type subscription-susp-reason;
description
"Provides a reason for why the subscription was
suspended.";
}
}
notification subscription-resumed {
notif-bis:control-plane-notif;
description
"This notification indicates that a subscription that had
previously been suspended has resumed. Notifications
will once again be sent.";
leaf subscription-id {
type subscription-id;
mandatory true;
description
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"This references the affected subscription.";
}
}
notification subscription-modified {
notif-bis:control-plane-notif;
description
"This notification indicates that a subscription has
been modified. Notifications sent from this point
on will conform to the modified terms of the
subscription.";
leaf subscription-id {
type subscription-id;
mandatory true;
description
"This references the affected subscription.";
}
uses subscription-info;
}
notification subscription-terminated {
notif-bis:control-plane-notif;
description
"This notification indicates that a subscription has been
terminated.";
leaf subscription-id {
type subscription-id;
mandatory true;
description
"This references the affected subscription.";
}
leaf reason {
type subscription-term-reason;
description
"Provides a reason for why the subscription was
terminated.";
}
}
/*
* DATA NODES
*/
container streams {
config false;
description
"This container contains a leaf list of built-in
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streams that are provided by the system.";
leaf-list stream {
type stream;
description
"Identifies the built-in streams that are supported by the
system. Built-in streams are associated with their own
identities, each of which carries a special semantics.
In case configurable custom streams are supported,
as indicated by the custom-stream identity, the
configuration of those custom streams is provided
separately.";
}
}
container filters {
description
"This container contains a list of configurable filters
that can be applied to subscriptions. This facilitates
the reuse of complex filters once defined.";
list filter {
key "filter-id";
description
"A list of configurable filters that can be applied to
subscriptions.";
leaf filter-id {
type filter-id;
description
"An identifier to differentiate between filters.";
}
uses base-filter;
}
}
container subscription-config {
if-feature "configured-subscriptions";
description
"Contains the list of subscriptions that are configured,
as opposed to established via RPC or other means.";
list subscription {
key "subscription-id";
description
"Content of a subscription.";
leaf subscription-id {
type subscription-id;
description
"Identifier to use for this subscription.";
}
uses subscription-info;
uses receiver-info {
if-feature "configured-subscriptions";
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}
uses push-source-info {
if-feature "configured-subscriptions";
}
}
}
container subscriptions {
config false;
description
"Contains the list of currently active subscriptions,
i.e. subscriptions that are currently in effect,
used for subscription management and monitoring purposes.
This includes subscriptions that have been setup via RPC
primitives, e.g. create-subscription, establish-
subscription, and modify-subscription, as well as
subscriptions that have been established via
configuration.";
list subscription {
key "subscription-id";
config false;
description
"Content of a subscription.
Subscriptions can be created using a control channel
or RPC, or be established through configuration.";
leaf subscription-id {
type subscription-id;
description
"Identifier of this subscription.";
}
leaf configured-subscription {
if-feature "configured-subscriptions";
type empty;
description
"The presence of this leaf indicates that the
subscription originated from configuration, not
through a control channel or RPC.";
}
leaf subscription-status {
type subscription-status;
description
"The status of the subscription.";
}
uses subscription-info;
uses receiver-info {
if-feature "configured-subscriptions";
}
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uses push-source-info {
if-feature "configured-subscriptions";
}
}
}
}
<CODE ENDS>
9. Backwards Compatibility
Capabilities are advertised in messages sent by each peer during
session establishment [RFC6241]. Publishers supporting the features
in this document must advertise both capabilities
"urn:ietf:params:netconf:capability:notification:1.0" and
"urn:ietf:params:netconf:capability:notification:1.1".
An example of a hello message by a publisher during session
establishment would be:
<hello xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<capabilities>
<capability>
urn:ietf:params:xml:ns:netconf:base:1.0
</capability>
<capability>
urn:ietf:params:netconf:capability:startup:1.0
</capability>
<capability>
urn:ietf:params:netconf:capability:notification:1.0
</capability>
<capability>
urn:ietf:params:netconf:capability:notification:1.1
</capability>
</capabilities>
<session-id>4</session-id>
</hello>
Figure 9: Hello message
Subscribers that only support [RFC5277] recognize capability
"urn:ietf:params:netconf:capability:notification:1.0" and ignore
capability "urn:ietf:params:netconf:capability:notification:1.1".
This allows them interacting with the publisher as per [RFC5277].
Subscribers that support the features in this document recognize both
capabilities. This allows them interacting with the publisher as per
this document.
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Note that to support backwards compatibility, the yang models in this
document include two types of naming conventions. That used in
[RFC5277], e.g., replayComplete; and that commonly used in yang
models, e.g., subscription-started.
10. Security Considerations
The <notification> elements are never sent before the transport
layer, including capabilities exchange, has been established and the
manager has been securely established.
A secure transport is highly recommended and the publisher must
ensure that the user has sufficient authorization to perform the
function they are requesting against the specific subset of content
involved. When a <get> is received that refers to the content
defined in this memo, clients should only be able to view the content
for which they have sufficient privileges. <create-subscription> and
<establish-subscription> operations can be considered like deferred
<get>, and the content that different users can access may vary.
This different access is reflected in the <notificationt> to which
different users are able to subscribe.
The contents of notifications, as well as the names of event streams,
may contain sensitive information and care should be taken to ensure
that they are viewed only by authorized users. The publisher MUST
NOT include any content in a notification that the user is not
authorized to view.
If a malicious or buggy subscriber sends a number of <create-
subscription> requests, then these subscriptions accumulate and may
use up system resources. In such a situation, subscriptions can be
terminated by terminating the suspect underlying NETCONF sessions
using the <kill-session> operation. If the subscriber uses
<establish-subscription>, the publisher can also suspend or terminate
subscriptions with per-subscription granularity.
A subscription could be configured on another receiver's behalf, with
the goal of flooding that receiver with updates. One or more
publishers could be used to overwhelm a receiver, which doesn't even
support subscriptions. Subscribers that do not want pushed data need
only terminate or refuse any transport sessions from the publisher.
In addition, the NETCONF Authorization Control Model [RFC6536] SHOULD
be used to control and restrict authorization of subscription
configuration. This control models permits specifying per-user
permissions to receive specific event notification types. The
permissions are specified as a set of access control rules.
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Note that streams can define additional authorization requirements.
For instance, in [I-D.ietf-netconf-yang-push], each of the elements
in its data plane notifications must also go through access control.
11. Acknowledgments
For their valuable comments, discussions, and feedback, we wish to
acknowledge Andy Bierman, Yang Geng, Peipei Guo, Susan Hares, Tim
Jenkins, Balazs Lengyel, Kent Watsen, Michael Scharf, and Guangying
Zheng.
12. References
12.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC3339] Klyne, G. and C. Newman, "Date and Time on the Internet:
Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002,
<http://www.rfc-editor.org/info/rfc3339>.
[RFC5277] Chisholm, S. and H. Trevino, "NETCONF Event
Notifications", RFC 5277, DOI 10.17487/RFC5277, July 2008,
<http://www.rfc-editor.org/info/rfc5277>.
[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>.
[RFC6536] Bierman, A. and M. Bjorklund, "Network Configuration
Protocol (NETCONF) Access Control Model", RFC 6536,
DOI 10.17487/RFC6536, March 2012,
<http://www.rfc-editor.org/info/rfc6536>.
[RFC7950] Bjorklund, M., "The YANG 1.1 Data Modeling Language",
RFC 7950, August 2016.
12.2. Informative References
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[I-D.ietf-netconf-netconf-event-notif]
Gonzalez Prieto, Alberto., Clemm, Alexander., Voit, Eric.,
Nilsen-Nygaard, E., Tripathy, A., Chisholm, S., and H.
Trevino, "NETCONF support for event notifications", August
2016, <https://datatracker.ietf.org/doc/draft-ietf-
netconf-netconf-event-notifications/>.
[I-D.ietf-netconf-restconf]
Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
Protocol", I-D draft-ietf-netconf-restconf-17, September
2016.
[I-D.ietf-netconf-restconf-notif]
Voit, Eric., Clemm, Alexander., Tripathy, A., Nilsen-
Nygaard, E., and Alberto. Gonzalez Prieto, "Restconf and
HTTP transport for event notifications", August 2016,
<https://datatracker.ietf.org/doc/draft-ietf-netconf-
restconf-notif/>.
[I-D.ietf-netconf-yang-push]
Clemm, Alexander., Gonzalez Prieto, Alberto., Voit, Eric.,
Tripathy, A., and E. Nilsen-Nygaard, "Subscribing to YANG
datastore push updates", June 2016,
<https://datatracker.ietf.org/doc/draft-ietf-netconf-yang-
push/>.
Appendix A. Issues that are currently being worked and resolved
(To be removed by RFC editor prior to publication)
A.1. Unresolved and yet-to-be addressed issues
EN1 - Definition of basic set of Stream types. What streams are
provided and what do they contain (includes default 5277 stream).
EN2 - Clarify interplay between filter definitions and different
streams. Includes information in subtrees of event payloads.
EN3 - Mechanisms for diagnostics, e.g. deal with dropped updates,
monitoring when they occur, etc
A.2. Agreement in principal
EN4 - How to allow for seamless integration with non-standard
encodings and transports (like GPB/GRPC). Specify requirements
encoding and transport must meet, provide examples.
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EN7 - Detecting loss of a sequential update notification, and
mechanisms to resend. Implications to transports must be thought
through.
EN6 - Stream discovery. Allow to discover additional stream
properties.
EN12 - Test-only option for a subscription is desired. But it still
needs to be defined.
EN14 - Ensure that Configured Subscriptions are fully defined in YANG
model.
A.3. Resolved Issues
EN5 - This draft obsoletes 5277, as opposed to being in parallel with
it
EN8 - No mandatory transport
EN15 - Term for Dynamic and Static Subscriptions (move to
"Configured")
EN9 - Multiple receivers per Configured Subscription is ok.
EN13 - RFC6241 Subtree-filter definition in 5277bis cannot apply to
elements of an event. Must explicitly define how 6241 doesn't apply
filtering within a 5277bis event.
EN10 - Replay support will be provided for selected stream types
(modify vs. delete)
EN11 - Required layering security requirements/considerations will be
added into the YANG model for Configured Subscriptions. It will be
up to the transport to meet these requirements.
Appendix B. Changes between revisions
(To be removed by RFC editor prior to publication)
v00 - v01
o YANG Model changes. New groupings for subscription info to allow
restriction of what is changable via RPC. Removed notifications
for adding and removing receivers of configured subscriptions.
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o Expanded/renamed defintions from event server to publisher, and
client to subscriber as applicable. Updated the definitions to
include and expand on RFC 5277.
o Removal of redundant with other drafts
o Many other clean-ups of wording and terminology
Authors' Addresses
Alexander Clemm
Sympotech
Email: alex@sympotech.com
Alberto Gonzalez Prieto
Cisco Systems
Email: albertgo@cisco.com
Eric Voit
Cisco Systems
Email: evoit@cisco.com
Einar Nilsen-Nygaard
Cisco Systems
Email: einarnn@cisco.com
Ambika Prasad Tripathy
Cisco Systems
Email: ambtripa@cisco.com
Sharon Chisholm
Ciena
Email: schishol@ciena.com
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Hector Trevino
Cisco Systems
Email: htrevino@cisco.com
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