Subscribing to Event Notifications
draft-ietf-netconf-subscribed-notifications-00
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft that was ultimately published as RFC 8639.
|
|
|---|---|---|---|
| Authors | Eric Voit , Alexander Clemm , Alberto Gonzalez Prieto , Einar Nilsen-Nygaard , Ambika Tripathy | ||
| Last updated | 2017-02-23 | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
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draft-ietf-netconf-subscribed-notifications-00
NETCONF E. Voit
Internet-Draft Cisco Systems
Intended status: Standards Track A. Clemm
Expires: August 27, 2017 Huawei
A. Gonzalez Prieto
E. Nilsen-Nygaard
A. Tripathy
Cisco Systems
February 23, 2017
Subscribing to Event Notifications
draft-ietf-netconf-subscribed-notifications-00
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 obsolete 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 August 27, 2017.
Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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(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. Filters . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3. Subscription State Model at the Publisher . . . . . . . . 6
3. Data Model Trees for Event Notifications . . . . . . . . . . 7
4. Dynamic Subscriptions . . . . . . . . . . . . . . . . . . . . 11
4.1. Establishing a Subscription . . . . . . . . . . . . . . . 11
4.2. Modifying a Subscription . . . . . . . . . . . . . . . . 12
4.3. Deleting a Subscription . . . . . . . . . . . . . . . . . 12
4.4. Killing a Subscription . . . . . . . . . . . . . . . . . 13
5. Configured Subscriptions . . . . . . . . . . . . . . . . . . 13
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. Subscription State Notifications . . . . . . . . . . . . . . 18
7.1. subscription-started . . . . . . . . . . . . . . . . . . 18
7.2. subscription-modified . . . . . . . . . . . . . . . . . . 18
7.3. subscription-terminated . . . . . . . . . . . . . . . . . 19
7.4. subscription-suspended . . . . . . . . . . . . . . . . . 19
7.5. subscription-resumed . . . . . . . . . . . . . . . . . . 19
7.6. notification-complete . . . . . . . . . . . . . . . . . . 19
7.7. replay-complete . . . . . . . . . . . . . . . . . . . . . 19
8. Administrative Functions . . . . . . . . . . . . . . . . . . 20
8.1. Subscription Monitoring . . . . . . . . . . . . . . . . . 20
8.2. Capability Advertisement . . . . . . . . . . . . . . . . 20
8.3. Event Stream Discovery . . . . . . . . . . . . . . . . . 21
9. Data Model for Event Notifications . . . . . . . . . . . . . 21
10. Considerations . . . . . . . . . . . . . . . . . . . . . . . 41
10.1. Implementation Considerations . . . . . . . . . . . . . 41
10.2. Security Considerations . . . . . . . . . . . . . . . . 41
11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 42
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 42
12.1. Normative References . . . . . . . . . . . . . . . . . . 42
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12.2. Informative References . . . . . . . . . . . . . . . . . 43
Appendix A. Issues that are currently being worked and resolved 43
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 [RFC8040]
(defined in [I-D.ietf-netconf-restconf-notif]). The capabilities and
operations defined in this document are intended to obsolete 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 [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.
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.
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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 created via RPC subscription state 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.
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.
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1.3. Solution Overview
This document describes mechanisms for subscribing and receiving
event notifications from an event server publisher. This document
has similarities to the capabilities orginally defined in [RFC5277].
This document extends the supported capabilties, and generalizes
functionality to be protocol-agnostic.
Some enhancements over [RFC5277] 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.
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. If the
publisher wants to serve this request, it will accept it, and
then start pushing event notifications. If the publisher does
not wish to serve it as requested, then an error response is
returned. This response may include hints at subscription
parameters which would have been 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
implies configured subscriptions persist across reboots, and
persists even when transport is unavailable.
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.
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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 established
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, there is one standardized event stream, this is the
"NETCONF" event stream. The NETCONF event stream contains all
NETCONF XML event information supported by the publisher, except for
where it has been explicitly indicate that this info must be excluded
from the NETCONF stream.
As events are raised by a system, they may be assigned to one or more
streams. The event is distributed to receivers meeting all three
critera: (1) a subscription includes the identified stream, (2)
susbcription filtering allows the event to traverse, and (3) no
access control rules prohibit the receiver from receiving the event.
2.2. Filters
a publisher implementation SHOULD support the ability to perform
filtering of notification records per [RFC5277]. (TODO: since 5277
is to be obsoleted, we should describe the filter here.)
2.3. 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.
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.-------.
| start |
'-------'
|
establish
|
| .----------modify--------------.
v v '
.-----------. .-----------.
.--------. | |------>suspend------->| |
modify '| active | | suspended |
'--------->| |<----resume----<------| |
'-----------' '-----------'
| |
delete/kill delete/kill
| |
v |
.-------. |
| end |<-----------------------------'
'-------'
Figure 1: Subscription states at publisher
Of interest in this state machine are the following:
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> or <kill-subscription> will end the
subscription.
3. Data Model Trees for Event Notifications
The YANG data model for event notifications is depicted in this
section.
module: ietf-subscribed-notifications
+--ro streams
| +--ro stream* stream
+--rw filters
| +--rw filter* [identifier]
| +--rw identifier filter-id
| +--rw (filter-type)?
| +--:(by-reference)
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| | +--rw filter-ref? filter-ref
| +--:(event-filter)
| +--rw filter?
+--rw subscription-config {configured-subscriptions}?
| +--rw subscription* [identifier]
| +--rw identifier subscription-id
| +--rw stream? stream
| +--rw encoding? encoding
| +--rw stop-time? yang:date-and-time
| +--rw (filter-type)?
| | +--:(by-reference)
| | | +--rw filter-ref? filter-ref
| | +--:(event-filter)
| | +--rw filter?
| +--rw receivers
| | +--rw receiver* [address port]
| | +--rw address inet:host
| | +--rw port inet:port-number
| | +--rw protocol? transport-protocol
| +--rw (notification-origin)?
| +--:(interface-originated)
| | +--rw source-interface? if:interface-ref
| +--:(address-originated)
| +--rw source-vrf? string
| +--rw source-address? inet:ip-address-no-zone
+--ro subscriptions
+--ro subscription* [identifier]
+--ro identifier subscription-id
+--ro configured-subscription?
| empty {configured-subscriptions}?
+--ro stream? stream
+--ro encoding? encoding
+--ro replay-start-time? yang:date-and-time
+--ro stop-time? yang:date-and-time
+--ro (filter-type)?
| +--:(by-reference)
| | +--ro filter-ref? filter-ref
| +--:(event-filter)
| +--ro filter?
+--ro (notification-origin)?
| +--:(interface-originated)
| | +--ro source-interface? if:interface-ref
| +--:(address-originated)
| +--ro source-vrf? string
| +--ro source-address? inet:ip-address-no-zone
+--ro receivers
| +--ro receiver* [address]
| +--ro address inet:host
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| +--ro port inet:port-number
| +--ro protocol? transport-protocol
| +--ro pushed-notifications? yang:counter64
| +--ro excluded-notifications? yang:counter64
+--ro subscription-status? subscription-status
rpcs:
+---x establish-subscription
| +---w input
| | +---w stream? stream
| | +---w encoding? encoding
| | +---w replay-start-time? yang:date-and-time
| | +---w stop-time? yang:date-and-time
| | +---w (filter-type)?
| | +--:(by-reference)
| | | +---w filter-ref? filter-ref
| | +--:(event-filter)
| | +---w filter?
| +--ro output
| +--ro subscription-result subscription-result
| +--ro (result)?
| +--:(no-success)
| | +--ro filter-failure? string
| | +--ro replay-start-time-hint? yang:date-and-time
| +--:(success)
| +--ro identifier subscription-id
+---x modify-subscription
| +---w input
| | +---w identifier? subscription-id
| | +---w stop-time? yang:date-and-time
| | +---w (filter-type)?
| | +--:(by-reference)
| | | +---w filter-ref? filter-ref
| | +--:(event-filter)
| | +---w filter?
| +--ro output
| +--ro subscription-result subscription-result
| +--ro (result)?
| +--:(no-success)
| +--ro filter-failure? string
+---x delete-subscription
| +---w input
| | +---w identifier subscription-id
| +--ro output
| +--ro subscription-result subscription-result
+---x kill-subscription
+---w input
| +---w identifier subscription-id
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+--ro output
+--ro subscription-result subscription-result
notifications:
+---n replay-complete
| +--ro identifier subscription-id
+---n notification-complete
| +--ro identifier subscription-id
+---n subscription-started
| +--ro identifier subscription-id
| +--ro stream? stream
| +--ro encoding? encoding
| +--ro replay-start-time? yang:date-and-time
| +--ro stop-time? yang:date-and-time
| +--ro (filter-type)?
| +--:(by-reference)
| | +--ro filter-ref? filter-ref
| +--:(event-filter)
| +--ro filter?
+---n subscription-resumed
| +--ro identifier subscription-id
+---n subscription-modified
| +--ro identifier subscription-id
| +--ro stream? stream
| +--ro encoding? encoding
| +--ro replay-start-time? yang:date-and-time
| +--ro stop-time? yang:date-and-time
| +--ro (filter-type)?
| +--:(by-reference)
| | +--ro filter-ref? filter-ref
| +--:(event-filter)
| +--ro filter?
+---n subscription-terminated
| +--ro identifier subscription-id
| +--ro error-id subscription-errors
| +--ro filter-failure? string
+---n subscription-suspended
+--ro identifier subscription-id
+--ro error-id subscription-errors
+--ro filter-failure? string
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
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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
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
The <establish-subscription> operation allows a subscriber to request
the creation of a subscription via RPC.
The input parameters of the operation are:
o A filter which identifies what is being subscribed to, as well as
what should be included (or not) in the pushed results.
o An optional stream which may identify or reduce the domain of
events against which the subscription is applied.
o The desired encoding for the returned events. By default, updates
are encoded using XML. Other encodings may be supported, such as
JSON.
o An optional stop time for the subscription.
o An optional start time which indicates that this subscription is
requesting a replay push of events previously generated.
If the publisher cannot satisfy the <establish-subscription> request,
it sends a negative <subscription-result> element. If the subscriber
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has no authorization to establish the subscription, the
<subscription-result> indicates an authorization error. Optionally,
the <subscription-result> may include one or more hints on
alternative input parameters and value which would have resulted in
an accepted subscription.
Subscription requests must fail if a filter with invalid syntax is
provided or if the name of a non-existent stream is provided.
4.1.1. Replay Subscription
The presence of a start time indicates that this is a replay
subscription. The start time must be earlier than the current time.
If the start time points earlier than the maintained history of
Publisher's event buffer, then the subscription must be rejected. In
this case the error response to the <establish-subscription> request
should include a start time supportable by the Publisher.
4.2. Modifying a Subscription
The <modify-subscription> operation permits changing the terms of an
existing dynamic subscription previously established on that
transport session. Subscriptions created by configuration operations
cannot be modified via this RPC. Dynamic subscriptions can be
modified one or multiple times. If the publisher accepts the
requested modifications, 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 a such a rejected modification may include one or more
hints on alternative input parameters and value which would have
resulted in a successfully modified subscription.
Dynamic subscriptions established via RPC can only be modified (or
deleted) via RPC using the same transport session used to establish
that subscription.
4.3. Deleting a Subscription
The <delete-subscription> operation permits canceling an existing
subscription previously established on that transport session. 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 established via RPC can only be deleted via RPC using
the same transport session used for subscription establishment.
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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.
4.4. Killing a Subscription
The <kill-subscription> operation permits an operator to end any
dynamic subscription. The publisher must accept the request for any
dynamic subscription, and immediately stop sending events.
Configured subscriptions cannot be kill using this RPC. Instead,
configured subscriptions are deleted as part of regular configuration
operations. Publishers MUST reject any RPC attempt to kill a
configured subscription.
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.
Configured subscriptions can be modified by any configuration client
with write permissions for the configuration of the subscription.
Subscriptions can be modified or terminated via the configuration
interface 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. If not included, push updates will go off a default
interface for the device.
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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 <edit-config> RPC operations
for subscription establishment. Firstly, <edit-config> operations
install a subscription without question, while RPCs may support
negotiation and rejection of requests. Secondly, while RPCs mandate
that the subscriber establishing the subscription is the only
receiver of the notifications, <edit-config> operations permit
specifying receivers independent of any tracked subscriber.
Immediately after a subscription is successfully established, the
publisher sends to any newly active receivers a control-plane
notification stating the subscription has been established
(subscription-started).
Because there is no explicit association with an existing transport
session, <edit-config> operations require additional parameters to
indicate the receivers of the notifications and possibly the source
of the notifications such as a specific egress interface.
For example at subscription establishment if NETCONF transport is
being used, a client may send:
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<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:2.0">
<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: Configured subscription creation via NETCONF
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: Successful NETCONF configured subscription response
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: A NETCONF response for a failed configured subscription
creation
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 of that subscription a control-plane
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notification stating the subscription has been terminated
(subscription-terminated).
6. Event (Data Plane) Notifications
Once a subscription has been set up, the publisher streams
(asynchronously) notifications per the terms of the subscription. We
refer to these as event notifications. For dynamic subscriptions set
up via RPC operations, event notifications are sent over the session
used to establish the subscription. For configured subscriptions,
event notifications are sent over the specified connections.
An event notification is sent to a receiver when something of
interest occurs which is able to traverse all specified filtering and
access control criteria. The event notification must include:
o a subscription-id element of type uint32 which corresponds to
responsible subscription in the Publisher.
o an eventTime element which provides the time the event was
generated by the event source. This event time parameter is of
type dateTime and compliant to [RFC3339]. Implementations must
support time zones.
o the event notification content tagged and provided by a source in
the publisher.
The following is an example of a compliant event notification. This
example extending the example within [RFC7950] section 7.16.3 to
include the mandatory information described above:
<notification
xmlns=" urn:ietf:params:xml:ns:netconf:notification:1.0">
<eventTime>2007-09-01T10:00:00Z</eventTime>
<subscription-id>500</subscription-id>
<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 6: Data plane notification
While this extended [RFC7950] section 7.16 notification provides a
valid method of encapsulating subscribed notifications, other
transport encapsulation methods are also viable. Improvements may be
achieved in some implementations in the following ways:
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o transport efficiency may be gained by allowing the encapsulation
and bundled push of multiple events within the same event
notification.
o identifiers to designate the current and previous event
notification can be used to discover duplicated and dropped
notifications
o additional header types can be used to pass relevant metadata.
o a signature or hash can be included to verify the efficacy of the
Publisher
This is being explored in NETMOD Notifications 2.0
[I-D.voit-notifications2].
7. Subscription State Notifications
In addition to data plane notifications, a publisher may send
subscription state notifications to indicate to receivers that an
event related to the subscription management has occurred.
Subscription state notifications are unlike other notifications in
that they are not general-purpose notifications. They cannot be
filtered out, and they are delivered only to directly impacted
receiver(s) of a subscription. The definition of subscription state
notifications is distinct from other notifications by making use of a
YANG extension tagging them as subscription state notification.
Subscription state 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.
7.1. 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.
7.2. 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
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and push-source information. Note that for RPC-based subscriptions,
no such notifications are sent.
7.3. 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 a
delete-subscription RPC. In such cases, no subscription-terminated
notifications are sent. However if a kill-subscription RPC is sent,
or some other event results in the end of a susbcription, then there
must be a notification that the subscription has been ended.
7.4. 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).
7.5. 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).
7.6. notification-complete
This notification is sent to indicate that a subscription, which
includes a stop time, has finished passing events.
7.7. replay-complete
This notification indicates that all of the notifications prior to
the current time have been sent. This includes new notifications
generated since the start of the subscription. This notification
must not be sent for any other reason.
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If subscription contains no stop time, or has a stop time which has
not been reached, then after the replay-complete notification has
been sent notifications will be sent in sequence as they arise
naturally within the system.
8. Administrative Functions
8.1. Subscription Monitoring
Container "subscriptions" in the YANG module below contains the state
of all subscriptions that are currently active. This includes
subscriptions that were established (and have not yet been deleted)
using RPCs, as well as subscriptions that have been configured as
part of configuration. Using the <get> operation with NETCONF, or
subscribing to this information via [I-D.ietf-netconf-yang-push]
allows the status of subscriptions to be monitored.
Each subscription is represented as a list element. The associated
information includes an identifier for the subscription, a
subscription status, as well as the various subscription parameters
that are in effect. The subscription status indicates whether the
subscription is currently active and healthy, or if it is degraded in
some form. Leaf "configured-subscription" indicates whether the
subscription came into being via configuration or via RPC.
Subscriptions that were established by RPC are removed from the list
once they expire (reaching stop-time) or when they are terminated.
Subscriptions that were established by configuration need to be
deleted from the configuration by a configuration editing operation
even if the stop time has been passed.
8.2. Capability Advertisement
Capabilities are advertised in messages sent by each peer during
session establishment [RFC6241]. Publishers supporting the features
in this document must advertise the capability
"urn:ietf:params:netconf:capability:notification:2.0".
The mechanism defined in this document is identified by
"urn:ietf:params:netconf:capability:notification:2.0". If a
subscriber only supports [RFC5277] and not this specification, then
they will recognize the capability
"urn:ietf:params:netconf:capability:notification:1.0" and ignore the
capability defined in this document.
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8.3. 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.
9. Data Model for Event Notifications
<CODE BEGINS> file "ietf-subscribed-notifications.yang"
module ietf-subscribed-notifications {
namespace
"urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications";
prefix sn;
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>
Editor: Alexander Clemm
<mailto:ludwig@clemm.org>
Editor: Eric Voit
<mailto:evoit@cisco.com>
Editor: Alberto Gonzalez Prieto
<mailto:albertgo@cisco.com>
Editor: Einar Nilsen-Nygaard
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<mailto:einarnn@cisco.com>
Editor: Ambika Prasad Tripathy
<mailto:ambtripa@cisco.com>";
description
"This module contains conceptual YANG specifications for NETCONF
Event Notifications.";
revision 2017-02-23 {
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-subscribed-notifications-00";
}
/*
* FEATURES
*/
feature json {
description
"This feature indicates that JSON encoding of notifications
is supported.";
}
feature configured-subscriptions {
description
"This feature indicates that management plane configuration
of subscription is supported.";
}
/*
* EXTENSIONS
*/
extension subscription-state-notif {
description
"This statement applies only to notifications. It indicates that
the notification is a subscription state notification (aka OAM
notification). Therefore it does not participate in a regular
event stream and does not need to be specifically subscribed
in order to receive notifications.";
}
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/*
* 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. This contains the same set of events in a default
RFC-5277 NETCONF stream";
}
/* 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.";
}
identity error {
base subscription-result;
description
"RPC was not successful.
Base identity for error return codes.";
}
/* Identities for subscription stream status */
identity subscription-stream-status {
description
"Base identity for the status of subscriptions and datastreams.";
}
identity active {
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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 internal-error {
base error;
description
"Error within publisher prohibits operation.";
}
identity suspension-timeout {
base error;
description
"Termination of previously suspended subscription. The publisher
has eliminated the subscription as it exceeded a time limit for
suspension.";
}
identity stream-unavailable {
base error;
description
"Stream name does not exist or is not available to the receiver.";
}
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identity encoding-unavailable {
base error;
description
"Encoding not supported";
}
identity replay-unsupported {
base error;
description
"Replay cannot be performed for this subscription. The publisher
does not provide the requested historic information via replay.";
}
identity history-unavailable {
base error;
description
"Replay request too far into the past. The publisher does store
historic information for all parts of requested subscription, but
not back to the requested timestamp.";
}
identity filter-unavailable {
base error;
description
"Referenced filter does not exist";
}
identity filter-unsupported {
base error;
description
"Cannot parse syntax within the filter. Failure can be from a
syntax error, or a syntax too complex to be processed by the
platform. The supplemental info should include the invalid part
of the filter.";
}
identity namespace-unavailable {
base error;
description
"Referenced namespace doesn't exist or is unavailable
to the receiver.";
}
identity no-such-subscription {
base error;
description
"Referenced subscription doesn't exist. This may be as a result of
a non-existent subscription ID, an ID which belongs to another
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subscriber, or an ID for acceptable subscription which has been
statically configured.";
}
/* 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
*/
typedef subscription-id {
type uint32;
description
"A type for subscription identifiers.";
}
typedef filter-id {
type uint32;
description
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"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-errors {
type identityref {
base error;
}
description
"The reason for the failure of an RPC request or the sending of a
subscription suspension or termination notification";
}
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;
}
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 notification-origin {
type enumeration {
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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 "/sn:filters/sn:filter/sn:identifier";
}
description
"This type is used to reference a filter.";
}
/*
* GROUPINGS
*/
grouping base-filter {
description
"This grouping defines the base for filters for notification
events.";
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 by-reference {
description
"Incorporate a filter that has been configured separately.";
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leaf filter-ref {
type filter-ref;
description
"References an existing filter which is to be applied to
the potential events of the subscription.";
}
}
case event-filter {
anyxml filter {
description
"Filter which excludes whole event-notifications. 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-policy-non-configurable {
description
"This grouping describes the information which can only be set
in a dynamic subscription request via RPC.";
leaf replay-start-time {
type yang:date-and-time;
description
"Used to trigger the replay feature and indicate that the
replay should start at the time specified. If replay-start-time
is not present, this is not a replay subscription and event
pushes should start immediately. It is never valid to
specify start times that are later than or equal to the
current time.";
}
}
grouping subscription-policy-non-modifiable {
description
"This grouping describes the information in a subscription which
should not change during the life of the subscription.";
leaf stream {
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type stream;
description
"Indicates which stream of events is of interest.
If not present, events in the default NETCONF stream
will be sent.";
}
leaf encoding {
type encoding;
default "encode-xml";
description
"The type of encoding for the subscribed data.
Default is XML";
}
}
grouping subscription-policy-modifiable {
description
"This grouping describes all objects which may be changed
in a subscription via an RPC.";
leaf stop-time {
type yang:date-and-time;
description
"Identifies a time after which notification events should not
be sent. If stop-time is not present, the notifications will
continue until the subscription is terminated. If
replay-start-time exists, stop-time must for a subsequent time.
If replay-start-time doesn't exist, stop-time must for a future
time.";
}
uses base-filter;
}
grouping subscription-policy {
description
"This grouping describes information concerning a subscription.";
uses subscription-policy-non-modifiable;
uses subscription-policy-non-configurable;
uses subscription-policy-modifiable;
}
grouping notification-origin-info {
description
"Defines the sender source from which notifications for a
configured subscription are sent.";
choice notification-origin {
description
"Identifies the egress interface on the Publisher from which
notifications will or are being sent.";
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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.";
}
}
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 string;
description
"Network instance name for the VRF. This could also have
been a leafref to draft-ietf-rtgwg-ni-model, but that model
in not complete, and may not be implemented on a box.";
}
leaf source-address {
type inet:ip-address-no-zone;
description
"The source address for the notifications.";
}
}
}
}
grouping receiver-info {
description
"Defines where and how to get notifications for a configured
subscriptions to one or more targeted recipient. This includes
specifying the destination addressing as well as a transport
protocol acceptable to the reciever.";
container receivers {
description
"Set of receivers in a subscription.";
list receiver {
key "address port";
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;
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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;
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. Each
protocol may use the address and port information
differently as applicable.";
}
}
}
}
grouping error-identifier {
description
"A code passed back within an RPC response to describe why the RFC
has failed, or within a state change notification to describe why
the change has occurred.";
leaf error-id {
type subscription-errors;
mandatory true;
description
"Identifies the subscription error condition.";
}
}
grouping error-hints {
description
"Objects passed back within an RPC response to descibe why the RFC
has failed, or within a state change notification to describe why
the change has occured.";
leaf filter-failure {
type string;
description
"Information describing where and/or why a provided filter was
unsupportable for a subscription.";
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}
}
grouping subscription-response-with-hints {
description
"Defines the output for the establish-subscription and
modify-subscription RPCs.";
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 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, 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 error-hints;
}
}
}
/*
* 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. 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 {
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uses subscription-policy;
}
output {
uses subscription-response-with-hints {
augment "result" {
description
"Allows information to be passed back as part of a
successful subscription establishment.";
case success {
description
"This case is used when the subscription request was
successful.";
leaf identifier {
type subscription-id;
mandatory true;
description
"Identifier used for this subscription.";
}
}
}
augment "result/no-success" {
description
"Contains establish RPC specific objects which can be
returned as hints for future attempts.";
leaf replay-start-time-hint {
type yang:date-and-time;
description
"If a replay has been requested, but the requested replay
time cannot be honored, this may provide a hint at an
alternate time which may be supportable.";
}
}
}
}
}
rpc modify-subscription {
description
"This RPC allows a subscriber to modify a subscription that was
previously created using establish-subscription. If successful,
the changed subscription remains in effect for the duration of
the subscriber's association with the publisher, or until the
subscription is again modified or terminated. 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 hints that would have
a high likelihood of succeeding in a subsequent
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modify-subscription request.";
input {
leaf identifier {
type subscription-id;
description
"Identifier to use for this subscription.";
}
uses subscription-policy-modifiable;
}
output {
uses subscription-response-with-hints;
}
}
rpc delete-subscription {
description
"This RPC allows a subscriber to delete a subscription that
was previously created from by that same subscriber using the
establish-subscription RPC.";
input {
leaf identifier {
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.";
}
}
output {
leaf subscription-result {
type subscription-result;
mandatory true;
description
"Indicates whether subscription is operational, or if a
problem was encountered.";
}
}
}
rpc kill-subscription {
description
"This RPC allows an operator to delete a dynamic subscription
without restrictions on the originating subscriber or underlying
transport session.";
input {
leaf identifier {
type subscription-id;
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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.";
}
}
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 {
sn:subscription-state-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 identifier {
type subscription-id;
mandatory true;
description
"This references the affected subscription.";
}
}
notification notification-complete {
sn:subscription-state-notif;
description
"This notification is sent to indicate that a subscription, has
finished passing events.";
leaf identifier {
type subscription-id;
mandatory true;
description
"This references the affected subscription.";
}
}
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notification subscription-started {
sn:subscription-state-notif;
description
"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 identifier {
type subscription-id;
mandatory true;
description
"This references the affected subscription.";
}
uses subscription-policy;
}
notification subscription-resumed {
sn:subscription-state-notif;
description
"This notification indicates that a subscription that had
previously been suspended has resumed. Notifications will once
again be sent.";
leaf identifier {
type subscription-id;
mandatory true;
description
"This references the affected subscription.";
}
}
notification subscription-modified {
sn:subscription-state-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 identifier {
type subscription-id;
mandatory true;
description
"This references the affected subscription.";
}
uses subscription-policy;
}
notification subscription-terminated {
sn:subscription-state-notif;
description
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"This notification indicates that a subscription has been
terminated.";
leaf identifier {
type subscription-id;
mandatory true;
description
"This references the affected subscription.";
}
uses error-identifier;
uses error-hints;
}
notification subscription-suspended {
sn:subscription-state-notif;
description
"This notification indicates that a suspension of the
subscription by the publisher has occurred. No further
notifications will be sent until the subscription resumes.
This notification shall only be sent to receivers of a
subscription; it does not constitute a general-purpose
notification.";
leaf identifier {
type subscription-id;
mandatory true;
description
"This references the affected subscription.";
}
uses error-identifier;
uses error-hints;
}
/*
* DATA NODES
*/
container streams {
config false;
description
"This container contains a leaf list of built-in
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
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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 "identifier";
description
"A list of configurable filters that can be applied to
subscriptions.";
leaf identifier {
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 "identifier";
description
"Content of a subscription.";
leaf identifier {
type subscription-id;
description
"Identifier to use for this subscription.";
}
uses subscription-policy-non-modifiable;
uses subscription-policy-modifiable;
uses receiver-info {
if-feature "configured-subscriptions";
}
uses notification-origin-info {
if-feature "configured-subscriptions";
}
}
}
container subscriptions {
config false;
description
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"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 as well as subscriptions
that have been established via configuration.";
list subscription {
key "identifier";
config false;
description
"Content of a subscription.
Subscriptions can be created using a control channel or RPC, or
be established through configuration.";
leaf identifier {
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.";
}
uses subscription-policy;
uses notification-origin-info {
if-feature "configured-subscriptions";
}
uses receiver-info {
augment receivers/receiver {
description
"include operational data on configured receivers.";
leaf pushed-notifications {
type yang:counter64;
description
"Operational data which provides the number of update
notifications pushed to a receiver.";
}
leaf excluded-notifications {
type yang:counter64;
description
"Operational data which provides the number of non-
datastore update notifications explicitly removed via
filtering so that they are not sent to a receiver.";
}
}
}
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leaf subscription-status {
type subscription-status;
description
"The status of the subscription.";
}
}
}
}
<CODE ENDS>
10. Considerations
10.1. Implementation Considerations
For a deployment including both configured and dynamic subscriptions,
split subscription identifiers into static and dynamic halves. That
way there should not be collisions if the configured subscriptions
attempt to set a subscription-id which might have already been
dynamically allocated.
The <notification> elements are never sent before the transport
layer, including capabilities exchange, has been established.
10.2. Security Considerations
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, recievers should only be able to view the
content for which they have sufficient privileges. <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 <establish-
subscription> requests, then these subscriptions accumulate and may
use up system resources. In such a situation, subscriptions can be
terminated by terminating the transport session. The publisher can
also suspend or terminate subscriptions with per-subscription
granularity.
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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.
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.
It is recommended that the NACM "very-secure" tag is placed on the
<kill-subscription> RPC so that only administrators can access.
11. Acknowledgments
For their valuable comments, discussions, and feedback, we wish to
acknowledge Andy Bierman, Tim Jenkins, Balazs Lengyel, Shaon
Chisholm, Hector Trevino, Susan Hares, 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>.
[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>.
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[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
RFC 7950, DOI 10.17487/RFC7950, August 2016,
<http://www.rfc-editor.org/info/rfc7950>.
12.2. Informative References
[I-D.ietf-netconf-netconf-event-notif]
Clemm, Alexander., Voit, Eric., Gonzalez Prieto, Alberto.,
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-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., Voit, Eric., Gonzalez Prieto, Alberto.,
Tripathy, A., and E. Nilsen-Nygaard, "Subscribing to YANG
datastore push updates", February 2017,
<https://datatracker.ietf.org/doc/draft-ietf-netconf-yang-
push/>.
[I-D.voit-notifications2]
Voit, Eric., Clemm, Alexander., Bierman, A., and T.
Jenkins, "YANG Notification Headers and Bundles", February
2017, <https://datatracker.ietf.org/draft-voit-netmod-
yang-notifications2/>.
[RFC5277] Chisholm, S. and H. Trevino, "NETCONF Event
Notifications", RFC 5277, DOI 10.17487/RFC5277, July 2008,
<http://www.rfc-editor.org/info/rfc5277>.
[RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
<http://www.rfc-editor.org/info/rfc8040>.
Appendix A. Issues that are currently being worked and resolved
(To be removed by RFC editor prior to publication)
Issue #9: validate that Subscription ID will only be relevant locally
to a single receiver
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Issue #6: Data plane notifications and layered headers
How to allow for seamless integration with non-standard encodings and
transports (like GPB/GRPC). Specify requirements encoding and
transport must meet, provide examples.
Appendix B. Changes between revisions
(To be removed by RFC editor prior to publication)
v01 5277bis - v00 subscribed notifications
o Kill subscription RPC added.
o Renamed from 5277bis to Subscribed Notifications.
o Changed the notification capabilities version from 1.1 to 2.0 as
this is not RFC-5277 compatible.
o Extracted create-subscription and other elements of RFC5277.
o Error conditions added, and made specific in return codes.
o Simplified yang model structure for removal of 'basic' grouping.
o Added a grouping for items which cannot be statically configured.
o Streams extracted if favor of more information in the filters
section.
o Operational counters per receiver.
o Subscription-id and filter-id renamed to identifier
o Section for replay added. Replay-start and stop-time updated.
Replay now cannot be configured.
o Control plane notification renamed to subscription state
notification
o Souce address: Source-vrf changed to string, default address
option added
o In yang model: 'info' changed to 'policy'
o Scattered text clarifications
v00 - v01 of 5277bis
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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.
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
Eric Voit
Cisco Systems
Email: evoit@cisco.com
Alexander Clemm
Huawei
Email: ludwig@clemm.org
Alberto Gonzalez Prieto
Cisco Systems
Email: albertgo@cisco.com
Einar Nilsen-Nygaard
Cisco Systems
Email: einarnn@cisco.com
Ambika Prasad Tripathy
Cisco Systems
Email: ambtripa@cisco.com
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