Internet DRAFT - draft-gonzalez-netconf-5277bis
draft-gonzalez-netconf-5277bis
NETCONF A. Gonzalez Prieto
Internet-Draft A. Clemm
Intended status: Standards Track E. Voit
Expires: September 22, 2016 E. Nilsen-Nygaard
A. Tripathy
Cisco Systems
March 21, 2016
NETCONF Event Notifications
draft-gonzalez-netconf-5277bis-01
Abstract
This document defines capabilities and operations for providing
asynchronous message notification delivery on top of the Network
Configuration protocol (NETCONF). This notification delivery is an
optional capability built on top of the base NETCONF definition.
This document is eventually 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 September 22, 2016.
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
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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 . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
1.3. Solution Overview . . . . . . . . . . . . . . . . . . . . 5
2. Solution . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1. Event Streams . . . . . . . . . . . . . . . . . . . . . . 7
2.2. Event Stream Discovery . . . . . . . . . . . . . . . . . 7
2.3. Default Event Stream . . . . . . . . . . . . . . . . . . 9
2.4. Data Model Trees for Event Notifications . . . . . . . . 9
2.5. Creating a Subscription . . . . . . . . . . . . . . . . . 13
2.6. Establishing a Subscription . . . . . . . . . . . . . . . 16
2.7. Modifying a Subscription . . . . . . . . . . . . . . . . 19
2.8. Deleting a Subscription . . . . . . . . . . . . . . . . . 24
2.9. Static Subscriptions . . . . . . . . . . . . . . . . . . 26
2.10. Event (Data Plane) Notifications . . . . . . . . . . . . 30
2.11. Control Plane Notifications . . . . . . . . . . . . . . . 32
2.12. Subscription Management . . . . . . . . . . . . . . . . . 33
3. Data Models for Event Notifications . . . . . . . . . . . . . 34
3.1. Data Model for RFC5277 (netmod namespace) . . . . . . . . 34
3.2. Data Model for RFC5277 (netconf namespace) . . . . . . . 38
3.3. Data Model for RFC5277-bis Extensions . . . . . . . . . . 41
4. Backwards Compatibility . . . . . . . . . . . . . . . . . . . 58
5. Security Considerations . . . . . . . . . . . . . . . . . . . 59
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 60
6.1. Normative References . . . . . . . . . . . . . . . . . . 60
6.2. Informative References . . . . . . . . . . . . . . . . . 61
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 61
1. Introduction
[RFC6241] can be conceptually partitioned into four layers:
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Layer Example
+-------------+ +-------------------------------------------+
| Content | | Configuration data |
+-------------+ +-------------------------------------------+
| |
+-------------+ +-------------------------------------------+
| Operations | |<get-config>, <edit-config>, <notification>|
+-------------+ +-------------------------------------------+
| | |
+-------------+ +-----------------------------+ |
| RPC | | <rpc>, <rpc-reply> | |
+-------------+ +-----------------------------+ |
| | |
+-------------+ +-------------------------------------------+
| Transport | | BEEP, SSH, SSL, console |
| Protocol | | |
+-------------+ +-------------------------------------------+
This document defines mechanisms that provide an asynchronous message
notification delivery service for the NETCONF protocol [RFC6241].
This is an optional capability built on top of the base NETCONF
definition. This document also defines the capabilities and
operations necessary to establish, monitor, and support subscriptions
into this notification delivery service.
1.1. Motivation
The motivation for this work is to enable the sending of asynchronous
notification messages that are consistent with the data model
(content) and security model used within a NETCONF implementation.
[RFC5277] defines a notification mechanism for NETCONF. However,
there are various limitations:
o Each subscription requires a separate NETCONF connection, which is
wasteful.
o The only mechanism to terminate a subscription is terminating the
underlying NETCONF connection.
o No ability to modify subscriptions once they have been created.
o No ability to notify the receiver of a subscription if the server
is dropping events.
o No mechanism to monitor subscriptions.
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o No alternative mechanism to create subscriptions via RPCs. Thus
the lifetime of the subscription is limited by that of the
underlaying NETCONF session.
o Predates YANG and defines RPCs, notifications, and data nodes
outside of the YANG framework.
The scope of the work aims at meeting the following operational
needs:
o Ability to dynamically or statically subscribe to event
notifications available on a NETCONF agent.
o Ability to negotiate acceptable dynamic subscription parameters.
o Ability to support multiple subscriptions over a single NETCONF
session.
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 NETCONF transport protocol. (In other words,
the encoded notification fully describes itself.)
o Mechanism to communicate the notifications.
o Ability to replay locally logged notifications.
o Backwards compatible with RFC 5277 implementations.
o Define in YANG, the RPCs, notifications, and data nodes in RFC
5277.
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].
Event: Something that happens 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 message sent by a server to a receiver
indicating that an event (of interest to the subscriber) has
occurred. Events can trigger notifications if an interested party
has subscribed to the stream(s) it belongs to.
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Stream (also referred to as "event stream"): A continuous flow of
event, status, state, or other information.
Subscriber: An entity able to request and negotiate a contract for
the receipt of event notifications from a NETCONF server.
Receiver: A target to which a NETCONF server pushes event
notifications. In many deployments, the receiver and subscriber will
be the same entity.
Subscription: A contract between a subscriber and a NETCONF server,
stipulating which information the receiver wishes to have pushed from
the server without the need for further solicitation.
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.
Dynamic subscription: A subscription agreed between subscriber and
NETCONF server via create, establish, modify, and delete RPC control
plane signaling messages.
Static subscription: A subscription installed via a configuration
interface.
Operation: In this document, this term refers to NETCONF protocol
operations [RFC6241] defined in support of NETCONF notifications.
NACM: NETCONF Access Control Model.
RPC: Remote Procedure Call.
1.3. Solution Overview
This document describes mechanisms for subscribing and receiving
event notifications from a NETCONF server. This document enhances
the capabilities of RFC 5277 while maintaining backwards capability
with existing implementations. It is intended that a final version
of this document might obsolete RFC 5277.
The enhancements over [RFC5277] include the ability to terminate
subscriptions without terminating the client session, to modify
existing subscriptions, and to have multiple subscriptions on a
NETCONF session.
These enhancements do not affect [RFC5277] clients that do not
support these particular subscription requirements.
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The solution supports subscribing to event notifications using two
mechanisms.
1. Dynamic subscriptions, where a NETCONF client initiates a
subscription negotiation with a NETCONF server. Here a client
initiates a negotiation by issuing a subscription request. If
the agent wants to serve this request, it will accept it, and
then start pushing event notifications as negotiated. If the
agent does not wish to serve it as requested, it may respond with
subscription parameters, which it would have accepted.
2. Static subscriptions, which is an optional mechanism that enables
managing subscriptions via a configuration interface so that a
NETCONF agent sends event notifications to given receiver(s).
Some key characteristics of static 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 static subscription is driven by configuration
being present on the running configuration. This implies static
subscriptions persist across reboots, and persists even when
transport is unavailable. This also means static subscriptions do
not support negotiation.
o Subscriptions can be modified or terminated at any point of their
lifetime. Static subscriptions can be modified by any
configuration client with write rights on the configuration of the
subscription.
o A NETCONF agent can support multiple dynamic subscriptions
simultaneously in the context of a single NETCONF session. (This
requires supporting interleaving.) The termination of any of
those subscriptions does not imply the termination of NETCONF
transport session.
Note that there is no mixing-and-matching of RPC and configuration
operations. Specifically, a static subscription cannot be modified
or deleted using RPC. Similarly, a subscription created via RPC
cannot be modified through configuration operations.
The NETCONF agent may decide to terminate a dynamic subscription at
any time. Similarly the NETCONF agent may decide to temporarily
suspend the sending of event notifications for either static or
dynamic subscriptions. Such termination or suspension may be driven
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by the agent running out of resources to serve the subscription, or
by internal errors on the server.
2. Solution
2.1. Event Streams
An event stream is a set of events available for subscription from a
NETCONF server. 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.
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.
2.2. Event Stream Discovery
A NETCONF client can retrieve the list of available event streams
from a NETCONF server using the <get> operation. The reply contains
the elements defined in the YANG model under the container /netconf/
streams, which includes the name and description of the streams.
The following example shows retrieving the list of available event
stream list using the <get> operation.
<rpc message-id="101"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<get>
<filter type="subtree">
<netconf
xmlns="urn:ietf:params:xml:ns:netmod:notification">
<streams/>
</netconf>
</filter>
</get>
</rpc>
Figure 1: Get streams
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The NETCONF server returns a list of event streams available for
subscription. In this example, the list contains the NETCONF, SNMP,
and syslog-critical streams.
<rpc-reply message-id="101"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<data>
<netconf
xmlns="urn:ietf:params:xml:ns:netmod:notification">
<streams>
<stream>
<name>
NETCONF
</name>
<description>
default NETCONF event stream
</description>
<replaySupport>
true
</replaySupport>
<replayLogCreationTime>
2016-02-05T00:00:00Z
</replayLogCreationTime>
</stream>
<stream>
<name>
SNMP
</name>
<description>
SNMP notifications
</description>
<replaySupport>
false
</replaySupport>
</stream>
<stream>
<name>
syslog-critical
</name>
<description>
Critical and higher severity
</description>
<replaySupport>
true
</replaySupport>
<replayLogCreationTime>
2007-07-01T00:00:00Z
</replayLogCreationTime>
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</stream>
</streams>
</netconf>
</data>
</rpc-reply>
Figure 2: Get streams response
2.3. Default Event Stream
A NETCONF server implementation supporting the notification
capability MUST support the "NETCONF" notification event stream.
This stream contains all NETCONF XML event notifications supported by
the NETCONF server, except for those belonging only to streams that
explicitly indicate that they must be excluded from the NETCONF
stream. The exact string "NETCONF" is used during the advertisement
of stream support during the <get> operation on <streams> and during
the <create-subscription> and <establish-subscription> operations.
2.4. Data Model Trees for Event Notifications
The YANG data models for event notifications are depicted in the
following sections.
2.4.1. Data Model Tree for RFC5277 (netconf namespace)
module: ietf-5277-netconf
rpcs:
+---x create-subscription
+--ro input
+--ro stream? string
+--ro (filter-type)?
| +--:(rfc5277)
| +--ro filter
+--ro startTime? yang:date-and-time
+--ro stopTime? yang:date-and-time
2.4.2. Data Model Tree for RFC5277 (netmod namespace)
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module: ietf-5277-netmod
+--rw netconf
+--rw streams
+--rw stream* [name]
+--rw name string
+--rw description string
+--rw replaySupport boolean
+--rw replayLogCreationTime yang:date-and-time
+--rw replayLogAgedTime yang:date-and-time
notifications:
+---n replayComplete
+---n notificationComplete
2.4.3. Data Model for RFC5277-bis Extensions
module: ietf-event-notifications
+--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? string
| +--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 encoding? encoding
| +--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
+--ro subscriptions* [subscription-id]
+--ro subscription-id subscription-id
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+--ro (subscription-type)?
| +--:(via-configuration)
| | +--ro configured-subscription?
empty {configured-subscriptions}?
| +--:(created-via-RPC)
| +--ro created-subscription? empty
+--ro subscription-status? identityref
+--ro stream? string
+--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 encoding? encoding
+--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
augment /netmod-notif:replayComplete:
+--ro subscription-id? subscription-id
augment /netmod-notif:notificationComplete:
+--ro subscription-id? subscription-id
augment /netmod-notif:netconf/netmod-notif:streams:
+--rw exclude-from-NETCONF-stream? empty
rpcs:
+---x establish-subscription
| +--ro input
| | +--ro stream? string
| | +--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 encoding? encoding
| +--ro output
| +--ro subscription-result subscription-result
| +--ro (result)?
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| +--:(success)
| | +--ro subscription-id subscription-id
| +--:(no-success)
| +--ro stream? string
| +--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 encoding? encoding
+---x modify-subscription
| +--ro input
| | +--ro subscription-id? subscription-id
| | +--ro stream? string
| | +--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 encoding? encoding
| +--ro output
| +--ro subscription-result subscription-result
| +--ro stream? string
| +--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 encoding? encoding
+---x delete-subscription
+--ro input
+--ro subscription-id? subscription-id
notifications:
+---n subscription-started
| +--ro subscription-id subscription-id
| +--ro stream? string
| +--ro (filter-type)?
| | +--:(rfc5277)
| | | +--ro filter
| | +--:(by-reference)
| | +--ro filter-ref? filter-ref
| +--ro startTime? yang:date-and-time
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| +--ro stopTime? yang:date-and-time
| +--ro encoding? encoding
+---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? string
| +--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 encoding? encoding
+---n subscription-terminated
| +--ro subscription-id subscription-id
| +--ro reason? subscription-term-reason
+---n added-to-subscription
| +--ro subscription-id subscription-id
| +--ro stream? string
| +--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 encoding? encoding
+---n removed-from-subscription
+--ro subscription-id subscription-id
2.5. Creating a Subscription
This operation is fully defined in [RFC5277]. It allows a subscriber
to request the creation of a dynamic subscription. If successful,
the subscription remains in effect for the duration of the NETCONF
session.
This operation is included in the document for supporting backwards
compatibility with [RFC5277] clients. New clients are expected not
to use this operation, but establish subscriptions as defined in
Section 2.6
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2.5.1. Parameters
The input parameters of the operation are:
stream: An optional parameter that indicates which stream of events
is of interest. If not present, events in the default NETCONF stream
will be sent.
filter: An optional parameter that indicates which subset of all
possible events is of interest. The format of this parameter is the
same as that of the filter parameter in the NETCONF protocol
operations. If not present, all events not precluded by other
parameters will be sent.
startTime: An optional parameter 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. Implementations must support time zones.
stopTime: An optional parameter 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.
Implementations must support time zones.
2.5.2. Usage Example
The following demonstrates dynamically creating a simple
subscription.
<netconf:rpc message-id="101"
xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
<create-subscription
xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
</create-subscription>
</netconf:rpc>
Figure 3: Create subscription
2.5.3. Positive Response
If the NETCONF server can satisfy the request, the server sends an
<ok> element.
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<netconf:rpc netconf:message-id="102"
xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
<create-subscription
xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
<filter netconf:type="xpath"
xmlns:ex="http://example.com/event/1.0"
select="/ex:event[ex:eventClass='fault' and
(ex:severity='minor' or ex:severity='major'
or ex:severity='critical')]"/>
</create-subscription>
</netconf:rpc>
<rpc-reply message-id="102"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<ok/>
</rpc-reply>
Figure 4: Successful create subscription
2.5.4. Negative Response
If the request cannot be completed for any reason, an <rpc-error>
element is included within the <rpc-reply>. Subscription requests
can fail for several reasons including if a filter with invalid
syntax is provided or if the name of a non-existent stream is
provided.
If a stopTime is specified in a request without having specified a
startTime, the following error is returned:
Tag: missing-element
Error-type: protocol
Severity: error
Error-info: <bad-element>: startTime
Description: An expected element is missing.
If the optional replay feature is requested but the NETCONF server
does not support it, the following error is returned:
Tag: operation-failed
Error-type: protocol
Severity: error
Error-info: none
Description: Request could not be completed because the
requested operation failed for some reason
not covered by any other error condition.
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If a stopTime is requested that is earlier than the specified
startTime, the following error is returned:
Tag: bad-element
Error-type: protocol
Severity: error
Error-info: <bad-element>: stopTime
Description: An element value is not correct;
e.g., wrong type, out of range, pattern mismatch.
If a startTime is requested that is later than the current time, the
following error is returned:
Tag: bad-element
Error-type: protocol
Severity: error
Error-info: <bad-element>: startTime
Description: An element value is not correct;
e.g., wrong type, out of range, pattern mismatch.
2.6. Establishing a Subscription
This operation is an evolution of the create subscription operation.
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 and enabling multiple subscriptions overs a
single NETCONF session (if interleaving [RFC6241] is supported), and
canceling subscriptions without terminating the NETCONF session.
2.6.1. Parameters
The input parameters of the operation are those of create
subscription plus:
filter-ref: filters that have been previously (and separately)
configured can be referenced by a subscription. This mechanism
enables the reuse of filters.
encoding: by default, updates are encoded using XML. Other encodings
may be supported, such as JSON.
2.6.2. Usage Example
The following demonstrates establishing a simple subscription.
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<netconf:rpc message-id="101"
xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
<establish-subscription
xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
</establish-subscription>
</netconf:rpc>
Figure 5: Establish subscription
2.6.3. Positive Response
If the NETCONF server can satisfy the request, the server sends a
positive <subscription-result> element, and the subscription-id of
the accepted subscription.
<netconf:rpc netconf:message-id="102"
xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
<establish-subscription
xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
<filter netconf:type="xpath"
xmlns:ex="http://example.com/event/1.0"
select="/ex:event[ex:eventClass='fault' and
(ex:severity='minor' or ex:severity='major'
or ex:severity='critical')]"/>
</establish-subscription>
</netconf:rpc>
<rpc-reply message-id="102"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<subscription-result
xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
ok
</subscription-result>
<subscription-id
xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
52
</subscription-id>
</rpc-reply>
Figure 6: Successful establish subscription
2.6.4. Negative Response
If the NETCONF server cannot satisfy the request, the server sends a
negative <subscription-result> element.
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If the client has no authorization to establish the subscription, the
<subscription-result> indicates an authorization error. For
instance:
<netconf:rpc netconf:message-id="103"
xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
<establish-subscription
xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
<stream>foo</stream>
</establish-subscription>
</netconf:rpc>
<rpc-reply message-id="103"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<subscription-result
xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
error-data-not-authorized
</subscription-result>
</rpc-reply>
Figure 7: Unsuccessful establish subscription
If the request is rejected because the server is not able to serve
it, the server SHOULD include in the returned error what subscription
parameters would have been accepted for the request when it was
processed. However, they are no guarantee that subsequent requests
with those parameters for this client or others will be accepted.
For instance, consider a subscription from [netconf-yang-push], which
augments the establish-subscription with some additional parameters,
including "period". If the client requests a period the NETCONF
server cannot serve, the exchange may be:
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<netconf:rpc message-id="101"
xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
<establish-subscription
xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
<stream>push-update</stream>
<filter netconf:type="xpath"
xmlns:ex="http://example.com/sample-data/1.0"
select="/ex:foo"/>
<period
xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-push:1.0">
500
</period>
<encoding>encode-xml</encoding>
</establish-subscription>
</netconf:rpc>
<rpc-reply message-id="101"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<subscription-result
xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
error-insufficient-resources
</subscription-result>
<period
xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-push:1.0">
2000
</period>
</rpc-reply>
Figure 8: Subscription establishment negotiation
Subscription requests will fail if a filter with invalid syntax is
provided or if the name of a non-existent stream is provided.
2.7. Modifying a Subscription
This operation permits modifying the terms of a subscription
previously established. Statically created subscriptions cannot be
modified. Dynamic subscriptions can be modified one or multiple
times. If the server accepts the request, it immediately starts
sending events based on the new terms, completely ignoring the
previous ones. If the server 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 same as in establish subscription
requests.
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Dynamic subscriptions established via RPC can only be modified (or
deleted) via RPC using the same session used to establish it.
Configuration-based (i.e., static) subscriptions cannot be modified
(or deleted) using RPCs. Instead, configured subscriptions are
modified (or deleted) as part of regular configuration operations.
Servers MUST reject any attempts to modify (or delete) static
subscriptions via RPC.
2.7.1. Parameters
The parameters to modify-subscription are those of establish-
subscription plus a mandatory subscription-id.
2.7.2. Usage Example
The following demonstrates modifying a subscription. Consider a
subscription from [netconf-yang-push], which augments the establish-
subscription with some additional parameters, including "period". A
subscription may be established as follows.
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<netconf:rpc message-id="101"
xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
<establish-subscription
xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
<stream>push-update</stream>
<filter netconf:type="xpath"
xmlns:ex="http://example.com/sample-data/1.0"
select="/ex:foo"/>
<period
xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-push:1.0">
500
</period>
<encoding>encode-xml</encoding>
</establish-subscription>
</netconf:rpc>
<rpc-reply message-id="101"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<subscription-result
xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
ok
</subscription-result>
<subscription-id
xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
1922
</subscription-id>
</rpc-reply>
Figure 9: Establish subscription to be modified
The subscription may be modified with:
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<netconf:rpc message-id="102"
xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
<modify-subscription
xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
<subscription-id>1922</subscription-id>
<period>1000</period>
</modify-subscription >
</netconf:rpc>
<rpc-reply message-id="102"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<subscription-result
xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
ok
</subscription-result>
<subscription-id
xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
1922
</subscription-id>
</rpc-reply>
Figure 10: Modify subscription
2.7.3. Positive Response
If the NETCONF server can satisfy the request, the server sends a
positive <subscription-result> element. This response is like that
to an establish-subscription request. but without the subscription-
id, which would be redundant.
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<netconf:rpc message-id="102"
xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
<modify-subscription
xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
<subscription-id>1922</subscription-id>
<period
xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-push:1.0">
1000
</period>
</modify-subscription >
</netconf:rpc>
<rpc-reply message-id="102"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<subscription-result
xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
ok
</subscription-result>
</rpc-reply>
Figure 11: Successful modify subscription
2.7.4. Negative Response
If the NETCONF server cannot satisfy the request, the server sends a
negative <subscription-result> element. Its contents and semantics
are identical to those to an establish-subscription request. For
instance:
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<netconf:rpc message-id="102"
xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
<modify-subscription
xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
<subscription-id>1922</subscription-id>
<period
xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-push:1.0">
100
</period>
</modify-subscription>
</netconf:rpc>
<rpc-reply message-id="102"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<subscription-result
xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
error-insufficient-resources
</subscription-result>
<period>500</period>
</rpc-reply>
Figure 12: Unsuccessful modify subscription
2.8. Deleting a Subscription
This operation permits canceling a subscription previously
established. Created subscriptions cannot be explicitly deleted. If
the server accepts the request, it immediately stops sending events
for the subscription. If the server rejects the request, all
subscriptions remain as prior to the request. That is, the request
has no impact whatsoever. A request may be rejected because the
provided subscription identifier is incorrect.
Subscriptions created via RPC can only be deleted via RPC using the
same session used for establishment. Static subscriptions cannot be
deleted using RPCs. Instead, configured subscriptions are deleted as
part of regular configuration operations. Servers MUST reject any
RPC attempt to delete static subscriptions.
2.8.1. Parameters
The only parameter to delete-subscription is the identifier of the
subscription to delete.
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2.8.2. Usage Example
The following demonstrates deleting a subscription.
<netconf:rpc message-id="101"
xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
<delete-subscription
xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
<subscription-id>1922</subscription-id>
</delete-subscription>
</netconf:rpc>
Figure 13: Delete subscription
2.8.3. Positive Response
If the NETCONF server can satisfy the request, the server sends an OK
element. For example:
<netconf:rpc message-id="103"
xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
<delete-subscription
xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
<subscription-id>1922</subscription-id>
</delete-subscription>
</netconf:rpc>
<rpc-reply message-id="103"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<ok/>
</rpc-reply>
Figure 14: Successful delete subscription
2.8.4. Negative Response
If the NETCONF server cannot satisfy the request, the server sends an
error-rpc element. For example:
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<netconf:rpc message-id="103"
xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
<delete-subscription
xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
<subscription-id>2017</subscription-id>
</delete-subscription>
</netconf:rpc>
<rpc-reply message-id="101"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<rpc-error>
<error-type>application</error-type>
<error-tag>invalid-value</error-tag>
<error-severity>error</error-severity>
<error-path
xmlns:t="urn:ietf:params:xml:ns:netconf:notification:1.1">
/t:subscription-id
</error-path>
<error-message xml:lang="en">
Subscription-id 2017 does not exist
</error-message>
</rpc-error>
</rpc-reply>
Figure 15: Unsuccessful delete subscription
2.9. Static Subscriptions
A static subscription is a subscription installed via a configuration
interface.
Static subscriptions persist across reboots, and persist even when
transport is unavailable. This also means static subscriptions do
not support negotiation.
Static subscriptions can be modified by any configuration client with
write rights on the configuration of the subscription. Subscriptions
can be modified or terminated at any point of their lifetime.
Supporting static subscriptions is optional and advertised using the
"configured-subscriptions" feature.
2.9.1. Creating a Static Subscription
Static subscriptions cannot be created via configuration operations.
New clients should use the mechanisms described in Section 2.9.2 for
establishing static subscriptions.
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2.9.2. Establishing a Static Subscription
Subscriptions can be 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
client 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 server sends to the
receivers a control-plane notification stating the subscription has
been established (subscription-started).
Because there is no explicit association with an existing transport
session, static configuration operations require additional
parameters to indicate the receivers of the notifications and
possibly the source of the notifications (i.e., a specific interface
or server address).
For example at subscription establishment, a NETCONF 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: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 16: Establish static subscription
if the request is accepted, the server would reply:
<rpc-reply message-id="101"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<ok/>
</rpc-reply>
Figure 17: Response to a successful static subscription establishment
if the request is not accepted because the server cannot serve it,
the server 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 server cannot serve this
subscription due to the current workload.
</error-message>
</rpc-error>
</rpc-reply>
Figure 18: Response to a failed static subscription establishment
2.9.3. Modifying a Static Subscription
Static subscriptions can be modified using configuration operations
against the top-level subtree subscription-config.
Immediately after a subscription is successfully modified, the server
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, added-to-subscription, with the same
contents as a modified-subscription) or removed (i.e., removed-from-
subscription)
2.9.4. Deleting a Static Subscription
Subscriptions can be deleted using configuration operations against
the top-level subtree subscription-config. For example:
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<rpc message-id="101"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<edit-config>
<target>
<running/>
</target>
<subscription-config
xmlns:xc="urn:ietf:params:xml:ns:netconf:notification:1.1">
<subscription xc:operation="delete">
<subscription-id>
1922
</subscription-id >
</subscription>
</subscription-config>
</edit-config>
</rpc>
<rpc-reply message-id="101"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<ok/>
</rpc-reply>
Figure 19: Deleting a static subscription
Immediately after a subscription is successfully deleted, the server
sends to the receivers a control-plane notification stating the
subscription has been terminated (subscription-terminated).
2.10. Event (Data Plane) Notifications
Once a subscription has been set up, the NETCONF server sends
(asynchronously) the event notifications from the subscribed stream.
We refer to these as data plane notifications. For dynamic
subscriptions set up via RPC operations, event notifications are sent
over the NETCONF session used to create or establish the
subscription. For static 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.
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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 notification also contains notification-specific tagged
content, if any. With the exception of <eventTime>, the content of
the notification is beyond the scope of this document.
For the encodings other than XML, notifications include an additional
XML element so that the notification is a well-formed XML. The
element is <notification-contents-{encoding}>, E.g., <notification-
contents-json>. That element contains the notification contents in
the desired encoding
The following is an example of an event notification from [RFC6020]:
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 20: Definition of a data plane notification
<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 21: Data plane notification
The equivalent using json encoding would be
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<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 22: Data plane notification using JSON encoding
2.11. Control Plane Notifications
In addition to data plane notifications, a server may send control
plane notifications to indicate to receivers that an event related to
the subscription management has occurred. Control plane
notifications cannot be filtered out. Types of control plane
notifications include:
2.11.1. replayComplete
This notification is originally defined in [RFC5277]. It is sent to
indicate that all of the replay notifications have been sent and must
not be sent for any other reason.
In the case of a subscription without a stop time, 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 as they arise
naturally within the system.
2.11.2. 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.
2.11.3. subscription-started
This notification indicates that a static subscription has started
and data updates are beginning to be sent. This notification
includes the parameters of the subscription, except for the
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receiver(s) addressing information and push-source information. Note
that for RPC-based subscriptions, no such notifications are sent.
2.11.4. subscription-modified
This notification indicates that a static 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.
2.11.5. subscription-terminated
This notification indicates that a subscription has been terminated.
The notification includes the reason for the termination. A
subscription may be terminated by a server or by a client. The
server may decide to terminate a subscription when it is running out
of resources for serving it, an internal error occurs, etc. Server-
driven terminations are notified to all receivers. The management
plane can also terminate static subscriptions using configuration
operations.
Clients can terminate via RPC subscriptions established via RPC. In
such cases, no subscription-terminated notifications are sent.
2.11.6. subscription-suspended
This notification indicates that a server 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
static subscriptions).
2.11.7. 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 static subscriptions).
2.12. Subscription Management
Below is the state machine for the server. It is important to note
that a subscription does not exist at the agent until it is accepted
and made active.
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.-------.
| start |
'-------'
|
create | establish
|
| .----------modify-------------.
v v '
.-----------. .-----------.
.--------. | |------>suspend------->| |
modify '| active | | suspended |
'--------->| |<----reactivate<------| |
'-----------' '-----------'
| |
delete delete
| |
v |
.-------. |
| end |<-----------------------------'
'-------'
Of interest in this state machine are the following:
o Successful <create-subscription>, <establish-subscription> or
<modify-subscription> actions must put the subscription into an
active state.
o Failed <modify-subscription> actions will leave the subscription
in its previous state, with no visible change to any
notifications.
o A <delete-subscription> action will delete the entire
subscription.
3. Data Models for Event Notifications
3.1. Data Model for RFC5277 (netmod namespace)
<CODE BEGINS>
file "ietf-5277-netmod@2016-03-21.yang"
module ietf-5277-netmod {
namespace
"urn:ietf:params:xml:ns:yang:ietf-5277-netmod";
// TODO: examples in the draft consider the namespace below
// which follows the namespace format in 5277
// "urn:ietf:params:xml:ns:netmod:notification";
prefix netmod-notif;
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import ietf-yang-types {
prefix yang;
}
organization "IETF";
contact
"WG Web: <http://tools.ietf.org/wg/netmod/>
WG List: <mailto:netmod@ietf.org>
WG Chair: Juergen Schoenwaelder
<mailto:j.schoenwaelder@jacobs-university.de>
WG Chair: Tom Nadeau
<mailto:tnadeau@lucidvision.com>
Editor: Alberto Gonzalez Prieto
<mailto:albertgo@cisco.com>
Editor: Alexander Clemm
<mailto:alex@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>";
description
"Model for RPC in RFC 5277: NETCONF Event Notifications";
revision 2016-03-21 {
description
"Model for data nodes and notifications in RFC 5277:
NETCONF Event Notifications";
reference
"RFC 5277: NETCONF Event Notifications";
}
/*
* EXTENSIONS
*/
extension control-plane-notif {
description
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"This statement applies only to notifications.
It indicates that the notification is a control-plane
notification and therefore it does not generate an
event stream.";
}
/*
* DATA NODES
*/
container netconf {
description
"Netconf container as defined in RFC 5277.";
reference
"RFC 5277: NETCONF Event Notifications";
container streams {
// TODO: should be config false?. That breaks the leafref
// from the config subscriptions config false;
description
"The container with the set of available event streams.";
reference
"RFC 5277: NETCONF Event Notifications";
list stream {
must "1 = count(./name == 'NETCONF')" {
description
"The list must contain a NETCONF stream.
A NETCONF server implementation supporting the
notification capability MUST support the
'NETCONF' notification event stream. This stream
contains all NETCONF XML event notifications supported
by the NETCONF server.
The exact string 'NETCONF' is used during the
advertisement of stream support during the <get>
operation on <streams> and during the
<create-subscription> operation.";
}
key "name";
description
"The list available event streams.";
leaf name {
type string;
description
"The name of the event stream.
If this is the default NETCONF stream, this must have
the value 'NETCONF'.";
}
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leaf description {
type string;
mandatory true;
description
"A description of the event stream, including such
information as the type of events that are sent over
this stream.";
}
leaf replaySupport {
type boolean;
mandatory true;
description
"An indication of whether or not event replay is
available on this stream.";
}
leaf replayLogCreationTime {
when "../replaySupport" {
description
"This object MUST be present if replay is supported.";
}
type yang:date-and-time;
mandatory true;
description
"The timestamp of the creation of the log used to
support the replay function on this stream.
Note that this might be earlier then the earliest
available notification in the log. This object
is updated if the log resets for some reason.
This object MUST be present if replay is supported.";
}
leaf replayLogAgedTime {
when "current()/../replaySupport" {
description
"This object MUST be present if replay is supported
and any notifications have been aged out of the log.";
}
type yang:date-and-time;
mandatory true;
description
"The timestamp of the last notification aged
out of the log. This object MUST be present
if replay is supported and any notifications
have been aged out of the log.";
}
} // list stream
} // container streams
} // container netconf
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/*
* NOTIFICATIONS
*/
notification replayComplete {
netmod-notif:control-plane-notif;
description
"This notification is sent to signal the end of a replay
portion of a subscription.";
}
notification notificationComplete {
netmod-notif:control-plane-notif;
description
"This notification is sent to signal the end of a notification
subscription. It is sent in the case that stopTime was
specified during the creation of the subscription.";
}
}
<CODE ENDS>
3.2. Data Model for RFC5277 (netconf namespace)
<CODE BEGINS>
file "ietf-5277-netconf@2016-03-21.yang"
module ietf-5277-netconf {
namespace
"urn:ietf:params:xml:ns:yang:ietf-5277-netconf";
// TODO: examples in the draft consider the namespace below
// which follows the namespace format in 5277
// "urn:ietf:params:xml:ns:netconf:notification:1.0";
prefix notif;
import ietf-yang-types {
prefix yang;
}
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
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<mailto:mehmet.ersue@nokia.com>
Editor: Alberto Gonzalez Prieto
<mailto:albertgo@cisco.com>
Editor: Alexander Clemm
<mailto:alex@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>";
description
"Model for RPCs and Notifications in RFC 5277: NETCONF Event
Notifications";
revision 2016-03-21 {
description
"Model for RPC in RFC 5277: NETCONF Event Notifications";
reference
"RFC 5277: NETCONF Event Notifications";
}
/*
* 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
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"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-5277 {
description
"This grouping describes the information in a 5277
subscription.";
leaf stream {
type string;
default "NETCONF";
description
"Indicates which stream of events is of interest.
If not present, events in the default NETCONF stream
will be sent.";
}
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;
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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.";
}
}
/*
* RPCs
*/
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 subscription terminates.";
input {
uses subscription-info-5277;
}
}
}
<CODE ENDS>
3.3. Data Model for RFC5277-bis Extensions
<CODE BEGINS>
file "ietf-event-notifications@2016-03-21.yang"
module ietf-event-notifications {
namespace
"urn:ietf:params:xml:ns:yang:ietf-event-notifications";
// TODO: examples in the draft consider the namespace below
// which follows the namespace format in 5277
// "urn:ietf:params:xml:ns:netconf:notification:1.1";
prefix notif-bis;
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import ietf-inet-types {
prefix inet;
}
import ietf-5277-netmod {
prefix netmod-notif;
}
import ietf-5277-netconf {
prefix notif;
}
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: Alberto Gonzalez Prieto
<mailto:albertgo@cisco.com>
Editor: Alexander Clemm
<mailto:alex@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>";
description
"This module contains conceptual YANG specifications
for NETCONF Event Notifications.";
revision 2016-03-21 {
description
"Initial version. Model for NETCONF Notifications (bis)";
reference
"RFC XXXX: NETCONF Event Notifications";
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}
/*
* 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.";
}
/*
* IDENTITIES
*/
/* Identities for subscription results */
identity subscription-result {
description
"Base identity for RPC responses to requests surrounding
management (e.g. creation, modification) 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.";
}
identity error-no-such-subscription {
base error;
description
"A subscription with the requested subscription ID
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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 server has insufficient resources to support the
subscription as requested.";
}
/* Identities for subscription stream status */
identity subscription-stream-status {
description
"Base identity for the status of subscriptions and
datastreams.";
}
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 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.
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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";
}
identity subscription-deleted {
base subscription-errors;
description
"The subscription was terminated because the subscription
was deleted.";
}
/* 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";
}
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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
"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 server to terminate a subscription.";
}
typedef subscription-susp-reason {
type identityref {
base subscription-errors;
}
description
"Reason for a server to suspend a subscription.";
}
typedef encoding {
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type identityref {
base encodings;
}
description
"Specifies a data encoding, e.g. for a data subscription.";
}
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
NETCONF server";
}
enum "address-originated" {
description
"Notifications will be sent from a specific address on a
NETCONF server";
}
}
description
"Specifies from where notifications will be sourced when
being sent by the NETCONF server.";
}
typedef stream-ref {
type leafref {
path "/netmod-notif:netconf/netmod-notif:streams/" +
"netmod-notif:stream/netmod-notif:name";
}
description
"This type is used to reference a stream.";
}
typedef filter-ref {
type leafref {
path "/notif-bis:filters/notif-bis:filter/notif-bis:filter-id";
}
description
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"This type is used to reference a filter.";
}
/*
* GROUPINGS
*/
grouping subscription-info {
description
"This grouping describes basic information concerning a
subscription.";
uses notif:subscription-info-5277 {
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.";
}
}
}
}
leaf encoding {
type encoding;
default "encode-xml";
description
"The type of encoding for the subscribed data.
Default is XML";
}
}
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 {
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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 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;
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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;
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;
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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,
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 create-subscription request.";
input {
uses subscription-info;
}
output {
uses subscription-response;
}
}
rpc modify-subscription {
description
"This RPC allows a subscriber to modify a subscription
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that was previously created using create-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;
}
output {
leaf subscription-result {
type subscription-result;
mandatory true;
description
"Indicates whether subscription was modified
or if a problem was encountered.
In case the subscription-result has a value
other than OK, the original subscription was not
changed.";
}
uses subscription-info;
}
}
rpc delete-subscription {
description
"This RPC allows a subscriber to delete a subscription that
was previously created using create-subscription.";
input {
leaf subscription-id {
type subscription-id;
description
"Identifier of the subscription that is to be deleted.
Only subscriptions that were created using
create-subscription can be deleted via this RPC.";
}
}
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}
/*
* NOTIFICATIONS
*/
notification subscription-started {
netmod-notif:control-plane-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 subscription-id {
type subscription-id;
mandatory true;
description
"This references the affected subscription.";
}
uses subscription-info;
}
notification subscription-suspended {
netmod-notif:control-plane-notif;
description
"This notification indicates that a suspension of the
subscription by the server 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.";
}
}
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notification subscription-resumed {
netmod-notif: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
"This references the affected subscription.";
}
}
notification subscription-modified {
netmod-notif: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 {
netmod-notif: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.";
}
}
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notification added-to-subscription {
netmod-notif:control-plane-notif;
description
"This notification is sent to a receiver when it has been
added to an existing subscription.
Note that if the receiver is added when the subscription
is created, it will receive a subscription-started
notification and no added-to-subscription.";
leaf subscription-id {
type subscription-id;
mandatory true;
description
"This references the affected subscription.";
}
uses subscription-info;
}
notification removed-from-subscription {
netmod-notif:control-plane-notif;
description
"This notification is sent to a receiver when it has been
removed from an existing subscription.
Note that if the subscription is terminated, the receiver
will receive a subscription-terminated notification
and no removed-from-subscription.";
leaf subscription-id {
type subscription-id;
mandatory true;
description
"This references the affected subscription.";
}
}
augment /netmod-notif:replayComplete {
description
"Augmenting the definition in RFC-5277 to include the
subscription identifier defined in 5277-bis";
leaf subscription-id {
type subscription-id;
description
"This references the affected subscription.
Not present for created subscriptions for backwards
compatibility.";
}
}
augment /netmod-notif:notificationComplete {
description
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"Augmenting the definition in RFC-5277 to include the
subscription identifier defined in 5277-bis";
leaf subscription-id {
type subscription-id;
description
"This references the affected subscription.
Not present for created subscriptions for backwards
compatibility.";
}
}
/*
* DATA NODES
*/
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 notif: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
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"Identifier to use for this subscription.";
}
uses subscription-info;
uses receiver-info {
if-feature "configured-subscriptions";
}
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, delete-subscription,
and modify-subscription, as well as subscriptions that
have been established via configuration.";
list subscriptions {
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.";
}
choice subscription-type {
description
"This choice contains a set of flags to indicate
the type of subscription.";
case via-configuration {
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.";
}
}
case created-via-RPC {
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leaf created-subscription {
type empty;
description
"The presence of this leaf indicates that the
subscription originated via RPC using RFC5277
mechanisms and semantics.";
}
}
}
leaf subscription-status {
type identityref {
base subscription-stream-status;
}
description
"The status of the subscription.";
}
uses subscription-info;
uses receiver-info {
if-feature "configured-subscriptions";
}
uses push-source-info {
if-feature "configured-subscriptions";
}
}
}
augment /netmod-notif:netconf/netmod-notif:streams {
description
"Augmenting the definition in RFC-5277 to so that streams
can opt out the default stream.";
leaf exclude-from-NETCONF-stream {
type empty;
description
"Indicates that the stream should not be part of the
default stream.";
}
}
}
<CODE ENDS>
4. Backwards Compatibility
Capabilities are advertised in messages sent by each peer during
session establishment [RFC6241]. Servers supporting the features in
this document must advertise both capabilities
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"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 server 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 23: Hello message
Clients 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 server as per [RFC5277].
Clients that support the features in this document recognize both
capabilities. This allows them interacting with the server as per
this document.
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.
5. Security Considerations
The security considerations from the base NETCONF document [RFC6241]
also apply to the notification capability.
The <notification> elements are never sent before the transport layer
and the NETCONF layer, including capabilities exchange, have been
established and the manager has been identified and authenticated.
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A secure transport must be used and the server must ensure that the
user has sufficient authorization to perform the function they are
requesting against the specific subset of NETCONF 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-subscriptiont> and <establish-
subscriptiont> 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> that different users are
able to subscribe to.
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 NETCONF server
MUST NOT include any content in a notification that the user is not
authorized to view.
If a malicious or buggy NETCONF client 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 client uses <establish-
subscription>, the server 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. Clients 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 [netconf-yang-push] each of the elements in its data
plane notifications must also go through access control.
6. References
6.1. 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>.
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[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>.
[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for
the Network Configuration Protocol (NETCONF)", RFC 6020,
DOI 10.17487/RFC6020, October 2010,
<http://www.rfc-editor.org/info/rfc6020>.
[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>.
6.2. Informative References
[netconf-yang-push]
Clemm, Alexander., Gonzalez Prieto, Alberto., Voit, Eric.,
Tripathy, A., and E. Nilsen-Nygaard, "Subscribing to YANG
datastore push updates", February 2016,
<https://datatracker.ietf.org/doc/draft-ietf-netconf-yang-
push/>.
Authors' Addresses
Alberto Gonzalez Prieto
Cisco Systems
Email: albertgo@cisco.com
Alexander Clemm
Cisco Systems
Email: alex@cisco.com
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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
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