NETCONF A. Gonzalez Prieto
Internet-Draft VMware
Intended status: Standards Track A. Clemm
Expires: January 4, 2018 Huawei
E. Voit
E. Nilsen-Nygaard
A. Tripathy
Cisco Systems
July 3, 2017
NETCONF Support for Event Notifications
draft-ietf-netconf-netconf-event-notifications-04
Abstract
This document defines how to transport network subscriptions and
event messages on top of the Network Configuration protocol
(NETCONF). This includes the full set of RPCs, subscription state
changes, and message payloads needing asynchronous delivery. The
capabilities and operations defined in this document used in
conjunction with [subscribe] are intended to obsolete [RFC5277]. In
addition, the capabilities within those two documents along with
[yang-push] are intended to enable an extract of a YANG datastore on
a remote device.
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 January 4, 2018.
Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
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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
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Solution . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3.1. Event Stream Discovery . . . . . . . . . . . . . . . . . 3
3.2. Mandatory NETCONF support . . . . . . . . . . . . . . . . 4
3.3. Dynamic Subscriptions . . . . . . . . . . . . . . . . . . 5
3.4. Configured Subscriptions . . . . . . . . . . . . . . . . 12
4. Interleave Capability . . . . . . . . . . . . . . . . . . . . 25
5. Security Considerations . . . . . . . . . . . . . . . . . . . 26
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 26
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 27
7.1. Normative References . . . . . . . . . . . . . . . . . . 27
7.2. Informative References . . . . . . . . . . . . . . . . . 27
Appendix A. Open Items . . . . . . . . . . . . . . . . . . . . . 28
Appendix B. Changes between revisions . . . . . . . . . . . . . 28
B.1. v03 to v04 . . . . . . . . . . . . . . . . . . . . . . . 28
B.2. v01 to v03 . . . . . . . . . . . . . . . . . . . . . . . 28
B.3. v00 to v01 . . . . . . . . . . . . . . . . . . . . . . . 28
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 28
1. Introduction
This document defines mechanisms that provide an asynchronous message
notification delivery service for the NETCONF protocol [RFC6241]
based on [subscribe]. This is an optional capability built on top of
the base NETCONF definition.
The document [subscribe] plus this transport specification document
provides a superset of the capabilities previously defined in
[RFC5277]. Newly introduced capabilities include the ability to have
multiple subscriptions on a single NETCONF session, the ability to
terminate subscriptions without terminating the client session, and
the ability to modify existing subscriptions.
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In addition, [yang-push] plus the capabilities of this document
provide a mechanism for a NETCONF client to maintain a subset/extract
of an actively changing YANG datastore.
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].
The following terms are defined in [RFC6241]: client, server,
operation, RPC.
The following terms are defined in [subscribe]: event, event
notification, stream, publisher, receiver, subscriber, subscription,
configured subscription.
Note that a publisher in [subscribe] corresponds to a server in
[RFC6241]. Similarly, a subscriber corresponds to a client. A
receiver is also a client. In the remainder of this document, we
will use the terminology in [RFC6241] to simplify [subscribe]'s
mental mappings to embedded NETCONF terminology.
3. Solution
In this section, we describe and exemplify how [subscribe] is to be
supported over NETCONF.
3.1. Event Stream Discovery
In the context of [subscribe] an event stream exposes a continuous
set of events available for subscription. A NETCONF client can
retrieve the list of available event streams from a NETCONF server
using the "get" operation against the top-level container "/streams"
defined in [subscribe]. The reply includes the stream identities
supported on the NETCONF server.
The following example illustrates the retrieval of the list of
available event streams using the <get> operation.
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<rpc message-id="101"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<get>
<filter type="subtree">
<streams
xmlns="urn:ietf:params:xml:ns:netconf:notification:2.0"/>
</filter>
</get>
</rpc>
Figure 1: Get streams request
The NETCONF server returns a list of event streams available. In
this example, the list contains the NETCONF, SNMP, and SYSLOG
streams.
<rpc-reply message-id="101"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<data>
<streams
xmlns="urn:ietf:params:xml:ns:netconf:notification:2.0">
<stream>NETCONF</stream>
<stream>SNMP</stream>
<stream>SYSLOG</stream>
</streams>
</data>
</rpc-reply>
Figure 2: Get streams response
For [yang-push], a similar get is needed to retrieve available
datastore names.
3.2. Mandatory NETCONF support
A NETCONF server implementation supporting [subscribe] must support
dynamic subscriptions and the "NETCONF" notification event stream.
The NETCONF event stream contains all NETCONF XML event information
supported by the server, except for where it has been explicitly
indicated that this the event must be excluded from the NETCONF
stream.
A NETCONF server implementation supporting [yang-push] must support
the "running" datastore.
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3.3. Dynamic Subscriptions
3.3.1. Establishing Dynamic Subscriptions
The dynamic subscription RFC and interactions operation is defined in
[subscribe].
3.3.1.1. Usage Example
An example of interactions over NETCONF transport for one sample
subscription is below:
<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:2.0">
<stream>NETCONF</stream>
<event-filter-type>xpath</event-filter-type>
<event-filter> 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')]"
</event-filter>
</establish-subscription>
</netconf:rpc>
Figure 3: establish-subscription over NETCONF
3.3.1.2. 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.
<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:2.0">
ok
</subscription-result>
<identifier
xmlns="urn:ietf:params:xml:ns:netconf:notification:2.0">
52
</identifier>
</rpc-reply>
Figure 4: Successful establish-subscription
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3.3.1.3. Negative Response
If the NETCONF server cannot satisfy the request, or client has no
authorization to establish the subscription, the server will send a
negative <subscription-result> element. For instance:
<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:2.0">
stream-unavailable
</subscription-result>
</rpc-reply>
Figure 5: Unsuccessful establish subscription
3.3.1.4. Subscription Negotiation
If the client requests parameters the NETCONF server cannot serve,
the negative <subscription-result> may include hints at subscription
parameters which would have been accepted. For instance, consider
the following subscription from [yang-push], which augments the
establish-subscription with some additional parameters, including
"period". If the client requests a period which the NETCONF server
cannot serve, the back-and-forth 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:2.0">
<stream>push-update</stream>
<event-filter-type>subtree</event-filter-type>
<event-filter>xmlns:ex="http://example.com/sample-data/1.0"
select="/ex:foo"</event-filter>
<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:2.0">
error-insufficient-resources
</subscription-result>
<period
xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-push:1.0">
2000
</period>
</rpc-reply>
Figure 6: Subscription establishment negotiation
3.3.1.5. Message Flow Examples
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+------------+ +-----------+
| Client | | Server |
+------------+ +-----------+
| |
| Capability Exchange |
|<---------------------------->|
| |
| |
| Establish Subscription |
|----------------------------->|
| RPC Reply: OK, id = 22 |
|<-----------------------------|
| |
| Notification (id 22) |
|<-----------------------------|
| |
| |
| Establish Subscription |
|----------------------------->|
| RPC Reply: OK, id = 23 |
|<-----------------------------|
| |
| |
| Notification (id 22) |
|<-----------------------------|
| Notification (id 23) |
|<-----------------------------|
| |
| |
Figure 7: Multiple subscription establishments over a single NETCONF
session
3.3.2. Modifying a Subscription
This operation is defined in [subscribe] and enhanced in [yang-push].
3.3.2.1. Usage Example
The following demonstrates modifying a subscription. Consider a
subscription from [yang-push], which augments the establish-
subscription with some additional parameters, including "period". A
subscription may be established and modified 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:2.0">
<datastore xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-push">running</datastore>
<event-filter-type>subtree</event-filter-type>
<event-filter>xmlns:ex="http://example.com/sample-data/1.0"
select="/ex:foo"</event-filter>
<period xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-push:1.0">
1000
</period>
</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:2.0">
ok
</subscription-result>
<identifier
xmlns="urn:ietf:params:xml:ns:netconf:notification:2.0">
1922
</identifier>
</rpc-reply>
<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:2.0">
<identifier>1922</identifier>
<period>100</period>
</modify-subscription>
</netconf:rpc>
Figure 8: Subscription modification
3.3.2.2. 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
identifier.
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<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:2.0">
ok
</subscription-result>
</rpc-reply>
Figure 9: Successful modify subscription
3.3.2.3. 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 in an establish-subscription request. For
instance:
<rpc-reply message-id="102"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<subscription-result
xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-push:1.0">
period-unsupported
</subscription-result>
<period-hint>500</period-hint>
</rpc-reply>
Figure 10: Unsuccessful modify subscription
3.3.2.4. Message Flow Example
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+------------+ +-----------+
| Client | | Server |
+------------+ +-----------+
| |
| Capability Exchange |
|<---------------------------->|
| |
| Establish Subscription |
|<---------------------------->|
| |
| Notification (id 22) |
|<-----------------------------|
| |
| Modify Subscription |
|----------------------------->|
| RPC Reply: OK |
|<-----------------------------|
| |
| Notification (id 22) |
|<-----------------------------|
| |
Figure 11: Message flow for successful subscription modification
3.3.3. Deleting a Subscription
This operation is defined in [subscribe] for events, and enhanced in
[yang-push] for datastores.
3.3.3.1. 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:2.0">
<identifier>1922</identifier>
</delete-subscription>
</netconf:rpc>
Figure 12: Delete subscription
3.3.3.2. Positive Response
If the NETCONF server can satisfy the request, the server sends an OK
element. For example:
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<rpc-reply message-id="103"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<ok/>
</rpc-reply>
Figure 13: Successful delete subscription
3.3.3.3. Negative Response
If the NETCONF server cannot satisfy the request, the server sends an
error-rpc element indicating the modification didn't work. For
example:
<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:2.0">
/t:identifier
</error-path>
<error-message xml:lang="en">
no-such-subscription
</error-message>
</rpc-error>
</rpc-reply>
Figure 14: Unsuccessful delete subscription
3.4. Configured Subscriptions
Configured subscriptions are established, modified, and deleted using
configuration operations against the top-level subtree of [subscribe]
or [yang-push] via configuration interface. In this document, we
focus on NETCONF operations. Any other configuration interface can
be used to establish a configured subscription that uses NETCONF to
push notifications to receivers. Configured susbscriptions are
supported by NETCONF servers using NETCONF Call Home [RFC8071]. Note
that this document only covers configured subscriptions where the
protocol of choice is NETCONF. In this section, we present examples
of how to manage the configuration subscriptions using a NETCONF
client. Key differences from dynamic subscriptions over NETCONF is
that subscription lifetimes are decoupled from NETCONF sessions.
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3.4.1. Establishing a Configured Subscription
For subscription establishment, a NETCONF client may send:
<rpc message-id="101"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"
xmlns:nc="urn:ietf:params:xml:ns:netconf:base:1.0">
<edit-config>
<target>
<running/>
</target>
<subscription-config
xmlns="urn:ietf:params:xml:ns:netconf:notification:2.0">
<subscription>
<identifier>
1922
</identifier>
<stream>
foo
</stream>
<receiver>
<address>
1.2.3.4
</address>
<port>
1234
</port>
<protocol>
netconf
</protocol>
</receiver>
</subscription>
</subscription-config>
</edit-config>
</rpc>
Figure 15: Establish configured subscription
if the request is accepted, the server would reply:
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<rpc-reply message-id="101"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<ok/>
</rpc-reply>
Figure 16: Response to a successful configuration subscription
establishment
if the request is not accepted because the server cannot serve it, no
configuration is changed. Int this case the server may reply:
<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 17: Response to a failed configured subscription establishment
For every configured receiver, once NETCONF transport session between
the server and the receiver is recognized as active, the server will
issue a "subscription-started" notification. After that, the server
will send notifications to the receiver as per the subscription
notification. The session is only intended for pushing
notifications. Client request on that session SHOULD be ignored by
the server.
The contents sent by the server on the Call Home session, once
established, are identical to those in a dynamic subscription.
Note that the server assumes that the receiver is ready to accept
notifications on the NETCONF session. This may require coordination
between the client that configures the subscription and the clients
for which the notifications are intended. This coordination is out
of the scope of this document.
3.4.2. Call Home for Configured Subscriptions
Once this configuration is active, if NETCONF transport is needed but
does not exist to one or more target IP address plus port, the server
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initiates a transport session via [RFC8071] to those receiver(s) in
the subscription using the address and port specified.
3.4.3. Full Establish Message Flow
+----------+ +-----------+ +---------+ +---------+
| Client | | Server | | Rcver A | | Rcver B |
+----------+ +-----------+ +---------+ +---------+
| | | |
| Capability Exchange | | |
|<-------------------------->| | |
| | | |
| | | |
| Edit-config | | |
|--------------------------->| | |
| RPC Reply: OK | | |
|<---------------------------| | |
| | Call Home | |
| |<-------------->| |
| |<--------------------------->|
| | | |
| | Subscription | |
| | Started | |
| | (id 22) | |
| |--------------->| |
| |---------------------------->|
| | | |
| | Notification | |
| | (id 22) | |
| |--------------->| |
| |---------------------------->|
| | | |
Figure 18: Message flow for configured subscription establishment
3.4.4. Modifying a Configured Subscription
Configured subscriptions can be modified using configuration
operations against the top-level subtree subscription-config.
For example, the subscription established in the previous section
could be modified as follows, choosing a different receiver:
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<rpc message-id="102"
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>
<identifier>
1922
</identifier>
<stream>
foo
</stream>
<receiver>
<address>
1.2.3.5
</address>
<port>
1234
</port>
</receiver>
</subscription>
</subscription-config>
</edit-config>
</rpc>
Figure 19: Modify configured subscription
if the request is accepted, the server would reply:
<rpc-reply message-id="102"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<ok/>
</rpc-reply>
Figure 20: A successful configured subscription modification
3.4.4.1. Message Flow Example
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+----------+ +-----------+ +---------+ +---------+
| Client | | Server | | Rcver A | | Rcver B |
+----------+ +-----------+ +---------+ +---------+
| | | |
| Capability Exchange | | |
|<-------------------------->| | |
| | | |
| | | |
| Edit-config | | |
|--------------------------->| | |
| RPC Reply: OK | | |
|<---------------------------| | |
| | Call Home | |
| |<-------------->| |
| |<--------------------------->|
| | | |
| | Subscription | |
| | Started | |
| | (id 22) | |
| |--------------->| |
| |---------------------------->|
| | | |
| | Notification | |
| | (id 22) | |
| |--------------->| |
| |---------------------------->|
| | | |
| Edit-config | | |
|--------------------------->| | |
| RPC Reply: OK | | |
|<---------------------------| | |
| | Subscription | |
| | Modified | |
| | (id 22) | |
| |--------------->| |
| |---------------------------->|
| | | |
| | Notification | |
| | (id 22) | |
| |--------------->| |
| |---------------------------->|
| | | |
Figure 21: Message flow for subscription modification (configured
subscription)
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3.4.5. Deleting a Configured Subscription
Subscriptions can be deleted using configuration operations against
the top-level subtree subscription-config. For example:
<rpc message-id="103"
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:2.0">
<subscription xc:operation="delete">
<identifier>
1922
</identifier>
</subscription>
</subscription-config>
</edit-config>
</rpc>
<rpc-reply message-id="103"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<ok/>
</rpc-reply>
Figure 22: Deleting a configured subscription
3.4.5.1. Message Flow Example
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+----------+ +-----------+ +---------+ +---------+
| Client | | Server | | Rcver A | | Rcver B |
+----------+ +-----------+ +---------+ +---------+
| | | |
| Capability Exchange | | |
|<-------------------------->| | |
| | | |
| | | |
| Edit-config | | |
|--------------------------->| | |
| RPC Reply: OK | | |
|<---------------------------| | |
| | Call Home | |
| |<-------------->| |
| |<--------------------------->|
| | | |
| | Subscription | |
| | Started | |
| | (id 22) | |
| |--------------->| |
| |---------------------------->|
| | | |
| | | |
| | Notification | |
| | (id 22) | |
| |--------------->| |
| |---------------------------->|
| | | |
| Edit-config | | |
|--------------------------->| | |
| RPC Reply: OK | | |
|<---------------------------| | |
| | Subscription | |
| | Terminated | |
| | (id 22) | |
| |--------------->| |
| |---------------------------->|
| | | |
Figure 23: Message flow for subscription deletion (configured
subscription)
3.4.6. Event (Data Plane) Notifications
Once a dynamic or configured subscription has been created, the
NETCONF server sends (asynchronously) event notifications from the
subscribed stream to receiver(s) over NETCONF. We refer to these as
data plane notifications. The data model for Event Notifications is
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defined in [subscribe]. This document extends that data model for
supporting different encondigs.
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 24: Definition of a event notification
This notification might result in the following, prior to it being
placed into NETCONF. Note that the mandatory eventTime and
Subscription id have been added.
<notification
xmlns=" urn:ietf:params:xml:ns:netconf:notification:2.0">
<eventTime>2007-09-01T10:00:00Z</eventTime>
<subscription-id>39</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 25: Event notification
In order to support JSON encoding, this document extends the data
model for Event Notifications, adding a new element, i.e.,
notification-contents-json. This element contains the event
notification-specific tagged content in JSON. For the event
notification above, the equivalent using JSON encoding would be
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<notification
xmlns="urn:ietf:params:xml:ns:netconf:notification:2.0">
<eventTime>2007-09-01T10:00:00Z</eventTime>
<subscription-id>39</subscription-id>
<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 26: Event notification using JSON encoding
3.4.7. Subscription State Notifications
In addition to data plane notifications, a publisher may send
subscription state notifications (defined in [subscribe]) to indicate
to receivers that an event related to the subscription management has
occurred. Subscription state notifications cannot be filtered out.
Next we exemplify them using both XML, and JSON encodings for the
notification-specific content:
3.4.7.1. subscription-started and subscription-modified
A subscription-started would look like:
<notification
xmlns=" urn:ietf:params:xml:ns:netconf:notification:2.0">
<eventTime>2007-09-01T10:00:00Z</eventTime>
<subscription-started
xmlns="urn:ietf:params:xml:ns:netconf:notification:2.0"/>
<identifier>39</identifier>
<event-filter-type>xpath</event-filter-type>
<event-filter 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')]"/>
</subscription-started/>
</notification>
Figure 27: subscription-started subscription state notification
The equivalent using JSON encoding would be:
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<notification
xmlns=" urn:ietf:params:xml:ns:netconf:notification:2.0">
<eventTime>2007-09-01T10:00:00Z</eventTime>
<notification-contents-json>
{
"notif-bis:subscription-started": {
"identifier" : 39
}
}
</notification-contents-json>
</notification>
Figure 28: subscription-started subscription state notification
(JSON)
The subscription-modified is identical, with just the word "started"
being replaced by "modified".
3.4.7.2. notification-complete, subscription-resumed, and replay-
complete
A notification-complete would look like:
<notification
xmlns=" urn:ietf:params:xml:ns:netconf:notification:2.0">
<eventTime>2007-09-01T10:00:00Z</eventTime>
<notification-complete
xmlns="urn:ietf:params:xml:ns:netconf:notification:2.0">
<identifier>39</identifier>
</notification-complete>
</notification>
Figure 29: notification-complete notification in XML
The equivalent using JSON encoding would be:
<notification
xmlns=" urn:ietf:params:xml:ns:netconf:notification:2.0">
<eventTime>2007-09-01T10:00:00Z</eventTime>
<notification-contents-json>
{
"netmod-notif:notification-complete": {
"identifier" : 39
}
</notification-contents-json>
</notification>
Figure 30: notification-complete notification in JSON
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The subscription-resumed and replay-complete are virutally identical,
with "notification-complete" simply being replaced by "subscription-
resumed" and "replay-complete" in both encodings.
3.4.7.3. subscription-terminated and subscription-suspended
A subscription-terminated would look like:
<notification
xmlns=" urn:ietf:params:xml:ns:netconf:notification:2.0">
<eventTime>2007-09-01T10:00:00Z</eventTime>
<subscription-terminated
xmlns="urn:ietf:params:xml:ns:netconf:notification:2.0">
<identifier>39</identifier>
<error-id>no-such-subscription</error-id>
</subscription-terminated>
</notification>
Figure 31: subscription-modified subscription state notification
The above, and the subscription-suspended are virutally identical,
with "subscription-terminated" simply being replaced by
"subscription-suspended".
3.4.7.4. Notification Message Flow Examples
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+------------+ +-----------+
| Client | | Server |
+------------+ +-----------+
| |
| Capability Exchange |
|<---------------------------->|
| |
| Establish Subscription |
|<---------------------------->|
| |
| Notification |
|<-----------------------------|
| |
| |
| Subscription Suspended |
|<-----------------------------|
| |
| |
| |
| Subscription Resumed |
|<-----------------------------|
| |
| Notification |
|<-----------------------------|
| |
Figure 32: subscription-suspended and resumed notifications
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+----------+ +-----------+ +---------+ +---------+
| Client | | Server | | Rcver A | | Rcver B |
+----------+ +-----------+ +---------+ +---------+
| | | |
| Capability Exchange | | |
|<-------------------------->| | |
| | | |
| Edit-config | | |
|--------------------------->| | |
| RPC Reply: OK | | |
|<---------------------------| | |
| | Subscription | |
| | Started | |
| |--------------->| |
| |---------------------------->|
| | | |
| | Notification | |
| |--------------->| |
| |---------------------------->|
| | | |
| | Subscription | |
| | Suspended | |
| |--------------->| |
| | | |
| | Notification | |
| |---------------------------->|
| | | |
| | Subscription | |
| | Resumed | |
| |--------------->| |
| | | |
| | Notification | |
| |--------------->| |
| |---------------------------->|
| | | |
Figure 33: Suspended and resumed notificatiosn for a single
configured receiver
4. Interleave Capability
The :interleave capability is originally defined in [RFC5277]. It is
incorporated in this document with essentialy the same semantics.
That is, the NETCONF server MUST receive, process, and respond to
NETCONF requests on a session with active notification subscriptions.
Note that subscription operations MUST be received, processed, and
responded on a session with active notification subscriptions This
mandatory requirement together with the :inteleave capability permits
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a client performing all operations against a server using a single
connection, allowing for better scalability with respect to the
number of NETCONF sessions required to manage an entity. The
:interleave capability is identified by the following string:
urn:ietf:params:netconf:capability:interleave:1.0
5. Security Considerations
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.
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 content involved.
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 <establish-
subscription>requests, then these subscriptions accumulate and may
use up system resources. In such a situation, subscriptions MAY be
terminated by terminating the suspect underlying NETCONF sessions.
The server MAY also suspend or terminate a subset of the active
subscriptions on the NETCONF session .
Configured subscriptions from one or more publishers could be used to
overwhelm a receiver, which perhaps doesn't even support
subscriptions. Clients that do not want pushed data need only
terminate or refuse any transport sessions from the publisher.
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.
6. Acknowledgments
We wish to acknowledge the helpful contributions, comments, and
suggestions that were received from: Andy Bierman, Yan Gang, Sharon
Chisholm, Hector Trevino, Peipei Guo, Susan Hares, Tim Jenkins,
Balazs Lengyel, Kent Watsen, and Guangying Zheng.
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7. References
7.1. 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>.
[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>.
[RFC8071] Watsen, K., "NETCONF Call Home and RESTCONF Call Home",
RFC 8071, DOI 10.17487/RFC8071, February 2017,
<http://www.rfc-editor.org/info/rfc8071>.
7.2. Informative References
[subscribe]
Voit, Eric., Clemm, A., Gonzalez Prieto, A., Nilsen-
Nygaard, E., and A. Tripathy, "Subscribing to Event
Notifications", April 2016,
<https://datatracker.ietf.org/doc/draft-ietf-netconf-
subscribed-notifications/>.
[yang-push]
Clemm, A., Gonzalez Prieto, A., Voit, Eric., Tripathy, A.,
and E. Nilsen-Nygaard, "Subscribing to YANG datastore push
updates", April 2017, <https://datatracker.ietf.org/doc/
draft-ietf-netconf-yang-push/>.
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Appendix A. Open Items
(To be removed by RFC editor prior to publication)
o Formal definition of: notification-contents-json. It depends on
the formal definition of the notification element
o Specify how to indicate a stream is not part of the NETCONF
stream. It depends on draft-ietf-netconf-subscribed-notifications
Appendix B. Changes between revisions
(To be removed by RFC editor prior to publication)
B.1. v03 to v04
o Added additional detail to "configured subscriptions"
o Added interleave capability
o Adjusted terminology to that in draft-ietf-netconf-subscribed-
notifications
o Corrected namespaces in examples
B.2. v01 to v03
o Text simplifications throughout
o v02 had no meaningful changes
B.3. v00 to v01
o Added Call Home in solution for configured subscriptions.
o Clarified support for multiple subscription on a single session.
No need to support multiple create-subscription.
o Added mapping between terminology in [yang-push] and [RFC6241]
(the one followed in this document).
o Editorial improvements.
Authors' Addresses
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Alberto Gonzalez Prieto
VMware
Email: agonzalezpri@vmware.com
Alexander Clemm
Huawei
Email: ludwig@clemm.org
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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