NETCONF E. Voit
Internet-Draft Cisco Systems
Intended status: Standards Track A. Clemm
Expires: November 5, 2018 Huawei
A. Gonzalez Prieto
VMware
E. Nilsen-Nygaard
A. Tripathy
Cisco Systems
May 4, 2018
NETCONF Support for Event Notifications
draft-ietf-netconf-netconf-event-notifications-09
Abstract
This document provides a NETCONF binding to subscribed notifications
and to YANG push.
RFC Editor note: please replace the four references to pre-RFC
normative drafts with the actual assigned RFC numbers.
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
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Internet-Drafts are draft documents valid for a maximum of six months
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This Internet-Draft will expire on November 5, 2018.
Copyright Notice
Copyright (c) 2018 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
(https://trustee.ietf.org/license-info) in effect on the date of
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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. Interleave Capability . . . . . . . . . . . . . . . . . . . . 3
4. Compatibility with RFC-5277's create-subscription . . . . . . 3
5. Mandatory XML, event stream and datastore support . . . . . . 4
6. NETCONF connectivity and the subscription lifecycle . . . . . 4
6.1. Dynamic Subscriptions . . . . . . . . . . . . . . . . . . 4
6.2. Configured Subscriptions . . . . . . . . . . . . . . . . 4
7. Notification Messages . . . . . . . . . . . . . . . . . . . . 5
8. Dynamic Subscriptions and RPC Error Responses . . . . . . . . 5
9. YANG module . . . . . . . . . . . . . . . . . . . . . . . . . 6
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
11. Security Considerations . . . . . . . . . . . . . . . . . . . 8
12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 9
13. Normative References . . . . . . . . . . . . . . . . . . . . 9
Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 10
A.1. Event Stream Discovery . . . . . . . . . . . . . . . . . 10
A.2. Dynamic Subscriptions . . . . . . . . . . . . . . . . . . 11
A.3. Configured Subscriptions . . . . . . . . . . . . . . . . 15
A.4. Subscription State Notifications . . . . . . . . . . . . 20
Appendix B. Changes between revisions . . . . . . . . . . . . . 22
B.1. v08 to v09 . . . . . . . . . . . . . . . . . . . . . . . 22
B.2. v07 to v08 . . . . . . . . . . . . . . . . . . . . . . . 22
B.3. v06 to v07 . . . . . . . . . . . . . . . . . . . . . . . 22
B.4. v05 to v06 . . . . . . . . . . . . . . . . . . . . . . . 22
B.5. v03 to v04 . . . . . . . . . . . . . . . . . . . . . . . 23
B.6. v01 to v03 . . . . . . . . . . . . . . . . . . . . . . . 23
B.7. v00 to v01 . . . . . . . . . . . . . . . . . . . . . . . 23
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23
1. Introduction
This document provides a binding for events streamed over the NETCONF
protocol [RFC6241] as per
[I-D.draft-ietf-netconf-subscribed-notifications]. In addition, as
[I-D.ietf-netconf-yang-push] is itself built upon
[I-D.draft-ietf-netconf-subscribed-notifications], this document
enables a NETCONF client to request and receive updates from a YANG
datastore located on a NETCONF server.
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2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
The following terms are defined in
[I-D.draft-ietf-netconf-subscribed-notifications]: notification
message, event stream, publisher, receiver, subscriber, subscription,
configured subscription.
3. Interleave Capability
To support multiple subscriptions on a single session, a NETCONF
publisher MUST support the :interleave capability as defined in
[RFC5277]. Advertisement of both the :interleave capability and
"urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications" within a
NETCONF capability exchange MUST indicate that a NETCONF publisher is
able to receive, process, and respond to NETCONF requests and
[I-D.draft-ietf-netconf-subscribed-notifications] subscription
operations.
4. Compatibility with RFC-5277's create-subscription
A publisher is allowed to concurrently support configured
subscriptions and dynamic subscription RPCs of
[I-D.draft-ietf-netconf-subscribed-notifications] at the same time as
[RFC5277]'s "create-subscription" RPC. However a single NETCONF
transport session cannot support both this specification and a
subscription established by [RFC5277]'s "create-subscription" RPC.
To protect against any attempts to use a single NETCONF transport
session in this way:
o A solution must reply with the [RFC6241] error "operation-not-
supported" if a "create-subscription" RPC is received on a NETCONF
session where any other
[I-D.draft-ietf-netconf-subscribed-notifications] or [RFC5277]
subscription exists.
o It is a prohibited to send updates or state change notifications
for a configured subscription on a NETCONF session where the
create-subscription RPC has successfully [RFC5277] created
subscription.
o A "create-subscription" RPC MUST be rejected if any
[I-D.draft-ietf-netconf-subscribed-notifications] or
[RFC5277]subscription is active across that NETCONF transport
session.
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If a publisher supports this specification but not subscriptions via
[RFC5277], the publisher MUST NOT advertise
"urn:ietf:params:netconf:capability:notification:1.0".
5. Mandatory XML, event stream and datastore support
The "encode-xml" feature of
[I-D.draft-ietf-netconf-subscribed-notifications] is mandatory to
support. This indicates that XML is a valid encoding for RPCs, state
change notifications, and subscribed content.
A NETCONF publisher supporting event stream subscription via
[I-D.draft-ietf-netconf-subscribed-notifications] MUST support the
"NETCONF" event stream identified in that draft.
A NETCONF publisher supporting [I-D.ietf-netconf-yang-push] MUST
support the operational state datastore as defined by
[I.D.draft-ietf-netmod-revised-datastores].
6. NETCONF connectivity and the subscription lifecycle
This section describes how the availability of NETCONF transport
impacts the establishment and lifecycle of different types of
[I-D.draft-ietf-netconf-subscribed-notifications] subscriptions.
6.1. Dynamic Subscriptions
For dynamic subscriptions, if the NETCONF session involved with the
"establish-subscription" terminates, the subscription MUST be
deleted.
6.2. Configured Subscriptions
For a configured subscription, there is no guarantee a transport
session is currently in place with each associated receiver. In
cases where a configured subscription has a receiver in the
CONNECTING state as described in
[I-D.draft-ietf-netconf-subscribed-notifications], section 2.5.1, and
the "transport" for that subscription is "NETCONF", but no NETCONF
transport session exists to that receiver (or all existing NETCONF
transport sessions are currently supporting [RFC5277] subscriptions),
then the publisher MUST initiate a transport session via NETCONF call
home [RFC8071], section 4.1 to that receiver. Until NETCONF
connectivity is established and a "subscription-started" state change
notification is successfully sent, that receiver MUST remain in
either the CONNECTING or the TIMEOUT state.
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If the call home fails because the publisher receives receiver
credentials which are subsequently declined per [RFC8071],
Section 4.1, step S5 authentication, then that receiver MUST be
placed into the TIMEOUT state.
If the call home fails to establish for any other reason, the
publisher MUST NOT progress the receiver to the ACTIVE state.
Additionally, the publisher SHOULD place the receiver into the
TIMEOUT state after a predetermined number of either failed call home
attempts or NETCONF sessions remotely terminated by the receiver.
NETCONF transport session connectivity SHOULD be verified via
Section 4.1, step S7.
If a NETCONF session is disconnected but the "stop-time" of a
subscription being transported over that session has not been
reached, the publisher restarts the call home process and return the
receiver to the CONNECTING state.
7. Notification Messages
Notification messages transported over the NETCONF protocol will be
identical in format and content to those encoded using one-way
operations defined within [RFC5277], section 4.
8. Dynamic Subscriptions and RPC Error Responses
Management of dynamic subscriptions occurs via RPCs as defined in
[I-D.ietf-netconf-yang-push] and
[I-D.draft-ietf-netconf-subscribed-notifications]. When an RPC error
occurs, the NETCONF RPC reply MUST include an "rpc-error" element per
[RFC6241] with the error information populated as follows:
o an "error-type" node of "application".
o an "error-tag" node of "operation-failed".
o an "error-severity" of "error" (this MAY but does not have to be
included).
o an "error-app-tag" node with the value being a string that
corresponds to an identity associated with the error, as defined
in [I-D.draft-ietf-netconf-subscribed-notifications] section 2.4.6
for general subscriptions, and [I-D.ietf-netconf-yang-push]
Appendix A.1, for datastore subscriptions. The tag to use depends
on the RPC for which the error occurred. Viable errors for
different RPCs are as follows:
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RPC use base identity
---------------------- ----------------------------
establish-subscription establish-subscription-error
modify-subscription modify-subscription-error
delete-subscription delete-subscription-error
kill-subscription kill-subscription-error
resynch-subscription resynch-subscription-error
o In case of error responses to an "establish-subscription" or
"modify-subscription" request there is the option of including an
"error-info" node. This node may contain XML-encoded data with
hints for parameter settings that might lead to successful RPC
requests in the future. Following are the yang-data structures
which may be returned:
establish-subscription returns hints in yang-data structure
---------------------- ------------------------------------
target: event stream establish-subscription-stream-error-info
target: datastore establish-subscription-datastore-error-info
modify-subscription returns hints in yang-data structure
---------------------- ------------------------------------
target: event stream modify-subscription-stream-error-info
target: datastore modify-subscription-datastore-error-info
The yang-data included within "error-info" SHOULD NOT include the
optional leaf "error-reason", as such a leaf would be redundant
with information that is already placed within the
"error-app-tag".
In case of an rpc error as a result of a "delete-subscription", a
"kill-subscription", or a "resynch-subscription" request, no
"error-info" needs to be included, as the "subscription-id" is
the only RPC input parameter and no hints regarding this RPC input
parameters need to be provided.
Note that "error-path" does not need to be included with the "rpc-
error" element, as subscription errors are generally not associated
with nodes in the datastore but with the choice of RPC input
parameters.
9. YANG module
This module references
[I-D.draft-ietf-netconf-subscribed-notifications].
[ note to the RFC Editor - please replace XXXX within this YANG model
with the number of this document ]
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module ietf-netconf-subscribed-notifications {
yang-version 1.1;
namespace
"urn:ietf:params:xml:ns:yang:ietf-netconf-subscribed-notifications";
prefix nsn;
import ietf-subscribed-notifications {
prefix sn;
}
organization "IETF NETCONF (Network Configuration) Working Group";
contact
"WG Web: <http:/tools.ietf.org/wg/netconf/>
WG List: <mailto:netconf@ietf.org>
Editor: Eric Voit
<mailto:evoit@cisco.com>
Editor: Alexander Clemm
<mailto:ludwig@clemm.org>
Editor: Alberto Gonzalez Prieto
<mailto:agonzalezpri@vmware.com>
Editor: Ambika Prasad Tripathy
<mailto:ambtripa@cisco.com>
Editor: Einar Nilsen-Nygaard
<mailto:einarnn@cisco.com>";
description
"Defines NETCONF as a supported transport for subscribed event
notifications.
Copyright (c) 2018 IETF Trust and the persons identified as authors
of the code. All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, is permitted pursuant to, and subject to the license
terms contained in, the Simplified BSD License set forth in Section
4.c of the IETF Trust's Legal Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX; see the RFC
itself for full legal notices.";
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revision 2018-04-20 {
description
"Initial version";
reference
"RFC XXXX: NETCONF Support for Event Notifications";
}
identity netconf {
base sn:transport;
base sn:inline-address;
description
"NETCONF is used as a transport for notification messages and
state change notifications.";
}
}
10. IANA Considerations
This document registers the following namespace URI in the "IETF XML
Registry" [RFC3688]:
URI: urn:ietf:params:xml:ns:yang:ietf-netconf-subscribed-
notifications
Registrant Contact: The IESG.
XML: N/A; the requested URI is an XML namespace.
This document registers the following YANG module in the "YANG Module
Names" registry [RFC6020]:
Name: ietf-netconf-subscribed-notifications
Namespace: urn:ietf:params:xml:ns:yang:ietf-netconf-subscribed-
notifications
Prefix: nsn
Reference: RFC XXXX: NETCONF Support for Event Notifications
11. Security Considerations
Notification messages (including state change notifications) are
never sent before the NETCONF capabilities exchange has completed.
If a malicious or buggy NETCONF subscriber 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 underlying NETCONF session. The
publisher MAY also suspend or terminate a subset of the active
subscriptions on that NETCONF session.
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This draft does not define a YANG module and therefore doesn't have
any YANG-related Security Considerations.
12. 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, Martin Bjorklund, Mahesh Jethanandani, Kent Watsen,
and Guangying Zheng.
13. Normative References
[I-D.draft-ietf-netconf-subscribed-notifications]
Voit, E., Clemm, A., Gonzalez Prieto, A., Tripathy, A.,
and E. Nilsen-Nygaard, "Customized Subscriptions to a
Publisher's Event Streams", draft-ietf-netconf-subscribed-
notifications-11 (work in progress), April 2018.
[I-D.ietf-netconf-yang-push]
Clemm, Alexander., Voit, Eric., Gonzalez Prieto, Alberto.,
Tripathy, A., Nilsen-Nygaard, E., Bierman, A., and B.
Lengyel, "YANG Datastore Subscription", February 2018,
<https://datatracker.ietf.org/doc/
draft-ietf-netconf-yang-push/>.
[I.D.draft-ietf-netmod-revised-datastores]
Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K.,
and R. Wilton, "Network Management Datastore
Architecture", draft-ietf-netmod-revised-datastores-10
(work in progress), January 2018.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004,
<https://www.rfc-editor.org/info/rfc3688>.
[RFC5277] Chisholm, S. and H. Trevino, "NETCONF Event
Notifications", RFC 5277, DOI 10.17487/RFC5277, July 2008,
<https://www.rfc-editor.org/info/rfc5277>.
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[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for
the Network Configuration Protocol (NETCONF)", RFC 6020,
DOI 10.17487/RFC6020, October 2010,
<https://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,
<https://www.rfc-editor.org/info/rfc6241>.
[RFC8071] Watsen, K., "NETCONF Call Home and RESTCONF Call Home",
RFC 8071, DOI 10.17487/RFC8071, February 2017,
<https://www.rfc-editor.org/info/rfc8071>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
Appendix A. Examples
This section is non-normative.
A.1. Event Stream Discovery
As defined in [I-D.draft-ietf-netconf-subscribed-notifications] 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 publisher using the "get" operation
against the top-level container "/streams" defined in
[I-D.draft-ietf-netconf-subscribed-notifications] Section 3.1.
The following example illustrates the retrieval of the list of
available event streams:
<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:yang:ietf-subscribed-notifications"/>
</filter>
</get>
</rpc>
Figure 1: Get streams request
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After such a request, the NETCONF publisher returns a list of event
streams available, as well as additional information which might
exist in the container.
A.2. Dynamic Subscriptions
A.2.1. Establishing Dynamic Subscriptions
The following figure shows two successful "establish-subscription"
RPC requests as per
[I-D.draft-ietf-netconf-subscribed-notifications]. The first request
is given a subscription identifier of 22, the second, an identifier
of 23.
+------------+ +-----------+
| Subscriber | | Publisher |
+------------+ +-----------+
| |
| Capability Exchange |
|<---------------------------->|
| |
| |
| establish-subscription |
|----------------------------->| (a)
| RPC Reply: OK, id = 22 |
|<-----------------------------| (b)
| |
| notification message (for 22)|
|<-----------------------------|
| |
| |
| establish-subscription |
|----------------------------->|
| RPC Reply: OK, id = 23 |
|<-----------------------------|
| |
| |
| notification message (for 22)|
|<-----------------------------|
| notification message (for 23)|
|<-----------------------------|
| |
Figure 2: Multiple subscriptions over a NETCONF session
To provide examples of the information being transported, example
messages for interactions (a) and (b) in Figure 2 are detailed below:
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<rpc message-id="102" xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<establish-subscription
xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications">
<stream>NETCONF</stream>
<stream-xpath-filter xmlns:ex="http://example.com/events">
/ex:foo/
</stream-xpath-filter>
<dscp>10</dscp>
</establish-subscription>
</rpc>
Figure 3: establish-subscription request (a)
As NETCONF publisher was able to fully satisfy the request (a), the
publisher sends the subscription identifier of the accepted
subscription within message (b):
<rpc-reply message-id="102"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<identifier
xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications">
22
</identifier>
</rpc-reply>
Figure 4: establish-subscription success (b)
If the NETCONF publisher had not been able to fully satisfy the
request, or subscriber has no authorization to establish the
subscription, the publisher would have sent an RPC error response.
For instance, if the "dscp" value of 10 asserted by the subscriber in
Figure 3 proved unacceptable, the publisher may have returned:
<rpc-reply message-id="102"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<rpc-error>
<error-type>application</error-type>
<error-tag>operation-failed</error-tag>
<error-severity>error</error-severity>
<error-app-tag>dscp-unavailable</error-app-tag>
</rpc-error>
</rpc-reply>
Figure 5: an unsuccessful establish subscription
The subscriber can use this information in future attempts to
establish a subscription.
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A.2.2. Modifying Dynamic Subscriptions
An existing subscription may be modified. The following exchange
shows a negotiation of such a modification via several exchanges
between a subscriber and a publisher. This negotiation consists of a
failed RPC modification request/response, followed by a successful
one.
+------------+ +-----------+
| Subscriber | | Publisher |
+------------+ +-----------+
| |
| notification message (for 23)|
|<-----------------------------|
| |
| modify-subscription (id = 23)|
|----------------------------->| (c)
| RPC error (with hint) |
|<-----------------------------| (d)
| |
| modify-subscription (id = 23)|
|----------------------------->|
| RPC Reply: OK |
|<-----------------------------|
| |
| notification message (for 23)|
|<-----------------------------|
| |
Figure 6: Interaction model for successful subscription modification
If the subscription being modified in Figure 6 is a datastore
subscription as per [I-D.ietf-netconf-yang-push], the modification
request made in (c) may look like that shown in Figure 7. As can be
seen, the modifications being attempted are the application of a new
xpath filter as well as the setting of a new periodic time interval.
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<rpc message-id="303"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<modify-subscription
xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications"
xmlns:yp="urn:ietf:params:xml:ns:yang:ietf-yang-push">
<identifier>23</identifier>
<yp:datastore-xpath-filter xmlns="http://example.com/datastore">
/interfaces-state/interface/oper-status
</yp:datastore-xpath-filter>
<yp:periodic>
<yp:period>500</yp:period>
</yp:periodic>
</modify-subscription>
</rpc>
Figure 7: Subscription modification request (c)
If the NETCONF publisher can satisfy both changes, the publisher
sends a positive result for the RPC. If the NETCONF publisher cannot
satisfy either of the proposed changes, the publisher sends an RPC
error response (d). The following is an example RPC error response
for (d) which includes a hint. This hint is an alternative time
period value which might have resulted in a successful modification:
<rpc-reply message-id="303"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<rpc-error>
<error-type>application</error-type>
<error-tag>operation-failed</error-tag>
<error-severity>error</error-severity>
<error-app-tag>
period-unsupported
</error-app-tag>
<error-info
xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-push">
<modify-subscription-datastore-error-info>
<period-hint>
3000
</period-hint>
</modify-subscription-datastore-error-info>
</error-info>
</rpc-error>
</rpc-reply>
Figure 8: Modify subscription failure with Hint (d)
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A.2.3. Deleting Dynamic Subscriptions
The following demonstrates deleting a subscription. This
subscription may have been to either a stream or a datastore.
<rpc message-id="103"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<delete-subscription
xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications">
<identifier>22</identifier>
</delete-subscription>
</rpc>
Figure 9: Delete subscription
If the NETCONF publisher can satisfy the request, the publisher
replies with success to the RPC request.
If the NETCONF publisher cannot satisfy the request, the publisher
sends an error-rpc element indicating the modification didn't work.
Figure 10 shows a valid response for existing valid subscription
identifier, but that subscription identifier was created on a
different NETCONF transport session:
<rpc-reply message-id="103"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<rpc-error>
<error-type>application</error-type>
<error-tag>operation-failed</error-tag>
<error-severity>error</error-severity>
<error-app-tag>
no-such-subscription
</error-app-tag>
</rpc-error>
</rpc-reply>
Figure 10: Unsuccessful delete subscription
A.3. Configured Subscriptions
Configured subscriptions may be established, modified, and deleted
using configuration operations against the top-level subtree of
[I-D.draft-ietf-netconf-subscribed-notifications] or
[I-D.ietf-netconf-yang-push].
In this section, we present examples of how to manage the
configuration subscriptions using a NETCONF client.
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A.3.1. Creating Configured Subscriptions
For subscription creation, a NETCONF client may send:
<rpc message-id="201" xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<edit-config>
<target>
<running/>
</target>
<default-operation>none</default-operation>
<config>
<subscriptions
xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications">
<subscription>
<identifier>1922</identifier>
<transport xmlns:nsn=
"urn:ietf:params:xml:ns:yang:ietf-netconf-subscribed-notifications">
nsn:netconf
<transport>
<stream>NETCONF</stream>
<receivers>
<receiver>
<name>receiver1</name>
<address>1.2.3.4</address>
</receiver>
</receivers>
</subscription>
</subscriptions>
</config>
</edit-config>
</rpc>
Figure 11: Create a configured subscription
If the request is accepted, the publisher will indicate this. If the
request is not accepted because the publisher cannot serve it, no
configuration is changed. In this case the publisher may reply:
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<rpc-reply message-id="201"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<rpc-error>
<error-type>application</error-type>
<error-tag>resource-denied</error-tag>
<error-severity>error</error-severity>
<error-message xml:lang="en">
Temporarily the publisher cannot serve this
subscription due to the current workload.
</error-message>
</rpc-error>
</rpc-reply>
Figure 12: Response to a failed configured subscription establishment
After a subscription has been created, NETCONF connectivity to each
receiver will be established if it does not already exist. This will
be accomplished via [RFC8071].
The following figure shows the interaction model for the successful
creation of a configured subscription.
+----------+ +-----------+ +---------+
|Config Ops| | Publisher | | 1.2.3.4 |
+----------+ +-----------+ +---------+
| | |
| Capability Exchange | |
|<-------------------------->| |
| | |
| | |
| Edit-config | |
|--------------------------->| |
| RPC Reply: OK | |
|<---------------------------| |
| | Call Home |
| |<-------------->|
| | |
| | subscription- |
| | started |
| |--------------->|
| | |
| | notification |
| | message |
| |--------------->|
Figure 13: Interaction model for configured subscription
establishment
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A.3.2. Modifying Configured Subscriptions
Configured subscriptions can be modified using configuration
operations against the top-level container "/subscriptions".
For example, the subscription established in the previous section
could be modified as follows, here a adding a second receiver:
<rpc message-id="202" xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<edit-config>
<target>
<running/>
</target>
<config>
<subscriptions
xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications">
<subscription>
<identifier>
1922
</identifier>
<receivers>
<receiver>
<name>receiver2</name>
<address>1.2.3.5</address>
</receiver>
</receivers>
</subscription>
</subscriptions>
</config>
</edit-config>
</rpc>
Figure 14: Modify configured subscription
If the request is accepted, the publisher will indicate success. The
result is that the interaction model described in Figure 13 may be
extended as follows.
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+----------+ +-----------+ +---------+ +---------+
|Config Ops| | Publisher | | 1.2.3.4 | | 1.2.3.5 |
+----------+ +-----------+ +---------+ +---------+
| | notification | |
| | message | |
| |--------------->| |
| Edit-config | | |
|--------------------------->| | |
| RPC Reply: OK | | |
|<---------------------------| | |
| | subscription- | |
| | started | |
| |---------------------------->|
| | | |
| | notification | |
| | message | |
| |--------------->| |
| |---------------------------->|
| | | |
Figure 15: Interaction model for configured subscription modification
Note in the above that in the specific example above, modifying a
configured subscription actually resulted in "subscription-started"
notification. And because of an existing NETCONF session, no
additional call home was needed. Also note that if the edit of the
configuration had impacted the filter, a separate modify-subscription
would have been required for the original receiver.
A.3.3. Deleting Configured Subscriptions
Configured subscriptions can be deleted using configuration
operations against the top-level container "/subscriptions".
Deleting the subscription above would result in the following flow
impacting all active receivers.
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+----------+ +-----------+ +---------+ +---------+
|Config Ops| | Publisher | | 1.2.3.4 | | 1.2.3.5 |
+----------+ +-----------+ +---------+ +---------+
| | | |
| | notification | |
| | message | |
| |--------------->| |
| |---------------------------->|
| | | |
| Edit-config | | |
|--------------------------->| | |
| RPC Reply: OK | | |
|<---------------------------| | |
| | subscription- | |
| | terminated | |
| |--------------->| |
| |---------------------------->|
| | | |
Figure 16: Interaction model for configured subscription deletion
A.4. Subscription State Notifications
A publisher will send subscription state notifications according to
the definitions within
[I-D.draft-ietf-netconf-subscribed-notifications]).
A.4.1. subscription-started and subscription-modified
A "subscription-started" over NETCONF encoded in XML would look like:
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<notification xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
<eventTime>2007-09-01T10:00:00Z</eventTime>
<subscription-started
xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications">
<identifier>39</identifier>
<transport xmlns:nsn=
"urn:ietf:params:xml:ns:yang:ietf-netconf-subscribed-notifications">
nsn:netconf
<transport>
<stream-xpath-filter xmlns:ex="http://example.com/events">
/ex:foo
</stream-xpath-filter>
<stream>NETCONF</stream>
</subscription-started>
</notification>
Figure 17: subscription-started subscription state notification
The "subscription-modified" is identical to Figure 17, with just the
word "started" being replaced by "modified".
A.4.2. subscription-completed, subscription-resumed, and replay-
complete
A "subscription-completed" would look like:
<notification
xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
<eventTime>2007-09-01T10:00:00Z</eventTime>
<subscription-completed
xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications">
<identifier>39</identifier>
</subscription-completed>
</notification>
Figure 18: subscription-completed notification in XML
The "subscription-resumed" and "replay-complete" are virtually
identical, with "subscription-completed" simply being replaced by
"subscription-resumed" and "replay-complete".
A.4.3. subscription-terminated and subscription-suspended
A "subscription-terminated" would look like:
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<notification
xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
<eventTime>2007-09-01T10:00:00Z</eventTime>
<subscription-terminated
xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications">
<identifier>39</identifier>
<error-id>
suspension-timeout
</error-id>
</subscription-terminated>
</notification>
Figure 19: subscription-terminated subscription state notification
The "subscription-suspended" is virtually identical, with
"subscription-terminated" simply being replaced by "subscription-
suspended".
Appendix B. Changes between revisions
(To be removed by RFC editor prior to publication)
B.1. v08 to v09
o Tweaks based on Kent's comments.
o Updated examples in Appendix A. And updates to some object names
based on changes in the subscribed-notifications draft.
o Added a YANG model for the NETCONF identity.
B.2. v07 to v08
o Tweaks and clarification on :interleave.
B.3. v06 to v07
o XML encoding and operational datastore mandatory.
o Error mechanisms and examples updated.
B.4. v05 to v06
o Moved examples to appendices
o All examples rewritten based on namespace learnings
o Normative text consolidated in front
o Removed all mention of JSON
o Call home process detailed
o Note: this is a major revision attempting to cover those comments
received from two week review.
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B.5. 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.6. v01 to v03
o Text simplifications throughout
o v02 had no meaningful changes
B.7. 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
Eric Voit
Cisco Systems
Email: evoit@cisco.com
Alexander Clemm
Huawei
Email: ludwig@clemm.org
Alberto Gonzalez Prieto
VMware
Email: agonzalezpri@vmware.com
Einar Nilsen-Nygaard
Cisco Systems
Email: einarnn@cisco.com
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Ambika Prasad Tripathy
Cisco Systems
Email: ambtripa@cisco.com
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