NETCONF T. Zhou
Internet-Draft G. Zheng
Intended status: Standards Track Huawei
Expires: 2 September 2025 E. Voit
Cisco Systems
T. Graf
Swisscom
P. Francois
INSA-Lyon
1 March 2025
Subscription to Distributed Notifications
draft-ietf-netconf-distributed-notif-13
Abstract
This document describes extensions to the YANG notifications
subscription to allow metrics being published directly from
processors on line cards to target receivers, while subscription is
still maintained at the route processor in a distributed forwarding
system.
Requirements Language
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.
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 https://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 2 September 2025.
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Copyright Notice
Copyright (c) 2025 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 publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminologies . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Solution Overview . . . . . . . . . . . . . . . . . . . . . . 4
5. Subscription Decomposition . . . . . . . . . . . . . . . . . 6
6. Publication Composition . . . . . . . . . . . . . . . . . . . 7
7. Subscription State Change Notifications . . . . . . . . . . . 7
8. Publisher Configurations . . . . . . . . . . . . . . . . . . 7
9. YANG Tree . . . . . . . . . . . . . . . . . . . . . . . . . . 8
10. YANG Module . . . . . . . . . . . . . . . . . . . . . . . . . 8
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
12. Implementation Status . . . . . . . . . . . . . . . . . . . . 12
12.1. Open Source Publisher . . . . . . . . . . . . . . . . . 12
12.2. Open Source Receiver Library . . . . . . . . . . . . . . 12
12.3. Pmacct Data Collection . . . . . . . . . . . . . . . . . 12
12.4. Huawei VRP . . . . . . . . . . . . . . . . . . . . . . . 12
12.5. 6WIND VSR . . . . . . . . . . . . . . . . . . . . . . . 12
13. Security Considerations . . . . . . . . . . . . . . . . . . . 12
14. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 13
15. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13
16. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
16.1. Normative References . . . . . . . . . . . . . . . . . . 13
16.2. Informative References . . . . . . . . . . . . . . . . . 14
Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 15
A.1. Dynamic Subscription . . . . . . . . . . . . . . . . . . 15
A.2. Configured Subscription . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21
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1. Introduction
The mechanism to support a subscription of a continuous and
customized stream of updates from a YANG datastore [RFC8342] is
defined in [RFC8639] and [RFC8641]. Requirements for Subscription to
YANG Datastores are defined in [RFC7923].
By streaming YANG-Push notifications from publishers to receivers,
much better performance and fine-grained sampling can be achieved
than with a polling-based mechanism. In a distributed forwarding
system, the packet forwarding is delegated to multiple processors on
line cards. To not to overwhelm the route processor resources, it is
not uncommon that data records are published directly from processors
on line cards to target Receivers to further increase efficiency on
the routing system.
This document complements the general subscription requirements
defined in section 4.2.1 of [RFC7923] by the paragraph: A
Subscription Service MAY support the ability to export from multiple
software processes on a single routing system and expose the
information which software process produced which message to maintain
data integrity.
2. Terminologies
The following terms are defined in [RFC8639] and are not redefined
here:
Subscriber
Publisher
Receiver
Subscription
In addition, this document defines the following terms:
Global Subscription: The Subscription requested by the subscriber.
It may be decomposed into multiple Component Subscriptions.
Component Subscription: The Subscription that defines a data source
which is managed and controlled by a single Publisher.
Global Capability: The overall subscription capability that the group
of Publishers can expose to the Subscriber.
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Component Capability: The subscription capability that each Publisher
can expose to the Subscriber.
Publisher Master: The Publisher that interacts with the Subscriber to
deal with the Global Subscription. It decomposes the Global
Subscription to multiple Component Subscriptions and interacts with
the Publisher Agents.
Publisher Agent: The Publisher that interacts with the Publisher
Master to deal with the Component Subscription and pushing the data
to the Receiver.
Node: The Publisher that obtains and pushes the data to the Receiver.
Message Publisher: The Publisher that pushes the message to the
Receiver.
Message Publisher ID: A 32-bit identifier of the publishing process
that is locally unique to the publisher node. With this identifier
the publishing process from where the message was published from can
be uniquely identified. Receivers SHOULD use the transport session
and the Publisher ID field to separate different publisher streams
originating from the same network node.
3. Motivation
Lost and corrupt YANG notification messages need to be recognized at
the receiver to ensure data integrity even when multiple publisher
processes publishing from the same transport session.
To preserve data integrity down to the publisher process, the Message
Publisher ID in the transport message header of the YANG notification
message is introduced. In case of UDP transport, this is described
in Section 3.2 of UDP-based transport [I-D.ietf-netconf-udp-notif].
4. Solution Overview
Figure 1 below shows the distributed data export framework.
A collector usually includes two components,
* the Subscriber generates the subscription instructions to express
what and how the Receiver wants to receive the data;
* the Receiver is the target for the data publication.
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For one subscription, there can be one or more Receivers. And the
Subscriber does not necessarily share the same IP address as the
Receivers.
In this framework, the Publisher pushes data to the Receiver
according to the subscription. The Publisher is either in the Master
or Agent role. The Publisher Master knows all the capabilities that
his Agents can provide and exposes the Global Capability to the
collector. The Subscriber maintains the Global Subscription at the
Publisher Master and disassembles the Global Subscription to multiple
Component Subscriptions, depending which source data is needed. The
Component Subscriptions are then distributed to the corresponding
Publisher Agents on route and processors on line cards.
Publisher Agents collects metrics according to the Component
Subscription, add its metadata, encapsulates, and pushes data to the
Receiver where packets are reassembled and decapsulated.
+-----------------------------------------+
| Collector |-------------+ |
| +------------+ | |
| +------------+ || Receiver | | |
| | Subscriber | |--------------+ |
| +-----^-+----+ +------------^ |
| | | | |
+-----------------------------------------+
Global | | Global |
Capability| | Subscription |
+-----------------------------------------+
| | | | |
| +--------+-v-------------------+ | |
| | Publisher(Master) | | |
| +--------^-+-------------------+ | |
| | | | |
| | | | |
| Component | | Component Push | |
| Capability| | Subscription | |
| +--------+-v-------------------+ | |
| | Publisher(Agent) +--+ |
| +------------------------------+ |
| |
| Network Node |
+-----------------------------------------+
Figure 1: The Distributed Data Export Framework
Publisher Master and Publisher Agents interact with each other in
several ways:
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* Publisher Agents need to register at the Master at the beginning
of their process life cycle.
* Contracts are created and maintained throughout the subscription
lifecycle between the Publisher Master and each Agent on the
Component Capability, and the format for notification data
structure.
* The Publisher Master relays the component subscriptions to the
Publisher Agents.
* The Publisher Agents announce the status of their Component
Subscriptions to the Publisher Master. The status of the overall
subscription is maintained by the Publisher Master. The Publisher
Master is responsible for notifying the subscriber in case of
problems with the Component Subscriptions.
The technical mechanisms or protocols used for the coordination of
operational information between Publisher Master and Agent is out of
scope of this document.
5. Subscription Decomposition
The Collector can only subscribe to the Master. This requires the
Publisher Master to:
1. expose the Global Capability that can be served by multiple
Publisher Agents;
2. disassemble the Global Subscription to multiple Component
Subscriptions, and distribute them to the Publisher Agents of the
corresponding metric sources so that they do not overlap;
3. notify changes related to the existing subscriptions to the
different Publisher Agents.
And the Publisher Agent to:
* Inherit the Global Subscription properties from Publisher Master
for its Component Subscription;
* share the same life-cycle as the Global Subscription;
* share the same Subscription ID as the Global Subscription.
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6. Publication Composition
The Publisher Agent collects data and encapsulates the packets per
Component Subscription. The format and structure of the data records
are defined by the YANG schema, so that the decomposition at the
Receiver can benefit from the structured and hierarchical data
records.
The Receiver can associate the YANG data records with Subscription ID
[RFC8639] to the subscribed subscription. Additionally, it can use
the Message Publisher ID to determine the corresponding publisher
process, ensuring message integrity.
For the dynamic subscription, the output of the "establish-
subscription" RPC defined in [RFC8639] MUST include a list of Message
Publisher IDs to indicate how the Global Subscription is decomposed
into several Component Subscriptions.
The "subscription-started" and "subscription-modified" notification
defined in [RFC8639] and "push-update" and "push-change-update"
notification defined in [RFC8641] MUST also include a list of Message
Publisher IDs to notify the current Publishers for the corresponding
Global Subscription.
7. Subscription State Change Notifications
In addition to sending event records to Receivers, the Master MUST
also send subscription state change notifications [RFC8639] when
events related to subscription management have occurred. All the
subscription state change notifications MUST be delivered by the
Master.
When the subscription decomposition result changed, the
"subscription-modified" notification MUST be sent to indicate the new
list of Publisher Agents.
8. Publisher Configurations
This document assumes that all Publisher Agents are preconfigured to
push data. The actual working Publisher Agents are selected based on
the subscription decomposition result.
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All Publisher Agents share the same source IP address for data
export. For connectionless data transport such as UDP based
transport [I-D.ietf-netconf-udp-notif] the same Layer 4 source port
for data export can be used. For connection based data transport
such as HTTPS based transport [I-D.ietf-netconf-https-notif], each
Publisher Agent MUST be able to acknowledge packet retrieval from
Receivers, and therefore requires a dedicated Layer 4 source port per
software process.
The specific configuration on transports is described in the
responsible documents.
9. YANG Tree
module: ietf-distributed-notif
augment /sn:subscriptions/sn:subscription:
+--ro message-publisher-ids* uint32
augment /sn:subscription-started:
+--ro message-publisher-ids* uint32
augment /sn:subscription-modified:
+--ro message-publisher-ids* uint32
augment /sn:establish-subscription/sn:output:
+--ro message-publisher-ids* uint32
augment /yp:push-update:
+--ro message-publisher-id? uint32
augment /yp:push-change-update:
+--ro message-publisher-id? uint32
10. YANG Module
<CODE BEGINS> file "ietf-distributed-notif@2024-04-14.yang"
module ietf-distributed-notif {
yang-version 1.1;
namespace
"urn:ietf:params:xml:ns:yang:ietf-distributed-notif";
prefix dn;
import ietf-subscribed-notifications {
prefix sn;
}
import ietf-yang-push {
prefix yp;
reference
"RFC 8641: Subscription to YANG Notifications for Datastore
Updates";
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}
organization "IETF NETCONF (Network Configuration) Working Group";
contact
"WG Web: <http:/tools.ietf.org/wg/netconf/>
WG List: <mailto:netconf@ietf.org>
Authors: Guangying Zheng
<mailto:zhengguangying@huawei.com>
Tianran Zhou
<mailto:zhoutianran@huawei.com>
Thomas Graf
<mailto:thomas.graf@swisscom.com>
Pierre Francois
<mailto:pierre.francois@insa-lyon.fr>
Eric Voit
<mailto:evoit@cisco.com>";
description
"Defines augmentation for ietf-subscribed-notifications to
enable the distributed publication with single subscription.
Copyright (c) 2025 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.";
revision 2024-04-21 {
description
"Initial version";
reference
"RFC XXXX: Subscription to Distributed Notifications";
}
grouping message-publisher-id {
description
"Provides a reusable leaf of te message-publisher-id.";
leaf message-publisher-id {
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type uint32;
config false;
description
"Identifies the software process which publishes the
message (e.g., processor 1 on line card 1). This field
is used to notify the receiver which publisher process
published which message.";
}
}
grouping message-publisher-ids {
description
"Provides a reusable leaf-list of message-publisher-id-list.";
leaf-list message-publisher-ids {
type uint32;
config false;
description
"Identifies the software process which publishes the
message (e.g., processor 1 on line card 1). This field
is used to notify the receiver which publisher processes
are going to publish.";
}
}
augment "/sn:subscriptions/sn:subscription" {
description
"This augmentation allows the Message
Publisher ID to be exposed for a subscription.";
uses message-publisher-ids;
}
augment "/sn:subscription-started" {
description
"This augmentation adds the Message Publisher ID to the
subscription-started subscription change notifications.";
uses message-publisher-ids;
}
augment "/sn:subscription-modified" {
description
"This augmentation adds the Message Publisher ID to the
subscription-modified subscription change notifications.";
uses message-publisher-ids;
}
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augment "/sn:establish-subscription/sn:output" {
description
"This augmentation adds the Message Publisher ID to the
dynamic establish-subscription output.";
uses message-publisher-ids;
}
augment "/yp:push-update" {
description
"This augmentation adds the Message Publisher ID in the
push-update notification.";
uses message-publisher-id;
}
augment "/yp:push-change-update" {
description
"This augmentation adds the Message Publisher ID in the
push-change-update notification.";
uses message-publisher-id;
}
}
<CODE ENDS>
11. IANA Considerations
This document registers the following namespace URI in the IETF XML
Registry [RFC3688]:
URI: urn:ietf:params:xml:ns:yang:ietf-distributed-notif
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 [RFC3688]:
Name: ietf-distributed-notif
Namespace: urn:ietf:params:xml:ns:yang:ietf-distributed-notif
Prefix: dn
Reference: RFC XXXX
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12. Implementation Status
Note to the RFC-Editor: Please remove this section before publishing.
12.1. Open Source Publisher
INSA Lyon implemented this document for a YANG Push publisher on
UDP-based Transport for Configured Subscriptions
[I-D.ietf-netconf-udp-notif] in an example implementation.
The open source code can be obtained here: [INSA-Lyon-Publisher].
12.2. Open Source Receiver Library
INSA Lyon implemented this document for a YANG Push receiver on
UDP-based Transport for Configured Subscriptions
[I-D.ietf-netconf-udp-notif] as a library.
The open source code can be obtained here: [INSA-Lyon-Receiver].
12.3. Pmacct Data Collection
The open source YANG push receiver library has been integrated into
the Pmacct open source Network Telemetry data collection.
The open source code can be obtained here: [Paolo-Lucente-Pmacct].
12.4. Huawei VRP
Huawei implemented this document for a YANG Push publisher on
UDP-based Transport for Configured Subscriptions
[I-D.ietf-netconf-udp-notif] in their VRP platform.
12.5. 6WIND VSR
6WIND implemented this document for a YANG Push publisher on
UDP-based Transport for Configured Subscriptions
[I-D.ietf-netconf-udp-notif] in their VSR platform.
13. Security Considerations
The YANG module specified in this document defines a schema for data
that is designed to be accessed via network management protocols such
as NETCONF [RFC6241] or RESTCONF [RFC8040]. The lowest NETCONF layer
is the secure transport layer, and the mandatory-to-implement secure
transport is Secure Shell (SSH) [RFC6242]. The lowest layer is
HTTPS, and the mandatory-to-implement secure transport is TLS
[RFC8446].
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The NETCONF Access Control Model (NACM) [RFC8341] provides the means
to restrict access particulary for NETCONF or RESTCONF users to a
preconfigured subset of all available NETCONF or RESTCONF protocol
operations and content.
The new data nodes introduced in this YANG module may be considered
sensitive or vulnerable in some network environments. It is thus
important to control read access (e.g., via get-config or
notification) to this data nodes. These are the subtrees and data
nodes and their sensitivity/vulnerability:
* /subscriptions/subscription/message-publisher-ids
The entries in the two lists above will show where subscribed
resources might be located on the publishers. Access control MUST be
set so that only someone with proper access permissions has the
ability to access this resource.
Other Security Considerations is the same as those discussed in
[RFC8639].
14. Contributors
Alexander Clemm
Futurewai
2330 Central Expressway
Santa Clara
California
United States of America
Email: ludwig@clemm.org
15. Acknowledgements
We thank Kent Watsen, Mahesh Jethanandani, Martin Bjorklund, Tim
Carey, Qin Wu, Robert Wilton, Benoit Claise, Alex Huang Feng and
Camilo Cardona for their constructive suggestions for improving this
document.
16. References
16.1. 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,
<https://www.rfc-editor.org/info/rfc2119>.
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[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004,
<https://www.rfc-editor.org/info/rfc3688>.
[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>.
[RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure
Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
<https://www.rfc-editor.org/info/rfc6242>.
[RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
<https://www.rfc-editor.org/info/rfc8040>.
[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>.
[RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration
Access Control Model", STD 91, RFC 8341,
DOI 10.17487/RFC8341, March 2018,
<https://www.rfc-editor.org/info/rfc8341>.
[RFC8342] Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K.,
and R. Wilton, "Network Management Datastore Architecture
(NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018,
<https://www.rfc-editor.org/info/rfc8342>.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>.
[RFC8639] Voit, E., Clemm, A., Gonzalez Prieto, A., Nilsen-Nygaard,
E., and A. Tripathy, "Subscription to YANG Notifications",
RFC 8639, DOI 10.17487/RFC8639, September 2019,
<https://www.rfc-editor.org/info/rfc8639>.
[RFC8641] Clemm, A. and E. Voit, "Subscription to YANG Notifications
for Datastore Updates", RFC 8641, DOI 10.17487/RFC8641,
September 2019, <https://www.rfc-editor.org/info/rfc8641>.
16.2. Informative References
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[I-D.ietf-netconf-https-notif]
Jethanandani, M. and K. Watsen, "An HTTPS-based Transport
for YANG Notifications", Work in Progress, Internet-Draft,
draft-ietf-netconf-https-notif-15, 1 February 2024,
<https://datatracker.ietf.org/doc/html/draft-ietf-netconf-
https-notif-15>.
[I-D.ietf-netconf-udp-notif]
Zheng, G., Zhou, T., Graf, T., Francois, P., Feng, A. H.,
and P. Lucente, "UDP-based Transport for Configured
Subscriptions", Work in Progress, Internet-Draft, draft-
ietf-netconf-udp-notif-19, 21 February 2025,
<https://datatracker.ietf.org/doc/html/draft-ietf-netconf-
udp-notif-19>.
[INSA-Lyon-Publisher]
"INSA Lyon, YANG Push publisher example implementation",
<https://github.com/network-analytics/udp-notif-scapy>.
[INSA-Lyon-Receiver]
"INSA Lyon, YANG Push receiver library implementation",
<https://github.com/network-analytics/udp-notif-
c-collector>.
[Paolo-Lucente-Pmacct]
"Paolo Lucente, Pmacct open source Network Telemetry Data
Collection", <https://github.com/pmacct/pmacct>.
[RFC7923] Voit, E., Clemm, A., and A. Gonzalez Prieto, "Requirements
for Subscription to YANG Datastores", RFC 7923,
DOI 10.17487/RFC7923, June 2016,
<https://www.rfc-editor.org/info/rfc7923>.
Appendix A. Examples
This appendix is non-normative.
A.1. Dynamic Subscription
Figure 2 shows a typical dynamic subscription to the network node
with distributed data export capability.
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+-------------+ +-------------+ +-------------+
| Subscriber/ | | Publisher | | Publisher |
| Receiver | | (Master) | | (Agent) |
+-------------+ +------+------+ +------+------+
| | |
| establish-subscription | |
+------------------------------>+ component |
| | subscription |
| RPC Reply: OK, id #22 +-------------->+
| Message Publisher ID [#1,#2] | |
+<------------------------------+ |
| | |
| notif-mesg, id #22 | |
| Message Publisher ID #1 | |
+<------------------------------+ |
| | |
| notif-mesg, id#22 | |
| Message Publisher ID #2 | |
+<----------------------------------------------+
| | |
| modify-subscription (id#22) | |
+------------------------------>+ component |
| | subscription |
| RPC Reply: OK, id #22 +-------------->+
+<------------------------------+ |
| | |
| subscription-modified, id#22 | |
| Message Publisher ID [#1] | |
+<------------------------------+ |
| | |
| notif-mesg, id #22 | |
| Message Publisher ID #1 | |
+<------------------------------+ |
| | |
| | |
+ + +
Figure 2: Call Flow for Dynamic Subscription
A "establish-subscription" RPC request as per [RFC8641] is sent to
the Master with a successful response. An example of using NETCONF:
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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:yang:ietf-subscribed-notifications"
xmlns:yp="urn:ietf:params:xml:ns:yang:ietf-yang-push">
<yp:datastore
xmlns:ds="urn:ietf:params:xml:ns:yang:ietf-datastores">
ds:operational
</yp:datastore>
<yp:datastore-xpath-filter
xmlns:ex="https://example.com/sample-data/1.0">
/ex:foo
</yp:datastore-xpath-filter>
<yp:periodic>
<yp:period>500</yp:period>
</yp:periodic>
</establish-subscription>
</netconf:rpc>
Figure 3: "establish-subscription" Request
As the network node is able to fully satisfy the request, the request
is given a subscription ID of 22. The response as in Figure 4
indicates that the subscription is decomposed into two component
subscriptions which will be published by two message Message
Publisher ID: #1 and #2.
<rpc-reply message-id="101"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<id
xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications">
22
</id>
<message-publisher-id
xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications">
1
</message-publisher-id>
<message-publisher-id
xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications">
2
</message-publisher-id>
</rpc-reply>
Figure 4: "establish-subscription" Positive RPC Response
Then, both Publishers send notifications with the corresponding piece
of data to the Receiver.
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The subscriber may invoke the "modify-subscription" RPC for a
subscription it previously established. The RPC has no difference to
the single publisher case as in [RFC8641]. Figure 5 provides an
example where a subscriber attempts to modify the period and
datastore XPath filter of a subscription using NETCONF.
<rpc message-id="102"
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">
<id>22</id>
<yp:datastore
xmlns:ds="urn:ietf:params:xml:ns:yang:ietf-datastores">
ds:operational
</yp:datastore>
<yp:datastore-xpath-filter
xmlns:ex="https://example.com/sample-data/1.0">
/ex:bar
</yp:datastore-xpath-filter>
<yp:periodic>
<yp:period>250</yp:period>
</yp:periodic>
</modify-subscription>
</rpc>
Figure 5: "modify-subscription" Request
If the modification is successfully accepted, the "subscription-
modified" subscription state notification is sent to the subscriber
by the Master. The notification, Figure 6 for example, indicates the
modified subscription is decomposed into one component subscription
which will be published by message Message Publisher ID #1.
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<notification
xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
<eventTime>2007-09-01T10:00:00Z</eventTime>
<subscription-modified
xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications"
xmlns:yp="urn:ietf:params:xml:ns:yang:ietf-yang-push">
<id>22</id>
<yp:datastore
xmlns:ds="urn:ietf:params:xml:ns:yang:ietf-datastores">
ds:operational
</yp:datastore>
<yp:datastore-xpath-filter
xmlns:ex="https://example.com/sample-data/1.0">
/ex:bar
</yp:datastore-xpath-filter>
<yp:periodic>
<yp:period>250</yp:period>
</yp:periodic>
<message-publisher-id
xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications">
1
</message-publisher-id>
</subscription-modified>
</notification>
Figure 6: "subscription-modified" Subscription State Notification
A.2. Configured Subscription
Figure 7 shows a typical configured subscription to the network node
with distributed data export capability.
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+-------------+ +-------------+ +-------------+
| Receiver | | Publisher | | Publisher |
| | | (Master) | | (Agent) |
+------+------+ +------+------+ +------+------+
| | |
| subscription-started, id#39 | |
| Message Publisher ID [#1,#2] | |
+<------------------------------+ |
| | |
| notif-mesg, id#39 | |
| Message Publisher ID #1 | |
+<------------------------------+ |
| | |
| notif-mesg, id#39 | |
| Message Publisher ID #2 | |
+<----------------------------------------------+
| | |
| | |
| | |
Figure 7: Call Flow for Configured Subscription
Before starting to push data, the "subscription-started" subscription
state notification is sent to the Receiver. The following example
assumes the NETCONF transport has already established. The
notification indicates that the configured subscription is decomposed
into two component subscriptions which will be published by two
message Message Publisher IDs: #1 and #2.
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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"
xmlns:yp="urn:ietf:params:xml:ns:yang:ietf-yang-push">
<identifier>39</identifier>
<yp:datastore
xmlns:ds="urn:ietf:params:xml:ns:yang:ietf-datastores">
ds:operational
</yp:datastore>
<yp:datastore-xpath-filter
xmlns:ex="https://example.com/sample-data/1.0">
/ex:foo
</yp:datastore-xpath-filter>
<yp:periodic>
<yp:period>250</yp:period>
</yp:periodic>
<message-publisher-ids
xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications>
1
</message-publisher-ids>
<message-publisher-ids
xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications>
2
</message-publisher-ids>
</subscription-started>
</notification>
Figure 8: "subscription-started" Subscription State Notification
Then, both Publishers send notifications with the corresponding data
record to the Receiver.
Authors' Addresses
Tianran Zhou
Huawei
156 Beiqing Rd., Haidian District
Beijing
China
Email: zhoutianran@huawei.com
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Guangying Zheng
Huawei
101 Yu-Hua-Tai Software Road
Nanjing
Jiangsu,
China
Email: zhengguangying@huawei.com
Eric Voit
Cisco Systems
United States of America
Email: evoit@cisco.com
Thomas Graf
Swisscom
Binzring 17
CH- Zuerich 8045
Switzerland
Email: thomas.graf@swisscom.com
Pierre Francois
INSA-Lyon
Lyon
France
Email: pierre.francois@insa-lyon.fr
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