Internet DRAFT - draft-zhou-netconf-multi-stream-originators
draft-zhou-netconf-multi-stream-originators
NETCONF T. Zhou
Internet-Draft G. Zheng
Intended status: Standards Track Huawei
Expires: May 7, 2020 E. Voit
Cisco Systems
A. Clemm
Futurewai
November 4, 2019
Subscription to Multiple Stream Originators
draft-zhou-netconf-multi-stream-originators-10
Abstract
This document describes the distributed data export mechanism that
allows multiple data streams to be managed by using a single
subscription. Specifically, device can decide to decompse one
subscription into multiple subscriptions to the line-cards. So that
each line-card can directly push data to the collector without
passing through a broker for internal consolidation. And the device
can indicate the subscription decomposition result to the receiver to
check the data integrity.
Requirements Language
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].
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 May 7, 2020.
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Copyright Notice
Copyright (c) 2019 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 Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Data Collection from Devices with Main-board and Line-cards . 3
3. Terminologies . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Solution Overview . . . . . . . . . . . . . . . . . . . . . . 5
5. Subscription Decomposition . . . . . . . . . . . . . . . . . 7
6. Publication Composition . . . . . . . . . . . . . . . . . . . 8
7. Subscription State Change Notifications . . . . . . . . . . . 9
8. Publisher Configurations . . . . . . . . . . . . . . . . . . 9
9. YANG Tree . . . . . . . . . . . . . . . . . . . . . . . . . . 9
10. YANG Module . . . . . . . . . . . . . . . . . . . . . . . . . 10
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
12. Transport Considerations . . . . . . . . . . . . . . . . . . 12
13. Security Considerations . . . . . . . . . . . . . . . . . . . 12
14. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13
15. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
15.1. Normative References . . . . . . . . . . . . . . . . . . 13
15.2. Informative References . . . . . . . . . . . . . . . . . 14
Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 15
A.1. Dynamic Subscription . . . . . . . . . . . . . . . . . . 15
A.2. Configured Subscription . . . . . . . . . . . . . . . . . 18
Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 20
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 22
1. Introduction
Streaming telemetry refers to sending a continuous stream of
operational data from a device to a remote receiver. This provides
an ability to monitor a network from remote and to provide network
analytics. Devices generate telemetry data and push that data to a
collector for further analysis. By streaming the data, much better
performance, finer-grained sampling, monitoring accuracy, and
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bandwidth utilization can be achieved than with polling-based
alternatives.
Mechanisms to support subscription to event notifications have been
defined in[RFC8639] and [RFC8641]. The current design involves
subscription to a single push server. This conceptually centralized
model encounters efficiency limitations in cases where the data
sources are themselves distributed, such as line cards in a piece of
network equipment. In such cases, it will be a lot more efficient to
have each data source (e.g., each line card) originate its own stream
of updates, rather than requiring updates to be tunneled through a
central server where they are combined. What is needed is a
distributed mechanism that allows to directly push multiple
individual data substreams, without needing to first pass them
through an additional processing stage for internal consolidation,
but still allowing those substreams to be managed and controlled via
a single subscription.
This document will describe such distributed data export mechanism
and how it can work by extending existing push mechanism.
Specifically, device can decide to decompse one subscription into
multiple subscriptions to the line-cards. So that each line-card can
directly push data to the collector without passing through a broker
for internal consolidation. And the device can indicate the
subscription decomposition result to the receiver to check the data
integrity. The proposal will focus on the scenario when data
collection from devices with main-board and line-cards. It could be
generalized to other distributed data export scenarios.
2. Data Collection from Devices with Main-board and Line-cards
For data collection from devices with main-board and line-cards,
existing push solutions consider only one push server typically
reside in the main board. As shown in the following figure, data are
collected from line cards and aggregate to the main board as one
consolidated stream. So the main board can easily become the
performance bottle-neck. The optimization is to apply the
distributed data export mechanism which can directly push data from
line cards to a collector. On one hand, this will reduce the cost of
scarce compute and memory resources on the main board for data
processing and assembling. On the other hand, distributed data push
can off-load the streaming traffic to multiple interfaces.
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+-------------------------------------+
| collector |
+------^-----------^-----------^------+
| | |
| | |
+-------------------------------------+
| | | | |
| | +-----+------+ | |
| | | main board | | |
| | +--^-----^---+ | |
| | | | | |
| | +---+ +---+ | |
| | | | | |
| +----+----+---+ +---+----+----+ |
| | line card 1 | | line card 2 | |
| +-------------+ +-------------+ |
| device |
+-------------------------------------+
Fig. 1 Data Collection from Devices with Main-board and Line-cards
3. 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: is the Subscription that defines the data
from each individual telemetry source which is managed and controlled
by a single Publisher.
Global Capability: is the overall subscription capability that the
group of Publishers can expose to the Subscriber.
Component Capability: is the subscription capability that each
Publisher can expose to the Subscriber.
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Master: is 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 Agents.
Agent: is the Publisher that interacts with the Master to deal with
the Component Subscription.
4. Solution Overview
Figure 2 below shows the distributed data export framework.
A collector usually includes two components,
o the Subscriber generates the subscription instructions to express
what and how the collector want to receive the data;
o the Receiver is the target for the data publication.
For one subscription, there may be one to many Receivers. And the
Subscriber does not necessarily share the same address with the
Receivers.
In this framework, the Publisher pushes data to the Receiver
according to the subscription information. The Publisher has the
Master role and the Agent role. The Master knows all the
capabilities that the attached Agents and itself can provide, and
exposes the Global Capability to the collector. The collector cannot
see the Agents directly, so it will only send the Global Subscription
information to the Master. The Master disassembles the Global
Subscription to multiple Component Subscriptions, each involving data
from a separate telemetry source. The Component Subscriptions are
then distributed to the corresponding Agents.
When data streaming, the Publisher collects and encapsulates the
packets per the Component Subscription, and pushes the piece of data
which can serve directly to the designated data collector. The
collector is able to assemble many pieces of data associated with one
Global Subscription, and can also deduce the missing pieces of data.
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+-----------------------------------------+
| Collector |-------------+ |
| +------------+ | |
| +------------+ || Receiver | | |
| | Subscriber | |--------------+ |
| +-----^-+----+ +-----^------^ |
| | | | | |
+-----------------------------------------+
Global | | Global | |
Capability| | Subscription | |
+-----------------------------------------+
| | | Push | | |
| +--------+-v---------------+---+ | |
| | Publisher(Master) | | |
| +--------^-+-------------------+ | |
| | | | |
| | | | |
| Component | | Component Push | |
| Capability| | Subscription | |
| +--------+-v-------------------+ | |
| | Publisher(Agent) +--+ |
| +------------------------------+ |
| |
| Device |
+-----------------------------------------+
Fig. 2 The Distributed Data Export Framework
Master and Agents may interact with each other in several ways:
o Agents need to have a registration or announcement handshake with
the Master, so the Master is aware of them and of life-cycle
events (such as Agent appearing and disappearing).
o Contracts are needed between the Master and each Agent on the
Component Capability, and the format for streaming data structure.
o The Master relays the component subscriptions to the Agents.
o The Agents indicate status of Component Subscriptions to the
Master. The status of the overall subscription is maintained by
the Master. The Master is also responsible for notifying the
subscriber in case of any problems of Component Subscriptions.
Any technical mechanisms or protocols used for the coordination of
operational information between Master and Agent is out-of-scope of
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this document. We will need to instrument the results of this
coordination on the Master.
5. Subscription Decomposition
The Collector can only subscribe to the Master. This requires the
Master to:
1. expose the Global Capability that can be served by multiple
Publishers;
2. disassemble the Global Subscription to multiple Component
Subscriptions, and distribute them to the corresponding telemetry
sources;
3. notify on changes when portions of a subscription moving between
different Agents over time.
The Master can keep track of the mapping between the resource and the
corresponding location of the Publisher which commits to serve the
data. If a Publisher does not have external connectivity or
permission to export, the master MUST NOT decompose a component
subscription to that Publisher. In some implementations, the Global
Subscription can be disassembled into multiple Component
Subscriptions according to the Resource-Location Table, and the
corresponding location can be associated. The decision whether to
decompose a Global Subscription into multiple Component Subscriptions
rests with the Resource-Location Table. A Master can decide to not
decompose a Global Subscription at all and push a single stream to
the receiver, because the location information indicates the Global
Subscription can be served locally by the Master. Similarly, it can
decide to entirely decompose a Global Subscription into multiple
Component Subscriptions that each push their own streams, but not
from the Master. It can also decide to decompose the Global
Subscription into several Component Subscriptions and retain some
aspects of the Global Subscription itself, also pushing its own
stream.
Component Subscriptions belonging to the same Global Subscription
MUST NOT overlap. The combination of all Component Subscriptions
MUST cover the same range of nodes as the Global Subscription. Also,
the same subscription settings apply to each Component Subscription,
i.e., the same receivers, the same time periods, the same encodings
are applied to each Component Subscription per the settings of the
Global Subscription.
Each Component Subscription in effect constitutes a full-fledged
subscription, with the following constraints:
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o Component subscriptions are system-controlled, i.e. managed by the
Master, not by the subscriber.
o Component subscription settings such as time periods, dampening
periods, encodings, receivers adopt the settings of their Global
Subscription.
o The life-cycle of the Component Subscription is tied to the life-
cycle of the Global Subscription. Specifically, terminating/
removing the Global Subscription results in termination/removal of
Component Subscriptions.
o The Component Subscriptions share the same Subscription ID as the
Global Subscription.
6. Publication Composition
The Publisher collects data and encapsulates the packets per the
Component Subscription. There are several potential encodings,
including XML, JSON, CBOR and GPB. The format and structure of the
data records are defined by the YANG schema, so that the composition
at the Receiver can benefit from the structured and hierarchical data
instance.
The Receiver is able to assemble many pieces of data associated with
one subscription, and can also deduce the missing pieces of data.
The Receiver recognizes data records associated with one subscription
according the Subscription ID [RFC8639]. Data records generated per
one subscription are assigned with the same Subscription ID.
For the periodic updates, records are produced periodically from each
Publisher. The message arrival time varies because of the
distributed nature of the publication. The Receiver assembles data
generated at the same time period based on the recording time
consisted in each data record. In this case, time synchronization is
required for all the Publishers.
Message Generator ID [I-D.ietf-netconf-notification-messages] is the
identifier for the process which created the notification message.
It's contained in every notification messages, and allows
disambiguation of different line cards sending the messages. This
document, in addition, requires the device to notify collector the
set of Message Generator IDs standing for the Publishers serving for
one Global Subscription. So that the collector can easily check the
integrity of the data collected from different Publishers at the same
time period. And the collector can deduce the Publishers which are
responsible for the missing pieces of data.
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For the dynamic subscription, the output of the "establish-
subscription" RPC defined in [RFC8639] MUST include a list of Message
Generator IDs to indicate how the Global Subscription is decomposed
into several Component Subscriptions.
The "subscription-started" and "subscription-modified" notification
defined in [RFC8639] MUST also include a list of Message Generator
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 Publishers.
8. Publisher Configurations
This document assumes all the Publishers are preconfigured to be able
to push data. The actual working Publishers are selected dynamically
based on the subscription decomposition result. For UDP Publishers,
the virtual IP address could be assigned for the publication. So all
the UDP Publishers on the device can use the same source IP address
configured, which may even not routeable. For connection based
Publishers, e.g., HTTPS-based transport
[I-D.ietf-netconf-https-notif], each Publisher MUST be able to
receive packets from the receivers. This document does not restrict
the way how the Publishers are accessible.
The specific configuration on transports is out of the scope of this
document.
9. YANG Tree
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module: ietf-multiple-stream-originators
augment /sn:subscriptions/sn:subscription:
+--ro message-generator-id* string
augment /sn:subscription-started:
+--ro message-generator-id* string
augment /sn:subscription-modified:
+--ro message-generator-id* string
augment /sn:establish-subscription/sn:output:
+--ro message-generator-id* string
10. YANG Module
<CODE BEGINS> file "ietf-multiple-stream-originators@2019-10-12.yang"
module ietf-multiple-stream-originators {
yang-version 1.1;
namespace
"urn:ietf:params:xml:ns:yang:ietf-multiple-stream-originators";
prefix mso;
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: Tianran Zhou
<mailto:zhoutianran@huawei.com>
Editor: Guangying Zheng
<mailto:zhengguangying@huawei.com>";
description
"Defines augmentation for ietf-subscribed-notifications to enable
the distributed publication with single subscription.
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
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itself for full legal notices.";
revision 2019-10-12 {
description
"Initial version";
reference
"RFC XXXX: Subscription to Multiple Stream Originators";
}
grouping message-generator-ids {
description
"Provides a reusable list of message-generator-ids.";
leaf-list message-generator-id {
type string;
config false;
ordered-by user;
description
"Software entity which created the message (e.g.,
linecard 1). This field is used to notify the
collector the working originator.";
}
}
augment "/sn:subscriptions/sn:subscription" {
description
"This augmentation allows the message generators to be exposed
for a subscription.";
uses message-generator-ids;
}
augment "/sn:subscription-started" {
description
"This augmentation allows MSO specific parameters to be
exposed for a subscription.";
uses message-generator-ids;
}
augment "/sn:subscription-modified" {
description
"This augmentation allows MSO specific parameters to be
exposed for a subscription.";
uses message-generator-ids;
}
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augment "/sn:establish-subscription/sn:output" {
description
"This augmentation allows MSO specific parameters to be
exposed for a subscription.";
uses message-generator-ids;
}
}
<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-multiple-stream-originators
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-multiple-stream-originators
Namespace: urn:ietf:params:xml:ns:yang:ietf-multiple-stream-
originators
Prefix: mso
Reference: RFC XXXX
12. Transport Considerations
The distributed data export mechanism enabled by this draft is
expected to generate more data than YANG-Push [RFC8641]. The large
amount of data may congest the network and impact other network
business. In this case, the collector may also not be able to accept
all the data. So the congestion control method is required for any
transport that is going to implement the solution proposed in this
document.
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
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is the secure transport layer, and the mandatory-to-implement secure
transport is Secure Shell (SSH) [RFC6242]. The lowest RESTCONF layer
is HTTPS, and the mandatory-to-implement secure transport is TLS
[RFC5246].
The NETCONF Access Control Model (NACM) [RFC6536] provides the means
to restrict access for particular 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:
o /subscriptions/subscription/message-generator-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 YANG-
Push [RFC8641].
14. Acknowledgements
We thank Kent Watsen, Mahesh Jethanandani, Martin Bjorklund, Tim
Carey and Qin Wu for their constructive suggestions for improving
this document.
15. References
15.1. 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>.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004,
<https://www.rfc-editor.org/info/rfc3688>.
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[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246,
DOI 10.17487/RFC5246, August 2008,
<https://www.rfc-editor.org/info/rfc5246>.
[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>.
[RFC6536] Bierman, A. and M. Bjorklund, "Network Configuration
Protocol (NETCONF) Access Control Model", RFC 6536,
DOI 10.17487/RFC6536, March 2012,
<https://www.rfc-editor.org/info/rfc6536>.
[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>.
[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>.
15.2. Informative References
[I-D.ietf-netconf-https-notif]
Jethanandani, M. and K. Watsen, "An HTTPS-based Transport
for Configured Subscriptions", draft-ietf-netconf-https-
notif-01 (work in progress), October 2019.
[I-D.ietf-netconf-notification-messages]
Voit, E., Birkholz, H., Bierman, A., Clemm, A., and T.
Jenkins, "Notification Message Headers and Bundles",
draft-ietf-netconf-notification-messages-07 (work in
progress), August 2019.
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Appendix A. Examples
This appendix is non-normative.
A.1. Dynamic Subscription
Figure 3 shows a typical dynamic subscription to the device with
distributed data export capability.
+-------------+ +-------------+ +-------------+
| Subscriber/ | | Publisher | | Publisher |
| Receiver | | (Master) | | (Agent) |
+-------------+ +------+------+ +------+------+
| | |
| establish-subscription | |
+------------------------------>+ component |
| | subscription |
| RPC Reply: OK, id #22 +-------------->+
| message generator ID [#1, #2] | |
+<------------------------------+ |
| | |
| notif-mesg, id #22 | |
| message generator ID #1 | |
+<------------------------------+ |
| | |
| notif-mesg, id#22 | |
| message generator ID #2 | |
+<----------------------------------------------+
| | |
| modify-subscription (id#22) | |
+------------------------------>+ component |
| | subscription |
| RPC Reply: OK, id #22 +-------------->+
+<------------------------------+ |
| | |
| subscription-modified, id#22 | |
| message generator ID [#1] | |
+<------------------------------+ |
| | |
| notif-mesg, id #22 | |
| message generator ID #1 | |
+<------------------------------+ |
| | |
| | |
+ + +
Fig. 3 Call Flow for Dynamic Subscription
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A "establish-subscription" RPC request as per [RFC8641] is sent to
the Master with a successful response. An example of using NETCONF
might look like:
<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>
Fig. 4 "establish-subscription" Request
As the device is able to fully satisfy the request, the request is
given a subscription ID of 22. The response as in Figure 5 indicates
that the subscription is decomposed into two component subscriptions
which will be published by two message generators: #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-generator-id
xmlns="urn:ietf:params:xml:ns:yang:ietf-multiple-stream-originators>
1
</message-generator-id>
<message-generator-id
xmlns="urn:ietf:params:xml:ns:yang:ietf-multiple-stream-originators>
2
</message-generator-id>
</rpc-reply>
Fig. 5 "establish-subscription" Positive RPC Response
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Then, both Publishers send notifications with the corresponding piece
of data to the receiver.
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 6 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>
Fig. 6 "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 7 for example, indicates the
modified subscription is decomposed into one component subscription
which will be published by message generator #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-generator-id
xmlns="urn:ietf:params:xml:ns:yang:ietf-multiple-stream-originators>
1
</message-generator-id>
</subscription-modified>
</notification>
Fig. 7 "subscription-modified" Subscription State Notification
A.2. Configured Subscription
Figure 8 shows a typical configured subscription to the device with
distributed data export capability.
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+-------------+ +-------------+ +-------------+
| Receiver | | Publisher | | Publisher |
| | | (Master) | | (Agent) |
+------+------+ +------+------+ +------+------+
| | |
| subscription-started, id#39 | |
| message generator ID [#1, #2] | |
+<------------------------------+ |
| | |
| notif-mesg, id#39 | |
| message generator ID #1 | |
+<------------------------------+ |
| | |
| notif-mesg, id#39 | |
| message generator ID #2 | |
+<----------------------------------------------+
| | |
| | |
| | |
Fig. 8 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 generators: #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-generator-id
xmlns="urn:ietf:params:xml:ns:yang:ietf-multiple-stream-originators>
1
</message-generator-id>
<message-generator-id
xmlns="urn:ietf:params:xml:ns:yang:ietf-multiple-stream-originators>
2
</message-generator-id>
</subscription-started>
</notification>
Fig. 9 "subscription-started" Subscription State Notification
Then, both Publishers send notifications with the corresponding piece
of data to the receiver.
Appendix B. Change Log
(To be removed by RFC editor prior to publication)
v01
o Minor revision on Subscription Decomposition
o Revised terminologies
o Removed most implementation related text
o Place holder of two sections: Subscription Management, and
Notifications on Subscription State Changes
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v02
o Revised section 4 and 5. Moved them from apendix to the main
text.
v03
o Added a section for Terminologies.
o Added a section for Subscription State Change Notifications.
o Improved the Publication Composition section by adding a method to
check the integrity of the data generated from different
Publishers at the same time period.
o Revised the solution overview for a more clear description.
v04
o Added the YANG data model for the proposed augment.
v05
o Added the IANA considerations, transport considerations and
security considerations.
v06
o Added examples.
v07
o Removed the IoT use case.
o Revised examples.
o Add discussion on Publisher Configurations in section 8.
v08
o Cleared up the document to fix Terms, nits.
o Reduced internal implementation descriptions.
o Clarified Message Generator ID.
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Authors' Addresses
Tianran Zhou
Huawei
156 Beiqing Rd., Haidian District
Beijing
China
Email: zhoutianran@huawei.com
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
Alexander Clemm
Futurewai
2330 Central Expressway
Santa Clara, California
United States of America
Email: ludwig@clemm.org
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