| NETCONF | B. Lengyel |
| Internet-Draft | Ericsson |
| Intended status: Standards Track | A. Clemm |
| Expires: August 17, 2020 | Futurewei |
| B. Claise | |
| Cisco Systems, Inc. | |
| February 14, 2020 |
Generic YANG-related System Capabilities and YANG-Push Notification Capabilities
draft-ietf-netconf-notification-capabilities-11
This document proposes two YANG modules. The module ietf-system-capabilities provides a structure that can be used to specify any YANG related system capability.
The module ietf-notification-capabilities allows a publisher to specify capabilities related to "Subscription to YANG Datastores" (YANG-Push). It proposes to use YANG Instance Data to document this information and make it already available at implementation-time, but also allow it to be reported at run-time.
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 August 17, 2020.
Copyright (c) 2020 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.
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 terms YANG-Push, On-change subscription and Periodic subscription are used as defined in [RFC8641]
The terms Subscriber, Publisher and Receiver are used as defined in [RFC8639]
The term Server is used as defined in [RFC8342]
On-change Notification Capability: The capability of the publisher to send on-change notifications for a specific datastore or a specific data node.
Implementation-time information: Information about the publisher's or server's behavior that is made available during the implementation of the publisher/server, available from a source other then a running server.
Run-time information: Information about the publisher's or server's behavior that is available from the running server via management protocols such as NETCONF [RFC6241] or RESTCONF [RFC8040].
Systems implementing a server and/or a publisher often have capabilities that are not defined by the YANG model itself. There is a need to publish this capability information as it part of the contract between the server and client. Examples include: maximum size of data that can be stored or transferred, information about counters (whether a node supports on-change telemetry), etc. Such capabilities are often dependent on a vendor's implementation or the available resources at deployment. Many such capabilities are specific to either the complete system, individual YANG datastores or specific parts of the YANG schema, or even to individual data nodes. It is a goal of this document to provide a common way of representing such capabilities in a format that is:
A specific case where we need to specify capabilities is the YANG-Push functionality. As defined in [RFC8641] a publisher may allow subscribers to subscribe to updates from a datastore and subsequently push such update notifications to the receiver. Notifications may be sent periodically or on-change (more or less immediately after each change).
A publisher supporting YANG-Push has a number of capabilities defined in [RFC8641] that are often determined during the implementation of the publisher. These include:
Additional capabilities if the optional on-change feature is supported include:
Publishers have limitations in how many update notifications and how many datastore node updates they can send out in a certain time-period.
Publishers might not support periodic subscriptions to all datastores.
In some cases, a publisher supporting on-change notifications will not be able to push updates for some object types on-change. Reasons for this might be that the value of the datastore node changes frequently (e.g., in-octets counter), that small object changes are frequent and irrelevant to the receiver (e.g., a temperature gauge changing 0.1 degrees within a predetermined and acceptable range), or that the implementation is not capable of on-change notification for a particular object. In those cases, it will be important for subscriber applications to have a way to identify which objects on-change notifications are supported and for which ones not.
Faced with the reality that support for on-change notification does not mean that such notifications will be sent for any specific data node, subscriber/management applications can not rely on the on-change functionality unless the subscriber has some means to identify which objects on-change notifications are supported. YANG models are meant to be used as an interface contract. Without identification of the data nodes actually supporting on-change, this contract would be incomplete.
Clients of a server, subscribers to a publisher need a method to gather capability information.
Implementation-time information is needed by Network Management System (NMS) implementers. A NMS implementation that wants to support notifications, needs the information about on-change notification capability. If the information is not documented in a way available to the NMS designer, but only as instance data from the network node once it is deployed, the NMS implementation will be delayed, because it has to wait for the network node to be ready. In addition, the assumption that all NMS implementers will have a correctly configured network node available to retrieve data from is an expensive proposition and may not always hold. (An NMS may need to be able to handle many dozens of network node types.) Often a fully functional NMS is a requirement for introducing a new network node type into a network, so delaying NMS readiness effectively also delays the time at which a new network node type can be introduced into the network.
Implementation-time information is needed by system integrators. When introducing a network node type into their network, operators often need to integrate the node type into their own management system. The NMS may have management functions that depend on on-change notifications. The network operator needs to plan his management practices and NMS implementation before he even decides to buy the specific network node type. Moreover the decision to buy the node type sometimes depends on these management possibilities.
Run-time information is needed:
Capability information is represented by instance-data based on one or more "capability defining YANG modules". This allows a user to discover capabilities both at implementation-time and run-time.
The module ietf-system-capabilities is defined to provide a structure that can be used to specify any YANG related system capability.
The module ietf-notification-capabilities is defined to allow a publisher to specify capabilities related to "Subscription to YANG Datastores" (YANG-Push) augmenting ietf-system-capabilities.
The module ietf-system-capabilities is defined to provide a structure that can be used to specify any YANG related system capability.
Capability values can be specified on system/publisher level, datastore level (by selecting all nodes in the datastore) or for specific data nodes of a specific datastore (and their contained sub-trees). Capability values specified for a specific datastore or node-set override values specified on the system/publisher level.
This module itself does not contain any capabilities. It SHOULD be used by other modules to augment-in specific capability information. Every set of such capabilities SHOULD be wrapped in a container under the augment statement to cleanly separate different groups of capabilities. These "wrapper containers" SHALL be augmented in at /sysc:system-capabilities and /sysc:system-capabilities/sysc:datastore-capabilities/sysc:per-node-capabilities.
Note: The solution is usable for both NMDA and non-NMDA systems. For non-NMDA servers/publishers config=false data is considered as if it was part of the running datastore.
The following tree diagram [RFC8340] provides an overview of the data model.
module: ietf-system-capabilities
+--ro system-capabilities
+--ro datastore-capabilities* [datastore]
+--ro datastore -> /yanglib:yang-library/datastore/name
+--ro per-node-capabilities* []
+--ro (node-selection)?
+--:(node-selector)
+--ro node-selector? nacm:node-instance-identifier
<CODE BEGINS> file "ietf-system-capabilities@2020-02-14.yang"
module ietf-system-capabilities {
yang-version 1.1;
namespace
"urn:ietf:params:xml:ns:yang:ietf-system-capabilities";
prefix sysc;
import ietf-netconf-acm { prefix nacm; }
import ietf-yang-library {
prefix yanglib;
description "Revision 2019-01-04 or a
revision derived from it is REQUIRED.";
}
organization
"IETF NETCONF (Network Configuration) Working Group";
contact
"WG Web: <https://datatracker.ietf.org/wg/netconf/>
WG List: <mailto:netconf@ietf.org>
Editor: Balazs Lengyel
<mailto:balazs.lengyel@ericsson.com>";
description
"This module specifies a module intended to contain system
capabilities. System capabilities may include capabilities of a
NETCONF or RESTCONF server or a notification publisher.
This module does not contain any specific capabilities it only
provides a structure where containers containing the actual
capabilities should be augmented in.
Capability values can be specified on system level,
datastore level (by selecting all nodes in the datastore) or
for specific data nodes of a specific datastore (and their
contained sub-trees).
Capability values specified for a specific datastore or
node-set override values specified on the system/publisher level.
To find a capability value for a specific data node in a
specific datastore the user SHALL
1) search for a datastore-capabilities list entry for
the specific datastore.
2) If the datastore entry is found within that entry process all
per-node-capabilities entries in the order they appear in the list.
The first entry that specifies the specific capability and has a
node-selector selecting the specific data node defines the
capability value.
3) If the capability value is not found above and the specific
capability is specified under the system-capabilities container
(outside the datastore-capabilities list) this value shall be used.
4) If no values are found in the previous steps the
system/publisher is not capable of providing a value because
it is unknown, the capability is changing for some reason,
there is no specified limit etc. In this case the
system's behavior is unspecified.
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 (RFC 2119)
(RFC 8174) when, and only when, they appear in all
capitals, as shown here.
Copyright (c) 2020 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
(http://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX
(https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself
for full legal notices.";
revision 2020-02-14 {
description
"Initial version";
reference
"RFC XXX: YANG-Push Notification Capabilities";
}
container system-capabilities {
config false;
description "System capabilities.
Capability values specified here at the system level
are valid for all datastores and
are used when the capability is not specified on the
datastore level or for specific data nodes.";
// augmentation point for system level capabilities
list datastore-capabilities {
key datastore;
description "Capabilities values per datastore.
For non-NMDA servers/publishers config=false data is
considered as if it was part of the running datastore.";
leaf datastore {
type leafref {
path /yanglib:yang-library/yanglib:datastore/yanglib:name;
}
description "The datastore for which capabilities are defined.
Only individual datastores can be specified
e.g., ds:conventional is not allowed.";
}
list per-node-capabilities {
description
"Each list entry specifies capabilities for the selected
data nodes. The same capabilities apply for the data nodes
in the subtree below the selected nodes.
The system SHALL order the entries according to their
precedence. The order of the entries MUST NOT change unless
the underlying capabilities also change.";
choice node-selection {
description
"A method to select all or some nodes within a datastore.";
leaf node-selector {
type nacm:node-instance-identifier;
description
"Selects the data nodes for which capabilities are
specified. The special value '/' denotes all data nodes
in the datastore.";
}
}
// augmentation point for datastore or data node level
// capabilities
}
}
}
}
<CODE ENDS>
The YANG module ietf-notification-capabilities is defined to provide YANG-Push related capability information.
The following tree diagram [RFC8340] provides an overview of the data model.
module: ietf-notification-capabilities
augment /sysc:system-capabilities:
+--ro subscription-capabilities
+--ro (update-period)?
| +--:(minimum-update-period)
| | +--ro minimum-update-period? uint32
| +--:(supported-update-period)
| +--ro supported-update-period* uint32
+--ro max-nodes-per-update? uint32
+--ro minimum-dampening-period? uint32 {yp:on-change}?
+--ro on-change-supported? notification-support
| {yp:on-change}?
+--ro periodic-notifications-supported? notification-support
+--ro supported-excluded-change-type* union {yp:on-change}?
augment /sysc:system-capabilities/sysc:datastore-capabilities/ +
| sysc:per-node-capabilities:
+--ro subscription-capabilities
+--ro (update-period)?
| +--:(minimum-update-period)
| | +--ro minimum-update-period? uint32
| +--:(supported-update-period)
| +--ro supported-update-period* uint32
+--ro max-nodes-per-update? uint32
+--ro minimum-dampening-period? uint32 {yp:on-change}?
+--ro on-change-supported? notification-support
| {yp:on-change}?
+--ro periodic-notifications-supported? notification-support
+--ro supported-excluded-change-type* union {yp:on-change}?
<CODE BEGINS> file "ietf-notification-capabilities@2020-02-14.yang"
module ietf-notification-capabilities {
yang-version 1.1;
namespace
"urn:ietf:params:xml:ns:yang:ietf-notification-capabilities";
prefix inc;
import ietf-yang-push { prefix yp; }
import ietf-system-capabilities { prefix sysc; }
organization
"IETF NETCONF (Network Configuration) Working Group";
contact
"WG Web: <https://datatracker.ietf.org/wg/netconf/>
WG List: <mailto:netconf@ietf.org>
Editor: Balazs Lengyel
<mailto:balazs.lengyel@ericsson.com>";
description
"This module specifies YANG-Push related publisher capabilities.
The module contains
- specification of which data nodes support on-change or periodic
notifications.
- capabilities related to the throughput of notification data the
publisher can support. (Note that for a specific subscription
the publisher MAY still allow only longer periods or smaller
updates depending on e.g., actual load conditions.)
Capability values can be specified on system/publisher level,
datastore level or for specific data nodes of a specific datastore
(and their contained sub-trees), as defined in the
ietf-system-capabilities module.
If, different data nodes covered by a single subscription
have different values for a specific capability, then using values
that are only acceptable for some of these data nodes, but not for
others, may result in the rejection of the subscription.
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 (RFC 2119)
(RFC 8174) when, and only when, they appear in all
capitals, as shown here.
Copyright (c) 2020 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
(http://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX
(https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself
for full legal notices.";
revision 2020-02-14 {
description
"Initial version";
reference
"RFC XXX: YANG-Push Notification Capabilities";
}
grouping subscription-capabilities {
description "Capabilities related to YANG-Push subscriptions
and notifications";
container subscription-capabilities {
description "Capabilities related to YANG-Push subscriptions
and notifications";
typedef notification-support {
type bits {
bit config-changes {
description "The publisher is capable of sending
notifications for config=true nodes for the relevant
scope and subscription type." ;
}
bit state-changes {
description "The publisher is capable of sending
notifications for config=false nodes for the relevant
scope and subscription type." ;
}
}
description "Type for defining whether on-change or
periodic notifications are supported for none, only
config=true, only config=false or all data nodes.
If the bit config-changes or state-changes is set
for a datastore or a set of nodes that does not contain
nodes with the indicated config value,
this has no effect, as if no support was declared.
E.g. indicating support for state-changes for
a candidate datastore has no effect.";
}
choice update-period {
description "Supported update period value or values for
periodic subscriptions.";
leaf minimum-update-period {
type uint32;
units "centiseconds";
description "Indicates the minimal update period that is
supported for a periodic subscription.
A subscription request to the selected data
nodes with a smaller period than what this leaf specifies
will result in a 'period-unsupported' error.";
reference
"The period leaf in RFC 8641 ietf-yang-push YANG module";
}
leaf-list supported-update-period {
type uint32;
units "centiseconds";
description "Supported update period values for a
periodic subscription.
A subscription request to the selected data nodes with a
period not included in the leaf-list will result in a
'period-unsupported' error.";
reference
"The period leaf in RFC 8641 ietf-yang-push YANG module";
}
}
leaf max-nodes-per-update {
type uint32 {
range "1..max";
}
description
"Maximum number of data nodes that can be sent
in an update. The publisher MAY support more data nodes,
but SHOULD support at least this number.";
}
leaf minimum-dampening-period {
if-feature yp:on-change;
type uint32;
units "centiseconds";
description
"The minimum dampening period supported for on-change
subscriptions for the selected data nodes.";
}
leaf on-change-supported {
if-feature yp:on-change;
type notification-support;
description
"Specifies whether the publisher is capable of
sending on-change notifications for the selected
data store or data nodes and the subtree below them.";
}
leaf periodic-notifications-supported {
type notification-support;
description
"Specifies whether the publisher is capable of
sending periodic notifications for the selected
data store or data nodes and the subtree below them.";
}
leaf-list supported-excluded-change-type {
if-feature yp:on-change;
type union {
type enumeration {
enum none {
value -2 ;
description "None of the change types can be excluded.";
}
enum all {
value -1 ;
description
"Any combination of change types can be excluded.";
}
}
type yp:change-type;
}
description "The change types that can be excluded in
YANG-Push subscriptions.";
}
}
}
augment /sysc:system-capabilities {
description "Add system level capabilities";
uses subscription-capabilities {
refine subscription-capabilities/supported-excluded-change-type {
default none;
}
}
}
augment "/sysc:system-capabilities/sysc:datastore-capabilities" +
"/sysc:per-node-capabilities" {
description "Add datastore and node level capabilities";
uses subscription-capabilities {
refine subscription-capabilities/supported-excluded-change-type {
default none;
}
}
}
}
<CODE ENDS>
The YANG modules specified in this document define 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 RESTCONF layer is HTTPS, and the mandatory-to-implement secure transport is TLS [RFC8446].
The Network Configuration Access Control Model (NACM) [RFC8341] 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.
All protocol-accessible data nodes are read-only and cannot be modified. The data in these modules is not security sensitive. Access control may be configured, to avoid exposing the read-only data.
When that data is in file format, data should be protected against modification or unauthorized access using normal file handling mechanisms.
This document registers two URIs in the IETF XML registry [RFC3688]. Following the format in [RFC3688], the following registrations are requested:
URI: urn:ietf:params:xml:ns:yang:ietf-system-capabilities
Registrant Contact: The NETCONF WG of the IETF.
XML: N/A, the requested URI is an XML namespace.
URI: urn:ietf:params:xml:ns:yang:ietf-notification-capabilities
Registrant Contact: The NETCONF WG of the IETF.
XML: N/A, the requested URI is an XML namespace.
This document registers two YANG modules in the YANG Module Names registry. Following the format in [RFC7950], the the following registrations are requested:
name: ietf-system-capabilities
namespace: urn:ietf:params:xml:ns:yang:ietf-system-capabilities
prefix: sysc
reference: RFC XXXX
name: ietf-notification-capabilities
namespace: urn:ietf:params:xml:ns:yang:ietf-notification-capabilities
prefix: inc
reference: RFC XXXX
| [I-D.ietf-netmod-yang-instance-file-format] | Lengyel, B. and B. Claise, "YANG Instance Data File Format", Internet-Draft draft-ietf-netmod-yang-instance-file-format-06, December 2019. |
| [RFC6241] | Enns, R., Bjorklund, M., Schoenwaelder, J. and A. Bierman, "Network Configuration Protocol (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011. |
| [RFC6242] | Wasserman, M., "Using the NETCONF Protocol over Secure Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011. |
| [RFC7950] | Bjorklund, M., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, August 2016. |
| [RFC8040] | Bierman, A., Bjorklund, M. and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017. |
| [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. |
| [RFC8446] | Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018. |
| [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. |
| [RFC8641] | Clemm, A. and E. Voit, "Subscription to YANG Notifications for Datastore Updates", RFC 8641, DOI 10.17487/RFC8641, September 2019. |
| [RFC2119] | Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997. |
| [RFC3688] | Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, January 2004. |
| [RFC8174] | Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017. |
| [RFC8340] | Bjorklund, M. and L. Berger, "YANG Tree Diagrams", BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018. |
| [RFC8341] | Bierman, A. and M. Bjorklund, "Network Configuration Access Control Model", STD 91, RFC 8341, DOI 10.17487/RFC8341, March 2018. |
<?xml version="1.0" encoding="UTF-8"?>
<instance-data-set xmlns=
"urn:ietf:params:xml:ns:yang:ietf-yang-instance-data">
<name>acme-switch-notification-capabilities</name>
<yid-version>1</yid-version>
<content-schema>
<module>ietf-system-capabilities@2020-02-14</module>
<module>ietf-notification-capabilities@2020-02-14</module>
</content-schema>
<!-- revision date, contact, etc. -->
<description>Notification capabilities of acme-switch.
Acme-switch implements the running, candidate and operational
datastores. Every change can be reported on-change from running,
nothing from candidate and all config=false data from operational.
Periodic subscriptions are supported for running and
operational, but not for candidate.
</description>
<content-data>
<system-capabilities
xmlns="urn:ietf:params:xml:ns:yang:ietf-system-capabilities"
xmlns:inc=
"urn:ietf:params:xml:ns:yang:ietf-notification-capabilities"
xmlns:ds="urn:ietf:params:xml:ns:yang:ietf-datastores">
<inc:subscription-capabilities>
<inc:minimum-update-period>500</inc:minimum-update-period>
<inc:max-nodes-per-update>2000</inc:max-nodes-per-update>
<inc:minimum-dampening-period>100</inc:minimum-dampening-period>
<inc:periodic-notifications-supported>
config-changes state-changes
</inc:periodic-notifications-supported>
</inc:subscription-capabilities>
<datastore-capabilities>
<datastore>ds:operational</datastore>
<per-node-capabilities>
<node-selector>/</node-selector>
<inc:subscription-capabilities>
<inc:on-change-supported>
state-changes
</inc:on-change-supported>
</inc:subscription-capabilities>
</per-node-capabilities>
</datastore-capabilities>
<datastore-capabilities>
<datastore>ds:candidate</datastore>
<per-node-capabilities>
<node-selector>/</node-selector>
<inc:subscription-capabilities>
<inc:on-change-supported/>
<inc:periodic-notifications-supported/>
</inc:subscription-capabilities>
</per-node-capabilities>
</datastore-capabilities>
<datastore-capabilities>
<datastore>ds:running</datastore>
<per-node-capabilities>
<node-selector>/</node-selector>
<inc:subscription-capabilities>
<inc:on-change-supported>
config-changes
</inc:on-change-supported>
</inc:subscription-capabilities>
</per-node-capabilities>
</datastore-capabilities>
</system-capabilities>
</content-data>
</instance-data-set>
Figure 1: Notification Capabilities with datastore level settings
The following example is instance-data describing the notification capabilities of a hypothetical "acme-switch". The switch implements the running, candidate and operational datastores. Every change can be reported on-change from running, nothing from candidate and all config=false data from operational. Periodic subscriptions are supported for running and operational, but not for candidate.
<?xml version="1.0" encoding="UTF-8"?>
<instance-data-set xmlns=
"urn:ietf:params:xml:ns:yang:ietf-yang-instance-data">
<name>acme-router-notification-capabilities</name>
<yid-version>1</yid-version>
<content-schema>
<module>ietf-system-capabilities@2020-02-14</module>
<module>ietf-notification-capabilities@2020-02-14</module>
</content-schema>
<!-- revision date, contact, etc. -->
<description>Defines the notification capabilities of an acme-router.
The router only has running, and operational datastores.
Every change can be reported on-change from running, but
only config=true nodes and some config=false data from operational.
Statistics are not reported on-change only 2 important counters,
for these a smaller dampening period is possible.
</description>
<content-data>
<system-capabilities
xmlns="urn:ietf:params:xml:ns:yang:ietf-system-capabilities"
xmlns:inc=
"urn:ietf:params:xml:ns:yang:ietf-notification-capabilities"
xmlns:ds="urn:ietf:params:xml:ns:yang:ietf-datastores">
<inc:subscription-capabilities>
<inc:minimum-update-period>500</inc:minimum-update-period>
<inc:max-nodes-per-update>2000</inc:max-nodes-per-update>
<inc:minimum-dampening-period>100</inc:minimum-dampening-period>
<inc:periodic-notifications-supported>
config-changes state-changes
</inc:periodic-notifications-supported>
<inc:on-change-supported>
config-changes state-changes
</inc:on-change-supported>
<inc:supported-excluded-change-type>
all
</inc:supported-excluded-change-type>
</inc:subscription-capabilities>
<datastore-capabilities>
<datastore>ds:operational</datastore>
<per-node-capabilities>
<node-selector>
/if:interfaces/if:interface[if:name='lo']
</node-selector>
<inc:subscription-capabilities>
<inc:on-change-supported/>
<inc:periodic-notifications-supported/>
</inc:subscription-capabilities>
</per-node-capabilities>
<per-node-capabilities>
<node-selector>
/if:interfaces/if:interface/if:statistics/if:in-octets
</node-selector>
<inc:subscription-capabilities>
<inc:minimum-dampening-period>10
</inc:minimum-dampening-period>
<inc:on-change-supported>
state-changes
</inc:on-change-supported>
</inc:subscription-capabilities>
</per-node-capabilities>
<per-node-capabilities>
<node-selector>
/if:interfaces/if:interface/if:statistics/if:out-octets
</node-selector>
<inc:subscription-capabilities>
<inc:minimum-dampening-period>10
</inc:minimum-dampening-period>
<inc:on-change-supported>
state-changes
</inc:on-change-supported>
</inc:subscription-capabilities>
</per-node-capabilities>
<per-node-capabilities>
<node-selector>
/if:interfaces/if:interface/if:statistics
</node-selector>
<inc:subscription-capabilities>
<inc:on-change-supported/>
</inc:subscription-capabilities>
</per-node-capabilities>
</datastore-capabilities>
</system-capabilities>
</content-data>
</instance-data-set>
Figure 2: Notification Capabilities with data node specific settings
The following is the instance-data describing the notification capabilities of a hypothetical "acme-router". The router implements the running, and operational datastores. Every change can be reported on-change from running, but only config=true nodes and some config=false data from operational. Interface statistics are not reported on-change only 2 important counters. Datastore subscription capabilities are not reported on-change as they never change on the acme-router during run-time.
v10 - v11
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