| Internet-Draft | Node Tags Capability | October 2020 |
| Wu, et al. | Expires 2 May 2021 | [Page] |
Before a client application subscribes to updates from a datastore, server capabilities related to "Subscription to YANG Datastores" can be advertised using YANG Instance Data format. These server capabilities can be documented at implement time or reported at run-time.¶
This document proposes a YANG module for self describing data Object tag capability which augments system capabilities model and provide additional self describing data node attributes associated with node selectors within per-node capabilities.¶
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 May 2021.¶
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.¶
As described in [I-D.netconf-notification-capabilities], a server supporting YANG-Push MAY have a number of capabilities such as¶
Notification capability model defined in [I-D.netconf-notification-capabilities] allows a client to discover basic system capability and YANG-Push related capabilities both at implementation-time and run-time. Without using this notification capability, it might lead to unexpected failures or additional message exchanges for NETCONF clients to discover data objects with specific capability supported by a NETCONF server.¶
When all telemetry data on the server subscribed by a particular subscriber is huge, it becomes more likely that a burst of streamed data may temporarily overwhelm a receiver and consume expensive computing and storage resource. Accordingly, there is a need for filtering subscribed telemetry data on a server based on server capabilities, which can greatly reduce the amount of data to be streamed out to the destination.¶
However without telemetry data classification or prior knowledge of data objects correlation relationship, it is difficult for NETCONF clients to automatically select target data objects that are of interest to the client applications, e.g., identify a set of objects from different YANG data modules which have a common characteristic, collect specific object type nodes for multiple dimensional network visibility analysis.¶
This document proposes a YANG module for self describing data Node tag capability which augments System Capabilities model and provide additional self describing data node tag attributes associated with node selector for queries filtering.¶
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 YANG module ietf-notification-capabilities defined in [I-D.netconf-notification-capabilities] specifies the following server capabilities related to YANG Push:¶
These server capabilities can be provided either at implementation time or reported at run time.¶
This document augments system capabilities model and provide additional data node self explaination tag attributes associated with node selector within per-node capabilities:¶
The following tree diagram [RFC8340] provides an overview of the data model.¶
module: ietf-self-describing-capabilities
augment /sysc:system-capabilities/sysc:datastore-capabilities/ +
sysc:per-node-capabilities/sys:node-selection/sys:node-selector:
+--ro self-describing-attributes
+--ro opm-tag* tags:tag
+--ro metric-group tags:tag
+--ro muli-source-tag tags:tag¶
<CODE BEGINS> file "ietf-self-describing-capabilities.yang"
module ietf-self-describing-capabilities {
yang-version 1.1;
namespace urn:ietf:params:xml:ns:yang:ietf-self-description-capabilities;
prefix sdc;
import ietf-system-capabilities { prefix sysc ; }
import ietf-module-tags { prefix tags; }
organization
"IETF NETMOD (Network Modeling) Working Group";
contact
"WG Web: <https://tools.ietf.org/wg/netconf/>
WG List: <mailto:netconf@ietf.org>
Editor: Qin Wu
<mailto:bill.wu@huawei.com>
Qiufang Ma
<mailto:maqiufang1@huawei.com>
Peng Liu
<liupengyjy@chinamobile.com>
Hui Cai
<caihui@chinamobile.com>";
description
"This module defines an extension to System Capabilities model
and provides additional self explaination data node tag attributes
associated with node selector for queries filtering.
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;
see the RFC itself for full legal notices.";
revision 2020-07-08 {
description
"Initial revision";
reference
"RFC XXXX";
}
augment "/sysc:system-capabilities/sysc:datastore-capabilities" +
"/sysc:per-node-capabilities" +
"/sysc:node-selection/sysc:node-selector" {
description "Allows per-node capabilities have additional self-explanation attributes";
container self-describing-attributes {
description "self describing attributes for specific data node.";
leaf-list opm-tag {
type tags:tag;
description
"Object, Property and Metric(OPM) Tags associated with
specific data object within YANG module.
See the IANA 'YANG Data Node Tag Prefixes' registry
for reserved prefixes and the IANA
'IETF YANG Data Node Tags' registry for IETF tags.";
}
leaf metric-group {
type tags:tag;
description
"The metric-group can be used to provide correlation between
different performance metric information associated with YANG
data node.";
}
leaf multi-source-tag {
type tags:tag;
description
"The multiple source tag can be used to aggregate peformance
metric from different sources.";
}
}
}
}
<CODE ENDS>¶
This document registers a URI in the "IETF XML Registry" [RFC3688]. Following the format in [RFC3688], the following registration has been made:¶
URI:
urn:ietf:params:xml:ns:yang:ietf-self-describing-capabilities
Registrant Contact:
The IESG.
XML:
N/A; the requested URI is an XML namespace.¶
This document registers one YANG module in the "YANG Module Names" registry [RFC6020]. Following the format in [RFC6020], the following registration has been made:¶
name:
ietf-self-describing-capabilities
namespace:
urn:ietf:params:xml:ns:yang:ietf-self-describing-capabilities
prefix:
sec
reference:
RFC XXXX (RFC Ed.: replace XXX with actual RFC number and remove
this note.)¶
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 RESTCONF layer is HTTPS, and the mandatory-to-implement secure transport is TLS [RFC8446].¶
The NETCONF 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.¶
There are a number of data nodes defined in this YANG module that are writable/creatable/deletable (i.e., config true, which is the default). These data nodes may be considered sensitive in some network environments. Write operations (e.g., edit-config) to these data nodes without proper protection can have a negative effect on network operations. These are the subtrees and data nodes and their sensitivity/vulnerability:¶
The authors would like to thank Ran Tao, Hui Cai for his major contributions to the initial modeling and use cases.¶
The following subsections provides targeted data object subscription example. The subscription "id" values of 22 used below is just an example. In production, the actual values of "id" might not be small integers.¶
+-----------+ +-----------+
| Subscriber| | Publisher |
+------+----+ +-----+-----+
| |
| |
|Telemery data Tagging Advertisement
| (node-selector, opm-tag = metric)
|<---------------------------------|
| |
| establish-subscription |
| (datasore,node-selector) |
|--------------------------------->|
| |
| |
| |
| RPC Reply: OK, id = 22 |
|<---------------------------------|
| |
| |
| |
| Notification Message (for 22) |
| <--------------------------------|
| |
| |
| |¶
The publisher advertise telemetry data node capability to the subscriber to instruct the receiver to subscribe targeted data object with specific characteristics (e.g., performance metric related data object) and specific data path corresponding to the targeted data object.¶
The following XML example [W3C.REC-xml-20081126] illustrates the advertisment of the list of available target objects:¶
<?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>
<content-schema>
<module>ietf-system-capabilities@2020-03-23</module>
<module>ietf-notification-capabilities@2020-03-23</module>
<module>ietf-data-export-capabilities@2020-03-23</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 based on timer based trigger and counter
threshold based trigger.
</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">
<datastore-capabilities>
<datastore>ds:operational</datastore>
<per-node-capabilities>
<node-selector>\
/if:interfaces/if:interface/if:statistics/if:in-errors\
</node-selector>
<sec:self-describing-capabilities>
<sec:opm-tag>metric</sec:opm-tag>
<sec:metric-group>loss</sec:metric-group>
</sec:self-describing-capabilities>
</per-node-capabilities>
</datastore-capabilities>
</system-capabilities>
</content-data>
</instance-data-set>¶
With telemetry data tagging information carried in the Telemetry data Tagging Advertisement, the subscriber identifies targeted data object and associated data path to the datastore node and sends a establish- subscription RPC to subscribe specific data objects that are interests to the client application from the publisher.¶
<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">
/if:interfaces/if:interface/if:statistics/if:in-errors
</yp:datastore-xpath-filter>
<yp:periodic>
<yp:period>500</yp:period>
</yp:periodic>
</establish-subscription>
</netconf:rpc>¶
The publisher returns specific object type of operational state related to the subscriber.¶