OPSAWG B. Claise
Internet-Draft J. Quilbeuf
Intended status: Standards Track Huawei
Expires: April 28, 2022 D. Lopez
Telefonica I+D
T. Graf
Swisscom
October 25, 2021
Data Manifest for Streaming Telemetry
draft-claise-opsawg-collected-data-manifest-00
Abstract
Most network equipments feature telemetry as a mean to monitoring
their status. Several protocols exist to this end; for example, the
model-driven telemetry governed by YANG models. These protocols
provide the data itself, without any contextual information about the
collection method. This can render the data unusable if that context
is lost, for instance when the data is stored without the relevent
information. This draft proposes a YANG model to store that
contextual information, that must be stored along with the collected
data in order to keep the collected data exploitable.
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 April 28, 2022.
Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved.
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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. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Platform Manifest . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Overview of the model . . . . . . . . . . . . . . . . . . 4
3.2. YANG module ietf-collected-data-platform-manifest . . . . 6
4. Collection Manifest . . . . . . . . . . . . . . . . . . . . . 8
4.1. Overview of the model . . . . . . . . . . . . . . . . . . 8
4.2. YANG module ietf-collected-data-manifest . . . . . . . . 9
5. Mapping data to data manifest . . . . . . . . . . . . . . . . 11
6. Security Considerations . . . . . . . . . . . . . . . . . . . 12
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 12
9. Open Issues . . . . . . . . . . . . . . . . . . . . . . . . . 12
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
10.1. Normative References . . . . . . . . . . . . . . . . . . 12
10.2. Informative References . . . . . . . . . . . . . . . . . 13
Appendix A. Changes between revisions . . . . . . . . . . . . . 13
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
1. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
Data Manifest: all the necessary metadata required to interpret the
telemetry information.
Platform Manifest: part of the Data Manifest that completely
identifies the platform producing the data.
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2. Introduction
Network elements use Model-driven Telemetry (MDT) to continuously
stream information, both counters and state information. This
streamed information is used for network monitoring, directly in the
data collection, in a closed-loop automation systems, or in a
database (sometimes called a big data lake) for further analysis.
When streaming YANG objects with YANG-PUSH [RFC8641], there is a
semantic definition in the corresponding YANG module definition. On
top of that definition, it's also important to understand any
contextual information about the collection environment.
As an example, a database could contain a specific counter time
series. When analyzing the data, it's important to understand that
this counter was requested from the network element at specific
cadence, as this exact cadence might not be observed in the time
series, potentially implying that the network element was under
stress. The same time series might report some values as 0, or might
even omit some values in the series. This might be explained by a
too small observation period, compared to the minimum-observed-period
[I-D.claise-netconf-metadata-for-collection]. Again, knowing the
conditions under which the counter was collected and streamed is key.
Indeed, taking into account the value of 0 might lead to the wrong
conclusion that the counter dropped to zero. This document specifies
the data manifest, which contains the information how and when the
telemetry information were metered.
Precisely identifying the device used for producing the data (that is
the platform manifest) is also key to complete the collection
context. As an example, knowing the exact device software
specification might reveal a particularity in the observed data,
explained by a specific bug, or a specific bug fix. On top of that,
in particular for MDT, it is crucial to know the set of YANG modules
supported by the device, along with their deviation. In some cases,
there might even be some backwards incompatible changes in native
modules between one OS version to the next one. These information
must be compiled in a platform manifest that must be included in the
data manifest.
Some related YANG modules have been specified to discover the device
capabilities:
o [I-D.ietf-netconf-notification-capabilities] which models the
device capabilities regarding the production and export of
telemetry data.
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o [I-D.claise-netconf-metadata-for-collection], which is based on
the previous draft to define the optimal settings to stream
specfic items (i.e. per sensor-path).
While these YANG modules are important to discover the capabilities
before applying the telemetry configuration (such as on-change), some
of this information is part of the context for the streaming data.
Our goal is to represent the data manifest for a given device. This
manifest contains two parts, the platform manifest and the data-
collection manifest. The platform manifest is pretty stable and
should change only when the device is updated or patched. On the
other hand, the data collection is likely to change each time a new
MDT subscription is requested and might even change if the device
load increases and collection periods are updated. To separate these
two parts, we enclose each of them in its own module. We first
present the module for the platform manifest in Section 3 and then
the module for the collection manifest in Section 4. The full data
manifest is obtained by combining these two modules.
This data manifest instance file MUST be streamed all with the data
and stored along with the collected data. In case the data are moved
to different place (typically a database), the data manifest MUST
follow the collected data. This can render the data unusable if that
context is lost, for instance when the data is stored without the
relevent information. The data manifest MUST be encoded with the
YANG instance data file format
[I-D.ietf-netmod-yang-instance-file-format]. The YANG instance data
file MUST be updated when the data manifest information changes (for
example, when a router is upgraded), and the new timestamps MUST be
used [I-D.ietf-netmod-yang-instance-file-format].
3. Platform Manifest
3.1. Overview of the model
Figure 1 contains the YANG tree diagram [RFC8340] of the ietf-
collected-data-platform-manifest module.
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module: ietf-collected-data-platform-manifest
+--rw platform
+--rw platform? string
+--rw software-version? string
+--rw software-flavor? string
+--rw os-version? string
+--rw os-type? string
+--rw module-set* [name]
+--rw name string
+--rw module* [name]
| +--rw name yang:yang-identifier
| +--rw revision? revision-identifier
| +--rw namespace inet:uri
| +--rw location* inet:uri
| +--rw submodule* [name]
| | +--rw name yang:yang-identifier
| | +--rw revision? revision-identifier
| | +--rw location* inet:uri
| +--rw feature* yang:yang-identifier
| +--rw deviation* -> ../../module/name
+--rw import-only-module* [name revision]
+--rw name yang:yang-identifier
+--rw revision union
+--rw namespace inet:uri
+--rw location* inet:uri
+--rw submodule* [name]
+--rw name yang:yang-identifier
+--rw revision? revision-identifier
+--rw location* inet:uri
Figure 1: YANG tree diagram for ietf-collected-data-platform-manifest
module
The platform manifest contains all the information to unambiguously
identify a device. The platform is identified by a set of parameters
(platform, software-version, software-flavor, os-version, os-type)
that are aligned with the YANG Catalog www.yangcatalog.org draft
[I-D.clacla-netmod-model-catalog] so that the YANG catalog could be
used to retrieve the YANG modules a posteriori.
The platform manifest also includes the module-set, as defined in the
YANG Library [RFC8525]. That module set is particularly useful to
define to define the sensor paths, as they are based on module names.
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3.2. YANG module ietf-collected-data-platform-manifest
<CODE BEGINS> file "ietf-collected-data-platform-
manifest@2021-10-15.yang"
module ietf-collected-data-platform-manifest {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-collected-data-plaftorm-manifest";
prefix platform-manifest;
import ietf-yang-library {
prefix yanglib;
reference
"RFC8525: YANG Library";
}
organization
"IETF NETCONF (Network Configuration) Working Group";
contact
"WG Web: <https://datatracker.ietf.org/wg/netconf/>
WG List: <mailto:netconf@ietf.org>
Author: Benoit Claise <mailto:benoit.claise@huawei.com>
Author: Jean Quilbeuf <mailto:jean.quilbeuf@huawei.com>";
description
"This module describes the platform information to be used as
context of data collection from a given network element. The
contents of this model must be streamed along with the data
streamed from the network element so that the platform context
of the data collection can be retrieved later.
The data content of this model should not change except on
upgrade or patching of the device.
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) 2021 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
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(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 2021-10-15 {
description
"Initial revision";
reference
"RFC xxxx: Title to be completed";
}
container platform {
description
"Contains information about the platform that allows to identify and
understand the individual data collection information. ";
leaf platform {
type string;
description
"Platform on which this module is implemented.";
}
leaf software-version {
type string;
description
"Name of the version of software. With respect to most network device appliances,
this will be the operating system version. But for other YANG module
implementation, this would be a version of appliance software. Ultimately,
this should correspond to a version string that will be recognizable by
the consumers of the platform.";
}
leaf software-flavor {
type string;
description
"A variation of a specific version where
YANG model support may be different. Depending on the vendor, this could
be a license, additional software component, or a feature set.";
}
leaf os-version {
type string;
description
"Version of the operating system using this module. This is primarily useful if
the software implementing the module is an application that requires a specific
operating system.";
}
leaf os-type {
type string;
description
"Type of the operating system using this module. This is primarily useful if
the software implementing the module is an application that requires a
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specific operating system.";
}
list module-set {
key "name";
description
"The list of all modules defined on the device. The name of the modules
can be used in sensor-paths to identfy a specific collected object.";
uses yanglib:module-set-parameters;
}
}
}
<CODE ENDS>
4. Collection Manifest
4.1. Overview of the model
Figure 2 contains the YANG tree diagram [RFC8340] of the ietf-
collected-data-manifest module.
module: ietf-collected-data-manifest
+--rw data-collection
+--rw mdt-collection-item* [sensor-path]
+--rw sensor-path string
+--rw requested-period? int64
+--rw current-period? int64
+--rw on-change? boolean
+--rw suppress-redundancy? boolean
Figure 2: YANG tree diagram for ietf-collected-data-manifest module
The data-collection container contains the information related to
individual items collection. This subtree currently contains only
information about MDT collection. It should be extended and
extendable to represent other kinds of data collection.
With MDT collection, the granularity of the collection is defined by
the sensor path. Note that all devices do not support an arbitrary
granularity up to the leaf, usually for performance reasons. Each
sensor-path currently collected by the device should show up in the
mdt-collection-item list.
For each sensor-path, the collection context must be specified
including:
o on-change: when set to true, an update is sent as soon as and only
when a value changes. This is also known as Event-Driven
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Telemetry (EDT). When set to false, the values are sent
regularly.
o suppress-redundancy (only when on-change is false): reduce
bandwith usage by sending a regular udpate only if the value is
different from the previous udpate.
o requested-period (only when on-change is false): period between
two updates requested by the client for this sensor-path
o current-period (only when on-change is false): current period
between two updates
This information is crucial to understand the collected values. For
instance, the on-change and suppress-redundancy options, if set,
might remove a lot of messages from the database because values are
sent only when there is a change.
4.2. YANG module ietf-collected-data-manifest
<CODE BEGINS> file "ietf-collected-data-manifest@2021-10-15.yang"
module ietf-collected-data-manifest {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-collected-data-manifest";
prefix data-manifest;
organization
"IETF NETCONF (Network Configuration) Working Group";
contact
"WG Web: <https://datatracker.ietf.org/wg/netconf/>
WG List: <mailto:netconf@ietf.org>
Author: Benoit Claise <mailto:benoit.claise@huawei.com>
Author: Jean Quilbeuf <mailto:jean.quilbeuf@huawei.com>";
description
"This module describes the context of data collection from a
given network element. The contents of this model must be
streamed along with the data streamed from the netkwork
element so that the context of the data collection can
be retrieved later.
This module must be completed with
ietf-collected-data-platform-manifest
to capture the whole context of a data collection session.
The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL',
'SHALL NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED',
'NOT RECOMMENDED', 'MAY', and 'OPTIONAL' in this document
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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) 2021 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 2021-10-15 {
description
"Initial revision";
reference
"RFC xxxx: Title to be completed";
}
container data-collection {
description
"Defines the information for each collected objet";
list mdt-collection-item {
description
"Status of the collection for the given sensor-path";
key "sensor-path";
leaf sensor-path {
description
"The sensor path that was configured to collect information about
this object. Sensor path syntax is
module_name:node_name ( / (module_name:)? node_name)*
where module_name is the name of a module and node_name is the
name of a node (list, container or leaf). Module name is only
necessary if the preceding node in the path is not defined in
the same module.
Module name must be defined in the platform-manifest module and
every node name must be defined in the preceding node in the path.";
type string;
}
leaf requested-period {
description
"Requested period, in milisecond, between two succesive updates.";
type int64;
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// when on-change is false;
}
leaf current-period {
description
"Current period, in milisecond, between two succesive update.s";
type int64;
// when on-change is false;
}
leaf on-change {
description
"Whether the sensor path is collected only when there is a change,
i.e. Event-Driven Telemetry is enabled.";
type boolean;
}
leaf suppress-redundancy {
description
"Whether the information is sent at every period or only when there
is a change between two successive pollings..";
type boolean;
}
}
// we could augment here with other kind of collection items
}
}
<CODE ENDS>
5. Mapping data to data manifest
The data should be mapped to the data manifest. Since the data
manifest will not change as frequently as the data itself, it make
sense to map several data to the same data manifest. Somehow, the
collected data must include a metadata pointing to the corresponding
data manifest.
The platform manifest is likely to remain the same until the device
is updated. So the platform manifest only need to be collected once
per streaming session and updated after a device reboot.
For MDT, we can rely on the sensor-path to map the collected data to
the data manifest. In that sense, collecting one instance of the
data-manifest per device is sufficient to get the data manifest of
all data connected from that device.
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6. Security Considerations
7. IANA Considerations
This document includes no request to IANA.
8. Contributors
9. Open Issues
o Do we want to the hardware specifications, next to the OS
information?
o Do we want to handle the absence of values, i.e. add information
about missed collection or errors in the collection context ? It
could also explain why some values are missing. On the other
hand, this might also be out scope.
o How do we handle other kinds of collection than MDT like netflow,
SNMP, CLI ? How do we map the collected data to the data-manifest
?
o Align the terms with the YANG Push specifications. Ex: sensor-
path to subscription (TBC)
o Better explain the on-change example.
10. References
10.1. Normative References
[I-D.ietf-netmod-yang-instance-file-format]
Lengyel, B. and B. Claise, "YANG Instance Data File
Format", draft-ietf-netmod-yang-instance-file-format-21
(work in progress), October 2021.
[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>.
[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>.
[RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
<https://www.rfc-editor.org/info/rfc8340>.
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[RFC8525] Bierman, A., Bjorklund, M., Schoenwaelder, J., Watsen, K.,
and R. Wilton, "YANG Library", RFC 8525,
DOI 10.17487/RFC8525, March 2019,
<https://www.rfc-editor.org/info/rfc8525>.
[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>.
10.2. Informative References
[I-D.clacla-netmod-model-catalog]
Clarke, J. and B. Claise, "YANG module for
yangcatalog.org", draft-clacla-netmod-model-catalog-03
(work in progress), April 2018.
[I-D.claise-netconf-metadata-for-collection]
Claise, B., Nayyar, M., and A. Sesani, "Per-Node
Capabilities for Optimum Operational Data Collection",
draft-claise-netconf-metadata-for-collection-02 (work in
progress), July 2021.
[I-D.ietf-netconf-notification-capabilities]
Lengyel, B., Clemm, A., and B. Claise, "YANG Modules
describing Capabilities for Systems and Datastore Update
Notifications", draft-ietf-netconf-notification-
capabilities-21 (work in progress), October 2021.
Appendix A. Changes between revisions
Initial version
Acknowledgements
...
Authors' Addresses
Benoit Claise
Huawei
Email: benoit.claise@huawei.com
Jean Quilbeuf
Huawei
Email: jean.quilbeuf@huawei.com
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Diego R. Lopez
Telefonica I+D
Don Ramon de la Cruz, 82
Madrid 28006
Spain
Email: diego.r.lopez@telefonica.com
Thomas Graf
Swisscom
Binzring 17
Zurich 8045
Switzerland
Email: thomas.graf@swisscom.com
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