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. Claise, et al. Expires April 28, 2022 [Page 1] Internet-Draft Telemetry Data Manifest October 2021 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. Claise, et al. Expires April 28, 2022 [Page 2] Internet-Draft Telemetry Data Manifest October 2021 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. Claise, et al. Expires April 28, 2022 [Page 3] Internet-Draft Telemetry Data Manifest October 2021 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. Claise, et al. Expires April 28, 2022 [Page 4] Internet-Draft Telemetry Data Manifest October 2021 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. Claise, et al. Expires April 28, 2022 [Page 5] Internet-Draft Telemetry Data Manifest October 2021 3.2. YANG module ietf-collected-data-platform-manifest 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: WG List: Author: Benoit Claise Author: Jean Quilbeuf "; 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 Claise, et al. Expires April 28, 2022 [Page 6] Internet-Draft Telemetry Data Manifest October 2021 (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 Claise, et al. Expires April 28, 2022 [Page 7] Internet-Draft Telemetry Data Manifest October 2021 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; } } } 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 Claise, et al. Expires April 28, 2022 [Page 8] Internet-Draft Telemetry Data Manifest October 2021 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 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: WG List: Author: Benoit Claise Author: Jean Quilbeuf "; 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 Claise, et al. Expires April 28, 2022 [Page 9] Internet-Draft Telemetry Data Manifest October 2021 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; Claise, et al. Expires April 28, 2022 [Page 10] Internet-Draft Telemetry Data Manifest October 2021 // 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 } } 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. Claise, et al. Expires April 28, 2022 [Page 11] Internet-Draft Telemetry Data Manifest October 2021 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, . [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, Ed., "YANG Tree Diagrams", BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018, . Claise, et al. Expires April 28, 2022 [Page 12] Internet-Draft Telemetry Data Manifest October 2021 [RFC8525] Bierman, A., Bjorklund, M., Schoenwaelder, J., Watsen, K., and R. Wilton, "YANG Library", RFC 8525, DOI 10.17487/RFC8525, March 2019, . [RFC8641] Clemm, A. and E. Voit, "Subscription to YANG Notifications for Datastore Updates", RFC 8641, DOI 10.17487/RFC8641, September 2019, . 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 Claise, et al. Expires April 28, 2022 [Page 13] Internet-Draft Telemetry Data Manifest October 2021 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 Claise, et al. Expires April 28, 2022 [Page 14]