Network Working Group T. Graf Internet-Draft W. Du Intended status: Experimental Swisscom Expires: 16 September 2024 A. Huang Feng INSA-Lyon V. Riccobene A. Roberto Huawei 15 March 2024 Semantic Metadata Annotation for Network Anomaly Detection draft-netana-nmop-network-anomaly-semantics-01 Abstract This document explains why and how semantic metadata annotation helps to test, validate and compare outlier detection, supports supervised and semi-supervised machine learning development, enables data exchange among network operators, vendors and academia and make anomalies for humans apprehensible. The proposed semantics uniforms the network anomaly data exchange between and among operators and vendors to improve their network outlier detection systems. Requirements Language The keywords "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. 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 16 September 2024. Graf, et al. Expires 16 September 2024 [Page 1] Internet-Draft Network Anomaly Semantics March 2024 Copyright Notice Copyright (c) 2024 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 Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Outlier Detection . . . . . . . . . . . . . . . . . . . . . . 3 3. Data Mesh . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4. Observed Symptoms . . . . . . . . . . . . . . . . . . . . . . 4 5. Semantic Metadata . . . . . . . . . . . . . . . . . . . . . . 8 5.1. Overview of the Model for the Symptom Semantic Metadata . . . . . . . . . . . . . . . . . . . . . . . . 9 6. Security Considerations . . . . . . . . . . . . . . . . . . . 10 7. Implementation status . . . . . . . . . . . . . . . . . . . . 10 7.1. Antagonist . . . . . . . . . . . . . . . . . . . . . . . 10 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 10 9.1. Normative References . . . . . . . . . . . . . . . . . . 10 9.2. Informative References . . . . . . . . . . . . . . . . . 11 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13 1. Introduction Network Anomaly Detection Architecture [Ahf23] provides an overall introduction into how anomaly detection is being applied into the IP network domain and which operational data is needed. It approaches the problem space by automating what a Network Engineer would normally do when verifying a network connectivity service. Monitor from different network plane perspectives to understand wherever one network plane affects another negatively. In order to fine tune outlier detection, the results provided as analytical data need to be reviewed by a Network Engineer. Keeping the human out of the monitoring but still involving him in the alert verification loop. Graf, et al. Expires 16 September 2024 [Page 2] Internet-Draft Network Anomaly Semantics March 2024 This document describes what information is needed to understand the output of the outlier detection for a Network Engineer, but also at the same time is semantically structured that it can be used for outlier detection testing by comparing the results systematically and set a baseline for supervised machine learning which requires labeled operational data. 2. Outlier Detection Outlier Detection, also known as anomaly detection, describes a systematic approach to identify rare data points deviating significantly from the majority. Outliers can manifest as single data point or as a sequence of data points. There are multiple ways in general to classify anomalies, but for the context of this draft, the following three classes are taken into account: Global outliers: An outlier is considered "global" if its behaviour is outside the entirety of the considered data set. For example, if the average dropped packet count is between 0 and 10 per minute and a small time-window gets the value 1000, this is considered a global anomaly. Contextual outliers: An outlier is considered "contextual" if its behaviour is within a normal (expected) range, but it would not be expected based on some context. Context can be defined as a function of multiple parameters, such as time, location, etc. For example, the forwarded packet volume overnight reaches levels which might be totally normal for the daytime, but anomalous and unexpected for the nighttime. Collective outliers: An outlier is considered "collective" if the behaviour of each single data point that are part of the anomaly are within expected ranges (so they are not anomalous it either a contextual or a global sense), but the group, taking all the data points together, is. Note that the group can be made within a single time series (a sequence of data points is anomalous) or across multiple metrics (e.g. if looking at two metrics together, the combined behavior turns out to be anomalous). In Network Telemetry time series, one way this can manifest is that the amount of network paths and interface state changes matches the time range when the forwarded packet volume decreases as a group. For each outlier a score between 0 and 1 is being calculated. The higher the value, the higher the probability that the observed data point is an outlier. Anomaly detection: A survey [VAP09] gives additional details on anomaly detection and its types. Graf, et al. Expires 16 September 2024 [Page 3] Internet-Draft Network Anomaly Semantics March 2024 3. Data Mesh The Data Mesh [Deh22] Architecture distinguishes between operational and analytical data. Operational data refers to collected data from operational systems. While analytical data refers to insights gained from operational data. In terms of network observability, semantics of operational network metrics are defined by IETF and are categorized as described in the Network Telemetry Framework [RFC9232] in the following three different network planes: Management Plane: Time series data describing the state changes and statistics of a network node and its components. For example, Interface state and statistics modelled in ietf-interfaces.yang [RFC8343] Control Plane: Time series data describing the state and state changes of network reachability. For example, BGP VPNv6 unicast updates and withdrawals exported in BGP Monitoring Protocol (BMP) [RFC7854] and modeled in BGP [RFC4364] Forwarding Plane: Time series data describing the forwarding behavior of packets and its data-plane context. For example, dropped packet count modelled in IPFIX entity forwardingStatus(IE89) [RFC7270] and packetDeltaCount(IE2) [RFC5102] and exportet with IPFIX [RFC7011]. In terms of network observability, this applies to operational semantic metadata and service level indicators. The health status and symptoms described in the Service Assurance Intend Based Networking [RFC9418], the precision availability metrics defined in [I-D.ietf-ippm-pam] or network anomalies and its symptoms as described in this document and applied in the network anomaly postmortem lifecycle described in [I-D.netana-nmop-network-anomaly-lifecycle] where the applied semantic metadata of this document is refined for each detected anomaly. 4. Observed Symptoms In this section observed network symptoms are specified and categorized according to the following scheme: Action: Which action the network node performed for a packet in the Forwarding Plane, a path or adjacency in the Control Plane or state or statistical changes in the Management Plane. For Forwarding Plane we distinguish between missing, where the drop Graf, et al. Expires 16 September 2024 [Page 4] Internet-Draft Network Anomaly Semantics March 2024 occured outside the measured network node, drop and on-path delay, which was measured on the network node. For Control Plane we distinguish between reachability, which refers to a change in the routing or forwarding information base (RIB/FIB) and adjcacency which refers to a change in peering or link-layer resolution. For Management Plane we refer to state or statistical changes on interfaces. Reason: For each action, one or more reasons describe why this action was used. For Drops in Forwarding Plane we distinguish between Unreachable because network layer reachability information was missing, Administered because an administrator configured a rule preventing the forwarding for this packet and Corrupt where the network node was unable to determine where to forward to due to packet, software or hardware error. For on-path delay we distinguish between Minimum, Average and Maximum Delay for a given flow. For Control Plane wherever a the reachability was updated or withdrawn or the adjcacency was established or teared down. For Management Plane we distinguish between interfaces states up and down, and statistical erros, discards or unknown protocol counters. Cause: For each reason one or more cause describe the cause why the network node has chosen that action. Table 1 consolidates for the forwarding plane a list of common symptoms with their Actions, Reasons and Causes. Graf, et al. Expires 16 September 2024 [Page 5] Internet-Draft Network Anomaly Semantics March 2024 +=========+==============+========================+ | Action | Reason | Cause | +=========+==============+========================+ | Missing | Previous | Time | +---------+--------------+------------------------+ | Drop | Unreachable | next-hop | +---------+--------------+------------------------+ | Drop | Unreachable | link-layer | +---------+--------------+------------------------+ | Drop | Unreachable | Time To Life expired | +---------+--------------+------------------------+ | Drop | Unreachable | Fragmentation needed | | | | and Don't Fragment set | +---------+--------------+------------------------+ | Drop | Administered | Access-List | +---------+--------------+------------------------+ | Drop | Administered | Unicast Reverse Path | | | | Forwarding | +---------+--------------+------------------------+ | Drop | Administered | Discard Route | +---------+--------------+------------------------+ | Drop | Administered | Policed | +---------+--------------+------------------------+ | Drop | Administered | Shaped | +---------+--------------+------------------------+ | Drop | Corrupt | Bad Packet | +---------+--------------+------------------------+ | Drop | Corrupt | Bad Egress Interface | +---------+--------------+------------------------+ | Delay | Min | - | +---------+--------------+------------------------+ | Delay | Mean | - | +---------+--------------+------------------------+ | Delay | Max | - | +---------+--------------+------------------------+ Table 1: Describing Symptoms and their Actions, Reason and Cause for Forwarding Plane Table 2 consolidates for the control plane a list of common symptoms with their actions, reasons and causess. +==============+=============+====================================+ | Action | Reason | Cause | +==============+=============+====================================+ | Reachability | Update | Imported | +--------------+-------------+------------------------------------+ | Reachability | Update | Received | Graf, et al. Expires 16 September 2024 [Page 6] Internet-Draft Network Anomaly Semantics March 2024 +--------------+-------------+------------------------------------+ | Reachability | Withdraw | Received | +--------------+-------------+------------------------------------+ | Reachability | Withdraw | Peer Down | +--------------+-------------+------------------------------------+ | Reachability | Withdraw | Suppressed | +--------------+-------------+------------------------------------+ | Reachability | Withdraw | Stale | +--------------+-------------+------------------------------------+ | Reachability | Withdraw | Route Policy Filtered | +--------------+-------------+------------------------------------+ | Reachability | Withdraw | Maximum Number of Prefixes Reached | +--------------+-------------+------------------------------------+ | Adjacency | Established | Peer | +--------------+-------------+------------------------------------+ | Adjacency | Established | Link-Layer | +--------------+-------------+------------------------------------+ | Adjacency | Locally | Peer | | | Teared Down | | +--------------+-------------+------------------------------------+ | Adjacency | Remotely | Peer | | | Teared Down | | +--------------+-------------+------------------------------------+ | Adjacency | Locally | Link-Layer | | | Teared Down | | +--------------+-------------+------------------------------------+ | Adjacency | Remotely | Link-Layer | | | Teared Down | | +--------------+-------------+------------------------------------+ | Adjacency | Locally | Administrative | | | Teared Down | | +--------------+-------------+------------------------------------+ | Adjacency | Remotely | Administrative | | | Teared Down | | +--------------+-------------+------------------------------------+ | Adjacency | Locally | Maximum Number of Prefixes Reached | | | Teared Down | | +--------------+-------------+------------------------------------+ | Adjacency | Remotely | Maximum Number of Prefixes Reached | | | Teared Down | | +--------------+-------------+------------------------------------+ | Adjacency | Locally | Transport Connection Failed | | | Teared Down | | +--------------+-------------+------------------------------------+ | Adjacency | Remotely | Transport Connection Failed | | | Teared Down | | +--------------+-------------+------------------------------------+ Graf, et al. Expires 16 September 2024 [Page 7] Internet-Draft Network Anomaly Semantics March 2024 Table 2: Describing Symptoms and their Actions, Reason and Cause for Control Plane Table 3 consolidates for the management plane a list of common symptoms with their Actions, Reasons and Causes. +===========+==================+============+ | Action | Reason | Cause | +===========+==================+============+ | Interface | Up | Link-Layer | +-----------+------------------+------------+ | Interface | Down | Link-Layer | +-----------+------------------+------------+ | Interface | Errors | - | +-----------+------------------+------------+ | Interface | Discards | - | +-----------+------------------+------------+ | Interface | Unknown Protocol | - | +-----------+------------------+------------+ Table 3: Describing Symptoms and their Actions, Reason and Cause for Management Plane 5. Semantic Metadata Metadata adds additional context to data. For instance, in networks the software version of a network node where Management Plane metrics are obtained from as described in[I-D.claise-opsawg-collected-data-manifest]. Where in Semantic Metadata the meaning or ontology of the annotated data is being described. In this section a YANG model is defined in order to provide a structure for the metadata related to anomalies happening in the network. The module is intended to describe the metadata used to "annotate" the operational data collected from the network nodes, which can include time series data and logs, as well as other forms of data that is "time-bounded". The aspects discussed so far in this document are grouped under the concept of "anomaly" which represents a collection of symptoms. The anomaly overall has a set of parameters that describe the overall behavior of the network in a given time-window including all the spotted symptoms (network anomalies). Graf, et al. Expires 16 September 2024 [Page 8] Internet-Draft Network Anomaly Semantics March 2024 5.1. Overview of the Model for the Symptom Semantic Metadata Figure 1 contains the YANG tree diagram [RFC8340] of the ietf- symptom-semantic-metadata module. For each symptom, the following parameters have been assigned: A unique ID for identification, a description of the symptom, a list of affected metrics or counters, atart and end time to specify the time-window, a confident score indicating how accurate the symptom was detected, a concern score indicating how critical the symptom is, the source indicating if it has been identified by a network expert or an algorithm, the tags with key value where Action, Reason and Cause can be annotated as described in previous section. module: ietf-symptom-semantic-metadata +--rw symptom +--rw id yang:uuid +--rw event-id yang:uuid +--rw description string +--rw start-time yang:date-and-time +--rw end-time yang:date-and-time +--rw confidence-score float +--rw concern-score? float +--rw tags* [key] | +--rw key string | +--rw value string +--rw (pattern)? | +--:(drop) | | +--rw drop empty | +--:(spike) | | +--rw spike empty | +--:(mean-shift) | | +--rw mean-shift empty | +--:(seasonality-shift) | | +--rw seasonality-shift empty | +--:(trend) | | +--rw trend empty | +--:(other) | +--rw other string +--rw source +--rw (source-type) | +--:(human) | | +--rw human empty | +--:(algorithm) | +--rw algorithm empty +--rw name? string Figure 1: YANG tree diagram for ietf-symptom-semantic-metadata Graf, et al. Expires 16 September 2024 [Page 9] Internet-Draft Network Anomaly Semantics March 2024 6. Security Considerations The security considerations. 7. Implementation status This section provides pointers to existing open source implementations of this draft. Note to the RFC-editor: Please remove this before publishing. 7.1. Antagonist A tool called Antagonist has been implemented during the IETF 119 Hackathon, in order to validate the application of the YANG models defined in this draft. Antagonist provides visual support for two important use cases in the scope of this document: * the generation of a ground truth in relation to symptoms and incidents in timeseries data * the visual validation of results produced by automated network anomaly detection tools. The open source code can be found here: [Antagonist] 8. Acknowledgements The authors would like to thank xxx for their review and valuable comments. 9. References 9.1. Normative References [Ahf23] Huang Feng, A., "Daisy: Practical Anomaly Detection in large BGP/MPLS and BGP/SRv6 VPN Networks", IETF 117, Applied Networking Research Workshop, DOI 10.1145/3606464.3606470, July 2023, . [Antagonist] Riccobene, V., Roberto, A., Du, W., Graf, T., and H. Huang Feng, "Antagonist: Anomaly tagging on historical data", . Graf, et al. Expires 16 September 2024 [Page 10] Internet-Draft Network Anomaly Semantics March 2024 [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, . [RFC9232] Song, H., Qin, F., Martinez-Julia, P., Ciavaglia, L., and A. Wang, "Network Telemetry Framework", RFC 9232, DOI 10.17487/RFC9232, May 2022, . 9.2. Informative References [Deh22] Dehghani, Z., "Data Mesh", O'Reilly Media, ISBN 9781492092391, March 2022, . [I-D.claise-opsawg-collected-data-manifest] Claise, B., Quilbeuf, J., Lopez, D., Martinez-Casanueva, I. D., and T. Graf, "A Data Manifest for Contextualized Telemetry Data", Work in Progress, Internet-Draft, draft- claise-opsawg-collected-data-manifest-06, 10 March 2023, . [I-D.ietf-ippm-pam] Mirsky, G., Halpern, J. M., Min, X., Clemm, A., Strassner, J., and J. François, "Precision Availability Metrics for Services Governed by Service Level Objectives (SLOs)", Work in Progress, Internet-Draft, draft-ietf-ippm-pam-09, 1 December 2023, . [I-D.ietf-opsawg-ipfix-on-path-telemetry] Graf, T., Claise, B., and A. H. Feng, "Export of On-Path Delay in IPFIX", Work in Progress, Internet-Draft, draft- ietf-opsawg-ipfix-on-path-telemetry-06, 14 January 2024, . Graf, et al. Expires 16 September 2024 [Page 11] Internet-Draft Network Anomaly Semantics March 2024 [I-D.netana-nmop-network-anomaly-lifecycle] Riccobene, V., Roberto, A., Graf, T., Du, W., and A. H. Feng, "Experiment: Network Anomaly Postmortem Lifecycle", Work in Progress, Internet-Draft, draft-netana-nmop- network-anomaly-lifecycle-00, 28 February 2024, . [RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February 2006, . [RFC5102] Quittek, J., Bryant, S., Claise, B., Aitken, P., and J. Meyer, "Information Model for IP Flow Information Export", RFC 5102, DOI 10.17487/RFC5102, January 2008, . [RFC7011] Claise, B., Ed., Trammell, B., Ed., and P. Aitken, "Specification of the IP Flow Information Export (IPFIX) Protocol for the Exchange of Flow Information", STD 77, RFC 7011, DOI 10.17487/RFC7011, September 2013, . [RFC7270] Yourtchenko, A., Aitken, P., and B. Claise, "Cisco- Specific Information Elements Reused in IP Flow Information Export (IPFIX)", RFC 7270, DOI 10.17487/RFC7270, June 2014, . [RFC7854] Scudder, J., Ed., Fernando, R., and S. Stuart, "BGP Monitoring Protocol (BMP)", RFC 7854, DOI 10.17487/RFC7854, June 2016, . [RFC8343] Bjorklund, M., "A YANG Data Model for Interface Management", RFC 8343, DOI 10.17487/RFC8343, March 2018, . [RFC9418] Claise, B., Quilbeuf, J., Lucente, P., Fasano, P., and T. Arumugam, "A YANG Data Model for Service Assurance", RFC 9418, DOI 10.17487/RFC9418, July 2023, . [VAP09] Chandola, V., Banerjee, A., and V. Kumar, "Anomaly detection: A survey", IETF 117, Applied Networking Research Workshop, DOI 10.1145/1541880.1541882, July 2009, . Graf, et al. Expires 16 September 2024 [Page 12] Internet-Draft Network Anomaly Semantics March 2024 Authors' Addresses Thomas Graf Swisscom Binzring 17 CH-8045 Zurich Switzerland Email: thomas.graf@swisscom.com Wanting Du Swisscom Binzring 17 CH-8045 Zurich Switzerland Email: wanting.du@swisscom.com Alex Huang Feng INSA-Lyon Lyon France Email: alex.huang-feng@insa-lyon.fr Vincenzo Riccobene Huawei Dublin Ireland Email: vincenzo.riccobene@huawei-partners.com Antonio Roberto Huawei Dublin Ireland Email: antonio.roberto@huawei.com Graf, et al. Expires 16 September 2024 [Page 13]