Network Working Group T. Graf Internet-Draft Swisscom Intended status: Standards Track B. Claise Expires: 7 January 2024 Huawei A. Huang Feng INSA-Lyon 6 July 2023 Export of On-Path Delay in IPFIX draft-ietf-opsawg-ipfix-on-path-telemetry-04 Abstract This document introduces new IP Flow Information Export (IPFIX) information elements to expose the On-Path Telemetry measured delay on the IOAM transit and decapsulation nodes. 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 7 January 2024. Copyright Notice Copyright (c) 2023 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. Graf, et al. Expires 7 January 2024 [Page 1] Internet-Draft Export of On-Path Delay in IPFIX July 2023 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 3. Performance Metrics . . . . . . . . . . . . . . . . . . . . . 6 3.1. IP One-Way Delay Hybrid Type I Passive Performance Metrics . . . . . . . . . . . . . . . . . . . . . . . . . 6 3.1.1. Summary . . . . . . . . . . . . . . . . . . . . . . . 6 3.1.2. Description . . . . . . . . . . . . . . . . . . . . . 7 3.1.3. Change Controller . . . . . . . . . . . . . . . . . . 7 3.1.4. Version of Registry Format . . . . . . . . . . . . . 7 3.2. Metric Definition . . . . . . . . . . . . . . . . . . . . 7 3.2.1. Reference Definition . . . . . . . . . . . . . . . . 7 3.2.2. Fixed Parameters . . . . . . . . . . . . . . . . . . 8 3.3. Method of Measurement . . . . . . . . . . . . . . . . . . 8 3.3.1. Reference Methods . . . . . . . . . . . . . . . . . . 8 3.3.2. Packet Stream Generation . . . . . . . . . . . . . . 8 3.3.3. Traffic Filtering (Observation) Details . . . . . . . 8 3.3.4. Sampling Distribution . . . . . . . . . . . . . . . . 9 3.3.5. Runtime Parameters and Data Format . . . . . . . . . 9 3.3.6. Roles . . . . . . . . . . . . . . . . . . . . . . . . 9 3.4. Output . . . . . . . . . . . . . . . . . . . . . . . . . 10 3.4.1. Type . . . . . . . . . . . . . . . . . . . . . . . . 10 3.4.2. Reference Definition . . . . . . . . . . . . . . . . 10 3.4.3. Administrative Items . . . . . . . . . . . . . . . . 12 3.4.4. Comments and Remarks . . . . . . . . . . . . . . . . 13 4. IPFIX Information Elements . . . . . . . . . . . . . . . . . 13 5. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 14 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 6.1. Performance Metrics . . . . . . . . . . . . . . . . . . . 15 6.2. IPFIX Entities . . . . . . . . . . . . . . . . . . . . . 15 6.2.1. PathDelayMeanDeltaMicroseconds . . . . . . . . . . . 16 6.2.2. PathDelayMinDeltaMicroseconds . . . . . . . . . . . . 16 6.2.3. PathDelayMaxDeltaMicroseconds . . . . . . . . . . . . 17 6.2.4. PathDelaySumDeltaMicroseconds . . . . . . . . . . . . 17 7. Operational Considerations . . . . . . . . . . . . . . . . . 17 7.1. Time Accuracy . . . . . . . . . . . . . . . . . . . . . . 17 7.2. Mean Delay . . . . . . . . . . . . . . . . . . . . . . . 18 7.3. Reduced-size encoding . . . . . . . . . . . . . . . . . . 18 7.4. IOAM Application . . . . . . . . . . . . . . . . . . . . 18 8. Security Considerations . . . . . . . . . . . . . . . . . . . 18 9. Implementation Status . . . . . . . . . . . . . . . . . . . . 18 9.1. FD.io VPP . . . . . . . . . . . . . . . . . . . . . . . . 19 9.2. Huawei VRP . . . . . . . . . . . . . . . . . . . . . . . 19 9.3. Pmacct Data Collection . . . . . . . . . . . . . . . . . 19 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 19 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 19 11.1. Normative References . . . . . . . . . . . . . . . . . . 19 Graf, et al. Expires 7 January 2024 [Page 2] Internet-Draft Export of On-Path Delay in IPFIX July 2023 11.2. Informative References . . . . . . . . . . . . . . . . . 20 Appendix A. IPFIX Encoding Examples . . . . . . . . . . . . . . 23 A.1. Aggregated On-Path Dealay Examples . . . . . . . . . . . 23 A.1.1. Template Record and Data Set with Mean Delta . . . . 23 A.1.2. Template Record and Data Set with Sum Delta . . . . . 25 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 27 1. Introduction Network operators want a statistical delay view of their networks. They want to understand where in the network, for which customer traffic, how much and why delay is being accummlated. In order to answer why and where, delay needs to be reported into device and control-plane context. In order to understand which customer traffic is affected, delay needs to be reported into customer data-plane context. That enables network operators to quickly identify when the control-plane updates the current path with a different next-hop and therefore the forwarding path changes to different nodes and interfaces, how the path delay changes for which customer traffic. With On-Path Telemetry, described in the Network Telemetry Framework [RFC9232] and applied in In-situ OAM [I-D.ietf-ippm-ioam-deployment], Path Tracing [I-D.filsfils-spring-path-tracing] and In-situ Flow Information Telemetry [I-D.song-opsawg-ifit-framework], the path delay between two endpoints is measured by inserting a timestamp in the packet. On-Path Telemetry can be distinguished between two modes. Passport mode, [RFC9197], where only the last hop in the forwarding path of the On-Path Telemetry domain exposes all the metrics, and postcard mode, [I-D.song-ippm-postcard-based-telemetry], where the metrics are also exposed in the transit nodes. In both modes the forwarding path exposes performance metrics allowing to determine how much delay has been accumulated on which hop. This document defines four new IPFIX Information Elements (IEs), exposing the On-Path delay on IOAM transit and decapsulation nodes, following the postcard mode principles. Since these IPFIX IEs are performance metrics [RFC8911], they must be registered in the "IANA Performance Metric Registry [IANA-PERF-METRIC]. Following the guidelines for Registered Performance Metric requesters and reviewers [RFC8911], the different characteristics of the performance metrics (Identifier, Name, URI, Status, Requester, Revision, Revision Date, Description, etc) must be clearly specified in the "IANA Performance Metric Registry [IANA-PERF-METRIC] in order for the results of measurements using the Performance Metrics to be comparable even if they are performed by different implementations Graf, et al. Expires 7 January 2024 [Page 3] Internet-Draft Export of On-Path Delay in IPFIX July 2023 and in different networks. These characteristics start by selecting a meaningful name, following the "MetricType_Method_SubTypeMethod_... Spec_Units_Output" naming convention (See Section 7.1.2 of [RFC8911]). +------------------------------------+-------------------------------+ | Performance Metric | IPFIX Information Element | +------------------------------------+-------------------------------+ |OWDelay_HybridType1_Passive_I |PathDelayMeanDeltaMicroseconds | |P_RFC[RFC-to-be]_Seconds_Mean (TBD1)|(TBD5) | +------------------------------------+-------------------------------+ |OWDelay_HybridType1_Passive_I |PathDelayMinDeltaMicroseconds | |P_RFC[RFC-to-be]_Seconds_Min (TBD2) |(TBD6) | +------------------------------------+-------------------------------+ |OWDelay_HybridType1_Passive_I |PathDelayMaxDeltaMicroseconds | |P_RFC[RFC-to-be]_Seconds_Max (TBD3) |(TBD7) | +------------------------------------+-------------------------------+ |OWDelay_HybridType1_Passive_I |PathDelaySumDeltaMicroseconds | |P_RFC[RFC-to-be]_Seconds_Sum (TBD4) |(TBD8) | +------------------------------------+-------------------------------+ Table 1: Correspondance between IPFIX IE and Performance Metric The delay is measured by calculating the difference between the timestamp imposed with On-Path Telemetry in the packet at the IOAM encapsulation node and the timestamp exported in the IPFIX flow record from the IOAM transit and decapsulation nodes. The lowest, highest, mean, and/or the sum of measured path delay can be exported, thanks to the different IPFIX IE specifications. On-Path Telemetry Domain ......................................... . . . D1 . . <------> . . . . D2 . . <--------------------> . . . . D3 . . <-----------------------------------> . . . (H1) ------ (R1) ------- (R2) ------- (R3) -------- (R4) ------ (H2) Host 1 Encapsulation Transit Transit Decapsulation Host 2 Node Node 1 Node 2 Node . . . . ......................................... Graf, et al. Expires 7 January 2024 [Page 4] Internet-Draft Export of On-Path Delay in IPFIX July 2023 Figure 1: Delay use case. Packets flow from host 1 to host 2. On the usecase showed in Figure 1 using On-path Telemetry to export the delay metrics, the node R2 exports the delay D1, the node R3 exports the delay D2 and the decapsulation node R4 exports the total delay D3 using IPFIX. 2. 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. This document makes use of the terms defined in [RFC7011] and [I-D.ietf-ippm-ioam-deployment]. The following terms are used as defined in [RFC7011]. * IPFIX * IPFIX Information Elements (IEs) * Flow Record * Exporter The following terms are used as defined in [RFC8911]. * Performance Metric * Registered Performance Metric * Performance Metrics Registry The following terms are used as defined in [I-D.ietf-ippm-ioam-deployment]. * IOAM encapsulation node * IOAM transit node * IOAM decapsulation node Graf, et al. Expires 7 January 2024 [Page 5] Internet-Draft Export of On-Path Delay in IPFIX July 2023 3. Performance Metrics This section defines and describes the new performance metrics by applying the template defined in Section 11 of [RFC8911]. 3.1. IP One-Way Delay Hybrid Type I Passive Performance Metrics This section specifies four performance metrics for the Hybrid Type I Passive assessment of IP One-Way Delay, to be registered in the "IANA Performance Metric Registry [IANA-PERF-METRIC]. All column entries besides the ID, Name, Description, and Output Reference Method categories are the same; thus, this section defines four closely related performance metrics. As a result, IANA has assigned corresponding URLs to each of the four registered performance metrics. 3.1.1. Summary This category includes multiple indexes of the registered performance metrics: the element ID and Metric Name. 3.1.1.1. ID (Identifier) 3.1.1.2. Name IANA has allocated the numeric Identifiers TBD1-4 for the four Named Metric Entries in this section 3.1.1.3. Name TBD1: OWDelay_HybridType1_Passive_IP_RFC[RFC-to-be]_Seconds_Mean TBD2: OWDelay_HybridType1_Passive_IP_RFC[RFC-to-be]_Seconds_Min TBD3: OWDelay_HybridType1_Passive_IP_RFC[RFC-to-be]_Seconds_Max TBD4: OWDelay_HybridType1_Passive_IP_RFC[RFC-to-be]_Seconds_Sum 3.1.1.4. URI URL: https://www.iana.org/assignments/performance-metrics/ OWDelay_HybridType1_Passive_IP_RFC[RFC-to-be]_Seconds_Mean URL: https://www.iana.org/assignments/performance-metrics/ OWDelay_HybridType1_Passive_IP_RFC[RFC-to-be]_Seconds_Min Graf, et al. Expires 7 January 2024 [Page 6] Internet-Draft Export of On-Path Delay in IPFIX July 2023 URL: https://www.iana.org/assignments/performance-metrics/ OWDelay_HybridType1_Passive_IP_RFC[RFC-to-be]_Seconds_Max URL: https://www.iana.org/assignments/performance-metrics/ OWDelay_HybridType1_Passive_IP_RFC[RFC-to-be]_Seconds_Sum 3.1.2. Description This metric assesses the one-way delay of IP packets constituting a single connection between two hosts. We consider the measurement of one-way delay based on a single Observation Point (OP) [RFC7011] somewhere in the network. The output is the one-way delay for all successfully forwarded packets expressed as the of their conditional delay distribution, where is one of: * Mean * Min * Max * Sum 3.1.3. Change Controller IETF 3.1.4. Version of Registry Format 1.0 3.2. Metric Definition This category includes columns to prompt the entry of all necessary details related to the metric definition, including the immutable document reference and values of input factors, called "Fixed Parameters". 3.2.1. Reference Definition Almes, G., Kalidindi, S., Zekauskas, M., and A. Morton, Ed., "A One- Way Delay Metric for IP Performance Metrics (IPPM)", STD 81, RFC 7679, DOI 10.17487/RFC7679, January 2016, . [RFC7679] Morton, A. and E. Stephan, "Spatial Composition of Metrics", RFC 6049, DOI 10.17487/RFC6049, January 2011, . [RFC6049] Graf, et al. Expires 7 January 2024 [Page 7] Internet-Draft Export of On-Path Delay in IPFIX July 2023 Section 3.4 of [RFC7679] provides the reference definition of the singleton (single value) one-way delay metric. Section 4.4 of [RFC7679] provides the reference definition expanded to cover a multi-value sample. Note that terms such as "singleton" and "sample" are defined in section 2 of [RFC2330]. With the OP [RFC7011] typically located between the hosts participating in the IP connection, the one-way delay metric requires one individual measurement between the OP and sourcing host, such that the Spatial Composition [RFC6049] of the measurements yields a one-way delay singleton. 3.2.2. Fixed Parameters Traffic Filters: IPv4 header values: DSCP: Set to 0 IPv6 header values: DSCP: Set to 0 Hop Count: Set to 255 Flow Label: Set to 0 Extension Headers: None 3.3. Method of Measurement This category includes columns for references to relevant sections of the RFC(s) and any supplemental information needed to ensure an unambiguous method for implementations. 3.3.1. Reference Methods The foundational methodology for this metric is defined in section 4 of [RFC7323] using the Timestamps option with modifications that allow application at a mid-path OP [RFC7011]. 3.3.2. Packet Stream Generation N/A 3.3.3. Traffic Filtering (Observation) Details The Fixed Parameters above give a portion of the Traffic Filter. Other aspects will be supplied as Runtime Parameters (below). Graf, et al. Expires 7 January 2024 [Page 8] Internet-Draft Export of On-Path Delay in IPFIX July 2023 3.3.4. Sampling Distribution This metric requires a partial sample of all packets that qualify according to the Traffic Filter criteria. 3.3.5. Runtime Parameters and Data Format Runtime Parameters are input factors that must be determined, configured into the measurement system, and reported with the results for the context to be complete. The hybrid type I metering parameters must must be reported to provide the complete measurement context. As an example, if the IPFIX metering process is used, then the IPFIX metering process parameters (IPFIX template record used, potential traffic filters, and potential sampling method and parameters) that generates the flow records must be reported to provide the complete measurement context. Src: The IP address of the host in the host A Role (format ipv4-address-no-zone value for IPv4 or ipv6-address-no-zone value for IPv6; see section 4 of [RFC6991]. Dst: The IP address of the host in the host B Role (format ipv4-address-no-zone value for IPv4 or ipv6-address-no-zone value for IPv6; see section 4 of [RFC6991]. TTL or Hop Limit: Set at desired value. DSCP: Set at desired value. IPv6 Flow Label: Set at desired value. Timestamp: The timestamp when the packet is being received at IOAM encapsulation node. Format depends on On-Path Telemetry implementation. For IOAM, Section 4.4.1 of [RFC9197] describes what kind of timestamps are supported. Section 4.4.2.3 and 4.4.2.4 describe where the timestamp is being inserted. For Path Tracing, Section 4.1 of [I-D.filsfils-spring-path-tracing] describes what kind of timestamps are supported. Section 9.2 describe the SRH path tracing TLV where the timestamp is being inserted. 3.3.6. Roles host A: Launches the IP packet to open the connection. The Role of "host A" is synonymous with the IP address used at host A. host B: Receives the IP packet to open the connection. The Role of Graf, et al. Expires 7 January 2024 [Page 9] Internet-Draft Export of On-Path Delay in IPFIX July 2023 "host B" is synonymous with the IP address used at host B. Encapsulation Node: Receives the IP packet to open the connection and encapsulates the timestamp into the packet. The Role of "Encapsulation Node" is synonymous with the timestamp inserted in the packet. Transit Node: Receives the IP packet to open the connection and measures the delay between the timestamp in the packet and the timestamp when the packet was received. Decapsulation Node: Receives the IP packet to open the connection and measures the delay between the timestamp in the packet and the timestamp when the packet was received and removes the IOAM header from the packet. 3.4. Output This category specifies all details of the output of measurements using the metric. 3.4.1. Type OWDelay Types are discussed in the subsections below. 3.4.2. Reference Definition For all output types: OWDelay_HybridType1_Passive_IP: The one-trip delay of one IP packet is a Singleton For each Singleton one of the following subsections applies. 3.4.2.1. Mean The mean SHALL be calculated using the conditional distribution of all packets with a finite value of one-way delay (undefined delays are excluded) -- a single value, as follows: See section 4.1 of [RFC3393] for details on the conditional distribution to exclude undefined values of delay, and see section 5 of [RFC6703] for background on this analysis choice. See section 4.2.2 of [RFC6049] for details on calculating this statistic; see also section 4.2.3 of [RFC6049]. Graf, et al. Expires 7 January 2024 [Page 10] Internet-Draft Export of On-Path Delay in IPFIX July 2023 Mean: The time value of the result is expressed in units of seconds, as a positive value of type decimal64 with fraction digits = 9 (see section 9.3 of [RFC6020]) with a resolution of 0.000000001 seconds (1.0 ns), and with lossless conversion to/from the 64-bit NTP timestamp as per section 6 of [RFC5905]. 3.4.2.2. Min The minimum SHALL be calculated using the conditional distribution of all packets with a finite value of one-way delay (undefined delays are excluded) -- a single value, as follows: See section 4.1 of [RFC3393] for details on the conditional distribution to exclude undefined values of delay, and see section 5 of [RFC6703] for background on this analysis choice. See section 4.3.2 of [RFC6049] for details on calculating this statistic; see also section 4.3.3 of [RFC6049]. Min: The time value of the result is expressed in units of seconds, as a positive value of type decimal64 with fraction digits = 9 (see section 9.3 of [RFC6020]) with a resolution of 0.000000001 seconds (1.0 ns), and with lossless conversion to/from the 64-bit NTP timestamp as per section 6 of [RFC5905]. 3.4.2.3. Max The maximum SHALL be calculated using the conditional distribution of all packets with a finite value of one-way delay (undefined delays are excluded) -- a single value, as follows: See section 4.1 of [RFC3393] for details on the conditional distribution to exclude undefined values of delay, and see section 5 of [RFC6703] for background on this analysis choice. See section 4.3.2 of [RFC6049] for a closely related method for calculating this statistic; see also section 4.3.3 of [RFC6049]. The formula is as follows: Max = (FiniteDelay[j]) such that for some index, j, where 1 <= j <= N FiniteDelay[j] >= FiniteDelay[n] for all n where all packets n = 1 through N have finite singleton delays. Max: The time value of the result is expressed in units of seconds, Graf, et al. Expires 7 January 2024 [Page 11] Internet-Draft Export of On-Path Delay in IPFIX July 2023 as a positive value of type decimal64 with fraction digits = 9 (see section 9.3 of [RFC6020]) with a resolution of 0.000000001 seconds (1.0 ns), and with lossless conversion to/from the 64-bit NTP timestamp as per section 6 of [RFC5905]. 3.4.2.4. Sum The sum SHALL be calculated using the conditional distribution of all packets with a finite value of one-way delay (undefined delays are excluded) -- a single value, as follows: See section 4.1 of [RFC3393] for details on the conditional distribution to exclude undefined values of delay, and see section 5 of [RFC6703] for background on this analysis choice. See section 4.3.5 of [RFC6049] for details on calculating this statistic. However in this case FiniteDelay or MaxDelay MAY be used. Sum: The time value of the result is expressed in units of seconds, as a positive value of type decimal64 with fraction digits = 9 (see section 9.3 of [RFC6020]) with a resolution of 0.000000001 seconds (1.0 ns), and with lossless conversion to/from the 64-bit NTP timestamp as per section 6 of [RFC5905]. 3.4.2.5. Metric Units The of one-way delay is expressed in seconds, where is one of: * Mean * Min * Max * Sum The one-way delay of the IP connection singleton is expressed in seconds. 3.4.2.6. Calibration Passive Measurements at an OP could be calibrated against an Active Measurement at host A where the Active Measurement represents the ground truth. 3.4.3. Administrative Items Graf, et al. Expires 7 January 2024 [Page 12] Internet-Draft Export of On-Path Delay in IPFIX July 2023 3.4.3.1. Status Current 3.4.3.2. Requester This RFC 3.4.3.3. Revision 1.0 3.4.3.4. Revision Date RFC Date 3.4.4. Comments and Remarks none 4. IPFIX Information Elements This section defines and describes the new IPFIX IEs. PathDelayMeanDeltaMicroseconds 32-bit unsigned integer that identifies the mean path delay in microseconds, between the IOAM encapsulation node and the local node with the IOAM domain (either an IOAM transit node or an IOAM decapsulation node). PathDelayMinDeltaMicroseconds 32-bit unsigned integer that identifies the lowest path delay in microseconds, between the IOAM encapsulation node and the local node with the IOAM domain (either an IOAM transit node or an IOAM decapsulation node). PathDelayMaxDeltaMicroseconds 32-bit unsigned integer that identifies the highest path delay in microseconds, between the IOAM encapsulation node and the local node with the IOAM domain (either an IOAM transit node or an IOAM decapsulation node). PathDelaySumDeltaMicroseconds 64-bit unsigned integer that identifies the sum of the path delay in microseconds, between the IOAM encapsulation node and the local node with the IOAM domain (either an IOAM transit node or an IOAM decapsulation node). Graf, et al. Expires 7 January 2024 [Page 13] Internet-Draft Export of On-Path Delay in IPFIX July 2023 5. Use Cases The measured On-Path delay can be aggregated with Flow Aggregation as defined in [RFC7015] to the following device and control-plane dimensions to determine: * With node id and egressInterface(IE14), on which node which logical egress interfaces have been contributing to how much delay. * With node id and egressPhysicalInterface(253), on which node which physical egress interfaces have been contributing to how much delay. * With ipNextHopIPv4Address(IE15) or ipNextHopIPv6Address(IE62), the forwarding path to which next-hop IP contributed to how much delay. * With mplsTopLabelIPv4Address(IE47) or destinationIPv6Address and srhActiveSegmentIPv6 from [I-D.tgraf-opsawg-ipfix-srv6-srh], the forwarding path to which MPLS top label IPv4 address or IPv6 destination address and SRv6 active segment contributed to how much delay. * BGP communities are often used for setting a path priority or service selection. With bgpDestinationExtendedCommunityList(488) or bgpDestinationCommunityList(485) or bgpDestinationLargeCommunityList(491) which group of prefixes accumulated at which node how much delay. * With destinationIPv4Address(13), destinationTransportPort(11), protocolIdentifier (4) and sourceIPv4Address(IE8), the forwarding path delay on each node from each IPv4 source address to a specific application in the network. Taking figure 1 from section 1 as topology example. Below example table shows the aggregated delay per each node, ingressInterface, egressInterface, destinationIPv6Address and srhActiveSegmentIPv6. Graf, et al. Expires 7 January 2024 [Page 14] Internet-Draft Export of On-Path Delay in IPFIX July 2023 +-----------+-----------+------+-------------+-------------+------------+ | ingress | egress | Node | destination | srhActive | Path Delay | | Interface | Interface | | IPv6Address | SegmentIPv6 | | +-----------+-----------+------+-------------+-------------+------------+ | 271 | 276 | R1 | 2001:db8::2 | 2001:db8::4 | 0 us | +-----------+-----------+------+-------------+-------------+------------+ | 301 | 312 | R2 | 2001:db8::3 | 2001:db8::4 | 22 us | +-----------+-----------+------+-------------+-------------+------------+ | 22 | 27 | R3 | 2001:db8::4 | 2001:db8::4 | 42 us | +-----------+-----------+------+-------------+-------------+------------+ | 852 | 854 | R4 | 2001:db8::4 | 2001:db8::4 | 122 us | +-----------+-----------+------+-------------+-------------+------------+ Table 2: Example table of measured delay. Ascending by delay. 6. IANA Considerations 6.1. Performance Metrics This document requests IANA to create new performance metrics under the "Performance Metrics" registry [RFC8911] with the values defined in section 2. 6.2. IPFIX Entities This document requests IANA to create new IPFIX IEs (see table 3) under the "IPFIX Information Elements" registry [RFC7012] available at "IANA Performance Metric Registry [IANA-PERF-METRIC] and assign the following initial code points. +-------+--------------------------------+ |Element| Name | | ID | | +-------+--------------------------------+ | TBD5 | PathDelayMeanDeltaMicroseconds | | | | +-------+--------------------------------+ | TBD6 | PathDelayMinDeltaMicroseconds | | | | +-------+--------------------------------+ | TBD7 | PathDelayMaxDeltaMicroseconds | | | | +-------+--------------------------------+ | TBD8 | PathDelaySumDeltaMicroseconds | | | | +-------+--------------------------------+ Table 3: Creates IPFIX IEs in the "IPFIX Information Elements" registry Graf, et al. Expires 7 January 2024 [Page 15] Internet-Draft Export of On-Path Delay in IPFIX July 2023 Note to the RFC-Editor: * Please replace TBD5 - TBD8 with the values allocated by IANA * Please replace the [RFC-to-be] with the RFC number assigned to this document 6.2.1. PathDelayMeanDeltaMicroseconds Name: PathDelayMeanDeltaMicroseconds ElementID: TBD5 Description: This Information Element identifies the mean path delay between the IOAM encapsulation node and the local node with the IOAM domain (either an IOAM transit node or an IOAM decapsulation node) in microseconds, according to OWDelay_HybridType1_Passive_IP_RFC[RFC-to-be]_Seconds_Mean in the IANA Performance Metric Registry Abstract Data Type: unsigned32 Data Type Semantics: deltaCounter Reference: [RFC-to-be], OWDelay_HybridType1_Passive_IP_RFC[RFC-to- be]_Seconds_Mean in the IANA Performance Metric Registry. 6.2.2. PathDelayMinDeltaMicroseconds Name: PathDelayMinDeltaMicroseconds ElementID: TBD6 Description: This Information Element identifies the lowest path delay between the IOAM encapsulation node and the local node with the IOAM domain (either an IOAM transit node or an IOAM decapsulation node) in microseconds, according to the OWDelay_HybridType1_Passive_IP_RFC[RFC-to-be]_Seconds_Min in the IANA Performance Metric Registry. Abstract Data Type: unsigned32 Data Type Semantics: deltaCounter Reference: [RFC-to-be], OWDelay_HybridType1_Passive_IP_RFC[RFC-to- be]_Seconds_Min in the IANA Performance Metric Registry. Graf, et al. Expires 7 January 2024 [Page 16] Internet-Draft Export of On-Path Delay in IPFIX July 2023 6.2.3. PathDelayMaxDeltaMicroseconds Name: PathDelayMaxDeltaMicroseconds ElementID: TBD7 Description: This Information Element identifies the highest path delay between the IOAM encapsulation node and the local node with the IOAM domain (either an IOAM transit node or an IOAM decapsulation node) in microseconds, according to OWDelay_HybridType1_Passive_IP_RFC[RFC-to-be]_Seconds_Max in the IANA Performance Metric Registry. Abstract Data Type: unsigned32 Data Type Semantics: deltaCounter Reference: [RFC-to-be], OWDelay_HybridType1_Passive_IP_RFC[RFC-to- be]_Seconds_Max in the IANA Performance Metric Registry. 6.2.4. PathDelaySumDeltaMicroseconds Name: PathDelaySumDeltaMicroseconds ElementID: TBD8 Description: This Information Element identifies the sum of the path delay between the IOAM encapsulation node and the local node with the IOAM domain (either an IOAM transit node or an IOAM decapsulation node) in microseconds, according to OWDelay_HybridType1_Passive_IP_RFC[RFC-to-be]_Seconds_Sum in the IANA Performance Metric Registry. Abstract Data Type: unsigned64 Data Type Semantics: deltaCounter Reference: [RFC-to-be], OWDelay_HybridType1_Passive_IP_RFC[RFC-to- be]_Seconds_Sum in the IANA Performance Metric Registry. 7. Operational Considerations 7.1. Time Accuracy The same recommendation as defined in section 4.5 of [RFC5153] for IPFIX applies in terms of clock precision to this document as well. Graf, et al. Expires 7 January 2024 [Page 17] Internet-Draft Export of On-Path Delay in IPFIX July 2023 7.2. Mean Delay The mean (average) path delay can be calculated by dividing the PathDelaySumDeltaMicroseconds(TBD5) by the packetDeltaCount(2) at the IPFIX data collection in order to offload the IPFIX Exporter from calculating the mean for every Flow at export time. 7.3. Reduced-size encoding Unsigned64 has been chosen as type for PathDelaySumDeltaMicroseconds to support cases with large delay numbers and where many packets are being accounted. As an example, a specific flow record with path delay of 100 microseconds can not observe more than 42949 packets without overflowing the unsigned32 counter. The procedure described in Section 6.2 of [RFC7011] could be applied to reduce network bandwidth between the IPFIX Exporter and Collector if unsigned32 would be large enough without wrapping around. 7.4. IOAM Application This document is applicable in IOAM to the Edge-to-Edge and Direct Exporting Option-Type. In case of Edge-to-Edge Option-Type, as described in Section 4.6 of [RFC9197], by setting bits 2 and 3, timestamps can be encoded as defined in Section 4.4.2.3 and 4.4.2.4 of [RFC9197]. In case of Direct Exporting Option-Type, as described in Section 2 of [I-D.ahuang-ippm-dex-timestamp-ext], by setting Extension-Flags 2 and 3, timestamps can be encoded as defined in Section 4.4.2.3 and 4.4.2.4 of [RFC9197]. For Path Tracing, Section 4.1 of [I-D.filsfils-spring-path-tracing] describes what kind of timestamps are supported. Section 9.2 describe the SRH path tracing TLV where the timestamp is being inserted. 8. Security Considerations There are no significant extra security considerations regarding the allocation of these new IPFIX IEs compared to [RFC7012]. 9. Implementation Status Note to the RFC-Editor: Please remove this section before publishing. Graf, et al. Expires 7 January 2024 [Page 18] Internet-Draft Export of On-Path Delay in IPFIX July 2023 9.1. FD.io VPP INSA Lyon implemented the following IEs as part of a prototype in the FD.io VPP (Vector Packet Processing) platform: * PathDelayMeanDeltaMicroseconds * PathDelayMaxDeltaMicroseconds * PathDelayMinDeltaMicroseconds * PathDelaySumDeltaMicroseconds The open source code can be obtained here: [INSA-Lyon-VPP] and was validated at the IETF 116 hackathon. 9.2. Huawei VRP Huawei implemented the following IEs as part of a a production implementation in the VRP platform: * PathDelayMeanDeltaMicroseconds * PathDelayMaxDeltaMicroseconds * PathDelayMinDeltaMicroseconds * PathDelaySumDeltaMicroseconds The implementation was validated at the IETF 116 hackathon. 9.3. Pmacct Data Collection Paolo Lucente implemented the IE PathDelayMeanDeltaMicroseconds by dividing IE PathDelaySumDeltaMicroseconds by IE packetDeltaCount in the open source Network Telemetry data collection project pmacct. The source code can be obtained here: [Paolo-Lucente-Pmacct] and was validated at the IETF 116 hackathon. 10. Acknowledgements The authors would like to thank Al Morton and Greg Mirsky for their review and valuable comments. 11. References 11.1. Normative References Graf, et al. Expires 7 January 2024 [Page 19] Internet-Draft Export of On-Path Delay in IPFIX July 2023 [RFC7012] Claise, B., Ed. and B. Trammell, Ed., "Information Model for IP Flow Information Export (IPFIX)", RFC 7012, DOI 10.17487/RFC7012, September 2013, . [RFC8911] Bagnulo, M., Claise, B., Eardley, P., Morton, A., and A. Akhter, "Registry for Performance Metrics", RFC 8911, DOI 10.17487/RFC8911, November 2021, . 11.2. Informative References [I-D.ahuang-ippm-dex-timestamp-ext] Feng, A. H., Francois, P., Claise, B., and T. Graf, "Timestamp extension for In Situ Operations, Administration, and Maintenance (IOAM) Direct Export", Work in Progress, Internet-Draft, draft-ahuang-ippm-dex- timestamp-ext-00, 15 February 2023, . [I-D.filsfils-spring-path-tracing] Filsfils, C., Abdelsalam, A., Camarillo, P., Yufit, M., Graf, T., Su, Y., Matsushima, S., Valentine, M., and A. Dhamija, "Path Tracing in SRv6 networks", Work in Progress, Internet-Draft, draft-filsfils-spring-path- tracing-03, 13 February 2023, . [I-D.ietf-ippm-ioam-deployment] Brockners, F., Bhandari, S., Bernier, D., and T. Mizrahi, "In-situ OAM Deployment", Work in Progress, Internet- Draft, draft-ietf-ippm-ioam-deployment-05, 4 January 2023, . [I-D.song-ippm-postcard-based-telemetry] Song, H., Mirsky, G., Zhou, T., Li, Z., Graf, T., Mishra, G. S., Shin, J., and K. Lee, "On-Path Telemetry using Packet Marking to Trigger Dedicated OAM Packets", Work in Progress, Internet-Draft, draft-song-ippm-postcard-based- telemetry-16, 2 June 2023, . Graf, et al. Expires 7 January 2024 [Page 20] Internet-Draft Export of On-Path Delay in IPFIX July 2023 [I-D.song-opsawg-ifit-framework] Song, H., Qin, F., Chen, H., Jin, J., and J. Shin, "Framework for In-situ Flow Information Telemetry", Work in Progress, Internet-Draft, draft-song-opsawg-ifit- framework-20, 24 April 2023, . [I-D.tgraf-opsawg-ipfix-srv6-srh] Graf, T., Claise, B., and P. Francois, "Export of Segment Routing IPv6 Information in IP Flow Information Export (IPFIX)", Work in Progress, Internet-Draft, draft-tgraf- opsawg-ipfix-srv6-srh-05, 24 July 2022, . [IANA-PERF-METRIC] "IANA Performance Metric Registry", . [INSA-Lyon-VPP] "INSA Lyon, FD.io VPP implementation", . [Paolo-Lucente-Pmacct] "Paolo Lucente, Pmacct open source Network Telemetry Data Collection", . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC2330] Paxson, V., Almes, G., Mahdavi, J., and M. Mathis, "Framework for IP Performance Metrics", RFC 2330, DOI 10.17487/RFC2330, May 1998, . [RFC3393] Demichelis, C. and P. Chimento, "IP Packet Delay Variation Metric for IP Performance Metrics (IPPM)", RFC 3393, DOI 10.17487/RFC3393, November 2002, . Graf, et al. Expires 7 January 2024 [Page 21] Internet-Draft Export of On-Path Delay in IPFIX July 2023 [RFC5153] Boschi, E., Mark, L., Quittek, J., Stiemerling, M., and P. Aitken, "IP Flow Information Export (IPFIX) Implementation Guidelines", RFC 5153, DOI 10.17487/RFC5153, April 2008, . [RFC5905] Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch, "Network Time Protocol Version 4: Protocol and Algorithms Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010, . [RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, October 2010, . [RFC6049] Morton, A. and E. Stephan, "Spatial Composition of Metrics", RFC 6049, DOI 10.17487/RFC6049, January 2011, . [RFC6703] Morton, A., Ramachandran, G., and G. Maguluri, "Reporting IP Network Performance Metrics: Different Points of View", RFC 6703, DOI 10.17487/RFC6703, August 2012, . [RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types", RFC 6991, DOI 10.17487/RFC6991, July 2013, . [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, . [RFC7015] Trammell, B., Wagner, A., and B. Claise, "Flow Aggregation for the IP Flow Information Export (IPFIX) Protocol", RFC 7015, DOI 10.17487/RFC7015, September 2013, . [RFC7323] Borman, D., Braden, B., Jacobson, V., and R. Scheffenegger, Ed., "TCP Extensions for High Performance", RFC 7323, DOI 10.17487/RFC7323, September 2014, . [RFC7679] Almes, G., Kalidindi, S., Zekauskas, M., and A. Morton, Ed., "A One-Way Delay Metric for IP Performance Metrics (IPPM)", STD 81, RFC 7679, DOI 10.17487/RFC7679, January 2016, . Graf, et al. Expires 7 January 2024 [Page 22] Internet-Draft Export of On-Path Delay in IPFIX July 2023 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC9197] Brockners, F., Ed., Bhandari, S., Ed., and T. Mizrahi, Ed., "Data Fields for In Situ Operations, Administration, and Maintenance (IOAM)", RFC 9197, DOI 10.17487/RFC9197, May 2022, . [RFC9232] Song, H., Qin, F., Martinez-Julia, P., Ciavaglia, L., and A. Wang, "Network Telemetry Framework", RFC 9232, DOI 10.17487/RFC9232, May 2022, . Appendix A. IPFIX Encoding Examples This appendix represents two different encodings for the newly introduced IEs. Taking figure 1 from section 1 as topology example. Below example Table 4 shows the aggregated delay with ingressInterface, egressInterface, destinationIPv6Address and srhActiveSegmentIPv6. +------ +------+-----------+-----------+------+---------+---------+---------+---------+ |ingress|egress|destination|srhActive |packet|PathDelay|PathDelay|PathDelta|PathDelta| |Inter |Inter |IPv6Address|SegmentIPv6|Delta |MinDelta |MaxDelta |MeanDelta|MeanDelta| |face |face | | |Count |Micro.. |Micro.. |Micro.. |Micro.. | +-------+------+-----------+-----------+------+---------+---------+---------+---------+ | 271 | 276 |2001:db8::4|2001:db8::2| 5 | 22 us | 74 us | 36 us | 180 us | +-------+------+-----------+-----------+------+---------+---------+---------+---------+ Table 4: Aggregated delay with egressInterface and srhActiveSegmentIPv6 A.1. Aggregated On-Path Dealay Examples A.1.1. Template Record and Data Set with Mean Delta With encoding in Figure 1, the mean (average) path delay is calculated on the exporting node. * Ingress interface => ingressInterface * Egress interface => egressInterface * IPv6 destination address => destinationIPv6Address * Active SRv6 Segment => srhIPv6ActiveSegment * Packet Delta Count => packetDeltaCount Graf, et al. Expires 7 January 2024 [Page 23] Internet-Draft Export of On-Path Delay in IPFIX July 2023 * Minimum One-Way Delay => PathDelayMinDeltaMicroseconds (TBD6) * Maximum One-Way Delay => PathDelayMaxDeltaMicroseconds (TBD7) * Mean One-Way Delay => PathDelayMeanDeltaMicroseconds (TBD5) 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SET ID = 2 | Length = 40 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Template ID = 256 | Field Count = 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| ingressInterface = 10 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| egressInterface = 14 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| destinationIPv6Address = 28 | Field Length = 16 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| srhIPv6ActiveSegment = 495 | Field Length = 16 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| packetDeltaCount = 5 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| PathDelayMinDelta.. = TBD6 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| PathDelayMaxDelta.. = TBD7 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| PathDelayMeanDelta.. = TBD5 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1: Template Record for PathDelayMeanDeltaMicroseconds The data set is represented as follows: Graf, et al. Expires 7 January 2024 [Page 24] Internet-Draft Export of On-Path Delay in IPFIX July 2023 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SET ID = 256 | Length = 60 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ingressInterface = 271 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | egressInterface = 276 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | destinationIPv6Address = | | ... | | ... | | 2001:db8::2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | srhIPv6ActiveSegment = ... | | ... | | ... | | 2001:db8::4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | packetDeltaCount = 5 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | PathDelayMinDeltaMicroseconds = 22 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | PathDelayMaxDeltaMicroseconds = 74 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | PathDelayMeanDeltaMicroseconds = 36 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2: Data Set Encoding for PathDelayMeanDeltaMicroseconds A.1.2. Template Record and Data Set with Sum Delta With encoding in Figure 3, the mean (average) path delay is calculated on the IPFIX data collection. * Ingress interface => ingressInterface * Egress interface => egressInterface * IPv6 destination address => destinationIPv6Address * Active SRv6 Segment => srhIPv6ActiveSegment * Packet Delta Count => packetDeltaCount * Minimum One-Way Delay => PathDelayMinDeltaMicroseconds (TBD6) Graf, et al. Expires 7 January 2024 [Page 25] Internet-Draft Export of On-Path Delay in IPFIX July 2023 * Maximum One-Way Delay => PathDelayMaxDeltaMicroseconds (TBD7) * Sum of One-Way Delay => PathDelaySumDeltaMicroseconds (TBD8) 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SET ID = 2 | Length = 40 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Template ID = 257 | Field Count = 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| ingressInterface = 10 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| egressInterface = 14 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| destinationIPv6Address = 28 | Field Length = 16 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| srhIPv6ActiveSegment = 495 | Field Length = 16 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| packetDeltaCount = 5 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| PathDelayMinDelta.. = TBD6 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| PathDelayMaxDelta.. = TBD7 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| PathDelaySumDelta.. = TBD8 | Field Length = 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 3: Template Record for PathDelaySumDeltaMicroseconds The data set is represented as follows: Graf, et al. Expires 7 January 2024 [Page 26] Internet-Draft Export of On-Path Delay in IPFIX July 2023 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SET ID = 257 | Length = 60 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ingressInterface = 271 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | egressInterface = 276 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | destinationIPv6Address = | | ... | | ... | | 2001:db8::2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | srhIPv6ActiveSegment = ... | | ... | | ... | | 2001:db8::4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | packetDeltaCount = 5 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | PathDelayMinDeltaMicroseconds = 22 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | PathDelayMaxDeltaMicroseconds = 74 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | PathDelaySumDeltaMicroseconds = 180 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2: Data Set Encoding for PathDelaySumDeltaMicroseconds Authors' Addresses Thomas Graf Swisscom Binzring 17 CH-8045 Zurich Switzerland Email: thomas.graf@swisscom.com Benoit Claise Huawei Email: benoit.claise@huawei.com Graf, et al. Expires 7 January 2024 [Page 27] Internet-Draft Export of On-Path Delay in IPFIX July 2023 Alex Huang Feng INSA-Lyon Lyon France Email: alex.huang-feng@insa-lyon.fr Graf, et al. Expires 7 January 2024 [Page 28]