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Export of On-Path Delay in IPFIX
draft-tgraf-opsawg-ipfix-on-path-telemetry-01

Document Type Active Internet-Draft (candidate for opsawg WG)
Authors Thomas Graf , Benoît Claise , Alex Huang Feng
Last updated 2022-12-21 (Latest revision 2022-12-19)
Replaces draft-tgraf-opsawg-ipfix-inband-telemetry
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draft-tgraf-opsawg-ipfix-on-path-telemetry-01
Network Working Group                                            T. Graf
Internet-Draft                                                  Swisscom
Intended status: Standards Track                               B. Claise
Expires: 23 June 2023                                             Huawei
                                                           A. Huang Feng
                                                               INSA-Lyon
                                                        20 December 2022

                    Export of On-Path Delay in IPFIX
             draft-tgraf-opsawg-ipfix-on-path-telemetry-01

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 23 June 2023.

Copyright Notice

   Copyright (c) 2022 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.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   5
   3.  Performance Metrics . . . . . . . . . . . . . . . . . . . . .   5
     3.1.  IP One-Way Delay Hybrid Type I Passive Registry
           Entries . . . . . . . . . . . . . . . . . . . . . . . . .   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 . . . . . . . . . . . . . . . .   8
       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.  PathDelayMeanDeltaNanoseconds . . . . . . . . . . . .  17
       6.2.3.  PathDelayMinDeltaMicroseconds . . . . . . . . . . . .  17
       6.2.4.  PathDelayMinDeltaNanoseconds  . . . . . . . . . . . .  17
       6.2.5.  PathDelayMaxDeltaMicroseconds . . . . . . . . . . . .  18
       6.2.6.  PathDelayMaxDeltaNanoseconds  . . . . . . . . . . . .  18
       6.2.7.  PathDelaySumDeltaMicroseconds . . . . . . . . . . . .  18
       6.2.8.  PathDelaySumDeltaNanoseconds  . . . . . . . . . . . .  19
   7.  Operational Considerations  . . . . . . . . . . . . . . . . .  19
     7.1.  Time Accuracy . . . . . . . . . . . . . . . . . . . . . .  19
     7.2.  Mean Delay  . . . . . . . . . . . . . . . . . . . . . . .  19
     7.3.  IOAM Packet Time Stamps . . . . . . . . . . . . . . . . .  20
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  20
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  20
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  20
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  20
     10.2.  Informative References . . . . . . . . . . . . . . . . .  20

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   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  23

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 eight new IPFIX Information Elements (IEs),
   exposing the On-Path delay on IOAM transit and decapsulation nodes.
   Since these IPFIX IEs are performance metrics [RFC8911], they must be
   registered as registered performance metrics [RFC8911] in the "IANA
   Performance Metric Registry [IANA-PERF-METRIC].

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   +-----------------------------+-------------------------------------+
   |      Performance Metric     |             IPFIX Entity            |
   +-----------------------------+-------------------------------------+
   |OWDelay_HybridType1_Passive_I|PathDelayMeanDeltaMicroseconds (TBD5)|
   |P_RFCTBD_Seconds_Mean (TBD1) |PathDelayMeanDeltaNanoseconds (TBD6) |
   +-----------------------------+-------------------------------------+
   |OWDelay_HybridType1_Passive_I|PathDelayMinDeltaMicroseconds (TBD7) |
   |P_RFCTBD_Seconds_Min (TBD2)  |PathDelayMinDeltaNanoseconds (TBD8)  |
   +-----------------------------+-------------------------------------+
   |OWDelay_HybridType1_Passive_I|PathDelayMaxDeltaMicroseconds (TBD9) |
   |P_RFCTBD_Seconds_Max (TBD3)  |PathDelayMaxDeltaNanoseconds (TBD10) |
   +-----------------------------+-------------------------------------+
   |OWDelay_HybridType1_Passive_I|PathDelaySumDeltaMicroseconds (TBD11)|
   |P_RFCTBD_Seconds_Sum (TBD4)  |PathDelaySumDeltaNanoseconds (TBD12) |
   +-----------------------------+-------------------------------------+

   Table 1: Correspondance between IE and performance metric registry

   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.  Depending on
   the IE, the lowest, highest or the sum of measured path delay is
   being exported.

                                   IOAM-Domain
                 .........................................
                 .                                       .
                 .    D1                                 .
                 . <------>                              .
                 .                                       .
                 .          D2                           .
                 . <-------------------->                .
                 .                                       .
                 .                  D3                   .
                 . <-----------------------------------> .
                 .                                       .
   (H1) ------ (R1) ------- (R2) ------- (R3) -------- (R4) ------ (H2)
   Host 1  Encapsulation   Transit      Transit   Decapsulation  Host 2
               Node         Node 1       Node 2        Node
                 .                                       .
                 .                                       .
                 .........................................

    Figure 1: IOAM Delay use case.  Packets flow from host 1 to host 2.

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   On the usecase showed in Figure 1 using IOAM 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

   *  Template

   *  Template Record

   *  Options Template

   *  Options Template Record

   *  Data Record

   *  Data Set

   The following terms are used as defined in
   [I-D.ietf-ippm-ioam-deployment].

   *  IOAM encapsulation node

   *  IOAM transit node

   *  IOAM deacsulation node

3.  Performance Metrics

   This section defines and describes the new performance metrics by
   applying the template defined in [RFC8911].

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3.1.  IP One-Way Delay Hybrid Type I Passive Registry Entries

   This section specifies four Registry Entries for the Hybrid Type I
   Passive assessment of IP One-Way Delay.

   All column entries besides the ID, Name, Description, and Output
   Reference Method categories are the same; thus, this section defines
   four closely related Registry Entries.  As a result, IANA has
   assigned corresponding URLs to each of the four Named Metrics.

3.1.1.  Summary

   This category includes multiple indexes to the Registry Entry: the
   element ID and Metric Name.

3.1.1.1.  ID (Identifier)

   <insert a numeric Identifier, an integer, TBD>

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_RFCTBD_Seconds_Mean

   TBD2: OWDelay_HybridType1_Passive_IP_RFCTBD_Seconds_Min

   TBD3: OWDelay_HybridType1_Passive_IP_RFCTBD_Seconds_Max

   TBD4: OWDelay_HybridType1_Passive_IP_RFCTBD_Seconds_Sum

3.1.1.4.  URI

   URL: https://www.iana.org/assignments/performance-metrics/
   OWDelay_HybridType1_Passive_IP_RFCTBD_Seconds_Mean

   URL: https://www.iana.org/assignments/performance-metrics/
   OWDelay_HybridType1_Passive_IP_RFCTBD_Seconds_Min

   URL: https://www.iana.org/assignments/performance-metrics/
   OWDelay_HybridType1_Passive_IP_RFCTBD_Seconds_Max

   URL: https://www.iana.org/assignments/performance-metrics/
   OWDelay_HybridType1_Passive_IP_RFCTBD_Seconds_Sum

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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 <statistic> of their
   conditional delay distribution, where <statistic> 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, <https://www.rfc-
   editor.org/info/rfc7679>.  [RFC7679]

   Morton, A. and E.  Stephan, "Spatial Composition of Metrics", RFC
   6049, DOI 10.17487/RFC6049, January 2011, <https://www.rfc-
   editor.org/info/rfc6049>.  [RFC6049]

   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].

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   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).

3.3.4.  Sampling Distribution

   This metric requires a partial sample of all packets that qualify
   according to the Traffic Filter criteria.

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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.

   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
      "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

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      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 <statistic>, 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].

   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:

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   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

   Max:  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].

3.4.2.4.  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.

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   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 <statistic> of one-way delay is expressed in seconds, where
   <statistic> 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

3.4.3.1.  Status

   Current

3.4.3.2.  Requester

   This RFC

3.4.3.3.  Revision

   1.0

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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
      16-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).

   PathDelayMeanDeltaNanoseconds
      32-bit unsigned integer that identifies the mean path delay in
      nanoseconds, between the IOAM encapsulation node and the local
      node with the IOAM domain (either an IOAM transit node or an IOAM
      decapsulation node).

   PathDelayMinDeltaMicroseconds
      16-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).

   PathDelayMinDeltaNanoseconds
      32-bit unsigned integer that identifies the lowest path delay in
      nanoseconds, between the IOAM encapsulation node and the local
      node with the IOAM domain (either an IOAM transit node or an IOAM
      decapsulation node).

   PathDelayMaxDeltaMicroseconds
      16-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).

   PathDelayMaxDeltaNanoseconds
      32-bit unsigned integer that identifies the highest path delay in
      nanoseconds, between the IOAM encapsulation node and the local
      node with the IOAM domain (either an IOAM transit node or an IOAM
      decapsulation node).

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   PathDelaySumDeltaMicroseconds
      32-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).

   PathDelaySumDeltaNanoseconds
      64-bit unsigned integer that identifies the sum of the path delay
      in nanoseconds, between the IOAM encapsulation node and the local
      node with the IOAM domain (either an IOAM transit node or an IOAM
      decapsulation node).

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 srhActiveSegmentIPv6 from
      [I-D.tgraf-opsawg-ipfix-srv6-srh], the forwarding path to which
      MPLS top label IPv4 address or 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.

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   Taking figure 1 from section 1 as topology example.  Below example
   table shows the aggregated delay per each node, egressInterface and
   srhActiveSegmentIPv6.

        +------------+------+-----------------+----------------------+
        | Path Delay | Node | egressInterface | srhActiveSegmentIPv6 |
        +------------+------+-----------------+----------------------+
        |     0 ns   |  R1  |      276        |      2001:db8::4     |
        +------------+------+-----------------+----------------------+
        |  3122 ns   |  R2  |      312        |      2001:db8::4     |
        +------------+------+-----------------+----------------------+
        |  4432 ns   |  R3  |       27        |      2001:db8::4     |
        +------------+------+-----------------+----------------------+
        |  7237 ns   |  R4  |      854        |      2001:db8::4     |
        +------------+------+-----------------+----------------------+

     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 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.

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        +-------+--------------------------------+
        |Element|              Name              |
        |   ID  |                                |
        +-------+--------------------------------+
        | TBD5  | PathDelayMeanDeltaMicroseconds |
        |       |                                |
        +-------+--------------------------------+
        | TBD6  | PathDelayMeanDeltaNanoseconds  |
        |       |                                |
        +-------+--------------------------------+
        | TBD7  | PathDelayMinDeltaMicroseconds  |
        |       |                                |
        +-------+--------------------------------+
        | TBD8  | PathDelayMinDeltaNanoseconds   |
        |       |                                |
        +-------+--------------------------------+
        | TBD9  | PathDelayMaxDeltaMicroseconds  |
        |       |                                |
        +-------+--------------------------------+
        | TBD10 | PathDelayMaxDeltaNanoseconds   |
        |       |                                |
        +-------+--------------------------------+
        | TBD11 | PathDelaySumDeltaMicroseconds  |
        |       |                                |
        +-------+--------------------------------+
        | TBD12 | PathDelaySumDeltaNanoseconds   |
        |       |                                |
        +-------+--------------------------------+
     Table 3: Creates IEs in the "IPFIX Information Elements" registry

   Note to the RFC-Editor:

   *  Please replace TBD5 - TBD12 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.

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   Abstract Data Type:  unsigned16

   Data Type Semantics:  OctedDelta

   Reference:  [RFC-to-be], xxx

6.2.2.  PathDelayMeanDeltaNanoseconds

   Name:  PathDelayMeanDeltaNanoseconds

   ElementID:  TBD6

   Description:  This Information Element identifies the mean path
      delaybetween the IOAM encapsulation node and the local node with
      the IOAM domain (either an IOAM transit node or an IOAM
      decapsulation node) in nanoseconds.

   Abstract Data Type:  unsigned32

   Data Type Semantics:  OctedDelta

   Reference:  [RFC-to-be], xxx

6.2.3.  PathDelayMinDeltaMicroseconds

   Name:  PathDelayMinDeltaMicroseconds

   ElementID:  TBD7

   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.

   Abstract Data Type:  unsigned16

   Data Type Semantics:  OctedDelta

   Reference:  [RFC-to-be], xxx

6.2.4.  PathDelayMinDeltaNanoseconds

   Name:  PathDelayMinDeltaNanoseconds

   ElementID:  TBD8

   Description:  This Information Element identifies the lowest path

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      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 nanoseconds.

   Abstract Data Type:  unsigned32

   Data Type Semantics:  OctedDelta

   Reference:  [RFC-to-be], xxx

6.2.5.  PathDelayMaxDeltaMicroseconds

   Name:  PathDelayMaxDeltaMicroseconds

   ElementID:  TBD9

   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.

   Abstract Data Type:  unsigned16

   Data Type Semantics:  OctedDelta

   Reference:  [RFC-to-be], xxx

6.2.6.  PathDelayMaxDeltaNanoseconds

   Name:  PathDelayMaxDeltaNanoseconds

   ElementID:  TBD10

   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 nanoseconds.

   Abstract Data Type:  unsigned32

   Data Type Semantics:  OctedDelta

   Reference:  [RFC-to-be], xxx

6.2.7.  PathDelaySumDeltaMicroseconds

   Name:  PathDelaySumDeltaMicroseconds

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   ElementID:  TBD11

   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.

   Abstract Data Type:  unsigned32

   Data Type Semantics:  OctedDelta

   Reference:  [RFC-to-be], xxx

6.2.8.  PathDelaySumDeltaNanoseconds

   Name:  PathDelaySumDeltaNanoseconds

   ElementID:  TBD12

   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 nanoseconds.

   Abstract Data Type:  unsigned64

   Data Type Semantics:  OctedDelta

   Reference:  [RFC-to-be], xxx

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.

7.2.  Mean Delay

   The mean (average) path delay can be calculated by dividing the
   PathDelaySumDeltaMicroseconds(TBD5) or
   PathDelaySumDeltaNanoseconds(TBD6) by the packetDeltaCount(2) at the
   IPFIX data collection.

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7.3.  IOAM Packet Time Stamps

   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.

8.  Security Considerations

   There are no significant extra security considerations regarding the
   allocation of these new IPFIX IEs compared to [RFC7012].

9.  Acknowledgements

   The authors would like to thank Al Morton and Greg Mirsky for their
   review and valuable comments.

10.  References

10.1.  Normative References

   [IANA-PERF-METRIC]
              "IANA Performance Metric Registry",
              <https://www.iana.org/assignments/performance-metrics/
              performance-metrics.xhtml>.

   [RFC7012]  Claise, B., Ed. and B. Trammell, Ed., "Information Model
              for IP Flow Information Export (IPFIX)", RFC 7012,
              DOI 10.17487/RFC7012, September 2013,
              <https://www.rfc-editor.org/info/rfc7012>.

   [RFC8911]  Bagnulo, M., Claise, B., Eardley, P., Morton, A., and A.
              Akhter, "Registry for Performance Metrics", RFC 8911,
              DOI 10.17487/RFC8911, November 2021,
              <https://www.rfc-editor.org/info/rfc8911>.

10.2.  Informative References

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   [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-02, 16 August 2022,
              <https://www.ietf.org/archive/id/draft-filsfils-spring-
              path-tracing-02.txt>.

   [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-02, 12 October
              2022, <https://www.ietf.org/archive/id/draft-ietf-ippm-
              ioam-deployment-02.txt>.

   [I-D.song-ippm-postcard-based-telemetry]
              Song, H., Mirsky, G., Filsfils, C., Abdelsalam, A., Zhou,
              T., Li, Z., Graf, T., Mishra, G. S., Shin, J., and K. Lee,
              "Postcard-Based On-Path Telemetry using Packet Marking",
              Work in Progress, Internet-Draft, draft-song-ippm-
              postcard-based-telemetry-15, 28 November 2022,
              <https://www.ietf.org/archive/id/draft-song-ippm-postcard-
              based-telemetry-15.txt>.

   [I-D.song-opsawg-ifit-framework]
              Song, H., Qin, F., Chen, H., Jin, J., and J. Shin, "A
              Framework for In-situ Flow Information Telemetry", Work in
              Progress, Internet-Draft, draft-song-opsawg-ifit-
              framework-19, 24 October 2022,
              <https://www.ietf.org/archive/id/draft-song-opsawg-ifit-
              framework-19.txt>.

   [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,
              <https://www.ietf.org/archive/id/draft-tgraf-opsawg-ipfix-
              srv6-srh-05.txt>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

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   [RFC2330]  Paxson, V., Almes, G., Mahdavi, J., and M. Mathis,
              "Framework for IP Performance Metrics", RFC 2330,
              DOI 10.17487/RFC2330, May 1998,
              <https://www.rfc-editor.org/info/rfc2330>.

   [RFC3393]  Demichelis, C. and P. Chimento, "IP Packet Delay Variation
              Metric for IP Performance Metrics (IPPM)", RFC 3393,
              DOI 10.17487/RFC3393, November 2002,
              <https://www.rfc-editor.org/info/rfc3393>.

   [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,
              <https://www.rfc-editor.org/info/rfc5153>.

   [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,
              <https://www.rfc-editor.org/info/rfc5905>.

   [RFC6020]  Bjorklund, M., Ed., "YANG - A Data Modeling Language for
              the Network Configuration Protocol (NETCONF)", RFC 6020,
              DOI 10.17487/RFC6020, October 2010,
              <https://www.rfc-editor.org/info/rfc6020>.

   [RFC6049]  Morton, A. and E. Stephan, "Spatial Composition of
              Metrics", RFC 6049, DOI 10.17487/RFC6049, January 2011,
              <https://www.rfc-editor.org/info/rfc6049>.

   [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,
              <https://www.rfc-editor.org/info/rfc6703>.

   [RFC6991]  Schoenwaelder, J., Ed., "Common YANG Data Types",
              RFC 6991, DOI 10.17487/RFC6991, July 2013,
              <https://www.rfc-editor.org/info/rfc6991>.

   [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,
              <https://www.rfc-editor.org/info/rfc7011>.

   [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,
              <https://www.rfc-editor.org/info/rfc7015>.

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   [RFC7323]  Borman, D., Braden, B., Jacobson, V., and R.
              Scheffenegger, Ed., "TCP Extensions for High Performance",
              RFC 7323, DOI 10.17487/RFC7323, September 2014,
              <https://www.rfc-editor.org/info/rfc7323>.

   [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, <https://www.rfc-editor.org/info/rfc7679>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [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, <https://www.rfc-editor.org/info/rfc9197>.

   [RFC9232]  Song, H., Qin, F., Martinez-Julia, P., Ciavaglia, L., and
              A. Wang, "Network Telemetry Framework", RFC 9232,
              DOI 10.17487/RFC9232, May 2022,
              <https://www.rfc-editor.org/info/rfc9232>.

Authors' Addresses

   Thomas Graf
   Swisscom
   Binzring 17
   CH-8045 Zurich
   Switzerland
   Email: thomas.graf@swisscom.com

   Benoit Claise
   Huawei
   Email: benoit.claise@huawei.com

   Alex Huang Feng
   INSA-Lyon
   Lyon
   France
   Email: alex.huang-feng@insa-lyon.fr

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