Network Working Group                                            T. Graf
Internet-Draft                                                  Swisscom
Intended status: Standards Track                               B. Claise
Expires: 29 January 2023                                          Huawei
                                                           A. Huang Feng
                                                               INSA-Lyon
                                                            28 July 2022


                Export of Forwarding Path Delay in IPFIX
              draft-tgraf-opsawg-ipfix-inband-telemetry-01

Abstract

   This document introduces new IP Flow Information Export (IPFIX)
   information elements to expose the Inband Telemetry measured
   forwarding path 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 29 January 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/
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   Please review these documents carefully, as they describe your rights
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   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.  Performance Metrics . . . . . . . . . . . . . . . . . . . . .   5
     2.1.  IP One-Way Delay Hybrid Type I Passive Registry
           Entries . . . . . . . . . . . . . . . . . . . . . . . . .   5
       2.1.1.  Summary . . . . . . . . . . . . . . . . . . . . . . .   5
       2.1.2.  Description . . . . . . . . . . . . . . . . . . . . .   6
       2.1.3.  Change Controller . . . . . . . . . . . . . . . . . .   6
       2.1.4.  Version of Registry Format  . . . . . . . . . . . . .   6
     2.2.  Metric Definition . . . . . . . . . . . . . . . . . . . .   6
       2.2.1.  Reference Definition  . . . . . . . . . . . . . . . .   6
       2.2.2.  Fixed Parameters  . . . . . . . . . . . . . . . . . .   7
     2.3.  Method of Measurement . . . . . . . . . . . . . . . . . .   7
       2.3.1.  Reference Methods . . . . . . . . . . . . . . . . . .   7
       2.3.2.  Packet Stream Generation  . . . . . . . . . . . . . .   7
       2.3.3.  Traffic Filtering (Observation) Details . . . . . . .   8
       2.3.4.  Sampling Distribution . . . . . . . . . . . . . . . .   8
       2.3.5.  Runtime Parameters and Data Format  . . . . . . . . .   8
       2.3.6.  Roles . . . . . . . . . . . . . . . . . . . . . . . .   8
     2.4.  Output  . . . . . . . . . . . . . . . . . . . . . . . . .   9
       2.4.1.  Type  . . . . . . . . . . . . . . . . . . . . . . . .   9
       2.4.2.  Reference Definition  . . . . . . . . . . . . . . . .   9
       2.4.3.  Administrative Items  . . . . . . . . . . . . . . . .  11
       2.4.4.  Comments and Remarks  . . . . . . . . . . . . . . . .  12
   3.  IPFIX Information Elements  . . . . . . . . . . . . . . . . .  12
   4.  Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . .  13
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  14
     5.1.  Performance Metrics . . . . . . . . . . . . . . . . . . .  14
     5.2.  IPFIX Entities  . . . . . . . . . . . . . . . . . . . . .  14
       5.2.1.  PathDelayMeanDeltaMicroseconds  . . . . . . . . . . .  15
       5.2.2.  PathDelayMeanDeltaNanoseconds . . . . . . . . . . . .  16
       5.2.3.  PathDelayMinDeltaMicroseconds . . . . . . . . . . . .  16
       5.2.4.  PathDelayMinDeltaNanoseconds  . . . . . . . . . . . .  16
       5.2.5.  PathDelayMaxDeltaMicroseconds . . . . . . . . . . . .  16
       5.2.6.  PathDelayMaxDeltaNanoseconds  . . . . . . . . . . . .  16
       5.2.7.  PathDelaySumDeltaMicroseconds . . . . . . . . . . . .  17
       5.2.8.  PathDelaySumDeltaNanoseconds  . . . . . . . . . . . .  17
   6.  Operational Considerations  . . . . . . . . . . . . . . . . .  17
     6.1.  Time Accuracy . . . . . . . . . . . . . . . . . . . . . .  17
     6.2.  Mean Delay  . . . . . . . . . . . . . . . . . . . . . . .  17
     6.3.  IOAM Packet Time Stamps . . . . . . . . . . . . . . . . .  17
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  17
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  18
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  18
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  18
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  18
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  20



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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 Inband Telemetry, defined 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.

   Inband Telemetry can be distinguished between two modes.  Passport
   mode, [RFC9197], where only the last hop in the forwarding path of
   the Inband 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 forwarding 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 Inband 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.  Performance Metrics

   This section defines and describes the new performance metrics

2.1.  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.

2.1.1.  Summary

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

2.1.1.1.  ID (Identifier)

   <insert a numeric Identifier, an integer, TBD>

2.1.1.2.  Name

   IANA has allocated the numeric Identifiers TBD1-4 for the four Named
   Metric Entries in this section

2.1.1.3.  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

2.1.1.4.  URI

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




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   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

2.1.2.  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

2.1.3.  Change Controller

   IETF

2.1.4.  Version of Registry Format

   1.0

2.2.  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".

2.2.1.  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]




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   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].

   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.

2.2.2.  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

2.3.  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.

2.3.1.  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].

   The Traffic Filter at the OP is configured to observe a single IP
   connection.

2.3.2.  Packet Stream Generation

   N/A




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2.3.3.  Traffic Filtering (Observation) Details

   The Fixed Parameters above give a portion of the Traffic Filter.
   Other aspects will be supplied as Runtime Parameters (below).

2.3.4.  Sampling Distribution

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

2.3.5.  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 Inband 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.

2.3.6.  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.




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   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.

2.4.  Output

   This category specifies all details of the output of measurements
   using the metric.

2.4.1.  Type

   OWDelay Types are discussed in the subsections below.

2.4.2.  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.

2.4.2.1.  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,




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      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].

2.4.2.2.  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].

2.4.2.3.  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].



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2.4.2.4.  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].

2.4.2.5.  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.

2.4.2.6.  Calibration

   Passive Measurements at an OP could be calibrated against an Active
   Measurement at host A where the Active Measurement represents the
   ground truth.

2.4.3.  Administrative Items

2.4.3.1.  Status

   Current





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2.4.3.2.  Requester

   This RFC

2.4.3.3.  Revision

   1.0

2.4.3.4.  Revision Date

   RFC Date

2.4.4.  Comments and Remarks

   None

3.  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).








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   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).

   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).

4.  Use Cases

   The measured forwarding 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.





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   *  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, 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.

5.  IANA Considerations

5.1.  Performance Metrics

   This document requests IANA to create new performance metrics under
   the "Performance Metrics" registry [RFC8911] with the values defined
   in section 2.

5.2.  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

5.2.1.  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.  Abstract Data Type: unsigned16 Data Type Semantics:
   OctedDelta Reference: [RFC-to-be], xxx






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5.2.2.  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

5.2.3.  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

5.2.4.  PathDelayMinDeltaNanoseconds

   Name: PathDelayMinDeltaNanoseconds ElementID: TBD8 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 nanoseconds.
   Abstract Data Type: unsigned32 Data Type Semantics: OctedDelta
   Reference: [RFC-to-be], xxx

5.2.5.  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

5.2.6.  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







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5.2.7.  PathDelaySumDeltaMicroseconds

   Name: PathDelaySumDeltaMicroseconds 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

5.2.8.  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

6.  Operational Considerations

6.1.  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.

6.2.  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.

6.3.  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.

7.  Security Considerations

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




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8.  Acknowledgements

   The authors would like to thank xxx for their review and valuable
   comments.

9.  References

9.1.  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",
              DOI 10.17487/RFC8911, RFC 8911, November 2021,
              <https://www.rfc-editor.org/info/rfc8911>.

9.2.  Informative References

   [I-D.filsfils-spring-path-tracing]
              Filsfils, C., Abdelsalam, A., Garvia, P. C., Yufit, M.,
              Graf, T., Su, Y., Matsushima, S., and M. Valentine, "Path
              Tracing in SRv6 networks", Work in Progress, Internet-
              Draft, draft-filsfils-spring-path-tracing-01, 30 May 2022,
              <https://www.ietf.org/archive/id/draft-filsfils-spring-
              path-tracing-01.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-01, 11 April 2022,
              <https://www.ietf.org/archive/id/draft-ietf-ippm-ioam-
              deployment-01.txt>.

   [I-D.song-ippm-postcard-based-telemetry]
              Song, H., Mirsky, G., Filsfils, C., Abdelsalam, A., Zhou,
              T., Li, Z., Mishra, G., Shin, J., and K. Lee, "In-Situ OAM
              Marking-based Direct Export", Work in Progress, Internet-
              Draft, draft-song-ippm-postcard-based-telemetry-12, 12 May
              2022, <https://www.ietf.org/archive/id/draft-song-ippm-
              postcard-based-telemetry-12.txt>.



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   [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-17, 22 February 2022,
              <https://www.ietf.org/archive/id/draft-song-opsawg-ifit-
              framework-17.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>.

   [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>.







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   [RFC6703]  Morton, A., Ramachandran, G., and G. Maguluri, "Reporting
              IP Network Performance Metrics: Different Points of View",
              DOI 10.17487/RFC6703, RFC 6703, 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",
              DOI 10.17487/RFC7015, RFC 7015, September 2013,
              <https://www.rfc-editor.org/info/rfc7015>.

   [RFC7323]  Borman, D., Braden, B., Jacobson, V., and R.
              Scheffenegger, Ed., "TCP Extensions for High Performance",
              DOI 10.17487/RFC7323, RFC 7323, 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>.

   [RFC9197]  Brockners, F., Ed., Bhandari, S., Ed., and T. Mizrahi,
              Ed., "Data Fields for In Situ Operations, Administration,
              and Maintenance (IOAM)", DOI 10.17487/RFC9197, RFC 9197,
              May 2022, <https://www.rfc-editor.org/info/rfc9197>.

Authors' Addresses

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


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



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














































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