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Versions: 00 01                                                         
IPPM                                                            H. Wang
Internet-Draft                                                    Y. Liu
Intended status: Standards Track                            China Mobile
Expires: May 29, 2022                                            C. Lin
                                                    New H3C Technologies
                                                                 M. Xiao
                                                        ZTE Corporation
                                                         October 25, 2021


                    Flow Measurement in IPv6 Network
               draft-wang-ippm-ipv6-flow-measurement-00

Abstract

   In-situ Operations, Administration, and Maintenance (OAM) need
   carrying necessary measurement information in the packet while the
   packet transverses a path between two points in the network to mark
   the packet.  The Alternate-Marking is a kind of marking method and is
   presented in RFC 8321, Alternate-Marking Method for Passive and
   Hybrid Performance Monitoring, and RFC 8889, Multipoint Alternate-
   Marking Method for Passive and Hybrid Performance Monitoring.  This
   document describes how to deploy in-situ flow performance measurement
   based on Alternate-Marking method in IPv6 domain.

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 May 29, 2022.

Copyright Notice

   Copyright (c) 2021 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



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   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
     1.2.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Flow Measurement in IPv6 Network  . . . . . . . . . . . . . .   3
     2.1.  Carrying Flow Measurement Data  . . . . . . . . . . . . .   3
     2.2.  Flow Measurement Data Definition  . . . . . . . . . . . .   4
   3.  Definition of Flow Monitor Option . . . . . . . . . . . . . .   4
     3.1.  Data Fields Format  . . . . . . . . . . . . . . . . . . .   4
   4.  Definition of Flow Monitor Option . . . . . . . . . . . . . .   6
     4.1.  Flow Monitoring Identification  . . . . . . . . . . . . .   6
   5.  Flow Measurement Operation  . . . . . . . . . . . . . . . . .   7
     5.1.  Packet Loss Measurement . . . . . . . . . . . . . . . . .   7
     5.2.  Packet Delay Measurement  . . . . . . . . . . . . . . . .   7
     5.3.  Measurement Type  . . . . . . . . . . . . . . . . . . . .   8
     5.4.  Two-way Flow Measurement  . . . . . . . . . . . . . . . .   8
     5.5.  Data Collection and Report  . . . . . . . . . . . . . . .   9
     5.6.  Function Extension Consideration  . . . . . . . . . . . .   9
       5.6.1.  The Use of Ext FM Type Bitmap . . . . . . . . . . . .  10
       5.6.2.  Bitmap Extension  . . . . . . . . . . . . . . . . . .  10
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  12
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  12
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  12
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  12
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  13
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  13

1.  Introduction

   The Alternate-Marking method, as described in [RFC8321] and
   [RFC8889], allows the synchronization of the measurements in
   different points by dividing the packet flow into batches.  So it is
   possible to get coherent counters and show what is happening in every
   marking period for each monitored flow.  Based on this ability, the
   method could be used to perform packet loss, delay and jitter
   measurements on live traffic.

   This document discusses how to deploy performance measurement based
   on Alternate-Marking method in IPv6 domain.  The measurement




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   operation is described and the applications are proposed in
   Section 5.

   A specific data structure is defined to carrying in-situ flow
   measurement data with traffic flow, and the extensibility is taken
   into account in designing.  The structure is called Flow Monitor
   Option, and detail is in Section 3.

   How to encapsulate the Flow Monitor Option in IPv6 traffic flow is
   discussed in Section 2.  A new type of IPv6 Extension Header is
   proposed, Flow Monitor Option is encapsulated in Hop-by-Hop options
   Header or Destination Options Header depending on the measurement
   type.

1.1.  Requirements Language

   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.

1.2.  Terminology

   The definitions of the basic terms are identical to those found in
   Alternate Marking [RFC8321] and Multipoint Alternate-Marking
   [RFC8889].

   The important new terms that need to be explained are listed below:

   ACL: access-control list

2.  Flow Measurement in IPv6 Network

2.1.  Carrying Flow Measurement Data

   The flow measurement method described by this document need to add
   measurement data in the flow used to perform measure.  In IPv6, the
   general way to carry packet's additional information is IPv6
   Extension Header.  Several IPv6 Extension Headers have been defined
   in [RFC8200].  It is necessary to determine suitable Ipv6 Extension
   Header to carry measuring data for deploying of performance measure
   in IPv6.

   There are two measurement types: End-to-End and Hop-by-Hop. The
   participating nodes in two types are different.





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   The source node allocates measurement data and encodes it in packet.
   For End-to-End measurement, just destination node processes the
   measuring data.  According to Section 4.1 of [RFC8200], IPv6
   Destination Options Header before the upper-layer header is
   appropriate for End-to-End measurement.

   For Hop-by-Hop measurement, all nodes on the delivery path are
   expected to examine and process the measurement data.  According to
   [RFC8200], the measurement data can be carried as an option of Hop-
   by-Hop Options Header.

2.2.  Flow Measurement Data Definition

   As description in Section 2.1, flow measurement data is encoded in
   IPv6 Destination Options Header and IPv6 Hop-by-Hop Options Header.
   Flow measurement data structure must be defined following IPv6
   Option's principle.

   This document defines Flow Monitor Option for flow measurement.
   Using Flow Monitor Option to marking packets required by Alternate-
   Marking, and to carry flow identity and measure parameters.

3.  Definition of Flow Monitor Option

   Flow Monitor Option is defined to carry flow measurement data, below
   is detailed description.

3.1.  Data Fields Format

   The following figure shows the data field's format for Flow Monitor
   Option.  This flow monitoring and measurement data structure can be
   encapsulated in the Hop-by-Hop Options Header and Destination Options
   Header.

   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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Option Type   |  Opt Data Len |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            FlowMonID                  |L|D| R |      HTI      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         NodeMonID                     |F|  P  |      Rsv      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         Ext FM Type           |          Reserved             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                       Figure 1: Flow Monitor Option




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   where:

   o  Option Type: 8-bit identifier of the type of Flow Monitor Option.
      The encoding format references Section 4.2 of [RFC8200].  The
      value is to be assigned by IANA.

   o  Opt Data Len: The length of the Option Data Fields of this option
      in bytes.

   o  FlowMonID: 20 bits unsigned integer.  The FlowMon identifier is
      used to identify one flow in the node.

   o  L: Loss Flag, a marking bit of packet loss measurement.

   o  D: Delay Flag, a marking bit of packet delay measurement.

   o  R: Reserved for future use, now initialized to zero for
      transmission and ignored on reception.

   o  HTI: Header Type Indication.  It indicates the type of the option
      header, has the following value:

      *  0: Reserved, indicate that the format of Flow Monitor Option is
         the same as [I-D.ietf-6man-ipv6-alt-mark].

      *  1~15: Private type.

      *  16~255: Extensible type value.  When the value is 16, the
         format of the option header is as shown in Figure 2.

   o  NodeMonID: 20 bits unsigned integer.  It is used to identify a
      node in the measurement domain, combined with the FlowMonID field
      to uniquely identify a monitored flow.  Detail description sees
      Section 4.1.

   o  F: The marking bit of two-way flow measurement.  If the field is
      set to 1, the end node generates reverse flow measurement
      configuration dynamically according to the current flow.

   o  P: 3 bits, measurement period.  It has the following values:

      *  000: 1 second

      *  001: 10 seconds

      *  010: 30 seconds

      *  011: 60 seconds



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      *  100: 300 seconds

      *  Others: Reserved

   o  Ext FM Type: A 16 bits Bitmap for Extended Flow Measurement type.
      The Bitmap can present 15 different measurement types.  From bit 0
      to 14, each bit presents a specific measurement type.  The bit15
      is reserved for extension Bitmap, 1 indicates carrying the
      extension Bitmap.  The use case about Ext FM Type is described in
      Section 5.6.

4.  Definition of Flow Monitor Option

   When flow measurement is enabled, source node allocates Flow Monitor
   Option for monitored flows, fills measurement parameters, sets
   marking bits, and adds an extension header for packet encapsulating
   the Flow Monitor Option.

   For Hop-by-Hop measurement, the Flow Monitor Option is encapsulated
   in the Hop-by-Hop Options Header.

   For End-to-End measurement, the Flow Monitor Option is encapsulated
   in the Destination Options Header before the upper-layer header.

4.1.  Flow Monitoring Identification

   The Flow Monitoring Identification is required for some general
   reasons:

   First, it helps to reduce the per node configuration.  Otherwise,
   each node needs to configure an access-control list (ACL) for each of
   the monitored flows.  Moreover, using a Flow Monitoring
   Identification allows a flexible granularity for the flow definition.

   Second, it simplifies the counters handling.  Hardware processing of
   flow tuples (and ACL matching) is challenging and often incurs into
   performance issues, especially in tunnel interfaces.

   Third, it eases the data export encapsulation and correlation for the
   collectors.

   The NodeMon identifier (NodeMonID) field is filled with the source
   node's identifier.  The NodeMonID as configuration is set on the
   source node by the central controller.  The controller ensures
   NodeMonID is unique within the measurement domain.

   The FlowMon identifier (FlowMonID) field is used to uniquely identify
   a monitored flow within a specified source node.  The FlowMonID can



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   be uniformly assigned by the central controller, also can be
   algorithmically generated by the source node based on the flow
   information.

   Using the combination of FlowMonID and NodeMonID, a monitored flow
   can be uniquely identified within the measurement domain.  The
   FlowMonID field and NodeMonID field are set at the source node.

5.  Flow Measurement Operation

   [RFC8321] describes a method to perform packet loss, delay and jitter
   measurements on live traffic.  This section describes how the method
   can be applied in IPv6 network.

5.1.  Packet Loss Measurement

   The L marking bit in the Flow Monitor Option is used to color the
   flows that need packet loss measurement.  By setting the L marking
   bit to 1 or 0 according to the measurement period filled in P field
   in the source node, the monitored flows can be split into consecutive
   blocks.  The intermediate and end nodes read the L marking bit and
   identify the packet blocks.  By counting the number of packets in
   each block and comparing the values measured by different nodes along
   the path, it is possible to measure packet loss occurred in any
   single block between any two points.

5.2.  Packet Delay Measurement

   The same principle used to measure packet loss also can be applied to
   one-way delay measurement.  Packet delay measurement references
   Double-Marking Method described in [RFC8321] using the L marking bit
   and D marking bit in Flow Monitor Option.

   The L marking bit is used to mark the alternate flow.  By marking the
   L marking bit to 1 or 0, the monitored flows can be split into
   consecutive blocks.  And, within this colored flow identified by the
   L marking bit, a second marked D marking bit is used to select the
   packets for measuring delay.  The D marking bit creates a new set of
   marked packets that are fully identified over the network, so that a
   network node can store the timestamps of these packets; these
   timestamps can be compared with the timestamps of the same packets on
   a second node to compute packet delay values for each packet.

   Likewise to packet delay measurement, the on-path jitter can be
   measured by measuring multiple blocks.






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5.3.  Measurement Type

   For different measurement requirements, there are End-to-End
   measurement type and Hop-by-Hop measurement type.

   With the End-to-End measurement type, it can measure the forwarding
   performance between source node and end node when the traffic passes
   through the measurement domain.  The performance of each intermediate
   node or link is not cared about.  Therefore, when using the End-to-
   End measurement type, only the source node and end node need to
   collect performance data and report data to controller.

   With the Hop-by-Hop measurement type, each node along the path which
   has enabled performance measurement SHOULD collect performance data
   and report data to the controller when the traffic passes through the
   measurement domain.

   Compared to the End-to-End measurement type, the Hop-by-Hop
   measurement type can more accurately locate the network packet loss
   and delay in position.

   The measurement type is determined by the position of Flow Monitor
   Option in the IPv6 Extension Header.  The Flow Monitor Option can be
   encapsulated in Hop-by-Hop Options Header or Destination Options
   Header.  When it is encapsulated in the Hop-by-Hop Options Header,
   each node along the path will deal with it.  That is Hop-by-Hop
   measurement.  When the Flow Monitor Option is encapsulated in the
   Destination Options Header, it means End-to-End measurement.

5.4.  Two-way Flow Measurement

   As described in [RFC8321] the source node needs to virtually split
   traffic flows into consecutive blocks according to some methods, such
   as configuring an access-control list (ACL) for each of the monitored
   flows.  But, if we want to measure bidirectional forwarding
   performance of monitored flows on the specified path, we need to
   configure ACLs associated monitored flows on the source node and end
   node at the same time.  This will increase the configuration and
   maintenance workload.  And this work is more complex, such as source
   IP addresses in the source node configuration need to be transformed
   as destination IP addresses in the end node, and other
   characteristics are similar.

   Therefore, this document provides a two-way flow measurement method.
   It generates reverse flow measurement configuration dynamically in
   the end node according to the forward flow.

   Two-way flow performance measurement is implemented as follows:



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   1.  The source node configures ACLs for monitored flows that need
   bidirectional flow measurement.

   2.  When the source node receives the corresponding monitored flow,
   it encapsulates Flow Monitor Option into the IPv6 Extension Header,
   and sets the F field to 1.

   3.  When the end node receives the monitored flow which F field has
   been set to 1, it analysis the information of positive monitored
   flow, changes the source and destination information, dynamically
   generates ACLs with the characteristics of reverse monitored flows,
   and distributes configuration on end node.

   4.  At the same time, the end node assigns FlowMonID for reverse
   monitored flows, and reports the new reserve FlowMonID, the NodeMonID
   of the end node and the reverse flow information to controller.

   5.  When the end node receives the reserve monitored flow, the end
   node encapsulates Flow Monitor Option into IPv6 Extension Header,
   sets F field to 0, uses the FlowMonID and NodeMonID of end node, and
   fills other fields of Flow Monitor option according to the end node's
   configuration.

   6.  All nodes along the reserve path enabled performance measurement
   collect performance data, report to controller according Flow Monitor
   option in the packet header.

5.5.  Data Collection and Report

   Each node which participates in performance measurement collects
   performance data, records packet counts, received timestamps, sent
   timestamps, FlowMonID, NodeMonID and other related information
   specified by Flow Measure Type bitmap, and reports to the controller.
   For the source node, it needs to report characteristic information of
   monitored flow additionally.

   The network nodes report to controller by Telemetry technique.  The
   period of report can be the measurement period filled in the P field
   of Flow Monitor Option, can also be specified in the Telemetry
   subscription, or is designated by local configuration.  This document
   does not limit the specific method.

5.6.  Function Extension Consideration








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5.6.1.  The Use of Ext FM Type Bitmap

   At present, the performance measurement is commonly attention to
   network packet loss, delay and jitter.  However, with the expanding
   of network applications, other network performance parameters begin
   to be concerned, such as out-of-order rate.  When network failure,
   controller wants to be able to obtain more abundant information, and
   in order to locate fault point quickly requires all nodes along the
   path to report current queue depth, input and output interface name,
   and so on.

   By defining bits of Ext FM Type field in the Flow Monitor Option and
   carrying additional information in the monitored flows, the
   measurement function can be extended.

   For example, in order to measure out-of-order rate, bit0 of Ext FM
   Type is defined as an out-of-order measurement mark.  When the source
   node receives monitored flow, it sets bit0 to indicate to count out-
   of-order packets.  At the same time, it fills in additional
   information after Ext FM Type bitmap with ordinal Sequence
   parameters.  After extension, the Flow Monitor Option package format
   is as follows:

   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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            FlowMonID                  |L|D| R |   HTI         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            NodeMonID                  |F|  P  |      Rsv      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |1|                             |   Bit0 Data(Sequence Num)     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   .                                                               .
   .                      Bit0 Data(Other information)             .
   .                                                               .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

              Figure 2: Use Bit0 For Out-of-order Measurement

   Using the same method, the other bits of Ext FM Type field can be
   extended.  Additional information is optional, whether it is carried
   is decided by the specified extension function.

5.6.2.  Bitmap Extension

   The Ext FM Type field has 16 bit, so 16 measurement functions can be
   extended.  For general applications, the bitmap is enough.  In order




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   to reduce the effect on forwarding performance, it is also not
   recommended too much measurement processes at the same time.

   However, considering functionality to be expanded in the future,
   bit15 is reserved, used to break the bitmap limit of 16.  If bit15 is
   set to 1, it indicates carrying the extension bitmap.  By default,
   bit15 is zero.

   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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            FlowMonID                  |L|D| R |   HTI         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            NodeMonID                  |F|  P  |      Rsv      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Ext FM Type(Bitmap)     |1|                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
   .                                                               .
   .          Additional Data of FM Bitmap (Optional)              .
   .                                                               .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      Extension Bitmap         |                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
   .                                                               .
   .        Additional Data of Extension Bitmap (Optional)         .
   .                                                               .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                     Figure 3: Extension Bitmap Format

   Based on the previous out-of-order measurement example, for example,
   after the bits of Ext FM Type have been exhausted, use bit2 of
   Extension Bitmap to expand FM type.  Flow Monitor Option package
   format is as shown below:

















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   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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            FlowMonID                  |L|D| R |   HTI         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            NodeMonID                  |F|  P  |      Rsv      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |1|0|0|0|0|0|0|0|0|0|0|0|0|0|0|1|   Bit0 Data (Sequence Num)    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   .                                                               .
   .                      Bit0 Data(Other information)             .
   .                                                               .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |0|0|1|0|0|0|0|0|0|0|0|0|0|0|0|0|                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
   .                                                               .
   .             Extension Bit2 Data (Optional)                    .
   .                                                               .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                     Figure 4: Extension Bit2 Example

6.  IANA Considerations

   The Flow Monitor Option Type should be assigned in IANA.

7.  Security Considerations

   The potential security threats of Alternate-Marking method have been
   described in detail in Section 9 of [RFC8321].  The performance
   measurement method described in this document does not introduce
   additional new security issues.

8.  References

8.1.  Normative References

   [I-D.ietf-6man-ipv6-alt-mark]
              Fioccola, G., Zhou, T., Cociglio, M., Qin, F., and R.
              Pang, "IPv6 Application of the Alternate Marking Method",
              draft-ietf-6man-ipv6-alt-mark-08 (work in progress),
              January 2022.

   [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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   [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>.

   [RFC8200]  Deering, S. and R. Hinden, "Internet Protocol, Version 6
              (IPv6) Specification", STD 86, RFC 8200,
              DOI 10.17487/RFC8200, July 2017,
              <https://www.rfc-editor.org/info/rfc8200>.

8.2.  Informative References

   [RFC8321]  Fioccola, G., Ed., Capello, A., Cociglio, M., Castaldelli,
              L., Chen, M., Zheng, L., Mirsky, G., and T. Mizrahi,
              "Alternate-Marking Method for Passive and Hybrid
              Performance Monitoring", RFC 8321, DOI 10.17487/RFC8321,
              January 2018, <https://www.rfc-editor.org/info/rfc8321>.

   [RFC8889]  Fioccola, G., Ed., Cociglio, M., Sapio, A., and R. Sisto,
              "Multipoint Alternate-Marking Method for Passive and
              Hybrid Performance Monitoring", RFC 8889,
              DOI 10.17487/RFC8889, August 2020,
              <https://www.rfc-editor.org/info/rfc8889>.

Authors' Addresses

   Haojie Wang
   China Mobile

   Email: wanghaojie@chinamobile.com


   Yisong Liu
   China Mobile

   Email: liuyisong@chinamobile.com


   Changwang Lin
   New H3C Technologies

   Email: linchangwang.04414@h3c.com


   Min Xiao
   ZTE Corporation

   Email: xiao.min2@zte.com.cn










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