MPLS Working Group                                              W. Cheng
Internet-Draft                                              China Mobile
Intended status: Standards Track                             X. Min, Ed.
Expires: 2 January 2023                                        ZTE Corp.
                                                                 T. Zhou
                                                                  Huawei
                                                                 X. Dong
                                                               FiberHome
                                                                Y. Peleg
                                                                Broadcom
                                                             1 July 2022


 Encapsulation For MPLS Performance Measurement with Alternate Marking
                                 Method
               draft-ietf-mpls-inband-pm-encapsulation-03

Abstract

   This document defines the encapsulation for MPLS performance
   measurement with alternate marking method, which performs flow-based
   packet loss, delay, and jitter measurements on live traffic.

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
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   This Internet-Draft will expire on 2 January 2023.

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   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.



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   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
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   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Conventions Used in This Document . . . . . . . . . . . .   3
       1.1.1.  Abbreviations . . . . . . . . . . . . . . . . . . . .   3
       1.1.2.  Requirements Language . . . . . . . . . . . . . . . .   4
   2.  Flow-based PM Encapsulation in MPLS . . . . . . . . . . . . .   4
     2.1.  Examples for Applying Flow-ID Label in a label stack  . .   5
   3.  Procedures of Encapsulation, Look-up and Decapsulation  . . .   8
   4.  Procedures of Flow-ID allocation  . . . . . . . . . . . . . .   9
   5.  FLC and FRLD Considerations . . . . . . . . . . . . . . . . .  10
   6.  Equal-Cost Multipath Considerations . . . . . . . . . . . . .  10
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  11
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  11
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  11
   10. Contributors  . . . . . . . . . . . . . . . . . . . . . . . .  12
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  12
     11.1.  Normative References . . . . . . . . . . . . . . . . . .  12
     11.2.  Informative References . . . . . . . . . . . . . . . . .  12
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  14

1.  Introduction

   [I-D.ietf-ippm-rfc8321bis] describes a performance measurement
   method, which can be used to measure packet loss, delay, and jitter
   on live traffic.  Since this method is based on marking consecutive
   batches of packets, the method is often referred to as Alternate
   Marking Method.  [RFC8372] discusses the desired capabilities for
   MPLS flow identification, in order to perform a better in-band
   performance monitoring of user data packets.

   This document defines the encapsulation for MPLS performance
   measurement with alternate marking method, which performs flow-based
   packet loss, delay, and jitter measurements on live traffic.  The
   encapsulation defined in this document supports monitoring at
   intermediate nodes, as well as flow identification at both transport
   and service layers.

   This document employs a method, other than Synonymous Flow Label
   (SFL), to accomplish MPLS flow identification.  The method described
   in this document is complementary to the SFL method [RFC8957]
   [I-D.ietf-mpls-sfl-control], the former mainly aims at hop-by-hop



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   performance measurement, and the latter mainly aims at edge-to-edge
   performance measurement.  Different sets of flows may use different
   methods.

   The method described in this document is also complementary to the
   In-situ OAM method [RFC9197] [I-D.ietf-ippm-ioam-direct-export], the
   former doesn't introduce any new header whereas the latter introduces
   a new In-situ OAM header, furthermore, the former requests the
   network nodes to report the data used for performance measurement,
   and the latter requests the network nodes to report the data used for
   operational and telemetry information collection.  One set of flows
   may use both of the two methods concurrently.

1.1.  Conventions Used in This Document

1.1.1.  Abbreviations

   ACL: Access Control List

   bSPL: Base Special Purpose Label

   ECMP: Equal-Cost Multipath

   ELC: Entropy Label Capability

   ERLD: Entropy Readable Label Depth

   FLC: Flow-ID Label Capability

   FLI: Flow-ID Label Indicator

   FRLD: Flow-ID Readable Label Depth

   LSP: Label Switched Path

   MPLS: Multi-Protocol Label Switching

   NMS: Network Management System

   PHP: Penultimate Hop Popping

   PM: Performance Measurement

   PW: PseudoWire

   SFL: Synonymous Flow Label

   SID: Segment ID



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   SR: Segment Routing

   TC: Traffic Class

   TTL: Time to Live

   VC: Virtual Channel

   VPN: Virtual Private Network

1.1.2.  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.

2.  Flow-based PM Encapsulation in MPLS

   Flow-based MPLS performance measurement encapsulation with alternate
   marking method has the following format:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Flow-ID Label Indicator (TBA1)    |  TC |S|      TTL      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |             Flow-ID Label             |L|D|T|S|      TTL      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

               Figure 1: Flow-based PM Encapsulation in MPLS

   Flow-ID Label Indicator (FLI) is a Base Special Purpose Label (bSPL)
   as defined in [RFC9017].  The FLI is defined in this document as
   value TBA1.

   Traffic Class (TC) and Time to Live (TTL) for the FLI SHOULD follow
   the same field values of that label immediately preceding the FLI.

   Flow-ID label is used as MPLS flow identification [RFC8372], its
   value MUST be unique within the administrative domain.  Flow-ID
   values can be allocated by an external NMS/controller, based on
   measurement object instance such as LSP or PW.  There is a one-to-one
   mapping between Flow-ID and flow.  The specific method on how to
   allocate the Flow-ID values is described in Section 4.





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   Flow-ID label can be placed at either the bottom or the middle of the
   MPLS label stack, and the Flow-ID label MAY appear multiple times in
   a label stack.  Section 2.1 of this document provides several
   examples to illustrate how to apply Flow-ID label in a label stack.
   TTL for the Flow-ID label MUST be zero to ensure that it is not used
   inadvertently for forwarding.  S bit for the Flow-ID Label depends on
   whether the Flow-ID label is placed at the bottom of the MPLS label
   stack.

   Besides flow identification, a color-marking field is also necessary
   for alternate marking method.  To achieve the purpose of coloring the
   MPLS traffic, as well as the distinction between hop-by-hop
   measurement and edge-to-edge measurement, TC for the Flow-ID label is
   defined as follows:

   *  L(oss) bit is used for coloring the MPLS packets for loss
      measurement.

   *  D(elay) bit is used for coloring the MPLS packets for delay/jitter
      measurement.

   *  T(ype) bit is used to indicate the measurement type.  When T bit
      is set to 1, it means edge-to-edge performance measurement.  When
      T bit is set to 0, it means hop-by-hop performance measurement.

2.1.  Examples for Applying Flow-ID Label in a label stack

   Three examples on different layout of Flow-ID label (4 octets) are
   illustrated as follows:

   (1) Layout of Flow-ID label when applied to MPLS transport.




















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                +----------------------+
                |          LSP         |
                |         Label        |
                +----------------------+
                |     Flow-ID Label    |
                |       Indicator      | <= bSPL
                +----------------------+
                |        Flow-ID       |
                |         Label        |
                +----------------------+
                |      Application     |
                |         Label        |
                +----------------------+ <= Bottom of stack
                |                      |
                |        Payload       |
                |                      |
                +----------------------+

                Figure 2: Applying Flow-ID to MPLS transport

   Note that here if penultimate hop popping (PHP) is in use, the PHP
   LSR that recognizes the bSPL MAY choose not to pop the bSPL and the
   following Flow-ID label, otherwise the egress LSR would be excluded
   from the performance measurement.

   Also note that in other examples of applying Flow-ID to MPLS
   transport, one LSP label can be substituted by multiple SID labels in
   the case of using SR Policy, and the combination of bSPL and Flow-ID
   label can be placed between SID labels, as specified in Section 5.

   (2) Layout of Flow-ID label when applied to MPLS service.




















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                +----------------------+
                |          LSP         |
                |         Label        |
                +----------------------+
                |      Application     |
                |         Label        |
                +----------------------+
                |     Flow-ID Label    |
                |       Indicator      | <= bSPL
                +----------------------+
                |        Flow-ID       |
                |         Label        |
                +----------------------+ <= Bottom of stack
                |                      |
                |        Payload       |
                |                      |
                +----------------------+

                 Figure 3: Applying Flow-ID to MPLS service

   Note that here application label can be MPLS PW label, MPLS Ethernet
   VPN label or MPLS IP VPN label, and it's also called VC label as
   defined in [RFC4026].

   (3) Layout of Flow-ID label when applied to both MPLS transport and
   MPLS service.

























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                +----------------------+
                |          LSP         |
                |         Label        |
                +----------------------+
                |     Flow-ID Label    |
                |       Indicator      | <= bSPL
                +----------------------+
                |        Flow-ID       |
                |         Label        |
                +----------------------+
                |      Application     |
                |         Label        |
                +----------------------+
                |     Flow-ID Label    |
                |       Indicator      | <= bSPL
                +----------------------+
                |        Flow-ID       |
                |         Label        |
                +----------------------+ <= Bottom of stack
                |                      |
                |        Payload       |
                |                      |
                +----------------------+

     Figure 4: Applying Flow-ID to both MPLS transport and MPLS service

   Note that for this example the two Flow-ID values appearing in a
   label stack MUST be different, that is to say, Flow-ID label applied
   to MPLS transport and Flow-ID label applied to MPLS service share the
   same value space.  Also note that the two Flow-ID label values are
   independent from each other, e.g., two packets can belong to the same
   VPN flow but different LSP flows, or two packets can belong to two
   different VPN flows but the same LSP flow.

3.  Procedures of Encapsulation, Look-up and Decapsulation

   The procedures for Flow-ID label encapsulation, look-up and
   decapsulation are summarized as follows:

   *  The ingress node inserts the Flow-ID Label Indicator and the Flow-
      ID label into the MPLS label stack.  At the same time, the ingress
      node sets the Flow-ID value, two color-marking bits and the T bit,
      as defined in this document.

   *  If the hop-by-hop measurement is applied, i.e., the T bit is set
      to 0, then whether the transit node or the egress node is the
      processing node.  If the edge-to-edge measurement is applied,
      i.e., the T bit is set to 1, then only the egress node is the



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      processing node.  The processing node looks up the Flow-ID label
      with the help of the Flow-ID Label Indicator, and exports the
      collected data, such as the Flow-ID, block counters and
      timestamps, to an external NMS/controller, referring to the
      alternate marking method.  Note that while looking up the Flow-ID
      label, the transit node needs to perform some deep packet
      inspection beyond the label (at the top of the label stack) used
      to take forwarding decisions.

   *  The processing node may also pop the Flow-ID Label Indicator and
      the Flow-ID label from the MPLS label stack.  The egress node pops
      the whole MPLS label stack, and this document doesn't introduce
      any new process to the decapsulated packet.

4.  Procedures of Flow-ID allocation

   There are two ways of allocating Flow-ID, one way is to allocate
   Flow-ID by manual trigger from the network operator, and the other
   way is to allocate Flow-ID by automatic trigger from the ingress
   node, details are as follows:

   *  In the case of manual trigger, the network operator would manually
      input the characteristics (e.g.  IP five tuples and IP DSCP) of
      the measured flow, then the NMS/controller would generate one or
      two Flow-IDs based on the input from the network operator, and
      provision the ingress node with the characteristics of the
      measured flow and the corresponding allocated Flow-ID(s).

   *  In the case of automatic trigger, the ingress node would identify
      the flow entering the measured path, export the characteristics of
      the identified flow to the NMS/controller by IPFIX [RFC7011], then
      the NMS/controller would generate one or two Flow-IDs based on the
      characteristics exported from the ingress node, and provision the
      ingress node with the characteristics of the identified flow and
      the corresponding allocated Flow-ID(s).

   The policy pre-configured at the NMS/controller decides whether one
   Flow-ID or two Flow-IDs would be generated.  If the performance
   measurement on MPLS service is enabled, then one Flow-ID applied to
   MPLS service would be generated; If the performance measurement on
   MPLS transport is enabled, then one Flow-ID applied to MPLS transport
   would be generated; If both of them are enabled, then two Flow-IDs
   respectively applied to MPLS service and MPLS transport would be
   generated, in this case the transit node needs to look up both of the
   two Flow-IDs by default, and that can be changed by configuration to,
   e.g., look up only the Flow-ID applied to MPLS transport.





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   Whether using manual trigger or automatic trigger, the NMS/controller
   MUST guarantee every generated Flow-ID is unique within the
   administrative domain.

5.  FLC and FRLD Considerations

   Analogous to the Entropy Label Capability (ELC) defined in Section 5
   of [RFC6790] and the Entropy Readable Label Depth (ERLD) defined in
   Section 4 of [RFC8662], the Flow-ID Label Capability (FLC) and the
   Flow-ID Readable Label Depth (FRLD) are defined in this document.
   Both FLC and FRLD have the similar semantics with ELC and ERLD to a
   router, except that the Flow-ID is used in its flow identification
   function while the Entropy is used in its load-balancing function.

   The ingress node MUST insert each Flow-ID label at an appropriate
   depth, which ensures the node to which the Flow-ID label is exposed
   has the FLC.  The ingress node SHOULD insert each Flow-ID label
   within an appropriate FRLD, which is the minimum FRLD of all on-path
   nodes that need to read and use the Flow-ID label in question.  How
   the ingress node knows the FLC and FRLD of all on-path nodes is
   outside the scope of this document, whereas
   [I-D.xzc-lsr-mpls-flc-frld] provides a method to achieve that.

   When SR paths are used as transport, the label stack grows as the
   number of on-path segments increases, if the number of on-path
   segments is high, that may become a challenge for the Flow-ID label
   to be placed within an appropriate FRLD.  In order to overcome this
   potential challenge, an implementation MAY provide flexibility to the
   ingress node to place Flow-ID label between SID labels, i.e.,
   multiple identical Flow-ID labels at different depths MAY be
   interleaved with SID labels, when that happens a sophisticated
   network planning may be needed and it's beyond the scope of this
   document.

6.  Equal-Cost Multipath Considerations

   Analogous to what's described in Section 5 of [RFC8957], under
   conditions of Equal-Cost Multipath (ECMP), the introduction of Flow-
   ID label may lead to the same problem as caused by SFL, and the two
   solutions proposed for SFL would also apply here.











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7.  Security Considerations

   This document introduces the performance measurement domain that is
   the scope of a Flow-ID label.  The Flow-ID Label Indicator and Flow-
   ID label MUST NOT be signaled and distributed outside one performance
   measurement domain.  Improper configuration so that the Flow-ID label
   being passed from one domain to another would likely result in
   potential Flow-ID conflicts.

   To prevent packets carrying Flow-ID label from leaking from one
   domain to another, the domain boundary nodes SHOULD deploy some
   policies (e.g., ACL) to filter out the packets.  Specifically, in the
   sending edge, the domain boundary node SHOULD filter out the packets
   that carry the Flow-ID Label Indicator and are sent to other domain;
   in the receiving edge, the domain boundary node SHOULD drop the
   packets that carry the Flow-ID Label Indicator and are from other
   domains.

8.  IANA Considerations

   In the Special-Purpose MPLS Label Values registry, a new Base
   Special-Purpose MPLS Label Value for Flow-ID Label Indicator is
   requested from IANA as follows:

     +======================+===============+============+===========+
     | Base Special-Purpose | Description   | Semantics  | Reference |
     | MPLS Label Value     |               | Definition |           |
     +======================+===============+============+===========+
     | TBA1 (12 is          | Flow-ID Label | Section 2  | This      |
     | recommended)         | Indicator     |            | Document  |
     +----------------------+---------------+------------+-----------+

        Table 1: New Base Special-Purpose MPLS Label Value for Flow-
                             ID Label Indicator

9.  Acknowledgements

   The authors would like to acknowledge Loa Andersson, Tarek Saad,
   Stewart Bryant, Rakesh Gandhi, Greg Mirsky, Aihua Liu, Shuangping
   Zhan and Ming Ke for their careful review and very helpful comments.

   The authors would like to acknowledge Italo Busi and Chandrasekar
   Ramachandran for their insightful MPLS-RT review and very helpful
   comments.







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10.  Contributors

   Minxue Wang
   China Mobile
   Email: wangminxue@chinamobile.com

   Wen Ye
   China Mobile
   Email: yewen@chinamobile.com

11.  References

11.1.  Normative References

   [I-D.ietf-ippm-rfc8321bis]
              Fioccola, G., Cociglio, M., Mirsky, G., Mizrahi, T., and
              T. Zhou, "Alternate-Marking Method", Work in Progress,
              Internet-Draft, draft-ietf-ippm-rfc8321bis-02, 7 June
              2022, <https://www.ietf.org/archive/id/draft-ietf-ippm-
              rfc8321bis-02.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>.

   [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>.

11.2.  Informative References

   [I-D.ietf-ippm-ioam-direct-export]
              Song, H., Gafni, B., Brockners, F., Bhandari, S., and T.
              Mizrahi, "In-situ OAM Direct Exporting", Work in Progress,
              Internet-Draft, draft-ietf-ippm-ioam-direct-export-09, 15
              June 2022, <https://www.ietf.org/archive/id/draft-ietf-
              ippm-ioam-direct-export-09.txt>.

   [I-D.ietf-mpls-sfl-control]
              Bryant, S., Swallow, G., and S. Sivabalan, "A Simple
              Control Protocol for MPLS SFLs", Work in Progress,
              Internet-Draft, draft-ietf-mpls-sfl-control-02, 21 January
              2022, <https://www.ietf.org/archive/id/draft-ietf-mpls-
              sfl-control-02.txt>.






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   [I-D.xzc-lsr-mpls-flc-frld]
              Min, X., Zhang, Z., and W. Cheng, "Signaling Flow-ID Label
              Capability and Flow-ID Readable Label Depth", Work in
              Progress, Internet-Draft, draft-xzc-lsr-mpls-flc-frld-00,
              15 February 2022, <https://www.ietf.org/archive/id/draft-
              xzc-lsr-mpls-flc-frld-00.txt>.

   [RFC4026]  Andersson, L. and T. Madsen, "Provider Provisioned Virtual
              Private Network (VPN) Terminology", RFC 4026,
              DOI 10.17487/RFC4026, March 2005,
              <https://www.rfc-editor.org/info/rfc4026>.

   [RFC6790]  Kompella, K., Drake, J., Amante, S., Henderickx, W., and
              L. Yong, "The Use of Entropy Labels in MPLS Forwarding",
              RFC 6790, DOI 10.17487/RFC6790, November 2012,
              <https://www.rfc-editor.org/info/rfc6790>.

   [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>.

   [RFC8372]  Bryant, S., Pignataro, C., Chen, M., Li, Z., and G.
              Mirsky, "MPLS Flow Identification Considerations",
              RFC 8372, DOI 10.17487/RFC8372, May 2018,
              <https://www.rfc-editor.org/info/rfc8372>.

   [RFC8662]  Kini, S., Kompella, K., Sivabalan, S., Litkowski, S.,
              Shakir, R., and J. Tantsura, "Entropy Label for Source
              Packet Routing in Networking (SPRING) Tunnels", RFC 8662,
              DOI 10.17487/RFC8662, December 2019,
              <https://www.rfc-editor.org/info/rfc8662>.

   [RFC8957]  Bryant, S., Chen, M., Swallow, G., Sivabalan, S., and G.
              Mirsky, "Synonymous Flow Label Framework", RFC 8957,
              DOI 10.17487/RFC8957, January 2021,
              <https://www.rfc-editor.org/info/rfc8957>.

   [RFC9017]  Andersson, L., Kompella, K., and A. Farrel, "Special-
              Purpose Label Terminology", RFC 9017,
              DOI 10.17487/RFC9017, April 2021,
              <https://www.rfc-editor.org/info/rfc9017>.

   [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>.



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Authors' Addresses

   Weiqiang Cheng
   China Mobile
   Beijing
   China
   Email: chengweiqiang@chinamobile.com


   Xiao Min (editor)
   ZTE Corp.
   Nanjing
   China
   Email: xiao.min2@zte.com.cn


   Tianran Zhou
   Huawei
   Beijing
   China
   Email: zhoutianran@huawei.com


   Ximing Dong
   FiberHome
   Wuhan
   China
   Email: dxm@fiberhome.com


   Yoav Peleg
   Broadcom
   United States of America
   Email: yoav.peleg@broadcom.com

















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