IPPM Working Group                                        R. Gandhi, Ed.
Internet-Draft                                               C. Filsfils
Intended status: Standards Track                     Cisco Systems, Inc.
Expires: 26 January 2022                                        D. Voyer
                                                             Bell Canada
                                                                 M. Chen
                                                                  Huawei
                                                             B. Janssens
                                                                    Colt
                                                                R. Foote
                                                                   Nokia
                                                            25 July 2021


      Simple TWAMP (STAMP) Extensions for Segment Routing Networks
                     draft-ietf-ippm-stamp-srpm-01

Abstract

   Segment Routing (SR) leverages the source routing paradigm.  SR is
   applicable to both Multiprotocol Label Switching (SR-MPLS) and IPv6
   (SRv6) forwarding planes.  This document specifies RFC 8762 (Simple
   Two-Way Active Measurement Protocol (STAMP)) extensions for SR
   networks, for both SR-MPLS and SRv6 forwarding planes by augmenting
   the optional extensions defined in RFC 8972.

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 26 January 2022.

Copyright Notice

   Copyright (c) 2021 IETF Trust and the persons identified as the
   document authors.  All rights reserved.




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   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components
   extracted from this document must include 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
   2.  Conventions Used in This Document . . . . . . . . . . . . . .   3
     2.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
     2.2.  Abbreviations . . . . . . . . . . . . . . . . . . . . . .   3
     2.3.  Reference Topology  . . . . . . . . . . . . . . . . . . .   3
   3.  Destination Node Address TLV  . . . . . . . . . . . . . . . .   4
   4.  Return Path TLV . . . . . . . . . . . . . . . . . . . . . . .   5
     4.1.  Return Path Sub-TLVs  . . . . . . . . . . . . . . . . . .   6
       4.1.1.  Return Path Control Code Sub-TLV  . . . . . . . . . .   6
       4.1.2.  Return Address Sub-TLV  . . . . . . . . . . . . . . .   7
       4.1.3.  Return Segment List Sub-TLVs  . . . . . . . . . . . .   8
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  11
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  11
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .  13
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  13

1.  Introduction

   Segment Routing (SR) leverages the source routing paradigm for
   Software Defined Networks (SDNs).  SR is applicable to both
   Multiprotocol Label Switching (SR-MPLS) and IPv6 (SRv6) forwarding
   planes [RFC8402].  SR Policies as defined in
   [I-D.ietf-spring-segment-routing-policy] are used to steer traffic
   through a specific, user-defined paths using a stack of Segments.
   Built-in SR Performance Measurement (PM) is one of the essential
   requirements to provide Service Level Agreements (SLAs).

   The Simple Two-way Active Measurement Protocol (STAMP) provides
   capabilities for the measurement of various performance metrics in IP
   networks [RFC8762] without the use of a control channel to pre-signal
   session parameters.  [RFC8972] defines optional extensions for STAMP.
   Note that the YANG data model defined in [I-D.ietf-ippm-stamp-yang]
   can be used to provision the STAMP Session-Sender and STAMP Session-
   Reflector.



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   The STAMP test packets are transmitted along an IP path between a
   Session-Sender and a Session-Reflector to measure performance delay
   and packet loss along that IP path.  It may be desired in SR networks
   that the same path (same set of links and nodes) between the Session-
   Sender and Session-Reflector is used for the STAMP test packets in
   both directions.  This is achieved by using the STAMP [RFC8762]
   extensions for SR-MPLS and SRv6 networks specified in this document
   by augmenting the optional extensions defined in [RFC8972].

2.  Conventions Used in This Document

2.1.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119] [RFC8174]
   when, and only when, they appear in all capitals, as shown here.

2.2.  Abbreviations

   MPLS: Multiprotocol Label Switching.

   PM: Performance Measurement.

   SID: Segment ID.

   SL: Segment List.

   SR: Segment Routing.

   SR-MPLS: Segment Routing with MPLS forwarding plane.

   SRv6: Segment Routing with IPv6 forwarding plane.

   SSID: STAMP Session Identifier.

   STAMP: Simple Two-way Active Measurement Protocol.

2.3.  Reference Topology

   In the reference topology shown below, the STAMP Session-Sender S1
   initiates a STAMP test packet and the STAMP Session-Reflector R1
   transmits a reply test packet.  The reply test packet may be
   transmitted to the Session-Sender S1 on the same path (same set of
   links and nodes) or a different path in the reverse direction from
   the path taken towards the Session-Reflector R1.





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   The nodes S1 and R1 may be connected via a link or an SR path
   [RFC8402].  The link may be a physical interface, virtual link, or
   Link Aggregation Group (LAG) [IEEE802.1AX], or LAG member link.  The
   SR path may be an SR Policy [I-D.ietf-spring-segment-routing-policy]
   on node S1 (called head-end) with destination to node R1 (called
   tail-end).

                          T1                T2
                         /                   \
                +-------+     Test Packet     +-------+
                |       | - - - - - - - - - ->|       |
                |   S1  |=====================|   R1  |
                |       |<- - - - - - - - - - |       |
                +-------+  Reply Test Packet  +-------+
                         \                   /
                          T4                T3

            STAMP Session-Sender        STAMP Session-Reflector

                          Reference Topology

3.  Destination Node Address TLV

   The Session-Sender may need to transmit test packets to the Session-
   Reflector with a different destination address not matching an
   address on the Session-Reflector e.g. when the STAMP test packet is
   encapsulated by a tunneling protocol or an MPLS Segment List with
   IPv4 address from 127/8 range or Segment Routing Header (SRH) with
   IPv6 address ::1/128.  Here, Session-Sender may select an IPv4
   address from 127/8 range or select a Flow Label in case of IPv6
   address ::1/128 for testing ECMPs.  In an error condition, the STAMP
   test packet may not reach the intended Session-Reflector, an un-
   intended node may transmit reply test packets resulting in reporting
   of invalid measurement metrics.

   [RFC8972] defines STAMP test packets that can include one or more
   optional TLVs.  In this document, Destination Node Address TLV (Type
   TBA1) is defined for STAMP test packet [RFC8972] and has the
   following format shown in Figure 1:

    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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |STAMP TLV Flags| Type=TBA1     |         Length                |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    .                           Address                             .
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+




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               Figure 1: Destination Node Address TLV Format

   The Length field is used to decide the Address Family of the Address.

   The STAMP TLV Flags are set using the procedures described in
   [RFC8972].

   The Destination Node Address TLV is optional.  The Destination Node
   Address TLV indicates the address of the intended Session-Reflector
   node of the test packet.  When Session-Sender test packet destination
   address is different than the actual Session-Reflector address, the
   actual Session-Reflector address MUST be transmitted to the Session-
   Reflector with a Destination Node Address TLV.

   The Session-Reflector that supports this TLV, MUST transmit reply
   test packet with Error D (Wrong Destination) in the STAMP TLV Flags
   field if it is not the intended destination of the received Session-
   Sender test packet.

   D (Wrong Destination): A one-bit flag at position TBA3.  A Session-
   Sender MUST set the D flag to 0 before transmitting an extended STAMP
   test packet.  A Session-Reflector MUST set the D flag to 1 if the
   Session-Reflector determined that it is not the intended Destination
   as identified in the Destination Node Address TLV.  Otherwise, the
   Session-Reflector MUST set the D flag in the Reply test packet to 0.

   Note that the Destination Node Address TLV is applicable to the P2P
   SR paths only.

4.  Return Path TLV

   For end-to-end SR paths, the Session-Reflector may need to transmit
   the reply test packet on a specific return path.  The Session-Sender
   can request this in the test packet to the Session-Reflector using a
   Return Path TLV.  With this TLV carried in the Session-Sender test
   packet, signaling and maintaining dynamic SR network state for the
   STAMP sessions on the Session-Reflector are avoided.

   For links, the Session-Reflector may need to transmit the reply test
   packet on the same incoming link in the reverse direction.  The
   Session-Sender can request this in the test packet to the Session-
   Reflector using a Return Path TLV.

   [RFC8972] defines STAMP test packets that can include one or more
   optional TLVs.  In this document, the TLV Type (value TBA2) is
   defined for the Return Path TLV that carries the return path for the
   Session-Sender test packet.  The format of the Return Path TLV is
   shown in Figure 2:



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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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |STAMP TLV Flags|   Type=TBA2   |         Length                |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                   Return Path Sub-TLVs                        |
    .                                                               .
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                         Figure 2: Return Path TLV

   The STAMP TLV Flags are set using the procedures described in
   [RFC8972].

   The Return Path TLV is optional.  The Session-Sender MUST only insert
   one Return Path TLV in the STAMP test packet.  The Session-Reflector
   that supports this TLV, MUST only process the first Return Path TLV
   in the test packet and ignore other Return Path TLVs if present, and
   it MUST NOT add Return Path TLV in the reply test packet.  The
   Session-Reflector that supports this TLV MUST reply using the Return
   Path received in the Session-Sender test packet.  Otherwise, the
   procedure defined in [RFC8762] is followed.

4.1.  Return Path Sub-TLVs

   The Return Path TLV contains one or more Sub-TLVs to carry the
   information for the requested return path.  A Return Path Sub-TLV can
   carry Return Path Control Code, Return Path IP Address or Return Path
   Segment List.

   The STAMP Sub-TLV Flags are set using the procedures described in
   [RFC8972].

   When Return Path Sub-TLV is present in the Session-Sender test
   packet, the Session-Reflector that supports this TLV, MUST transmit
   reply test packet using the return path information specified in the
   Return Path Sub-TLV.

   A Return Path TLV MUST NOT contain both Control Code Sub-TLV as well
   as Return Address or Return Segment List Sub-TLV.

4.1.1.  Return Path Control Code Sub-TLV

   The format of the Return Path Control Code Sub-TLV is shown in
   Figure 3.  The Type of the Return Path Control Code Sub-TLV is
   defined as following:





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   *  Type (value 1): Return Path Control Code.  The Session-Sender can
      request the Session-Reflector to transmit the reply test packet
      based on the flags defined in the Control Code field.

    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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |STAMP TLV Flags|   Type        |         Length                |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                   Control Code                                |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

             Figure 3: Control Code Sub-TLV in Return Path TLV

   Control Code Flags (32-bit): Defined as follows.

       0x0: No Reply Requested.

       0x1: Reply Requested on the Same Link.

   When Control Code flag is set to 0x0 in the Session-Sender test
   packet, the Session-Reflector does not transmit reply test packet to
   the Session-Sender and terminates the STAMP test packet.  Optionally,
   the Session-Reflector may locally stream performance metrics via
   telemetry using the information from the received test packet.  All
   other Return Path Sub-TLVs are ignored in this case.

   When Control Code flag is set to 0x1 in the Session-Sender test
   packet, the Session-Reflector transmits the reply test packet over
   the same incoming link where the test packet is received in the
   reverse direction towards the Session-Sender.

4.1.2.  Return Address Sub-TLV

   The STAMP reply test packet may be transmitted to the Session-Sender
   to a different destination address on the Session-Sender using Return
   Path TLV.  For this, the Session-Sender can specify in the test
   packet the receiving destination node address for the Session-
   Reflector reply test packet.  When transmitting the STAMP test packet
   to a different destination address, the Session-Sender MUST follow
   the procedure defined in Section 4.3 of [RFC8762].

   The format of the Return Address Sub-TLV is shown in Figure 4.  The
   Address Family field indicates the type of the address, and it SHALL
   be set to one of the assigned values in the "IANA Address Family
   Numbers" registry.  The Type of the Return Address Sub-TLV is defined
   as following:




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   *  Type (value 2): Return Address.  Destination node address of the
      Session-Reflector reply test packet different than the Source
      Address in the Session-Sender test packet.

    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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |STAMP TLV Flags|     Type      |         Length                |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    | Reserved                      | Address Family                |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    .                           Address                             .
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

            Figure 4: Return Address Sub-TLV in Return Path TLV

4.1.3.  Return Segment List Sub-TLVs

   The format of the Segment List Sub-TLVs in the Return Path TLV is
   shown in Figure 5.  The segment entries MUST be in network order.
   The Segment List Sub-TLV can be one of the following Types:

   *  Type (value 3): SR-MPLS Label Stack of the Return Path

   *  Type (value 4): SRv6 Segment List of the Return Path

    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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |STAMP TLV Flags|     Type      |         Length                |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                    Segment(1)                                 |
    .                                                               .
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    .                                                               .
    .                                                               .
    .                                                               .
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                    Segment(n) (bottom of stack)               |
    .                                                               .
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

             Figure 5: Segment List Sub-TLV in Return Path TLV

   An SR-MPLS Label Stack Sub-TLV may carry only Binding SID
   [I-D.ietf-pce-binding-label-sid] of the Return SR-MPLS Policy.





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   An SRv6 Segment List Sub-TLV may carry only Binding SID
   [I-D.ietf-pce-binding-label-sid] of the Return SRv6 Policy.

   The Session-Sender MUST only insert one Segment List Return Path Sub-
   TLV in the test packet.  The Session-Reflector MUST only process the
   first Segment List Return Path Sub-TLV in the test packet and ignore
   other Segment List Return Path Sub-TLVs if present.

   Note that in addition to the P2P SR paths, the Return Segment List
   Sub-TLV is also applicable to the P2MP SR paths.  For example, for
   P2MP SR paths, it may only carry the Node Segment Identifier of the
   Session-Sender in order for the reply test packet to follow an SR
   path to the Session-Sender.

5.  Security Considerations

   The usage of STAMP protocol is intended for deployment in limited
   domains [RFC8799].  As such, it assumes that a node involved in STAMP
   protocol operation has previously verified the integrity of the path
   and the identity of the far-end Session-Reflector.

   If desired, attacks can be mitigated by performing basic validation
   and sanity checks, at the Session-Sender, of the timestamp fields in
   received reply test packets.  The minimal state associated with these
   protocols also limits the extent of measurement disruption that can
   be caused by a corrupt or invalid test packet to a single test cycle.

   The security considerations specified in [RFC8762] and [RFC8972] also
   apply to the extensions defined in this document.  Specifically, the
   message integrity protection using HMAC, as defined in [RFC8762]
   Section 4.4, also apply to the procedure described in this document.

   STAMP uses the well-known UDP port number that could become a target
   of denial of service (DoS) or could be used to aid man-in-the-middle
   (MITM) attacks.  Thus, the security considerations and measures to
   mitigate the risk of the attack documented in Section 6 of [RFC8545]
   equally apply to the STAMP extensions in this document.

   The STAMP extensions defined in this document may be used for
   potential "proxying" attacks.  For example, a Session-Sender may
   specify a return path that has a destination different from that of
   the Session-Sender.  But normally, such attacks will not happen in an
   SR domain where the Session-Senders and Session-Reflectors belong to
   the same domain.  In order to prevent using the extension defined in
   this document for proxying any possible attacks, the return path has
   destination to the same node where the forward path is from.  The
   Session-Reflector may drop the Session-Sender test packet when it
   cannot determine whether the Return Path has the destination to the



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   Session-Sender.  That means, when sending reply test packet, the
   Session-Sender should choose a proper source address according the
   specified Return Path to help the Session-Reflector to make the
   decision.

6.  IANA Considerations

   IANA has created the "STAMP TLV Types" registry for [RFC8972].  IANA
   is requested to allocate a value for the Destination Address TLV Type
   and a value for the Return Path TLV Type from the IETF Review TLV
   range of the same registry.

         +=======+==============================+===============+
         | Value |         Description          | Reference     |
         +=======+==============================+===============+
         | TBA1  | Destination Node Address TLV | This document |
         +-------+------------------------------+---------------+
         | TBA2  |       Return Path TLV        | This document |
         +-------+------------------------------+---------------+

                         Table 1: STAMP TLV Types

   IANA is requested to create a sub-registry for "Return Path Sub-TLV
   Type".  All code points in the range 1 through 175 in this registry
   shall be allocated according to the "IETF Review" procedure as
   specified in [RFC8126].  Code points in the range 176 through 239 in
   this registry shall be allocated according to the "First Come First
   Served" procedure as specified in [RFC8126].  Remaining code points
   are allocated according to Table 2:

               +===========+==============+===============+
               | Value     | Description  | Reference     |
               +===========+==============+===============+
               | 0         |   Reserved   | This document |
               +-----------+--------------+---------------+
               | 1 - 175   |  Unassigned  | This document |
               +-----------+--------------+---------------+
               | 176 - 239 |  Unassigned  | This document |
               +-----------+--------------+---------------+
               | 240 - 251 | Experimental | This document |
               +-----------+--------------+---------------+
               | 252 - 254 | Private Use  | This document |
               +-----------+--------------+---------------+
               | 255       |   Reserved   | This document |
               +-----------+--------------+---------------+

                Table 2: Return Path Sub-TLV Type Registry




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   IANA is requested to allocate the values for the following Sub-TLV
   Types from this registry.

   *  Type (value 1): Return Path Control Code

   *  Type (value 2): Return Address

   *  Type (value 3): SR-MPLS Label Stack of the Return Path

   *  Type (value 4): SRv6 Segment List of the Return Path

   IANA has created the "STAMP TLV Flags" subregistry.  IANA is
   requested to allocate the following bit position in the "STAMP TLV
   Flags" subregistry.

       +==============+========+===================+===============+
       | Bit Position | Symbol |    Description    | Reference     |
       +==============+========+===================+===============+
       | TBA3         |   D    | Wrong Destination | This document |
       +--------------+--------+-------------------+---------------+

                          Table 3: STAMP TLV Flags

7.  References

7.1.  Normative References

   [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>.

   [RFC8762]  Mirsky, G., Jun, G., Nydell, H., and R. Foote, "Simple
              Two-Way Active Measurement Protocol", RFC 8762,
              DOI 10.17487/RFC8762, March 2020,
              <https://www.rfc-editor.org/info/rfc8762>.

   [RFC8972]  Mirsky, G., Min, X., Nydell, H., Foote, R., Masputra, A.,
              and E. Ruffini, "Simple Two-Way Active Measurement
              Protocol Optional Extensions", RFC 8972,
              DOI 10.17487/RFC8972, January 2021,
              <https://www.rfc-editor.org/info/rfc8972>.

7.2.  Informative References



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   [RFC8402]  Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
              Decraene, B., Litkowski, S., and R. Shakir, "Segment
              Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
              July 2018, <https://www.rfc-editor.org/info/rfc8402>.

   [RFC8126]  Cotton, M., Leiba, B., and T. Narten, "Guidelines for
              Writing an IANA Considerations Section in RFCs", BCP 26,
              RFC 8126, DOI 10.17487/RFC8126, June 2017,
              <https://www.rfc-editor.org/info/rfc8126>.

   [RFC8545]  Morton, A., Ed. and G. Mirsky, Ed., "Well-Known Port
              Assignments for the One-Way Active Measurement Protocol
              (OWAMP) and the Two-Way Active Measurement Protocol
              (TWAMP)", RFC 8545, DOI 10.17487/RFC8545, March 2019,
              <https://www.rfc-editor.org/info/rfc8545>.

   [RFC8799]  Carpenter, B. and B. Liu, "Limited Domains and Internet
              Protocols", RFC 8799, DOI 10.17487/RFC8799, July 2020,
              <https://www.rfc-editor.org/info/rfc8799>.

   [I-D.ietf-spring-segment-routing-policy]
              Filsfils, C., Talaulikar, K., Voyer, D., Bogdanov, A., and
              P. Mattes, "Segment Routing Policy Architecture", Work in
              Progress, Internet-Draft, draft-ietf-spring-segment-
              routing-policy-13, 28 May 2021,
              <https://www.ietf.org/archive/id/draft-ietf-spring-
              segment-routing-policy-13.txt>.

   [I-D.ietf-pce-binding-label-sid]
              Sivabalan, S., Filsfils, C., Tantsura, J., Previdi, S.,
              and C. Li, "Carrying Binding Label/Segment Identifier in
              PCE-based Networks.", Work in Progress, Internet-Draft,
              draft-ietf-pce-binding-label-sid-08, 14 April 2021,
              <https://www.ietf.org/archive/id/draft-ietf-pce-binding-
              label-sid-08.txt>.

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Internet-Draft  Simple TWAMP Extensions for Segment Rout       July 2021


Acknowledgments

   The authors would like to thank Thierry Couture for the discussions
   on the use-cases for Performance Measurement in Segment Routing.  The
   authors would also like to thank Greg Mirsky, Mike Koldychev, Gyan
   Mishra, Tianran Zhou, Al Mortons, Reshad Rahman, Zhenqiang Li, Frank
   Brockners, and Cheng Li for providing comments and suggestions.

Authors' Addresses

   Rakesh Gandhi (editor)
   Cisco Systems, Inc.
   Canada

   Email: rgandhi@cisco.com


   Clarence Filsfils
   Cisco Systems, Inc.

   Email: cfilsfil@cisco.com


   Daniel Voyer
   Bell Canada

   Email: daniel.voyer@bell.ca


   Mach(Guoyi) Chen
   Huawei

   Email: mach.chen@huawei.com


   Bart Janssens
   Colt

   Email: Bart.Janssens@colt.net


   Richard Foote
   Nokia

   Email: footer.foote@nokia.com






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