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Versions: (draft-ali-spring-srv6-pm) 00 01 02 draft-gandhi-spring-rfc6374-srpm-udp

SPRING Working Group                                      R. Gandhi, Ed.
Internet-Draft                                               C. Filsfils
Intended Status: Standards Track                                 S. Soni
                                                              P. Khordoc
                                                                  Z. Ali
                                                     Cisco Systems, Inc.
                                                                D. Voyer
                                                              D. Bernier
                                                             Bell Canada
                                                              S. Salsano
                                        Universita di Roma "Tor Vergata"
                                                            P. L. Ventre
                                                                    CNIT
                                                            D. Steinberg
                                                    Steinberg Consulting
                                                          March 19, 2018

              UDP Path for In-band Performance Measurement for
                          Segment Routing Networks
                     draft-gandhi-spring-udp-pm-00.txt

Abstract

   Segment Routing (SR) is applicable to both MPLS (SR-MPLS) and IPv6
   (SRv6) data planes.  This document specifies a procedure for using
   UDP path for sending and processing in-band Performance Measurement
   (PM) Probe query and response messages.  The procedure uses RFC 6374
   defined mechanisms for Delay and Loss performance measurement.  The
   procedure defined is applicable to IPv4, IPv6, SR-MPLS and SRv6 data
   planes.  This document also defines Return Path Segment List TLV for
   bidirectional performance measurement.


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 http://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."




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Copyright Notice

   Copyright (c) 2018 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
   (http://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 . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Conventions Used in This Document  . . . . . . . . . . . . . .  4
     2.1.  Requirements Language  . . . . . . . . . . . . . . . . . .  4
     2.2.  Abbreviations  . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Probe Messages . . . . . . . . . . . . . . . . . . . . . . . .  4
     3.1.  Probe Query Message  . . . . . . . . . . . . . . . . . . .  5
       3.1.1.  Delay Measurement Query Message  . . . . . . . . . . .  5
       3.1.2.  Loss Measurement Query Message . . . . . . . . . . . .  5
       3.1.3.  Probe Query Message for SR Links . . . . . . . . . . .  6
       3.1.4.  In-band Probe Query Message for SR Policy  . . . . . .  6
         3.1.4.1.  In-band Probe Query Message for SR-MPLS Policy . .  6
         3.1.4.2.  In-band Probe Query Message for SRv6 Policy  . . .  7
         3.1.4.3.  In-band Probe Query Message for Segment of SRv6
                   Policy . . . . . . . . . . . . . . . . . . . . . .  7
     3.2.  Probe Response Message . . . . . . . . . . . . . . . . . .  8
       3.2.1.  Probe Response Message for SR Links  . . . . . . . . .  8
       3.2.2.  One-way Performance Measurement  . . . . . . . . . . .  8
         3.2.2.1.  Probe Response Message to Controller . . . . . . .  9
     3.3.  Two-way Performance Measurement  . . . . . . . . . . . . .  9
       3.3.1.  Return Path Segment List TLV . . . . . . . . . . . . .  9
       3.3.2.  In-band Probe Response Message for SR-MPLS Policy  . . 10
       3.3.3.  In-band Probe Response Message for SRv6 Policy . . . . 10
     3.4.  ECMP Support . . . . . . . . . . . . . . . . . . . . . . . 11
   4.  Security Considerations  . . . . . . . . . . . . . . . . . . . 11
   5.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 11
   6.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
     6.1.  Normative References . . . . . . . . . . . . . . . . . . . 12
     6.2.  Informative References . . . . . . . . . . . . . . . . . . 12
   Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . . . 14
   Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14



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1.  Introduction

   Segment Routing (SR) technology greatly simplifies network operations
   for Software Defined Networks (SDNs).  SR is applicable to both
   Multiprotocol Label Switching (SR-MPLS) and IPv6 (SRv6) data planes.
   SR takes advantage of the Equal-Cost Multipath (ECMP) between source
   and destination nodes.  SR Traffic Engineering (TE) Policies as
   defined in [I-D.spring-segment-routing-policy] are used to steer
   traffic through a specific, user-defined path using a stack of
   Segments.  Built-in SR Performance Measurement (PM) is one of the
   essential requirements to provide Service Level Agreements (SLAs).

   [RFC6374] specifies protocol mechanisms to enable the efficient and
   accurate measurement of performance metrics in SR networks with MPLS
   data plane [I-D.spring-sr-mpls-pm].  However, [RFC6374] requires data
   plane to support Generic Associated Channel Label (GAL) and Generic
   Associated Channel (G-Ach), which may be not be supported on all
   nodes in the network.

   The One-Way Active Measurement Protocol (OWAMP) defined in [RFC4656]
   and Two-Way Active Measurement Protocol (TWAMP) defined in [RFC5357]
   provide capabilities for the measurement of various performance
   metrics in IP networks.  These protocols rely on control channel
   signaling to establish a connection over an UDP path to bootstrap PM
   sessions, and they are not compatible with the mechanisms defined in
   [RFC6374].  Furthermore, these protocols do not define handling for
   ECMP forwarding paths in SR networks (e.g. using 128/7 addresses
   defined in [RFC8029]).

   [RFC7876] specifies the procedures to be used when sending and
   processing out-of-band performance measurement Responses over an UDP
   return path and when receiving performance measurement queries using
   RFC 6374.  [RFC7876] can be used to send out-of-band PM Responses in
   both SR-MPLS and SRv6 networks.

   For SR Policies, there is a need to specify a return path in the form
   of a Segment List in PM query messages for bidirectional
   measurements.  Exiting protocols (e.g. TWAMP, RFC 6374, etc.) do not
   have such mechanisms to specify return path in the PM query messages.

   This document specifies a procedure for using UDP path for sending
   and processing in-band PM Probe query and response messages.  The
   procedure uses RFC 6374 defined mechanisms for Delay and Loss PM and
   unless otherwise specified, the procedures from RFC 6374 are not
   modified.  The procedure defined is applicable to IPv4, IPv6, SR-MPLS
   and SRv6 data planes.  The procedure does not require to bootstrap PM
   sessions and can be used for both SR links and SR Policies.  This
   document also defines Return Path Segment List TLV for bidirectional



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   performance measurement.


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].

2.2.  Abbreviations

   ACH: Associated Channel Header.

   DFLag: Data Format Flag.

   DM: Delay Measurement.

   G-ACh: Generic Associated Channel (G-ACh).

   GAL: Generic Associated Channel (G-ACh) Label.

   LM: Loss Measurement.

   MPLS: Multiprotocol Label Switching.

   PM: Performance Measurement.

   PTP: Precision Time Protocol.

   RPSL: Return Path Segment List.

   SID: Segment ID.

   SR: Segment Routing.

   SRv6: Segment Routing with IPv6 data plane.

   URO: UDP Return Object.


3.  Probe Messages

   In the reference topology shown in the following Figure, node R1
   initiates a query for performance measurement and node R5 sends a
   response for the query message received.  The response may be sent to
   the querier node R1 or to a controller node R100.  The nodes R1 and



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   R5 may be directly connected via a link enabled with segment routing
   or there exists an SR Policy [I-D.spring-segment-routing-policy] on
   node R1 with destination to node R5.  Both delay and loss performance
   measurement is performed for the traffic traversing between node R1
   and node R5.

                                           ------
                                           |R100|
                                           ------
                                              ^
                                              | Response (optional)
                                              |
           +-------+        Query        +-------+
           |       | - - - - - - - - - ->|       |
           |   R1  |---------------------|   R5  |
           |       |<- - - - - - - - - - |       |
           +-------+       Response      +-------+

                      Reference Topology

3.1.  Probe Query Message

3.1.1.  Delay Measurement Query Message

   The message content for Delay Measurement probe query message using
   UDP header [RFC768] is shown in Figure 1.

    +---------------------------------------------------------------+
    | IP Header                                                     |
    .   Source IP Address = Sender IP4 or IPv6 Address              .
    .   Destination IP Address = Responder IPv4 or IPv6 Address     .
    .   Protocol = UDP                                              .
    .   IP TTL = 1                                                  .
    .   Router Alert Option Not Set                                 .
    .                                                               .
    +---------------------------------------------------------------+
    | UDP Header                                                    |
    .   Source Port = As chosen by Sender                           .
    .   Destination Port = TBA1 by IANA                             .
    .                                                               .
    +---------------------------------------------------------------+
    | Message as specified in RFC 6374 Section 3.2                  |
    .                                                               .
    +---------------------------------------------------------------+

                  Figure 1: DM Probe Query Message

3.1.2.  Loss Measurement Query Message



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   The message content for loss measurement probe query message using
   UDP header is shown in Figure 2.

    +---------------------------------------------------------------+
    | IP Header                                                     |
    .   Source IP Address = Sender IPv4 or IPv6 Address             .
    .   Destination IP Address = Responder IPv4 or IPv6 Address     .
    .   Protocol = UDP                                              .
    .   IP TTL = 1                                                  .
    .   Router Alert Option Not Set                                 .
    .                                                               .
    +---------------------------------------------------------------+
    | UDP Header                                                    |
    .   Source Port = As chosen by Sender                           .
    .   Destination Port = TBA2 by IANA                             .
    .                                                               .
    +---------------------------------------------------------------+
    | Message as specified in RFC 6374 Section 3.1                  |
    .                                                               .
    +---------------------------------------------------------------+

                  Figure 2: LM Probe Query Message

   An LM message carries Data Format Flags (DFlags) as defined in
   [RFC6374].  New Flag is defined in this document for Color (C) in the
   DFlags field as follows.

                              +-+-+-+-+
                              |X|B|C|0|
                              +-+-+-+-+

                          Data Format Flags

   The Flag C indicates the Color of the counters in the LM message
   [RFC8321].

3.1.3.  Probe Query Message for SR Links

   The query message defined in Figure 1 can be used for delay
   measurement and Figure 2 for loss measurement for SR links.

3.1.4.  In-band Probe Query Message for SR Policy

3.1.4.1.  In-band Probe Query Message for SR-MPLS Policy

   The message content for in-band probe query message using UDP header
   for an SR-MPLS Policy is shown in Figure 3.




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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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                Segment List[0]        | EXP |S|      TTL      |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    .                                                               .
    .                                                               .
    .                                                               .
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                Segment List[n]        | EXP |S|      TTL      |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    | Message as shown in Figure 1 for DM or Figure 2 for LM        |
    .                                                               .
    +---------------------------------------------------------------+

         Figure 3: In-band Probe Query Message for SR-MPLS Policy

   The Segment List can be empty to indicate Implicit NULL case.

3.1.4.2.  In-band Probe Query Message for SRv6 Policy

   The in-band probe query messages using UDP message for an SRv6 Policy
   is sent using SRH and Segment List as defined in
   [I-D.6man-segment-routing-header] as shown in Figure 4.

    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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    | SRH                                                           |
    .                                                               .
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    | Message as shown in Figure 1 for DM or Figure 2 for LM        |
    .                                                               .
    +---------------------------------------------------------------+

         Figure 4: In-band Probe Query Message for SRv6 Policy

3.1.4.3.  In-band Probe Query Message for Segment of SRv6 Policy

   In order to measure performance of a segment of an SRv6 Policy, i.e.
   from the ingress node of the SRv6 Policy to one of the transit nodes
   of the SRv6 Policy, SID function END.OTP, as described in the pseudo
   code in [I-D.spring-srv6-network-programming] can be used.
   Specifically, SID function END.OTP is inserted just before the target
   SID in the SRH to punt probe messages on the target node, as shown in
   Figure 5.

    0                   1                   2                   3



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    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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    | SRH                                                           |
    . END.OTP Before Target SID                                     .
    .                                                               .
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    | Message as shown in Figure 1 for DM or Figure 2 for LM        |
    .                                                               .
    +---------------------------------------------------------------+

     Figure 5: In-band Probe Query Message for Segment of SRv6 Policy

3.2.  Probe Response Message

   The message format for probe response message using UDP header is
   shown in Figure 6.

    +---------------------------------------------------------------+
    | IP Header                                                     |
    .   Source IP Address = Responder IPv4 or IPv6 Address          .
    .   Destination IP Address = Source IP Address from Query       .
    .   Protocol = UDP                                              .
    .   Router Alert Option Not Set                                 .
    .                                                               .
    +---------------------------------------------------------------+
    | UDP Header                                                    |
    .   Source Port = As chosen by Responder                        .
    .   Destination Port = Source Port from Query                   .
    .                                                               .
    +---------------------------------------------------------------+
    | Message as specified in RFC 6374 Section 3.2 for DM, or       |
    . Message as specified in RFC 6374 Section 3.1 for LM           .
    .                                                               .
    +---------------------------------------------------------------+

                    Figure 6: Probe Response Message

3.2.1.  Probe Response Message for SR Links

   The response message defined in Figure 6 can be used for SR links.

3.2.2.  One-way Performance Measurement

   The PM response message defined in Section 3.2 can be used for one-
   way delay and loss measurement.

   Note that for one-way delay measurement, Clock synchronization
   between the querier and responder nodes using methods detailed in



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   [RFC6374] such as IEEE 1588 Precision Time Protocol (PTP) [IEEE1588],
   is required.  Two-way delay measurement does not require clock to be
   synchronized between the querier and responder nodes.

3.2.2.1.  Probe Response Message to Controller

   The PM querier node can receive out-of-band probe responses by
   properly setting the UDP Return Object (URO) TLV in the probe
   message.  The URO TLV (Type 131) is defined in [RFC7876] and includes
   the UDP-Destination-Port and IP Address.  If the querier node
   requires the probe response to be sent to the controller, it sets the
   IP address of the controller in the Address field of the URO TLV of
   the PM probe query message.

3.3.  Two-way Performance Measurement

   For two-way performance measurement [RFC6374], when using a
   bidirectional channel, the probe response message is sent back to the
   querier node using a message similar to the probe query message.  In
   this case, the "control code" in the probe message is set to "in-band
   response requested".

3.3.1.  Return Path Segment List TLV

   For bidirectional measurement, the responder node needs to send the
   response message on a specific reverse SR path.  The querier node can
   request in the probe query message to the responder node to send a
   response back on a given reverse path (e.g. co-routed path).

   [RFC6374] defines DM and LM Probe query messages that include one or
   more optional TLVs.  New TLV Types are defined in this document for
   Return Path Segment List (RPSL).  The format of the RPSL is shown in
   Figure 9:

    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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    | RPSL Type     |  Length         |    Reserved                 |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                     Segment List[0]                           |
    .                                                               .
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    .                                                               .
    .                                                               .
    .                                                               .
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                     Segment List[n]                           |
    .                                                               .



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    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                 Figure 9: Return Path Segment List TLV

   The Segment in Segment List may be SR-MPLS Label (Type TBA3), SRv6
   Segment (Type TBA4), SR-MPLS Binding SID of the Reverse SR Policy
   (Type TBA5) or SRv6 Binding SID of the Reverse SR Policy (Type TBA6).
    The Segment List[0] may be used by the responder node to compute the
   next-hop address and outgoing interface for the probe response
   message.

   The PM querier MUST only insert one RPSL TLV in the probe query
   message and the responder node MUST only process the first RPSL TLV
   in the probe query message and ignore the other RPSL TLVs if present.

3.3.2.  In-band Probe Response Message for SR-MPLS Policy

   The message format for in-band probe response message using UDP
   header for an SR-MPLS Policy is shown in Figure 7.  The SR-MPLS label
   stack in the packet header is built using the segments received in
   the RPSL TLV in the probe query message.

    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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                Segment List[0]        | EXP |S|      TTL      |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    .                                                               .
    .                                                               .
    .                                                               .
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                Segment List[n]        | EXP |S|      TTL      |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    | Message as shown in Figure 6                                  |
    . IP TTL = 1                                                    .
    .                                                               .
    +---------------------------------------------------------------+

       Figure 7: In-band Probe Response Message for SR-MPLS Policy

3.3.3.  In-band Probe Response Message for SRv6 Policy

   For SRv6 Policy, the SRv6 segment list in the message SRH is built
   using the SRv6 segments received in the RPSL TLV in the probe query
   message as shown in Figure 8.

    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



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    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    | SRH                                                           |
    .                                                               .
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    | Message as shown in Figure 6                                  |
    . IP TTL = 1                                                    .
    .                                                               .
    +---------------------------------------------------------------+

         Figure 8: In-band Probe Response Message for SRv6 Policy

3.4.  ECMP Support

   Equal-Cost Multipath (ECMP) mechanisms described in [RFC8029] are
   equally applicable to the performance measurement procedure defined
   in this document.

   Responder IPv4 addresses in the range of 127/8 [RFC8029] can be used
   in PM probe query messages to take advantage of the hashing function
   in the forwarding plane.  This allows the PM query messages to
   traverse different ECMP forwarding paths of an SR-MPLS Policy.  This
   is used by the querier node to measure the performance of an
   individual ECMP forwarding path of the SR Policy.  Optionally, the
   querier node may use different source-address and source-port to
   influence the ECMP forwarding path taken by the PM query message.

   Entropy label can also be used to take advantage of the hashing
   function in the forwarding plane to measure performance of various
   ECMP forwarding paths of an SR-MPLS Policy.

   ECMP for SRv6 Policies to be added in a future revision of this
   document.

4.  Security Considerations

   TBA.

5.  IANA Considerations

   IANA is requested to allocate an UDP port (TBA1) for Performance
   Delay Measurement and an UDP port (TBA2) for Performance Loss
   Measurement.

   IANA is also requested to allocate values for the following Return
   Path Segment List TLVs for RFC 6374 PM Query messages:

     o  TYPE TBA3: SR-MPLS Segment List




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     o  TYPE TBA4: SRv6 Segment List

     o  TYPE TBA5: SR-MPLS Binding SID of the Reverse SR Policy

     o  TYPE TBA6: SRv6 Binding SID of the Reverse SR Policy


6.  References

6.1.  Normative References

   [IEEE1588] IEEE, "1588-2008 IEEE Standard for a Precision Clock
              Synchronization Protocol for Networked Measurement and
              Control Systems", March 2008.

   [RFC768]   Postel, J., "User Datagram Protocol", STD 6, RFC 768,
              August 1980.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", RFC 2119, March 1997.

   [RFC6374]  Frost, D. and S. Bryant, "Packet Loss and Delay
              Measurement for MPLS networks', RFC 6374, September 2011.

   [RFC7876]  Bryant, S., Sivabalan, S., and Soni, S., "UDP Return Path
              for Packet Loss and Delay Measurement for MPLS Networks",
              RFC 7876, July 2016.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", RFC 8174, May 2017.

6.2.  Informative References

   [RFC4656]  Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M.
              Zekauskas, "A One-way Active Measurement Protoco (OWAMP)",
              RFC 4656, September 2006.

   [RFC5357]  Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J.
              Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)",
              RFC 5357, October 2008.

   [RFC8029]  Kompella, K., Swallow, G., Pignataro, C., Kumar, N.,
              Aldrin, S. and M. Chen, "Detecting Multiprotocol Label
              Switched (MPLS) Data-Plane Failures", RFC 8029, March
              2017.

   [RFC8321]  Fioccola, G. Ed., "Alternate-Marking Method for Passive
              and Hybrid Performance Monitoring", RFC 8321, January



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              2018.

   [I-D.spring-segment-routing-policy]  Filsfils, C., et al., "Segment
              Routing Policy for Traffic Engineering",
              draft-filsfils-spring-segment-routing-policy, work in
              progress.

   [I-D.6man-segment-routing-header]  Previdi, S., Filsfils, et al.,
              "IPv6 Segment Routing Header (SRH)",
              draft-ietf-6man-segment-routing-header, work in progress.

   [I-D.spring-srv6-network-programming]  C. Filsfils, et al., "SRv6
              Network Programming",
              draft-filsfils-spring-srv6-network-programming, work in
              progress.

   [I-D.spring-sr-mpls-pm]  Filsfils, C., et al. "Performance
              Measurement in Segment Routing Networks with MPLS Data
              Plane", draft-gandhi-spring-sr-mpls-pm, work in progress.
































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Acknowledgments

   The authors would like to thank Faisal Iqbal, Nagendra Kumar and
   Carlos Pignataro for the earlier discussions on SRv6 Performance
   Measurement using TLVs in SRH.


Contributors

   To be added.


Authors' Addresses

   Rakesh Gandhi (editor)
   Cisco Systems, Inc.
   Canada
   Email: rgandhi@cisco.com


   Clarence Filsfils
   Cisco Systems, Inc.
   Email: cfilsfil@cisco.com


   Sagar Soni
   Cisco Systems, Inc.
   Email: sagsoni@cisco.com


   Patrick Khordoc
   Cisco Systems, Inc.
   Email: pkhordoc@cisco.com


   Zafar Ali
   Cisco Systems, Inc.
   Email: zali@cisco.com


   Daniel Voyer
   Bell Canada
   Email: daniel.voyer@bell.ca


   Daniel Bernier
   Bell Canada
   Email: daniel.bernier@bell.ca



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   Stefano Salsano
   Universita di Roma "Tor Vergata"
   Italy
   Email: stefano.salsano@uniroma2.it


   Pier Luigi Ventre
   CNIT
   Italy
   Email: pierluigi.ventre@cnit.it


   Dirk Steinberg
   Steinberg Consulting
   Germany
   Email: dws@dirksteinberg.de



































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