[Docs] [txt|pdf] [Tracker] [Email] [Nits]

Versions: 00

SPRING Working Group                                      R. Gandhi, Ed.
Internet-Draft                                               C. Filsfils
Intended Status: Standards Track                     Cisco Systems, Inc.
Expires: August 13, 2019                                        D. Voyer
                                                             Bell Canada
                                                        February 9, 2019


               In-band Performance Measurement Using TWAMP
                       for Segment Routing Networks
                    draft-gandhi-spring-twamp-srpm-00

Abstract

   Segment Routing (SR) is applicable to both Multiprotocol Label
   Switching (SR-MPLS) and IPv6 (SRv6) data planes.  This document
   specifies procedures for sending and processing in-band probe query
   and response messages for Performance Measurement.  The procedure
   uses the mechanisms defined in RFC 5357 (Two-Way Active Measurement
   Protocol (TWAMP)) for Delay Measurement, and also uses the mechanisms
   for direct-mode loss measurement defined in this document.  The
   procedure specified is applicable to SR-MPLS and SRv6 data planes for
   both links and end-to-end measurement for SR Policies.


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."


Copyright Notice

   Copyright (c) 2019 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



Gandhi, et al.          Expires August 13, 2019                 [Page 1]


Internet-Draft         TWAMP for Segment Routing        February 9, 2019


   (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 . . . . . . . . . . . . . . . . . . . . . . . . .  2
   2.  Conventions Used in This Document  . . . . . . . . . . . . . .  3
     2.1.  Requirements Language  . . . . . . . . . . . . . . . . . .  3
     2.2.  Abbreviations  . . . . . . . . . . . . . . . . . . . . . .  3
     2.3.  Reference Topology . . . . . . . . . . . . . . . . . . . .  4
     2.4.  In-band Probe Messages . . . . . . . . . . . . . . . . . .  5
   3.  Probe Messages . . . . . . . . . . . . . . . . . . . . . . . .  5
     3.1.  Probe Query Message  . . . . . . . . . . . . . . . . . . .  5
       3.1.1.  Delay Measurement Probe Query Message  . . . . . . . .  5
       3.1.2.  Loss Measurement Probe Query Message . . . . . . . . .  6
       3.1.3.  Probe Query for SR Links . . . . . . . . . . . . . . . 10
       3.1.4.  Probe Query for End-to-end Measurement for SR Policy . 11
         3.1.4.1.  Probe Query Message for SR-MPLS Policy . . . . . . 11
         3.1.4.2.  Probe Query Message for SRv6 Policy  . . . . . . . 11
     3.2.  Probe Response Message . . . . . . . . . . . . . . . . . . 12
       3.2.1.  One-way Measurement  . . . . . . . . . . . . . . . . . 12
       3.2.2.  Two-way Measurement  . . . . . . . . . . . . . . . . . 12
         3.2.2.1.  Probe Response Message for SR-MPLS Policy  . . . . 13
         3.2.2.2.  Probe Response Message for SRv6 Policy . . . . . . 13
   4.  Packet Loss Calculation  . . . . . . . . . . . . . . . . . . . 13
   5.  Performance Measurement for P2MP SR Policies . . . . . . . . . 14
   6.  ECMP Support . . . . . . . . . . . . . . . . . . . . . . . . . 14
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 14
   8.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 15
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 15
     9.1.  Normative References . . . . . . . . . . . . . . . . . . . 15
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 15
   Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . . . 18
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18



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.



Gandhi, et al.          Expires August 13, 2019                 [Page 2]


Internet-Draft         TWAMP for Segment Routing        February 9, 2019


   SR takes advantage of the Equal-Cost Multipaths (ECMPs) between
   source, transit and destination nodes.  SR 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).

   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 test channel over an UDP path.  These
   protocols lack support for direct-mode Loss Measurement (LM) to
   detect actual data traffic loss which is required in SR networks.
   The Simple Two-way Active Measurement Protocol (STAMP)
   [I-D.ippm-stamp] alleviates the control channel signaling by using
   configuration data model to provision test channels and required UDP
   ports.  The TWAMP Light from broadband forum [BBF.TR-390] provides
   simplified mechanisms for active performance measurement in Customer
   Edge IP networks.

   This document specifies procedures for sending and processing in-band
   probe query and response messages for Performance Measurement.  The
   procedure uses the mechanisms defined in RFC 5357 (Two-Way Active
   Measurement Protocol (TWAMP)) for Delay Measurement, and also uses
   the mechanisms for direct-mode loss measurement defined in this
   document.  The procedure specified is applicable to SR-MPLS and SRv6
   data planes for both links and end-to-end measurement for SR
   Policies.  For SR Policies, there are ECMPs between the source and
   transit nodes, between transit nodes and between transit and
   destination nodes.  This document also defines mechanisms for
   handling ECMPs of SR Policies for performance delay 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]
   when, and only when, they appear in all capitals, as shown here.

2.2.  Abbreviations

   BSID: Binding Segment ID.

   DM: Delay Measurement.



Gandhi, et al.          Expires August 13, 2019                 [Page 3]


Internet-Draft         TWAMP for Segment Routing        February 9, 2019


   ECMP: Equal Cost Multi-Path.

   LM: Loss Measurement.

   MPLS: Multiprotocol Label Switching.

   NTP: Network Time Protocol.

   OWAMP: One-Way Active Measurement Protocol.

   PM: Performance Measurement.

   PSID: Path Segment Identifier.

   PTP: Precision Time Protocol.

   SID: Segment ID.

   SL: Segment List.

   SR: Segment Routing.

   SR-MPLS: Segment Routing with MPLS data plane.

   SRv6: Segment Routing with IPv6 data plane.

   STAMP: Simple Two-way Active Measurement Protocol.

   TC: Traffic Class.

   TWAMP: Two-Way Active Measurement Protocol.


2.3.  Reference Topology

   In the reference topology, the querier node R1 initiates a probe
   query for performance measurement and the responder node R5 sends a
   probe response for the query message received.  The probe response
   may be sent to the querier node R1.  The nodes R1 and R5 may be
   directly connected via a link enabled with Segment Routing or there
   exists a Point-to-Point (P2P) SR Policy
   [I-D.spring-segment-routing-policy] on node R1 with destination to
   node R5.  In case of Point-to-Multipoint (P2MP), SR Policy
   originating from source node R1 may terminate on multiple destination
   leaf nodes [I-D.spring-sr-p2mp-policy].






Gandhi, et al.          Expires August 13, 2019                 [Page 4]


Internet-Draft         TWAMP for Segment Routing        February 9, 2019


             +-------+        Query        +-------+
             |       | - - - - - - - - - ->|       |
             |   R1  |---------------------|   R5  |
             |       |<- - - - - - - - - - |       |
             +-------+       Response      +-------+

                        Reference Topology

   Both Delay and Loss performance measurement is performed in-band for
   the traffic traversing between node R1 and node R5.  One-way delay
   and two-way delay measurements are defined in [RFC4656] and
   [RFC5357], respectively.  One-way loss measurement provides receive
   packet loss whereas two-way loss measurement provides both transmit
   and receive packet loss.

2.4.  In-band Probe Messages

   For both Delay and Loss measurements for links and SR Policies, no PM
   session is created on the responder node.  The probe messages for
   Delay measurement are sent in-band by the querier node to measure the
   delay experienced by the actual traffic flowing on the links and SR
   Policies.  For Loss measurement, in-band probe messages are used to
   collect the traffic counter for the incoming link or incoming SID on
   which the probe query message is received at the responder node R5 as
   it has no PM session state present on the node.  The performance
   measurement for Delay and Loss using out-of-band probe query messages
   are outside the scope of this document.


3.  Probe Messages

3.1.  Probe Query Message

   In this document, procedures using [RFC5357] is used for Delay and
   Loss measurements for SR links and end-to-end SR Policies.  A
   user-configured UDP port is used for identifying PM probe packets
   that does not require to bootstrap PM sessions.  A UDP port number
   from the Dynamic and/or Private Ports range 49152-65535 is used as
   the destination UDP port.  This approach is similar to the one
   defined in STAMP protocol [I-D.ippm-stamp].  The IPv4 TTL or IPv6 Hop
   Limit field of the IP header MUST be set to 255.

3.1.1.  Delay Measurement Probe Query Message

   The message content for Delay Measurement probe query message using
   UDP header [RFC768] is shown in Figure 1.  The DM probe query message
   is sent with user-configured Destination UDP port number [I-D.ippm-
   stamp].  The Source UDP port is set to the same value for two-way



Gandhi, et al.          Expires August 13, 2019                 [Page 5]


Internet-Draft         TWAMP for Segment Routing        February 9, 2019


   delay measurement.  The DM probe query message contains the payload
   for delay measurement defined in Section 4.2.1 of [RFC5357] for TWAMP
   or in Section 4.1.2 of [RFC4656] for OWAMP.

    +---------------------------------------------------------------+
    | IP Header                                                     |
    .  Source IP Address = Querier IPv4 or IPv6 Address             .
    .  Destination IP Address = Responder IPv4 or IPv6 Address      .
    .  Protocol = UDP                                               .
    .  Router Alert Option Not Set                                  .
    .                                                               .
    +---------------------------------------------------------------+
    | UDP Header                                                    |
    .  Source Port = As chosen by Querier                           .
    .  Destination Port = User-configured Port for Delay Measurement.
    .                                                               .
    +---------------------------------------------------------------+
    | Payload = Message as specified in Section 4.2.1 of RFC 5357   |
    | | Payload = Message as specified in Section 4.1.2 of RFC 4656 |
    .                                                               .
    +---------------------------------------------------------------+

                   Figure 1: DM Probe Query Message

   Timestamp field is eight bytes and by default uses the IEEE 1588v2
   Precision Time Protocol (PTP) truncated 64-bit timestamp format
   [IEEE1588].

3.1.2.  Loss Measurement Probe Query Message

   The message content for Loss Measurement probe query message using
   UDP header [RFC768] is shown in Figure 2.  The LM probe query message
   is sent with user-configured Destination UDP port number [I-D.ippm-
   stamp].  The Source UDP port is set to the same value for two-way
   loss measurement.  The LM probe query message contains the payload
   for loss measurement defined below.


    +---------------------------------------------------------------+
    | IP Header                                                     |
    .  Source IP Address = Querier IPv4 or IPv6 Address             .
    .  Destination IP Address = Responder IPv4 or IPv6 Address      .
    .  Protocol = UDP                                               .
    .  Router Alert Option Not Set                                  .
    .                                                               .
    +---------------------------------------------------------------+
    | UDP Header                                                    |
    .  Source Port = As chosen by Querier                           .



Gandhi, et al.          Expires August 13, 2019                 [Page 6]


Internet-Draft         TWAMP for Segment Routing        February 9, 2019


    .  Destination Port = User-configured Port for Loss Measurement .
    .                                                               .
    +---------------------------------------------------------------+
    |                        Sequence Number                        |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                        Transmit Counter                       |
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                        Receive Counter                        |
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                        Sender Sequence Number                 |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                        Sender Counter                         |
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |  Sender TTL   |              Block Number                     |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                        Padding                                |
    .                                                               .
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

               Figure 2A: LM Probe Query Message for TWAMP


    +---------------------------------------------------------------+
    | IP Header                                                     |
    .  Source IP Address = Querier IPv4 or IPv6 Address             .
    .  Destination IP Address = Responder IPv4 or IPv6 Address      .
    .  Protocol = UDP                                               .
    .  Router Alert Option Not Set                                  .
    .                                                               .
    +---------------------------------------------------------------+
    | UDP Header                                                    |
    .  Source Port = As chosen by Querier                           .
    .  Destination Port = User-configured Port for Loss Measurement .
    .                                                               .
    +---------------------------------------------------------------+
    |                        Sequence Number                        |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                        MBZ (12 octets)                        |
    |                                                               |
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                        Transmit Counter                       |
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                        MBZ (8 octets)                         |



Gandhi, et al.          Expires August 13, 2019                 [Page 7]


Internet-Draft         TWAMP for Segment Routing        February 9, 2019


    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                        Receive Counter                        |
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                        MBZ (8 octets)                         |
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                        Sender Sequence Number                 |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                        MBZ (12 octets)                        |
    |                                                               |
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                        Sender Counter                         |
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                        MBZ (8 octets)                         |
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |  Sender TTL   |              Block Number                     |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                        MBZ (12 octets)                        |
    |                                                               |
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                        HMAC (16 octets)                       |
    |                                                               |
    |                                                               |
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                        Padding                                |
    .                                                               .
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     Figure 2B: LM Probe Query Message for TWAMP - Authenticated Mode


    +---------------------------------------------------------------+
    | IP Header                                                     |
    .  Source IP Address = Querier IPv4 or IPv6 Address             .
    .  Destination IP Address = Responder IPv4 or IPv6 Address      .
    .  Protocol = UDP                                               .
    .  Router Alert Option Not Set                                  .
    .                                                               .
    +---------------------------------------------------------------+
    | UDP Header                                                    |
    .  Source Port = As chosen by Querier                           .



Gandhi, et al.          Expires August 13, 2019                 [Page 8]


Internet-Draft         TWAMP for Segment Routing        February 9, 2019


    .  Destination Port = User-configured Port for Loss Measurement .
    .                                                               .
    +---------------------------------------------------------------+
    |                        Sequence Number                        |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                        Transmit Counter                       |
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |  Sender TTL   |              Block Number                     |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                        Padding                                |
    .                                                               .
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

               Figure 2C: LM Probe Query Message for OWAMP


    +---------------------------------------------------------------+
    | IP Header                                                     |
    .  Source IP Address = Querier IPv4 or IPv6 Address             .
    .  Destination IP Address = Responder IPv4 or IPv6 Address      .
    .  Protocol = UDP                                               .
    .  Router Alert Option Not Set                                  .
    .                                                               .
    +---------------------------------------------------------------+
    | UDP Header                                                    |
    .  Source Port = As chosen by Querier                           .
    .  Destination Port = User-configured Port for Loss Measurement .
    .                                                               .
    +---------------------------------------------------------------+
    |                        Sequence Number                        |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                        MBZ (12 octets)                        |
    |                                                               |
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                        Transmit Counter                       |
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                        MBZ (8 octets)                         |
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |  Sender TTL   |              Block Number                     |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                        MBZ (12 octets)                        |
    |                                                               |
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



Gandhi, et al.          Expires August 13, 2019                 [Page 9]


Internet-Draft         TWAMP for Segment Routing        February 9, 2019


    |                        HMAC (16 octets)                       |
    |                                                               |
    |                                                               |
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                        Padding                                |
    .                                                               .
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     Figure 2D: LM Probe Query Message for OWAMP - Authenticated Mode


   Sequence Number (32-bit): As defined in [RFC5357].

   Transmit Counter (64-bit): The number of packets sent by the querier
   node in the query message and by the responder node in the response
   message.  The counter is always written at fixed location in the
   probe query and response messages.

   Receive Counter (64-bit): The number of packets received at the
   responder node.  It is written by the responder node in the probe
   response message.

   Sender Counter (64-bit): This is the exact copy of the transmit
   counter from the received query message.  It is written by the
   responder node in the probe response message.

   Sender Sequence Number (32-bit): As defined in [RFC5357].

   Sender TTL: As defined in [RFC5357].

   Block Number (24-bit): The Loss Measurement using Alternate-Marking
   method defined in [RFC8321] requires to identify the Block Number (or
   color) of the traffic counters.  The probe query and response
   messages carry Block Number for the traffic counters for loss
   measurement.  In both probe query and response messages, the counters
   MUST belong to the same Block Number.

   The Path Segment Identifier (PSID) [I-D.spring-mpls-path-segment] of
   the SR-MPLS Policy is used for accounting received traffic on the
   egress node for loss measurement.

3.1.3.  Probe Query for SR Links

   The probe query message as defined in Figure 1 is sent in-band for
   Delay measurement.  The probe query message as defined in Figure 2 is
   sent in-band for Loss measurement.




Gandhi, et al.          Expires August 13, 2019                [Page 10]


Internet-Draft         TWAMP for Segment Routing        February 9, 2019


3.1.4.  Probe Query for End-to-end Measurement for SR Policy

3.1.4.1.  Probe Query Message for SR-MPLS Policy

   The message content for in-band probe query message using UDP header
   for end-to-end performance measurement of SR-MPLS Policy is shown in
   Figure 3.

    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)        | TC  |S|      TTL      |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    .                                                               .
    .                                                               .
    .                                                               .
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                Segment List(n)        | TC  |S|      TTL      |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |   Message as shown in Figure 1 for DM or Figure 2 for LM      |
    .                                                               .
    +---------------------------------------------------------------+

             Figure 3: Probe Query Message for SR-MPLS Policy

   The Segment List (SL) can be empty to indicate Implicit NULL label
   case.

3.1.4.2.  Probe Query Message for SRv6 Policy

   The in-band probe query messages using UDP header for end-to-end
   performance measurement of an SRv6 Policy is sent using SRv6 Segment
   Routing Header (SRH) and Segment List of the SRv6 Policy as defined
   in [I-D.6man-segment-routing-header] and is 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                                 |
    .   END.OTP (DM) or END.OP (LM) with Target SRv6 SID            .
    .                                                               .
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |   Message as shown in Figure 1 for DM or Figure 2 for LM      |
    .   (Using IPv6 Addresses)                                      .
    .                                                               .
    +---------------------------------------------------------------+

              Figure 4: Probe Query Message for SRv6 Policy



Gandhi, et al.          Expires August 13, 2019                [Page 11]


Internet-Draft         TWAMP for Segment Routing        February 9, 2019


   For delay measurement of SRv6 Policy, END function END.OTP
   [I-D.spring-srv6-oam] is used with the target SRv6 SID to punt probe
   messages on the target node, as shown in Figure 4.  Similarly, for
   loss measurement of SRv6 Policy, END function END.OP
   [I-D.spring-srv6-oam] is used with target SRv6 SID to punt probe
   messages on the target node.

3.2.  Probe Response Message

   The probe response message is sent using the IP/UDP information from
   the probe query message.  The content of the probe response message
   is shown in Figure 5.

    +---------------------------------------------------------------+
    | 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                    .
    .                                                               .
    +---------------------------------------------------------------+
    | Payload as specified in Section 4.2.1 of RFC 5357, or         |
    . Payload as specified in Figure 2 in this document             .
    .                                                               .
    +---------------------------------------------------------------+

                    Figure 5: Probe Response Message


3.2.1.  One-way Measurement

   For one-way performance measurement, the probe response message as
   defined in Figure 5 is sent for both SR links and SR Policies.

3.2.2.  Two-way Measurement

   For two-way performance measurement, when using a bidirectional
   channel, the probe response message as defined in Figure 5 is sent
   back in-band to the querier node.

   The Path Segment Identifier (PSID) [I-D.spring-mpls-path-segment] of
   the forward SR Policy can be used to find the reverse SR Policy to
   send the probe response message for two-way measurement of SR Policy.



Gandhi, et al.          Expires August 13, 2019                [Page 12]


Internet-Draft         TWAMP for Segment Routing        February 9, 2019


3.2.2.1.  Probe Response Message for SR-MPLS Policy

   The message content for sending probe response message in-band using
   UDP header for two-way end-to-end performance measurement of an
   SR-MPLS Policy is shown in Figure 6.

    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)        | TC  |S|      TTL      |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    .                                                               .
    .                                                               .
    .                                                               .
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                Segment List(n)        | TC  |S|      TTL      |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                Message as shown in Figure 5                   |
    .                                                               .
    +---------------------------------------------------------------+

           Figure 6: Probe Response Message for SR-MPLS Policy

3.2.2.2.  Probe Response Message for SRv6 Policy

   The message content for sending probe response message in-band using
   UDP header for two-way end-to-end performance measurement of an SRv6
   Policy is shown in Figure 7.

    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                                  |
    .   END.OTP (DM) or END.OP (LM) with Target SRv6 SID            .
    .                                                               .
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |   Message as shown in Figure 5 (with IPv6 Addresses)          |
    .                                                               .
    +---------------------------------------------------------------+

            Figure 7: Probe Response Message for SRv6 Policy


4.  Packet Loss Calculation

   The formula for calculating the one-way packet loss using counters
   for a given block number is as following:




Gandhi, et al.          Expires August 13, 2019                [Page 13]


Internet-Draft         TWAMP for Segment Routing        February 9, 2019


   o  One-way Packet_Loss[n-1, n] = (Sender_Counter[n] -
      Sender_Counter[n-1]) - (Receive_Counter[n] - Receive_Counter[n-1])


5.  Performance Measurement for P2MP SR Policies

   The procedures for delay and loss measurement described in this
   document for Point-to-Point (P2P) SR-MPLS Policies are also equally
   applicable to the Point-to-Multipoint (P2MP) SR Policies.


6.  ECMP Support

   An SR Policy can have ECMPs between the source and transit nodes,
   between transit nodes and between transit and destination nodes.
   Usage of Anycast SID [RFC8402] by an SR Policy can result in ECMP
   paths via transit nodes part of that Anycast group.  The PM probe
   messages need to be sent to traverse different ECMP paths to measure
   performance delay of an SR Policy.

   Forwarding plane has various hashing functions available to forward
   packets on specific ECMP paths.  Following mechanisms can be used in
   PM probe messages to take advantage of the hashing function in
   forwarding plane to influence the path taken by them.

   o  The mechanisms described in [RFC8029] [RFC5884] for handling ECMPs
      are also applicable to the performance measurement.  In the IP/UDP
      header of the PM probe messages, Destination Addresses in 127/8
      range for IPv4 or 0:0:0:0:0:FFFF:7F00/104 range for IPv6 can be
      used to exercise a particular ECMP path.  As specified in
      [RFC6437], 3-tuple of Flow Label, Source Address and Destination
      Address fields in the IPv6 header can also be used.

   o  For SR-MPLS, entropy label [RFC6790] in the PM probe messages can
      be used.

   o  For SRv6, Flow Label in SRH [I-D.6man-segment-routing-header] of
      the PM probe messages can be used.


7.  Security Considerations

   The performance measurement is intended for deployment in
   well-managed private and service provider networks.  As such, it
   assumes that a node involved in a measurement operation has
   previously verified the integrity of the path and the identity of the
   far end responder node.




Gandhi, et al.          Expires August 13, 2019                [Page 14]


Internet-Draft         TWAMP for Segment Routing        February 9, 2019


   If desired, attacks can be mitigated by performing basic validation
   and sanity checks, at the querier, of the counter or timestamp fields
   in received measurement response messages.  The minimal state
   associated with these protocols also limits the extent of measurement
   disruption that can be caused by a corrupt or invalid message to a
   single query/response cycle.

   Use of HMAC-SHA-256 in the authenticated mode defined in this
   document protects the data integrity of the probe messages.  SRv6 has
   HMAC protection authentication defined for SRH
   [I-D.6man-segment-routing-header].  Hence, PM probe messages for SRv6
   may not need authentication mode.  Cryptographic measures may be
   enhanced by the correct configuration of access-control lists and
   firewalls.


8.  IANA Considerations

   This document does not require any IANA actions.


9.  References

9.1.  Normative References

   [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.

   [RFC4656]  Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M.
              Zekauskas, "A One-way Active Measurement Protocol
              (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.

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

   [I-D.spring-srv6-oam]  Ali, Z., et al., "Operations, Administration,
              and Maintenance (OAM) in Segment Routing Networks with
              IPv6 Data plane (SRv6)", draft-ali-spring-srv6-oam.

9.2.  Informative References




Gandhi, et al.          Expires August 13, 2019                [Page 15]


Internet-Draft         TWAMP for Segment Routing        February 9, 2019


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

   [RFC5884]  Aggarwal, R., Kompella, K., Nadeau, T., and G. Swallow,
              "Bidirectional Forwarding Detection (BFD) for MPLS Label
              Switched Paths (LSPs)", RFC 5884, DOI 10.17487/RFC5884,
              June 2010.

   [RFC6437]  Amante, S., Carpenter, B., Jiang, S., and J. Rajahalme,
              "IPv6 Flow Label Specification", RFC 6437, November 2011.

   [RFC6790]  Kompella, K., Drake, J., Amante, S., Henderickx, W., and
              L. Yong, "The Use of Entropy Labels in MPLS Forwarding",
              RFC 6790, November 2012.

   [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
              2018.

   [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>.

   [I-D.spring-segment-routing-policy]  Filsfils, C., et al., "Segment
              Routing Policy Architecture",
              draft-ietf-spring-segment-routing-policy, work in
              progress.

   [I-D.spring-sr-p2mp-policy]  Voyer, D. Ed., et al., "SR Replication
              Policy for P2MP Service Delivery",
              draft-voyer-spring-sr-p2mp-policy, work in progress.

   [I-D.spring-mpls-path-segment]  Cheng, W., et al., "Path Segment in
              MPLS Based Segment Routing Network", draft-cheng-spring-
              mpls-path-segment, work in progress.

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

   [I-D.ippm-stamp]  Mirsky, G. et al. "Simple Two-way Active



Gandhi, et al.          Expires August 13, 2019                [Page 16]


Internet-Draft         TWAMP for Segment Routing        February 9, 2019


              Measurement Protocol", draft-ietf-ippm-stamp, work in
              progress.

   [BBF.TR-390]  "Performance Measurement from IP Edge to Customer
              Equipment using TWAMP Light", BBF TR-390, May 2017.














































Gandhi, et al.          Expires August 13, 2019                [Page 17]


Internet-Draft         TWAMP for Segment Routing        February 9, 2019


Acknowledgments

   TBA


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






























Gandhi, et al.          Expires August 13, 2019                [Page 18]


Html markup produced by rfcmarkup 1.129c, available from https://tools.ietf.org/tools/rfcmarkup/