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Versions: (draft-mirsky-ippm-stamp) 00 01 02 03 04 05 06 07 08 09 10

Network Working Group                                          G. Mirsky
Internet-Draft                                                 ZTE Corp.
Intended status: Standards Track                                  G. Jun
Expires: May 3, 2020                                     ZTE Corporation
                                                               H. Nydell
                                                       Accedian Networks
                                                                R. Foote
                                                                   Nokia
                                                        October 31, 2019


               Simple Two-way Active Measurement Protocol
                        draft-ietf-ippm-stamp-10

Abstract

   This document describes a Simple Two-way Active Measurement Protocol
   which enables the measurement of both one-way and round-trip
   performance metrics like delay, delay variation, and packet loss.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on May 3, 2020.

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
   (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



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   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.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
     2.2.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   3.  Operation and Management of Performance Measurement Based on
       STAMP . . . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Theory of Operation . . . . . . . . . . . . . . . . . . . . .   4
     4.1.  UDP Port Numbers in STAMP Testing . . . . . . . . . . . .   5
     4.2.  Session-Sender Behavior and Packet Format . . . . . . . .   5
       4.2.1.  Session-Sender Packet Format in Unauthenticated Mode    5
       4.2.2.  Session-Sender Packet Format in Authenticated Mode  .   7
     4.3.  Session-Reflector Behavior and Packet Format  . . . . . .   8
       4.3.1.  Session-Reflector Packet Format in Unauthenticated
               Mode  . . . . . . . . . . . . . . . . . . . . . . . .   9
       4.3.2.  Session-Reflector Packet Format in Authenticated Mode  10
     4.4.  Integrity Protection in STAMP . . . . . . . . . . . . . .  11
     4.5.  Confidentiality Protection in STAMP . . . . . . . . . . .  12
     4.6.  Interoperability with TWAMP Light . . . . . . . . . . . .  12
   5.  Operational Considerations  . . . . . . . . . . . . . . . . .  13
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  13
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  13
   8.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  14
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  14
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  14
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  15
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  16

1.  Introduction

   Development and deployment of the Two-Way Active Measurement Protocol
   (TWAMP) [RFC5357] and its extensions, e.g., [RFC6038] that defined
   Symmetrical Size for TWAMP, provided invaluable experience.  Several
   independent implementations of both TWAMP and TWAMP Light exist, have
   been deployed, and provide important operational performance
   measurements.

   At the same time, there has been noticeable interest in using a more
   straightforward mechanism for active performance monitoring that can
   provide deterministic behavior and inherent separation of control
   (vendor-specific configuration or orchestration) and test functions.
   Recent work on IP Edge to Customer Equipment using TWAMP Light from
   Broadband Forum [BBF.TR-390] demonstrated that interoperability among



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   implementations of TWAMP Light is difficult because the composition
   and operation of TWAMP Light were not sufficiently specified in
   [RFC5357].  According to [RFC8545], TWAMP Light includes a sub-set of
   TWAMP-Test functions.  Thus, to have a comprehensive tool to measure
   packet loss and delay requires support by other applications that
   provide, for example, control and security.

   This document defines an active performance measurement test
   protocol, Simple Two-way Active Measurement Protocol (STAMP), that
   enables measurement of both one-way and round-trip performance
   metrics like delay, delay variation, and packet loss.  Some TWAMP
   extensions, e.g., [RFC7750] are supported by the extensions to STAMP
   base specification in [I-D.ietf-ippm-stamp-option-tlv].

2.  Conventions used in this document

2.1.  Terminology

   STAMP - Simple Two-way Active Measurement Protocol

   NTP - Network Time Protocol

   PTP - Precision Time Protocol

   HMAC Hashed Message Authentication Code

   OWAMP One-Way Active Measurement Protocol

   TWAMP Two-Way Active Measurement Protocol

   MBZ Must be Zero

2.2.  Requirements Language

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

3.  Operation and Management of Performance Measurement Based on STAMP

   Figure 1 presents the Simple Two-way Active Measurement Protocol
   (STAMP) Session-Sender, and Session-Reflector with a measurement
   session.  In this document, a measurement session also referred to as
   STAMP session, is the bi-directional packet flow between one specific
   Session-Sender and one particular Session-Reflector for a time
   duration.  The configuration and management of the STAMP Session-



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   Sender, Session-Reflector, and management of the STAMP sessions are
   outside the scope of this document and can be achieved through
   various means.  A few examples are:  Command Line Interface,
   telecommunication services' OSS/BSS systems, SNMP, and Netconf/YANG-
   based SDN controllers.


         o----------------------------------------------------------o
         |                      Configuration and                   |
         |                         Management                       |
         o----------------------------------------------------------o
                ||                                          ||
                ||                                          ||
                ||                                          ||
     +----------------------+                +-------------------------+
     | STAMP Session-Sender | <--- STAMP---> | STAMP Session-Reflector |
     +----------------------+                +-------------------------+


                      Figure 1: STAMP Reference Model

4.  Theory of Operation

   STAMP Session-Sender transmits test packets over UDP transport toward
   STAMP Session-Reflector.  STAMP Session-Reflector receives Session-
   Sender's packet and acts according to the configuration.  Two modes
   of STAMP Session-Reflector characterize the expected behavior and,
   consequently, performance metrics that can be measured:

   o  Stateless - STAMP Session-Reflector does not maintain test state
      and will use the value in the Sequence Number field in the
      received packet as the value for the Sequence Number field in the
      reflected packet.  As a result, values in Sequence Number and
      Session-Sender Sequence Number fields are the same, and only
      round-trip packet loss can be calculated while the reflector is
      operating in stateless mode.

   o  Stateful - STAMP Session-Reflector maintains test state thus
      enabling the ability to determine forward loss, gaps recognized in
      the received sequence number.  As a result, both near-end
      (forward) and far-end (backward) packet loss can be computed.
      That implies that the STAMP Session-Reflector MUST keep a state
      for each configured STAMP-test session, uniquely identifying
      STAMP-test packets to one such session instance, and enabling
      adding a sequence number in the test reply that is individually
      incremented on a per-session basis.





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   STAMP supports two authentication modes: unauthenticated and
   authenticated.  Unauthenticated STAMP test packets, defined in
   Section 4.2.1 and Section 4.3.1, ensure interworking between STAMP
   and TWAMP Light as described in Section 4.6 packet formats.

   By default, STAMP uses symmetrical packets, i.e., size of the packet
   transmitted by Session-Reflector equals the size of the packet
   received by the Session-Reflector.

4.1.  UDP Port Numbers in STAMP Testing

   A STAMP Session-Sender MUST use UDP port 862 (TWAMP-Test Receiver
   Port) as the default destination UDP port number.  A STAMP
   implementation of Session-Sender MUST be able to use as the
   destination UDP port numbers from User, a.k.a.  Registered, Ports and
   Dynamic, a.k.a.  Private or Ephemeral, Ports ranges defined in
   [RFC6335].  Before using numbers from the User Ports range, the
   possible impact on the network MUST be carefully studied and agreed
   by all users of the network domain where the test has been planned.

   An implementation of STAMP Session-Reflector by default MUST receive
   STAMP test packets on UDP port 862.  An implementation of Session-
   Reflector that supports this specification MUST be able to define the
   port number to receive STAMP test packets from User Ports and Dynamic
   Ports ranges that are defined in [RFC6335].  STAMP defines two
   different test packet formats, one for packets transmitted by the
   STAMP-Session-Sender and one for packets transmitted by the STAMP-
   Session-Reflector.

4.2.  Session-Sender Behavior and Packet Format

   A STAMP Session-Reflector supports the symmetrical size of test
   packets, as defined in Section 3 [RFC6038], as the default behavior.
   A reflected test packet includes more information and thus is larger.
   Because of that, the base STAMP Session-Sender packet is padded to
   match the size of a reflected STAMP test packet.  Hence, the base
   STAMP Session-Sender packet has a minimum size of 44 octets in
   unauthenticated mode, see Figure 2, and 112 octets in the
   authenticated mode, see Figure 4.  The variable length of a test
   packet in STAMP is supported by using Extra Padding TLV defined in
   [I-D.ietf-ippm-stamp-option-tlv].

4.2.1.  Session-Sender Packet Format in Unauthenticated Mode

   STAMP Session-Sender packet format in unauthenticated mode:






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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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Sequence Number                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                          Timestamp                            |
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Error Estimate        |                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
      |                                                               |
      |                                                               |
      |                      Reserved (30 octets)                     |
      |                                                               |
      |                                                               |
      |                                                               |
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Figure 2: STAMP Session-Sender test packet format in unauthenticated
                                   mode

   where fields are defined as the following:

   o  Sequence Number is four octets long field.  For each new session
      its value starts at zero and is incremented with each transmitted
      packet.

   o  Timestamp is eight octets long field.  STAMP node MUST support
      Network Time Protocol (NTP) version 4 64-bit timestamp format
      [RFC5905], the format used in [RFC5357].  STAMP node MAY support
      IEEE 1588v2 Precision Time Protocol (PTP) truncated 64-bit
      timestamp format [IEEE.1588.2008], the format used in [RFC8186].
      The use of the specific format, NTP or PTP, is part of
      configuration of the Session-Sender or the particular test
      session.

   o  Error Estimate is two octets long field with format displayed in
      Figure 3

            0                   1
            0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
           +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
           |S|Z|   Scale   |   Multiplier  |
           +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                      Figure 3: Error Estimate Format




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      where S, Scale, and Multiplier fields are interpreted as they have
      been defined in section 4.1.2 [RFC4656]; and Z field - as has been
      defined in section 2.3 [RFC8186]:

      *  0 - NTP 64 bit format of a timestamp;

      *  1 - PTPv2 truncated format of a timestamp.

      The default behavior of the STAMP Session-Sender and Session-
      Reflector is to use the NTP 64-bit timestamp format (Z field value
      of 0) An operator, using configuration/management function, MAY
      configure STAMP Session-Sender and Session-Reflector to using the
      PTPv2 truncated format of a timestamp (Z field value of 1).  Note,
      that an implementation of a Session-Sender that supports this
      specification MAY be configured to use PTPv2 format of a timestamp
      even though the Session-Reflector is configured to use NTP format.

   o  Reserved field in the Session-Sender unauthenticated packet is 30
      octets long.  It MUST be all zeroed on the transmission and MUST
      be ignored on receipt.

4.2.2.  Session-Sender Packet Format in Authenticated Mode

   STAMP Session-Sender packet format in authenticated mode:



























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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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                      Sequence Number                          |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                                                               |
    |                      MBZ (12 octets)                          |
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                        Timestamp                              |
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |        Error Estimate         |                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
    ~                                                               ~
    |                         MBZ (70 octets)                       |
    ~                                                               ~
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                                                               |
    |                       HMAC (16 octets)                        |
    |                                                               |
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

    Figure 4: STAMP Session-Sender test packet format in authenticated
                                   mode

   The field definitions are the same as the unauthenticated mode,
   listed in Section 4.2.1.  Also, Must-Be-Zero (MBZ) fields are used to
   to make the packet length a multiple of 16 octets.  The value of the
   field MUST be zeroed on transmission and MUST be ignored on receipt.
   Note, that the MBZ field is used to calculate a key-hashed message
   authentication code (HMAC) ([RFC2104]) hash.  Also, the packet
   includes HMAC hash at the end of the PDU.  The detailed use of the
   HMAC field is described in Section 4.4.

4.3.  Session-Reflector Behavior and Packet Format

   The Session-Reflector receives the STAMP test packet and verifies it.
   If the base STAMP test packet validated, the Session-Reflector, that
   supports this specification, prepares and transmits the reflected
   test packet symmetric to the packet received from the Session-Sender
   copying the content beyond the size of the base STAMP packet (see
   Section 4.2).







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4.3.1.  Session-Reflector Packet Format in Unauthenticated Mode

   For unauthenticated mode:

     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                        Sequence Number                        |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                          Timestamp                            |
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Error Estimate        |           MBZ                 |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                          Receive Timestamp                    |
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                 Session-Sender Sequence Number                |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                  Session-Sender Timestamp                     |
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    | Session-Sender Error Estimate |           MBZ                 |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |Ses-Sender TTL |                   Reserved                    |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

          Figure 5: STAMP Session-Reflector test packet format in
                           unauthenticated mode

   where fields are defined as the following:

   o  Sequence Number is four octets long field.  The value of the
      Sequence Number field is set according to the mode of the STAMP
      Session-Reflector:

      *  in the stateless mode, the Session-Reflector copies the value
         from the received STAMP test packet's Sequence Number field;

      *  in the stateful mode, the Session-Reflector counts the
         transmitted STAMP test packets.  It starts with zero and is
         incremented by one for each subsequent packet for each test
         session.  The Session-Reflector uses that counter to set the
         value of the Sequence Number field.

   o  Timestamp and Receive Timestamp fields are each eight octets long.
      The format of these fields, NTP or PTPv2, indicated by the Z field
      of the Error Estimate field as described in Section 4.2.  Receive



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      Timestamp is the time the test packet was received by the Session-
      Reflector.  Timestamp - the time taken by the Session-Reflector at
      the start of transmitting the test packet.

   o  Error Estimate has the same size and interpretation as described
      in Section 4.2.  It is applicable to both Timestamp and Receive
      Timestamp.

   o  Session-Sender Sequence Number, Session-Sender Timestamp, and
      Session-Sender Error Estimate are copies of the corresponding
      fields in the STAMP test packet sent by the Session-Sender.

   o  Session-Sender TTL is one octet long field, and its value is the
      copy of the TTL field in IPv4 (or Hop Limit in IPv6) from the
      received STAMP test packet.

   o  MBZ is used to achieve alignment of fields within the packet on a
      four octets boundary.  The value of the field MUST be zeroed on
      transmission and MUST be ignored on receipt.

   o  Reserved field in the Session-Reflector unauthenticated packet is
      three octets long.  It MUST be all zeroed on the transmission and
      MUST be ignored on receipt.

4.3.2.  Session-Reflector Packet Format in Authenticated Mode

   For the authenticated mode:

      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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Sequence Number                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        MBZ (12 octets)                        |
      |                                                               |
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                          Timestamp                            |
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Error Estimate        |                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
      |                        MBZ (6 octets)                         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Receive Timestamp                      |
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        MBZ (8 octets)                         |



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      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                 Session-Sender Sequence Number                |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        MBZ (12 octets)                        |
      |                                                               |
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                 Session-Sender Timestamp                      |
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Session-Sender Error Estimate |                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
      |                        MBZ (6 octets)                         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |Ses-Sender TTL |                                               |
      +-+-+-+-+-+-+-+-+                                               +
      |                                                               |
      |                        MBZ (15 octets)                        |
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        HMAC (16 octets)                       |
      |                                                               |
      |                                                               |
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   Figure 6: STAMP Session-Reflector test packet format in authenticated
                                   mode

   The field definitions are the same as the unauthenticated mode,
   listed in Section 4.3.1.  Additionally, the MBZ field is used to to
   make the packet length a multiple of 16 octets.  The value of the
   field MUST be zeroed on transmission and MUST be ignored on receipt.
   Note, that the MBZ field is used to calculate HMAC hash value.  Also,
   STAMP Session-Reflector test packet format in authenticated mode
   includes HMAC ([RFC2104]) hash at the end of the PDU.  The detailed
   use of the HMAC field is in Section 4.4.

4.4.  Integrity Protection in STAMP

   Authenticated mode provides integrity protection to each STAMP
   message by adding Hashed Message Authentication Code (HMAC).  STAMP
   uses HMAC-SHA-256 truncated to 128 bits (similarly to the use of it
   in IPSec defined in [RFC4868]); hence the length of the HMAC field is
   16 octets.  In the Authenticated mode, HMAC covers the first six
   blocks (96 octets).  HMAC uses its own key that may be unique for



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   each STAMP test session; key management and the mechanisms to
   distribute the HMAC key are outside the scope of this specification.
   One example is to use an orchestrator to configure HMAC key based on
   STAMP YANG data model [I-D.ietf-ippm-stamp-yang].  HMAC MUST be
   verified as early as possible to avoid using or propagating corrupted
   data.

   Future specifications may define the use of other, more advanced
   cryptographic algorithms, possibly providing an update to the STAMP
   YANG data model [I-D.ietf-ippm-stamp-yang].

4.5.  Confidentiality Protection in STAMP

   If confidentiality protection for STAMP is required, a STAMP test
   session MUST use a secured transport.  For example, STAMP packets
   could be transmitted in the dedicated IPsec tunnel or share the IPsec
   tunnel with the monitored flow.  Also, Datagram Transport Layer
   Security protocol would provide the desired confidentiality
   protection.

4.6.  Interoperability with TWAMP Light

   One of the essential requirements to STAMP is the ability to
   interwork with a TWAMP Light device.  Because STAMP and TWAMP use
   different algorithms in Authenticated mode (HMAC-SHA-256 vs. HMAC-
   SHA-1), interoperability is only considered for Unauthenticated mode.
   There are two possible combinations for such use case:

   o  STAMP Session-Sender with TWAMP Light Session-Reflector;

   o  TWAMP Light Session-Sender with STAMP Session-Reflector.

   In the former case, the Session-Sender might not be aware that its
   Session-Reflector does not support STAMP.  For example, a TWAMP Light
   Session-Reflector may not support the use of UDP port 862 as
   specified in [RFC8545].  Thus Section 4. permits a STAMP Session-
   Sender to use alternative ports.  If any of STAMP extensions are
   used, the TWAMP Light Session-Reflector will view them as Packet
   Padding field.

   In the latter scenario, if a TWAMP Light Session-Sender does not
   support the use of UDP port 862, the test management system MUST set
   STAMP Session-Reflector to use UDP port number, as permitted by
   Section 4.  The Session-Reflector MUST be set to use the default
   format for its timestamps, NTP.

   A STAMP Session-Reflector that supports this specification will
   transmit the base packet (Figure 5) if it receives a packet smaller



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   than the STAMP base packet.  If the packet received from TWAMP
   Session-Sender is larger than the STAMP base packet, the STAMP
   Session-Reflector that supports this specification will copy the
   content of the remainder of the received packet to transmit reflected
   packet of symmetrical size.

5.  Operational Considerations

   STAMP is intended to be used on production networks to enable the
   operator to assess service level agreements based on packet delay,
   delay variation, and loss.  When using STAMP over the Internet,
   especially when STAMP test packets are transmitted with the
   destination UDP port number from the User Ports range, the possible
   impact of the STAMP test packets MUST be thoroughly analyzed.  The
   use of STAMP for each case MUST be agreed by users of nodes hosting
   the Session-Sender and Session-Reflector before starting the STAMP
   test session.

   Also, the use of the well-known port number as the destination UDP
   port number in STAMP test packets transmitted by a Session-Sender
   would not impede the ability to measure performance in an Equal Cost
   Multipath environment and analysis in Section 5.3 [RFC8545] fully
   applies to STAMP.

6.  IANA Considerations

   This document doesn't have any IANA action.  This section may be
   removed before the publication.

7.  Security Considerations

   [RFC5357] does not identify security considerations specific to
   TWAMP-Test but refers to security considerations identified for OWAMP
   in [RFC4656].  Since both OWAMP and TWAMP include control plane and
   data plane components, only security considerations related to OWAMP-
   Test, discussed in Sections 6.2, 6.3 [RFC4656] apply to STAMP.

   STAMP uses the well-known UDP port number allocated for the OWAMP-
   Test/TWAMP-Test Receiver port.  Thus the security considerations and
   measures to mitigate the risk of the attack using the registered port
   number documented in Section 6 [RFC8545] equally apply to STAMP.
   Because of the control and management of a STAMP test being outside
   the scope of this specification only the more general requirement is
   set:

      To mitigate the possible attack vector, the control, and
      management of a STAMP test session MUST use the secured transport.




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      The load of the STAMP test packets offered to a network MUST be
      carefully estimated, and the possible impact on the existing
      services MUST be thoroughly analyzed before launching the test
      session.  [RFC8085] section 3.1.5 provides guidance on handling
      network load for UDP-based protocol.  While the characteristic of
      test traffic depends on the test objective, it is highly
      recommended to stay in the limits as provided in [RFC8085].

   Use of HMAC-SHA-256 in the authenticated mode protects the data
   integrity of the STAMP test packets.

8.  Acknowledgments

   Authors express their appreciation to Jose Ignacio Alvarez-Hamelin
   and Brian Weis for their great insights into the security and
   identity protection, and the most helpful and practical suggestions.
   Also, our sincere thanks to David Ball and Rakesh Gandhi or their
   thorough reviews and helpful comments.

9.  References

9.1.  Normative References

   [I-D.ietf-ippm-stamp-option-tlv]
              Mirsky, G., Xiao, M., Jun, G., Nydell, H., Foote, R., and
              A. Masputra, "Simple Two-way Active Measurement Protocol
              Optional Extensions", draft-ietf-ippm-stamp-option-tlv-01
              (work in progress), September 2019.

   [IEEE.1588.2008]
              "Standard for a Precision Clock Synchronization Protocol
              for Networked Measurement and Control Systems",
              IEEE Standard 1588, March 2008.

   [RFC2104]  Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-
              Hashing for Message Authentication", RFC 2104,
              DOI 10.17487/RFC2104, February 1997,
              <https://www.rfc-editor.org/info/rfc2104>.

   [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>.

   [RFC4656]  Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M.
              Zekauskas, "A One-way Active Measurement Protocol
              (OWAMP)", RFC 4656, DOI 10.17487/RFC4656, September 2006,
              <https://www.rfc-editor.org/info/rfc4656>.



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   [RFC5357]  Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J.
              Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)",
              RFC 5357, DOI 10.17487/RFC5357, October 2008,
              <https://www.rfc-editor.org/info/rfc5357>.

   [RFC5905]  Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch,
              "Network Time Protocol Version 4: Protocol and Algorithms
              Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010,
              <https://www.rfc-editor.org/info/rfc5905>.

   [RFC6038]  Morton, A. and L. Ciavattone, "Two-Way Active Measurement
              Protocol (TWAMP) Reflect Octets and Symmetrical Size
              Features", RFC 6038, DOI 10.17487/RFC6038, October 2010,
              <https://www.rfc-editor.org/info/rfc6038>.

   [RFC6335]  Cotton, M., Eggert, L., Touch, J., Westerlund, M., and S.
              Cheshire, "Internet Assigned Numbers Authority (IANA)
              Procedures for the Management of the Service Name and
              Transport Protocol Port Number Registry", BCP 165,
              RFC 6335, DOI 10.17487/RFC6335, August 2011,
              <https://www.rfc-editor.org/info/rfc6335>.

   [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>.

   [RFC8186]  Mirsky, G. and I. Meilik, "Support of the IEEE 1588
              Timestamp Format in a Two-Way Active Measurement Protocol
              (TWAMP)", RFC 8186, DOI 10.17487/RFC8186, June 2017,
              <https://www.rfc-editor.org/info/rfc8186>.

   [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>.

9.2.  Informative References

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

   [I-D.ietf-ippm-stamp-yang]
              Mirsky, G., Xiao, M., and W. Luo, "Simple Two-way Active
              Measurement Protocol (STAMP) Data Model", draft-ietf-ippm-
              stamp-yang-05 (work in progress), October 2019.




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   [RFC4868]  Kelly, S. and S. Frankel, "Using HMAC-SHA-256, HMAC-SHA-
              384, and HMAC-SHA-512 with IPsec", RFC 4868,
              DOI 10.17487/RFC4868, May 2007,
              <https://www.rfc-editor.org/info/rfc4868>.

   [RFC7750]  Hedin, J., Mirsky, G., and S. Baillargeon, "Differentiated
              Service Code Point and Explicit Congestion Notification
              Monitoring in the Two-Way Active Measurement Protocol
              (TWAMP)", RFC 7750, DOI 10.17487/RFC7750, February 2016,
              <https://www.rfc-editor.org/info/rfc7750>.

   [RFC8085]  Eggert, L., Fairhurst, G., and G. Shepherd, "UDP Usage
              Guidelines", BCP 145, RFC 8085, DOI 10.17487/RFC8085,
              March 2017, <https://www.rfc-editor.org/info/rfc8085>.

Authors' Addresses

   Greg Mirsky
   ZTE Corp.

   Email: gregimirsky@gmail.com


   Guo Jun
   ZTE Corporation
   68# Zijinghua Road
   Nanjing, Jiangsu  210012
   P.R.China

   Phone: +86 18105183663
   Email: guo.jun2@zte.com.cn


   Henrik Nydell
   Accedian Networks

   Email: hnydell@accedian.com


   Richard Foote
   Nokia

   Email: footer.foote@nokia.com








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