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<rfc category="std" xmlns:xi="http://www.w3.org/2001/XInclude"
     docName="draft-ietf-ippm-stamp-option-tlv-10"
     number="8972"
     ipr="trust200902" updates="8762">

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     submissionType="IETF"
     category="std"
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<front>
    <title abbrev="STAMP Extensions">Simple Two-way Two-Way Active Measurement Protocol Optional Extensions</title>
    <seriesInfo name="RFC" value="8972"/>
    <author fullname="Greg Mirsky" initials="G." surname="Mirsky">
      <organization>ZTE Corp.</organization>
      <address>
        <postal>
          <street/>
          <city/>
          <code/>
          <country/>
        </postal>
        <email>gregimirsky@gmail.com</email>
      </address>
    </author>
    <author fullname="Xiao Min" initials="X." surname="Min">
      <organization>ZTE Corp.</organization>
      <address>
        <postal>
          <street/>
          <city/>
          <code/>
          <country/>
        </postal>
        <email>xiao.min2@zte.com.cn</email>
      </address>
    </author>

	<!--
		<author fullname="Guo Jun" initials="G." surname="Jun">
      <organization>ZTE Corporation</organization>
      <address>
        <postal>
          <street>68# Zijinghua Road</street>
          <city>Nanjing</city>
          <region>Jiangsu</region>
          <code>210012</code>
          <country>P.R.China</country>
        </postal>
        <phone>+86 18105183663</phone>
        <email>guo.jun2@zte.com.cn</email>
      </address>
    </author>
  -->
      <author fullname="Henrik Nydell" initials="H." surname="Nydell">
      <organization>Accedian Networks</organization>
      <address>
        <postal>
          <street/>
          <city/>
          <code/>
          <country/>
        </postal>
        <email>hnydell@accedian.com</email>
      </address>
    </author>
    <author initials="R." surname="Foote" fullname="Richard Foote">
      <organization>Nokia</organization>
      <address>
        <email>footer.foote@nokia.com </email>
      </address>
    </author>
    <author initials="A." surname="Masputra" fullname="Adi Masputra">
      <organization>Apple Inc.</organization>
      <address>
        <postal>
          <street>One Apple Park Way</street>
          <city>Cupertino</city>
          <region>CA</region>
          <code>95014</code>
<country>USA</country>
          <country>United States of America</country>
        </postal>
        <email>adi@apple.com</email>
      </address>
    </author>
    <author fullname="Ernesto Ruffini" initials="E." surname="Ruffini">
      <organization>OutSys</organization>
      <address>
        <postal>
          <street>via Caracciolo, 65</street>
          <city>Milano</city>
          <city>Milan</city>
          <code>20155</code>
          <country>Italy</country>
        </postal>
        <email>eruffini@outsys.org</email>
      </address>
    </author>
    <date year="2020"/> year="2021" month="January" />
    <area>Transport</area>
    <workgroup>Network Working Group</workgroup>

    <keyword>Internet-Draft</keyword>
    <keyword>IPPM</keyword>
    <keyword>Performance Measurement </keyword>
    <abstract>
      <t>
	This document describes optional extensions to Simple
	Two-way Active Measurement Protocol (STAMP) that enable
	measurement of performance metrics. The document also defines
	a STAMP Test Session Identifier and thus updates RFC 8762.
      </t>
    </abstract>
  </front>
  <middle>
    <section anchor="intro" title="Introduction"> numbered="true" toc="default">
      <name>Introduction</name>
      <t>
The Simple Two-way Active Measurement Protocol (STAMP) <xref target="RFC8762"/> defined target="RFC8762" format="default"/> defines the STAMP base functionalities.
This document specifies the use of
optional extensions that use Type-Length-Value (TLV) encoding.
Such extensions enhance the STAMP base functions,
   such as measurement of one-way and round-trip delay,
   latency, packet loss, packet duplication, and
   out-of-order delivery of test packets. This specification defines
optional STAMP extensions, their formats, and the theory of operation.
Also, a STAMP Test Session Identifier is defined
as an update of the base STAMP specification <xref target="RFC8762"/>. target="RFC8762" format="default"/>.
      </t>
    </section>
    <section title="Conventions numbered="true" toc="default">
      <name>Conventions Used in This Document"> Document</name>
      <section title="Acronyms">
         <t>BDS      BeiDou numbered="true" toc="default">
        <name>Acronyms</name>

<dl newline="false" indent="12">
        <dt>BDS</dt><dd>BeiDou Navigation Satellite System</t>
<t>BITS     Building System</dd>
<dt>BITS</dt><dd>Building Integrated Timing Supply </t>
<t>CoS         Class Supply</dd>
<dt>CoS</dt><dd>Class of Service</t>
<t>DSCP   Differentiated Service</dd>
<dt>DSCP</dt><dd>Differentiated Services Code Point</t>
<t>ECN   Explicit Point</dd>
<dt>ECN</dt><dd>Explicit Congestion Notification</t>
<t>GLONASS  Global Notification</dd>
<dt>GLONASS</dt><dd>Global Orbiting Navigation Satellite System</t>
<t>GPS      Global System</dd>
<dt>GPS</dt><dd>Global Positioning System <xref target="GPS"/></t>
<t>HMAC     Hashed target="GPS" format="default"/></dd>
<dt>HMAC</dt><dd>Hashed Message Authentication Code</t>
<t>LORAN-C    Long Code</dd>
<dt>LORAN-C</dt><dd>Long Range Navigation System Version C</t>
<t>MBZ           Must C</dd>
<dt>MBZ</dt><dd>Must Be Zero</t>
 <t>NTP     Network Zero</dd>
<dt>NTP</dt><dd>Network Time Protocol <xref target="RFC5905"/></t>
 <t>PMF         Performance target="RFC5905" format="default"/></dd>
<dt>PMF</dt><dd>Performance Measurement Function</t>
<t>PTP    Precision Function</dd>
<dt>PTP</dt><dd>Precision Time Protocol <xref target="IEEE.1588.2008"/></t>
<t>TLV       Type-Length-Value</t>
<t>SSID            STAMP target="IEEE.1588.2008" format="default"/></dd>
<dt>RP</dt><dd>Reverse Path</dd>
<dt>SMI</dt><dd>Structure of Management Information</dd>
<dt>SSID</dt><dd>STAMP Session Identifier</t>
<t>SSU       Synchronization Identifier</dd>
<dt>SSU</dt><dd>Synchronization Supply Unit</t>
<t>STAMP   Simple Unit</dd>
<dt>STAMP</dt><dd>Simple Two-way Active Measurement Protocol</t> Protocol</dd>
<dt>TLV</dt><dd>Type-Length-Value</dd>
</dl>
      </section>
      <section title="Requirements Language"> numbered="true" toc="default">
        <name>Requirements Language</name>
        <t>
    The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
   NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED",
   "MAY", "<bcp14>MUST</bcp14>", "<bcp14>MUST NOT</bcp14>", "<bcp14>REQUIRED</bcp14>", "<bcp14>SHALL</bcp14>", "<bcp14>SHALL
    NOT</bcp14>", "<bcp14>SHOULD</bcp14>", "<bcp14>SHOULD NOT</bcp14>", "<bcp14>RECOMMENDED</bcp14>", "<bcp14>NOT RECOMMENDED</bcp14>",
    "<bcp14>MAY</bcp14>", and "OPTIONAL" "<bcp14>OPTIONAL</bcp14>" in this document are to be interpreted as
    described in BCP 14 BCP&nbsp;14 <xref target="RFC2119"/> <xref target="RFC8174"/>
    when, and only when, they appear in all capitals, as shown here.
        </t>
      </section>
    </section>
    <section anchor="test-identifier-sec" title="STAMP numbered="true" toc="default">
      <name>STAMP Test Session Identifier"> Identifier</name>
      <t>
The STAMP Session-Sender transmits test packets to the STAMP Session-Reflector. The STAMP Session-Reflector
receives the Session-Sender's packet and acts according to the configuration and optional control information
communicated in the Session-Sender's test packet. STAMP defines two different test packet formats, formats: one for
   packets transmitted by the STAMP Session-Sender and one for packets
   transmitted by the STAMP Session-Reflector. STAMP supports two modes:
   unauthenticated and authenticated. Unauthenticated STAMP test packets
   are compatible on the wire with unauthenticated TWAMP-Test <xref target="RFC5357"/> target="RFC5357" format="default"/>
   packets.
</t>
      <t>
By default, STAMP uses symmetrical packets, i.e., the size of the packet
transmitted by the Session-Reflector equals the size of
the packet received by the Session-Reflector.
</t>
      <t>
  A STAMP Session is identified by the 4-tuple (source and destination IP addresses,
  source and destination UDP port numbers). A STAMP Session-Sender
  MAY
  <bcp14>MAY</bcp14> generate a locally unique STAMP Session Identifier (SSID).
  The SSID is a two-octet-long two-octet-long, non-zero unsigned integer. The SSID generation
   policy is implementation-specific. implementation specific. <xref target="I-D.gont-numeric-ids-generation"/> target="I-D.irtf-pearg-numeric-ids-generation" format="default"/> thoroughly analyzes common algorithms for identifier generation and their vulnerabilities.
   For example, an implementation can use the algorithms described in Section 7.1 of <xref target="I-D.gont-numeric-ids-generation"/>. target="I-D.irtf-pearg-numeric-ids-generation" sectionFormat="of" section="7.1"/>.
   An implementation MUST NOT <bcp14>MUST NOT</bcp14> assign the same identifier to different STAMP test sessions.
  A Session-Sender MAY <bcp14>MAY</bcp14> use the SSID to identify
  a STAMP test session. If the SSID is used, it MUST <bcp14>MUST</bcp14> be present in each test packet of the given test session.
  In the unauthenticated mode, the SSID is located as displayed in <xref target="session-sender-unauthenticated-format"/>. target="session-sender-unauthenticated-format" format="default"/>.
      </t>
      <figure align="left" anchor="session-sender-unauthenticated-format" title="The format anchor="session-sender-unauthenticated-format">
        <name>The Format of an extended Extended STAMP Session-Sender test packet Test Packet in unauthenticated mode">
          <artwork><![CDATA[ Unauthenticated Mode</name>
        <artwork name="" type="" align="left" alt=""><![CDATA[
    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        |             SSID              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   |                                                               |
   |                         MBZ (28 octets)                       |
   |                                                               |
   |                                                               |
   |                                                               |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   ~                            TLVs                               ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
      </figure>
      <t>
  An implementation of the STAMP Session-Reflector that supports this specification MUST <bcp14>MUST</bcp14>
   identify a STAMP Session using the SSID in combination with elements of the usual 4-tuple
   for the session. Before a test session commences, a Session-Reflector MUST <bcp14>MUST</bcp14> be provisioned
   with all the elements that identify the STAMP Session. A STAMP Session-Reflector MUST <bcp14>MUST</bcp14> discard
   non-matching STAMP test packet(s). packets. The means of provisioning the STAMP Session identification
   is outside the scope of this specification.
<!-- If the Session-Reflector finds that
the SSID and 4-tuple combination changes during a test session, then
the Session-Reflector MUST discard the non-matching packet(s) and take
no further action on them.
-->

   A conforming implementation of a STAMP Session-Reflector MUST <bcp14>MUST</bcp14> copy
  the SSID value from the received test packet and put it into the reflected packet,
  as displayed in <xref target="session-reflector-unauthenticated-format"/>. target="session-reflector-unauthenticated-format" format="default"/>.
      </t>
      <figure align="left" anchor="session-reflector-unauthenticated-format" title="The format anchor="session-reflector-unauthenticated-format">
        <name>The Format of an extended Extended STAMP Session-Reflector test packet Test Packet in unauthenticated mode">
          <artwork><![CDATA[ Unauthenticated Mode</name>
        <artwork name="" type="" align="left" alt=""><![CDATA[
  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        |           SSID                |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                          Receive Timestamp                    |
 |                                                               |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                 Session-Sender Sequence Number                |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                  Session-Sender Timestamp                     |
 |                                                               |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 | Session-Sender Error Estimate |           MBZ                 |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |Ses-Sender TTL |                   MBZ                         |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 ~                            TLVs                               ~
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
      </figure>
        </t>
      <t>
        A STAMP Session-Reflector that does not support this specification
will return the zeroed SSID field in the reflected STAMP test packet.
 The Session-Sender MAY <bcp14>MAY</bcp14> stop the session if it receives a zeroed SSID field. An implementation
 of a Session-Sender MUST <bcp14>MUST</bcp14> support control of its behavior in such a scenario.
 If the test session is not stopped, the Session-Sender, Session-Sender can, for example,
 send a base STAMP packet <xref target="RFC8762"/> target="RFC8762" format="default"/> or continue transmitting STAMP test packets with the SSID.
</t>
      <t>
 Location
 The location of the SSID field in the authenticated mode
  is shown in Figures <xref target="session-sender-authenticated-format"/> target="session-sender-authenticated-format" format="counter"/> and <xref target="session-reflector-authenticated-format"/>. target="session-reflector-authenticated-format" format="counter"/>.
      </t>
      <figure align="left" anchor="session-sender-authenticated-format" title="Base anchor="session-sender-authenticated-format">
        <name>The Format of an Extended STAMP Session-Sender test packet format Test Packet in authenticated mode">
          <artwork><![CDATA[ Authenticated Mode</name>
        <artwork name="" type="" align="left" alt=""><![CDATA[
  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         |            SSID               |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 ~                                                               ~
 |                         MBZ (68 octets)                       |
 ~                                                               ~
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                                                               |
 |                       HMAC (16 octets)                        |
 |                                                               |
 |                                                               |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 ~                            TLVs                               ~
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  ]]></artwork>
        </figure>
]]></artwork></figure>
      <figure align="left" anchor="session-reflector-authenticated-format" title="Base anchor="session-reflector-authenticated-format">
        <name>The Format of an Extended STAMP Session-Reflector test packet format Test Packet in authenticated mode">
          <artwork><![CDATA[ Authenticated Mode</name>
        <artwork name="" type="" align="left" alt=""><![CDATA[
   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        |            SSID               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        MBZ (4 octets)                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Receive Timestamp                      |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        MBZ (8 octets)                         |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                 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)                       |
   |                                                               |
   |                                                               |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   ~                            TLVs                               ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  ]]></artwork>
      </figure>
  </t>
    </section>
    <section anchor="stamp-extension-section" title="TLV numbered="true" toc="default">
      <name>TLV Extensions to STAMP"> STAMP</name>

      <t>
The Type-Length-Value (TLV) encoding scheme provides a flexible
extension mechanism for optional informational elements.
 TLV is an optional field in the STAMP test packet. Multiple TLVs
 MAY
 <bcp14>MAY</bcp14> be placed in a STAMP test packet. Additional TLVs
may be enclosed within a given TLV, subject to the semantics of the
(outer) TLV in question.
 TLVs have a one-octet-long STAMP TLV Flags field, a one-octet-long Type field, and
  a two-octet-long Length field that is equal to the length of the Value field in octets.
   If a Type value for a TLV or sub-TLV is in the range for Vendor
   Private Use, Use <xref target="RFC8126"/>, the Length MUST length <bcp14>MUST</bcp14> be at least 4, and the first four octets
   MUST
   <bcp14>MUST</bcp14> be that vendor's Structure of
   Management Information (SMI) Private Enterprise Code, as recorded in
   IANA's SMI "SMI Network Management Private Enterprise Codes sub-registry, Codes" subregistry, in network octet
   order. The rest of the Value field is private to the vendor.
The following sections describe the use of TLVs for STAMP
that extend the STAMP capability beyond its base specification.
      </t>
      <figure align="left" anchor="tlv-format" title="TLV anchor="tlv-format">
        <name>TLV Format in a STAMP Extended Packet">
          <artwork><![CDATA[ Packet</name>
        <artwork name="" type="" align="left" alt=""><![CDATA[
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |STAMP TLV Flags|     Type      |           Length              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   ~                            Value                              ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
      </figure>
       where
      <t>
       The fields are defined as the following:
        <list style="symbols">
        <t>STAMP follows:
      </t>
      <dl spacing="normal" newline="false">
        <dt>STAMP TLV Flags - Flags:</dt><dd>An eight-bit-long field. Detailed The detailed format and interpretation of flags defined in this specification is below.</t>
        <t>Type - are below.</dd>
        <dt>Type:</dt><dd>A one-octet-long field that characterizes the interpretation of
        the Value field. It is allocated by IANA, as specified in <xref target="iana-stamp-tlv-registry"/>.</t>
       <t>Length - target="iana-stamp-tlv-registry" format="default"/>.</dd>
        <dt>Length:</dt><dd>A two-octet-long field equal to the length of the Value field in octets.</t>
       <t>Value - a octets.</dd>
        <dt>Value:</dt><dd>A variable-length field. Its interpretation and encoding is are determined by the value of the Type field.</t>
       </list> field.</dd>
      </dl>
      <t>
       All multibyte multi-byte fields in TLVs defined in this specification are in network byte order.
      </t>

      <t>
The format of the STAMP TLV Flags is displayed in <xref target="tlv-flags-format"/> target="tlv-flags-format" format="default"/>, and the location of flags is according to defined in <xref target="iana-tlv-flags-reg"/>. target="iana-tlv-flags-reg" format="default"/>.
      </t>
      <figure align="left" anchor="tlv-flags-format" title="STAMP anchor="tlv-flags-format">
        <name>STAMP TLV Flags Format">
          <artwork><![CDATA[ Format</name>
        <artwork name="" type="" align="left" alt=""><![CDATA[
    0 1 2 3 4 5 6 7
   +-+-+-+-+-+-+-+-+
   |U|M|I|R|R|R|R|R|
   +-+-+-+-+-+-+-+-+
]]></artwork>
      </figure>

    where
      <t>
      The fields are defined as the following:
        <list style="symbols">
        <t>U (Unrecognized)  is a follows:
      </t>
      <dl newline="false" spacing="normal">
        <dt>U (Unrecognized):</dt><dd>A one-bit flag.
        A Session-Sender MUST <bcp14>MUST</bcp14> set the U flag to 1 before transmitting an extended STAMP test packet.
        A Session-Reflector MUST <bcp14>MUST</bcp14> set the U flag to 1 if the Session-Reflector has not understood the TLV.
        Otherwise, the Session-Reflector MUST <bcp14>MUST</bcp14> set the U flag in the reflected packet to 0.</t>
        <t>M (Malformed) is a 0.</dd>
        <dt>M (Malformed):</dt><dd>A one-bit flag.
        A Session-Sender MUST <bcp14>MUST</bcp14> set the M flag to 0 before transmitting an extended STAMP test packet.
        A Session-Reflector MUST <bcp14>MUST</bcp14> set the M flag to 1 if the Session-Reflector determined the TLV is malformed,
        i.e., the Length field value is not valid for the particular type, or
        the remaining length of the extended STAMP packet is less than the size of the TLV.
        Otherwise, the Session-Reflector MUST <bcp14>MUST</bcp14> set the M flag in the reflected packet to 0.
        </t>
        <t>I (Integrity) is a
        </dd>
        <dt>I (Integrity):</dt><dd>A one-bit flag.
        A Session-Sender MUST <bcp14>MUST</bcp14> set the I flag to 0 before transmitting an extended STAMP test packet.
        A Session-Reflector MUST <bcp14>MUST</bcp14> set the I flag to 1 if the STAMP extensions have failed HMAC verification (<xref target="hmac-sec"/>). target="hmac-sec" format="default"/>).
        Otherwise, the Session-Reflector MUST <bcp14>MUST</bcp14> set the I flag in the reflected packet to 0.</t>
       <t>R - reserved 0.</dd>
        <dt>R:</dt><dd>Reserved flags for future use. These flags MUST <bcp14>MUST</bcp14> be zeroed on transmit and ignored on receipt.</t>
       </list>
</t> receipt.</dd>
      </dl>
      <t>
A STAMP node, whether Session-Sender or Session-Reflector, receiving a test packet MUST <bcp14>MUST</bcp14>
determine whether the packet is a base STAMP packet or whether it includes one or more TLVs.
The node MUST <bcp14>MUST</bcp14> compare the value in the Length field of the UDP header and
the length of the base STAMP test packet in the mode, unauthenticated or authenticated authenticated, based
on the configuration of the particular STAMP test session. If the difference between the two values is
larger
greater than the length of the UDP header, then the test packet includes one or more STAMP TLVs
that immediately follow the base STAMP test packet.
A Session-Reflector that does not support STAMP extensions will not process but
copy them into the reflected packet, as defined in Section 4.3 <xref target="RFC8762"/>.
target="RFC8762" sectionFormat="of" section="4.3"/>.
A Session-Reflector that supports TLVs will indicate specific TLVs that
it did not process by setting the U flag to 1 in those TLVs.
</t>
      <t>
A STAMP Session-Sender that has received a reflected STAMP test packet with extension TLVs MUST <bcp14>MUST</bcp14> validate each TLV:
<list style="symbol">
<t>
</t>
      <ul spacing="normal">
        <li>
If the U flag is set, the STAMP system MUST <bcp14>MUST</bcp14> skip the processing of the TLV.
</t>
<t>
</li>
        <li>
If the M flag is set, the STAMP system MUST <bcp14>MUST</bcp14> stop processing the remainder of the extended STAMP packet.
</t>
<t>
</li>
        <li>
If the I flag is set, the STAMP system MUST <bcp14>MUST</bcp14> discard all TLVs and
MUST
<bcp14>MUST</bcp14> stop processing the remainder of the extended STAMP packet.
</t>
<t>
</li>
        <li>
If an implementation of a Session-Reflector does not recognize the Type field value,
it MUST <bcp14>MUST</bcp14> include a copy of the TLV into in the reflected STAMP packet.
The Session-Reflector MUST <bcp14>MUST</bcp14> set the U flag to 1.
The Session-Reflector MUST <bcp14>MUST</bcp14> skip the processing of the unrecognized TLV.
 </t>
<t>
 </li>
        <li>
If a TLV is malformed, the processing of extension TLVs MUST <bcp14>MUST</bcp14> be
stopped. The Session-Reflector MUST <bcp14>MUST</bcp14> copy the remainder of the received extended STAMP packet into the reflected STAMP packet.
The Session-Reflector MUST <bcp14>MUST</bcp14> set the M flag to 1.
</t>
</list>
<!--
An operator MUST be notified of the error. Detected error events MAY be logged. Note that the rate of logging MUST be controlled.
-->
</li>
      </ul>
      <t>
</t>
      <section anchor="padding-tlv-section" title="Extra numbered="true" toc="default">
        <name>Extra Padding TLV">
  <t> TLV</name>

        <figure align="left" anchor="padding-tlv-figuret" title="Extra anchor="padding-tlv-figuret">
          <name>Extra Padding TLV">
          <artwork><![CDATA[ TLV</name>
          <artwork name="" type="" align="left" alt=""><![CDATA[
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |STAMP TLV Flags|Extra Pad Flags|      Type     |           Length              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                         Extra Padding                         ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
        </figure>
        where
        <t>
        The fields are defined as the following:
        <list style="symbols">
        <t>STAMP follows:
        </t>
        <dl spacing="normal" newline="false">
          <dt>STAMP TLV Flags - is an Flags:</dt><dd>An eight-bit-long field. Its format is presented in <xref target="tlv-flags-format"/>.</t>
        <t>Extra Padding Type - is a target="tlv-flags-format" format="default"/>.</dd>
          <dt>Type:</dt><dd>A one-octet-long field, value TBA1 field. Value 1 has been allocated by IANA <xref target="iana-stamp-tlv-registry"/>.</t>
       <t>Length - (<xref target="iana-stamp-tlv-registry" format="default"/>).</dd>
          <dt>Length:</dt><dd>A two-octet-long field equal to the length of the Extra Padding field in octets.</t>
       <t>Extra Padding - SHOULD octets.</dd>
          <dt>Extra Padding:</dt><dd>This field <bcp14>SHOULD</bcp14> be filled by a sequence of a pseudo-random pseudorandom numbers. The field MAY <bcp14>MAY</bcp14> be filled with all zeros.
       An implementation MUST <bcp14>MUST</bcp14> control the type of filling content of the Extra Padding field.</t>
       </list>
  </t> field.</dd>
        </dl>
        <t>
  The Extra Padding TLV is similar to the Packet Padding field in a TWAMP-Test packet <xref target="RFC5357"/>. target="RFC5357" format="default"/>.
  The use of the Extra Padding TLV is RECOMMENDED <bcp14>RECOMMENDED</bcp14> to perform a STAMP test using
  test packets of that are larger size than the base STAMP packet
  <xref target="RFC8762"/>. target="RFC8762" format="default"/>. The length of the base STAMP packet is 44 octets
  in the unauthenticated mode or 112 octets in the authenticated mode.
  The Extra Padding TLV MAY <bcp14>MAY</bcp14> be present more than one time in an extended STAMP test packet.
        </t>
      </section>
      <section anchor="location-info-section" title="Location TLV"> numbered="true" toc="default">
        <name>Location TLV</name>

        <t>
  STAMP Session-Senders MAY <bcp14>MAY</bcp14> include the variable-size Location TLV to query location information from the Session-Reflector.
  The Session-Sender MUST NOT <bcp14>MUST NOT</bcp14> fill any information fields except for the STAMP TLV Flags, Type, and Length. Length fields.
  The Session-Reflector MUST <bcp14>MUST</bcp14> verify that the TLV is well-formed. well formed. If it is not, the Session-Reflector follows the procedure defined in <xref target="stamp-extension-section"/> target="stamp-extension-section" format="default"/>
  for a malformed TLV.
        </t>
        <figure anchor="location-tlv-figuret">
          <name>Location TLV</name>
          <artwork name="" type="" align="left" anchor="location-tlv-figuret" title="Location TLV">
          <artwork><![CDATA[ alt=""><![CDATA[
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |STAMP TLV Flags| Location      Type     |           Length              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |        Destination Port       |          Source Port          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   ~                         Sub-TLVs                              ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
        </figure>
         where
        <t>
        The fields are defined as the following:
        <list style="symbols">
          <t>STAMP follows:
        </t>
        <dl spacing="normal" newline="false">
          <dt>STAMP TLV Flags - is an Flags:</dt><dd>An eight-bit-long field. Its format is presented in <xref target="tlv-flags-format"/>.</t>
        <t>Location Type - is a target="tlv-flags-format" format="default"/>.</dd>
          <dt>Type:</dt><dd>A one-octet-long field, value TBA2 field. Value 2 has been allocated by IANA <xref target="iana-stamp-tlv-registry"/>.</t>
       <t>Length - (<xref target="iana-stamp-tlv-registry" format="default"/>).</dd>
          <dt>Length:</dt><dd>A two-octet-long field equal to the length of the Value field in octets.</t>
        <t>Destination Port - octets.</dd>
          <dt>Destination Port:</dt><dd>A two-octet-long UDP destination port number of the received STAMP packet.</t>
        <t>Source Port - packet.</dd>
          <dt>Source Port:</dt><dd>A two-octet-long UDP source port number of the received STAMP packet.</t>
        <t>Sub-TLVs - a packet.</dd>
          <dt>Sub-TLVs:</dt><dd>A sequence of sub-TLVs, as defined further in this section. The sub-TLVs are used by the
        Session-Sender to request location information with generic sub-TLV types, and the
        Session-Reflector responds with the corresponding more-specific sub-TLVs
        for the type of address (e.g., IPv4 or IPv6) used at the Session-Reflector.</t>
       </list>
  </t> Session-Reflector.</dd>
        </dl>
        <t>Note that all fields not filled by either a Session-Sender or Session-Reflector are transmitted with all bits set to zero.</t>
        <section anchor="location-sub-tlv-sec" title="Location Sub-TLVs"> numbered="true" toc="default">
          <name>Location Sub-TLVs</name>
          <t>
  A sub-TLV in the Location TLV uses the format displayed in <xref target="tlv-format"/>.
  <!--
  A Session-Sender MUST set the U flag in a sub-TLV to 1 before transmitting the extended STAMP test packet.
  The Session-Reflector MUST set the sub-TLV's U flag in the reflected test packet to 0 if it supports that type of sub-TLV.
  If the Session-Reflector doesn't recognize the sub-TLV, it must copy it from the received packet into the reflected packet.
  A Session-Sender MUST set the M flag in a sub-TLV to 0 before transmitting the extended STAMP test packet.
  The Session-Reflector MUST set the M flag in the sub-TLV in the reflected packet to 1 if the sub-TLV is malformed. The Session-Reflector MUST
  stop processing the Location TLV and MUST copy the remaining part of the Location TLV into the reflected test packet.
  --> target="tlv-format" format="default"/>.
  Handling of the U and M flags in the sub-TLV is as defined in <xref target="stamp-extension-section"/>. target="stamp-extension-section" format="default"/>.
  The I flag MUST <bcp14>MUST</bcp14> be set by a Session-Sender and Session-Reflector to 0 before transmission and its value ignored on receipt.
  The following types of sub-TLV sub-TLVs for the Location TLV are defined in this specification
  (type values are assigned according to <xref target="sub-tlv-type-tbl"/>):
  <list style="symbols">
    <t>
  Source
  (<xref target="sub-tlv-type-tbl" format="default"/> lists the Type values):
          </t>
          <dl newline="false" spacing="normal">
 <dt>Source MAC Address sub-TLV -  is a sub-TLV:</dt><dd>A 12-octet-long sub-TLV.
  The Type value is TBA9. 1.
  The value of the Length field MUST <bcp14>MUST</bcp14> be equal to 8.
  The Value field is an 8-octet-long MBZ field that MUST <bcp14>MUST</bcp14> be zeroed on transmission and ignored on receipt.
  </t>
  <t>
  </dd>
       <dt>
    Source EUI-48 Address sub-TLV -  is a sub-TLV:</dt><dd><t>A 12-octet-long sub-TLV that includes the EUI-48 source MAC address.
  The Type value is TBA10. 2.
  The value of the Length field MUST <bcp14>MUST</bcp14> be equal to 8. 8.</t>

              <figure align="left" anchor="eui-48-tlv-figure" title="The anchor="eui-48-tlv-figure">
                <name>The Value Field of the Source EUI-48 Address sub-TLV">
          <artwork><![CDATA[ Sub-TLV</name>
                <artwork name="" type="" align="left" alt=""><![CDATA[
 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                        EUI-48  Address                        |
+                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                               |            MBZ                |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
              </figure>
              <t>
  The Value field consists of the following fields (<xref target="eui-48-tlv-figure"/>):
  <list>
  <t>The EUI-48 is a target="eui-48-tlv-figure" format="default"/>):
              </t>
              <dl spacing="normal">
                <dt>EUI-48 Address:</dt><dd>A six-octet-long field.</t>
  <t>Two-octet-ling MBZ field MUST field.</dd>
                <dt>MBZ:</dt><dd>A two-octet-long field. It <bcp14>MUST</bcp14> be zeroed on transmission and ignored on receipt.</t>
  </list>
  </t>
    <t>
  Source receipt.</dd>
              </dl>
              </dd>

            <dt>Source EUI-64 Address sub-TLV -  is a sub-TLV:</dt><dd>A 12-octet-long sub-TLV that includes the EUI-64 source MAC address.
  The Type value is TBA11. 3.
  The value of the Length field MUST <bcp14>MUST</bcp14> be equal to 8.
  The Value field consists of an eight-octet-long EUI-64 field.
  </t>
          <t>
  </dd>
            <dt>
        Destination IP Address sub-TLV -  is a sub-TLV:</dt><dd>A 20-octet-long sub-TLV.
        The Type value is TBA12. 4.
        The value of the Length field MUST <bcp14>MUST</bcp14> be equal to 16.
        The Value field consists of a 16-octet-long  MBZ field that MUST <bcp14>MUST</bcp14> be zeroed on transmit and ignored on receipt
        </t>
        <t> receipt.
        </dd>
            <dt>
        Destination IPv4 Address sub-TLV -  is a sub-TLV:</dt><dd><t>A 20-octet-long sub-TLV that includes the IPv4 destination address.
        The Type value is TBA13. 5.
        The value of the Length field MUST <bcp14>MUST</bcp14> be equal to 16. 16.</t>

              <figure align="left" anchor="ipv4-value-figure" title="IPv4 anchor="ipv4-value-figure">
                <name>IPv4 Address in a Sub-TLV's Value Field">
          <artwork><![CDATA[ Field</name>
                <artwork name="" type="" align="left" alt=""><![CDATA[
 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                         IPv4 Address                          |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~                        MBZ (12 octets)                        ~
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
              </figure>
              <t>
        The Value field consists of the following fields (<xref target="ipv4-value-figure"/>):
        <list>
        <t>The IPv4 Address is a target="ipv4-value-figure" format="default"/>):
              </t>
              <dl spacing="normal">
                <dt>IPv4 Address:</dt><dd>A four-octet-long field.</t>
        <t>12-octet-long MBZ field MUST field.</dd>
                <dt>MBZ:</dt><dd>A 12-octet-long field. It <bcp14>MUST</bcp14> be zeroed on transmit and ignored on receipt.</t>
        </list>
        </t>
        <t> receipt.</dd>
              </dl>
            </dd>

            <dt>
        Destination IPv6 Address sub-TLV -  is a sub-TLV:</dt><dd>A 20-octet-long sub-TLV that includes the IPv6 destination address.
        The Type value is TBA14. 6.
        The value of the Length field MUST <bcp14>MUST</bcp14> be equal to 16.
        The Value field is a 16-octet-long IP v6 IPv6 Address field.
        </t>
        <t>
        </dd>
            <dt>
        Source IP Address sub-TLV - is a sub-TLV:</dt><dd>A 20-octet-long sub-TLV.
        The Type value is TBA15. 7.
        The value of the Length field MUST <bcp14>MUST</bcp14> be equal to 16.
        The Value field is a 16-octet-long MBZ field that MUST <bcp14>MUST</bcp14> be zeroed on transmit and ignored on receipt
        </t>
        <t> receipt.
        </dd>
              <dt>
        Source IPv4 Address sub-TLV - is a sub-TLV:</dt><dd><t>A 20-octet-long sub-TLV that includes the IPv4 source address.
        The Type value is TBA16. 8.
        The value of the Length field MUST <bcp14>MUST</bcp14> be equal to 16.
        The Value field consists of the following fields (<xref target="ipv4-value-figure"/>):
        <list>
        <t>The IPv4 Address is a target="ipv4-value-figure" format="default"/>):</t>

              <dl spacing="normal">
                <dt>IPv4 Address:</dt><dd>A four-octet-long field.</t>
        <t>12-octet-long MBZ field that MUST field.</dd>
                <dt>MBZ:</dt><dd>A 12-octet-long field. It <bcp14>MUST</bcp14> be zeroed on transmit and ignored on receipt.</t>
        </list>
        </t>
                <t> receipt.</dd>
              </dl>
            </dd>

            <dt>
        Source IPv6 Address sub-TLV - is a sub-TLV:</dt><dd>A 20-octet-long sub-TLV that includes the IPv6 source address.
        The Type value is TBA17. 9.
        The value of the Length field MUST <bcp14>MUST</bcp14> be equal to 16.
        The Value field is a 16-octet-long IPv6 Address field.
        </t>
  </list>
  </t>
        </dd>
</dl>
        </section>
        <section anchor="location-operation-sec" title="Theory numbered="true" toc="default">
          <name>Theory of Operation of Location TLV"> TLV</name>
          <t>

  The Session-Reflector that received an extended STAMP packet with
  the Location TLV MUST <bcp14>MUST</bcp14> include in the reflected packet the Location TLV of the size with a length equal
  to the size of Location TLV length in the received packet in the reflected packet.
  Based on the local policy, the Session-Reflector MAY <bcp14>MAY</bcp14> leave some fields unreported by filling them with zeroes.
  An implementation of the stateful Session-Reflector MUST <bcp14>MUST</bcp14> provide control for managing such policies.
          </t>
          <t>
  A Session-Sender MAY <bcp14>MAY</bcp14> include the Source MAC Address sub-TLV in the Location TLV.
  If the Session-Reflector receives the Location TLV that includes the Source MAC Address sub-TLV, it
  MUST
  <bcp14>MUST</bcp14> include the Source EUI-48 Address sub-TLV if the source MAC address of the
  received extended test packet is in EUI-48 format. And the Session-Reflector MUST <bcp14>MUST</bcp14>
  copy the value of the source MAC address in the EUI-48 field.
  Otherwise, the Session-Reflector MUST <bcp14>MUST</bcp14> use the Source EUI-64 Address sub-TLV and MUST <bcp14>MUST</bcp14> copy the value
  of the Source MAC address Address from the received packet into the EUI-64 field.
  If the received extended STAMP test packet does not have the Source MAC address, Address,
  the Session-Reflector MUST <bcp14>MUST</bcp14> zero the EUI-64 field before transmitting the reflected packet.
          </t>
          <t>
  A Session-Sender MAY <bcp14>MAY</bcp14> include the Destination IP Address sub-TLV in the Location TLV.
  If the Session-Reflector receives the Location TLV that includes the Destination IP Address sub-TLV, it
  MUST
  <bcp14>MUST</bcp14> include the Destination IPv4 Address sub-TLV if the source IP address of the
  received extended test packet is of the IPv4 address family. And the Session-Reflector MUST <bcp14>MUST</bcp14>
  copy the value of the destination IP address in the IPv4 Address field.
  Otherwise, the Session-Reflector MUST <bcp14>MUST</bcp14> use the Destination IPv6 Address sub-TLV and MUST <bcp14>MUST</bcp14> copy the value
  of the destination IP address from the received packet into the IPv6 Address field.
          </t>

          <t>
  A Session-Sender MAY <bcp14>MAY</bcp14> include the Source IP Address sub-TLV in the Location TLV.
  If the Session-Reflector receives the Location TLV that includes the Source IP Address sub-TLV, it
  MUST
  <bcp14>MUST</bcp14> include the Source IPv4 Address sub-TLV if the source IP address of the
  received extended test packet is of the IPv4 address family. And the Session-Reflector MUST <bcp14>MUST</bcp14>
  copy the value of the source IP address in the IPv4 Address field.
  Otherwise, the Session-Reflector MUST <bcp14>MUST</bcp14> use the Source IPv6 Address sub-TLV and MUST <bcp14>MUST</bcp14> copy the value
  of the source IP address from the received packet into the IPv6 Address field.
          </t>
          <t>
The Location TLV MAY <bcp14>MAY</bcp14> be used to determine the last-hop IP addresses, ports, and
  last-hop MAC address for&#160; for STAMP packets. The MAC address can indicate a path switch
  on the last hop. The IP addresses and UDP ports will indicate
  if there is a NAT router on the path. It allows the Session-Sender to identify the IP address
  of the Session-Reflector behind the NAT, NAT and detect changes in the NAT mapping that could
  cause result in sending the STAMP packets to the wrong Session-Reflector.
          </t>
        </section>
      </section>
      <section anchor="timestamp-info-section" title="Timestamp numbered="true" toc="default">
        <name>Timestamp Information TLV"> TLV</name>
        <t>
  The STAMP Session-Sender MAY <bcp14>MAY</bcp14> include the Timestamp Information TLV to request information from the Session-Reflector.
  The Session-Sender MUST NOT <bcp14>MUST NOT</bcp14> fill any information fields except for STAMP TLV Flags, Type, and Length.
  All other fields MUST <bcp14>MUST</bcp14> be filled with zeroes.
  The Session-Reflector MUST <bcp14>MUST</bcp14> validate the Length value of the TLV.
  If the value of the Length field is invalid, the Session-Reflector follows the procedure defined in <xref target="stamp-extension-section"/> target="stamp-extension-section" format="default"/> for a malformed TLV.

        </t>
        <figure align="left" anchor="timestamp-tlv-figuret" title="Timestamp anchor="timestamp-tlv-figuret">
          <name>Timestamp Information TLV">
          <artwork><![CDATA[ TLV</name>
          <artwork name="" type="" align="left" alt=""><![CDATA[
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |STAMP TLV Flags|Times Info Type| Flags|      Type     |           Length              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Sync.  Sync Src In  | Timestamp In  | Sync. Sync Src Out  | Timestamp Out |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   ~                    Optional sub-TLVs                          ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
        </figure>
         where
        <t>
        The fields are defined as the following:
        <list style="symbols">
          <t>STAMP follows:
        </t>
        <dl spacing="normal">
          <dt>STAMP TLV Flags - is an Flags:</dt><dd>An eight-bit-long field. Its format is presented in <xref target="tlv-flags-format"/>.</t>
        <t>Timestamp Information Type - is a target="tlv-flags-format" format="default"/>.</dd>
          <dt>Type:</dt><dd>A one-octet-long field, value TBA3 field. Value 3 has been allocated by IANA <xref target="iana-stamp-tlv-registry"/>.</t>
       <t>Length - (<xref target="iana-stamp-tlv-registry" format="default"/>).</dd>
          <dt>Length:</dt><dd>A two-octet-long field, set equal to the length of the Value field in octets (<xref target="tlv-format"/>).</t>
       <t>Sync target="tlv-format" format="default"/>).</dd>
          <dt>Sync Src In - In:</dt><dd>A one-octet-long field that characterizes the source of clock synchronization at the ingress of a Session-Reflector.
       There are several methods to synchronize for synchronizing the clock, e.g., the Network Time Protocol (NTP) <xref target="RFC5905"/>.
       The value is one of those listed in target="RFC5905" format="default"/>.

       <xref target="ssync-source-new-tbl"/>.</t>
       <t>Timestamp In - target="ssync-source-new-tbl" format="default"/> lists the possible values.</dd>
          <dt>Timestamp In:</dt><dd>A one-octet-long field that characterizes the
       method by which the ingress of the Session-Reflector obtained the timestamp T2.
       A timestamp may be obtained with hardware assistance, assistance via a software API from a local wall clock, clock or from a remote clock (the latter is referred to as a "control plane").
       The value is one of those listed in
<xref target="timestamp-method-new-tbl"/>.</t>
       <t>Sync target="timestamp-method-new-tbl" format="default"/> lists the possible values.</dd>
          <dt>Sync Src Out - Out:</dt><dd>A one-octet-long field that characterizes the source of clock synchronization at the egress of the Session-Reflector.
       The value is one of those listed in
<xref target="ssync-source-new-tbl"/>.</t>
       <t>Timestamp Out - target="ssync-source-new-tbl" format="default"/> lists the possible values.</dd>
          <dt>Timestamp Out:</dt><dd>A one-octet-long field that characterizes the
       method by which the egress of the Session-Reflector obtained the timestamp T3.
       The value is one of those listed in
<xref target="timestamp-method-new-tbl"/>.</t>
       <t>Optional sub-TLVs - target="timestamp-method-new-tbl" format="default"/> lists the possible values.</dd>
          <dt>Optional sub-TLVs:</dt><dd>An optional variable-length field.</t>
       </list>
  </t> field.</dd>
        </dl>
      </section>

      <section anchor="cos-info-section" title="Class numbered="true" toc="default">
        <name>Class of Service TLV"> TLV</name>
        <t>
  The STAMP Session-Sender MAY <bcp14>MAY</bcp14> include  a Class of Service (CoS) TLV in the STAMP test packet.
  The format of the CoS TLV is presented in <xref target="cos-tlv-figure"/>. target="cos-tlv-figure" format="default"/>.

        </t>
        <figure align="left" anchor="cos-tlv-figure" title="Class anchor="cos-tlv-figure">
          <name>Class of Service TLV">
          <artwork><![CDATA[ TLV</name>
          <artwork name="" type="" align="left" alt=""><![CDATA[
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |STAMP TLV Flags|    CoS      Type     |           Length              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   DSCP1   |   DSCP2   |ECN| RP|          Reserved             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
        </figure>
         where
        <t>
        The fields are defined as the following:
        <list style="symbols">
          <t>STAMP follows:
        </t>
        <dl spacing="normal">
          <dt>STAMP TLV Flags - is an Flags:</dt><dd>An eight-bit-long field. Its format is presented in <xref target="tlv-flags-format"/>.</t>
        <t>CoS (Class of Service) Type - is a target="tlv-flags-format" format="default"/>.</dd>
          <dt>Type:</dt><dd>A one-octet-long field, value TBA4 field. Value 4 has been allocated by IANA <xref target="iana-stamp-tlv-registry"/>.</t>
        <t>Length - (<xref target="iana-stamp-tlv-registry" format="default"/>).</dd>
          <dt>Length:</dt><dd>A two-octet-long field, set equal to the value 4.</t>
        <t>DSCP1 - The 4.</dd>
          <dt>DSCP1:</dt><dd>The Differentiated Services Code Point (DSCP) intended by the Session-Sender
        to be used as the DSCP value of the reflected test packet.</t>
        <t>DSCP2 - The packet.</dd>
          <dt>DSCP2:</dt><dd>The received value in the DSCP field at the ingress of the Session-Reflector.</t>
        <t>ECN - The Session-Reflector.</dd>
          <dt>ECN:</dt><dd>The received value in the ECN field at the ingress of the Session-Reflector.</t>
        <t>RP Session-Reflector.</dd>
          <dt>RP (Reverse Path) - is a Path):</dt><dd>A two-bit-long field. A Session-Sender MUST <bcp14>MUST</bcp14> set the value of the RP field to 0 on transmission.</t>
        <t>Reserved - transmission.</dd>
          <dt>Reserved:</dt><dd>A 16-bit-long field, MUST field that <bcp14>MUST</bcp14> be zeroed on transmission and ignored on receipt.</t>
       </list>
  </t> receipt.</dd>
        </dl>
        <t>
  A STAMP Session-Reflector that receives a test packet with the CoS TLV MUST <bcp14>MUST</bcp14> include
  the CoS TLV in the reflected test packet. Also, the Session-Reflector MUST <bcp14>MUST</bcp14> copy
  the value of the DSCP and ECN fields of the IP header of the received STAMP test packet into the DSCP2 field in
  the reflected test packet. Finally, the Session-Reflector MUST <bcp14>MUST</bcp14> use the local policy to verify whether
  the CoS corresponding to the value of the DSCP1 field is permitted in the domain. If it is, the Session-Reflectorset
  MUST Session-Reflector
  <bcp14>MUST</bcp14> set the DSCP field's value in the IP header
  of the reflected test packet equal to the value of the DSCP1 field of the received test packet. Otherwise, the Session-Reflector MUST <bcp14>MUST</bcp14> use
  the DSCP value of the received STAMP packet and set the value of the RP field to 1.
  Upon receiving the reflected packet, if the value of the RP field is 0,
  the Session-Sender will save the DSCP and ECN values for analysis of the CoS in the reverse direction.
  If the value of the RP field in the received reflected packet is 1, only CoS in the forward direction can be analyzed.
        </t>
        <t>
Re-mapping of CoS can be used to provide multiple services (e,g., (e.g., 2G, 3G, LTE in mobile backhaul networks)
over the same network.&#160; network.&nbsp; But if it is misconfigured, then it is often difficult to diagnose the root cause of
excessive packet drops of higher-level service while packet drops
for lower service packets are at a normal level.&#160; level.&nbsp; Using a CoS TLV in
STAMP testing helps to troubleshoot the existing problem and also verify
whether DiffServ policies are processing CoS as required by the configuration.
        </t>
      </section>
      <section anchor="direct-measurement-section" title="Direct numbered="true" toc="default">
        <name>Direct Measurement TLV"> TLV</name>
        <t>
  The Direct Measurement TLV enables collection of the number of in-profile packets,
  i.e., packets that form a specific data flow, that had been transmitted and received
  by the Session-Sender and Session-Reflector, respectively. The definition of "in-profile packet" is outside the
  scope of this document and is left to the test operators to determine.
        </t>
        <figure align="left" anchor="direct-tlv-figuret" title=" Direct anchor="direct-tlv-figuret">
          <name>Direct Measurement TLV">
          <artwork><![CDATA[ TLV</name>
          <artwork name="" type="" align="left" alt=""><![CDATA[
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |STAMP TLV Flags|  Direct      Type     |           Length              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |              Session-Sender Tx counter  (S_TxC)               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |             Session-Reflector Rx counter  (R_RxC)             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |             Session-Reflector Tx counter  (R_TxC)             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
        </figure>
         where
        <t>
        The fields are defined as the following:
        <list style="symbols">
          <t>STAMP follows:
        </t>
        <dl spacing="normal" newline="false">
          <dt>STAMP TLV Flags - is an Flags:</dt><dd>An eight-bit-long field. Its format is presented in <xref target="tlv-flags-format"/>.</t>
        <t>Direct (Measurement) Type - is a target="tlv-flags-format" format="default"/>.</dd>
          <dt>Type:</dt><dd>A one-octet-long field, value TBA5 field. Value 5 has been allocated by IANA <xref target="iana-stamp-tlv-registry"/>.</t>
       <t>Length - (<xref target="iana-stamp-tlv-registry" format="default"/>).</dd>
          <dt>Length:</dt><dd>A two-octet-long field equals equal to the length of the Value field in octets. The Length field value MUST <bcp14>MUST</bcp14> equal 12 octets.</t>
       <t>Session-Sender octets.</dd>
          <dt>Session-Sender Tx counter  (S_TxC) is a (S_TxC):</dt><dd>A four-octet-long field. The Session-Sender MUST <bcp14>MUST</bcp14> set its value equal to the number of the transmitted in-profile packets.</t>
       <t>Session-Reflector packets.</dd>
          <dt>Session-Reflector Rx counter  (R_RxC) is a (R_RxC):</dt><dd>A four-octet-long field. MUST It <bcp14>MUST</bcp14> be zeroed  by the Session-Sender on transmit and
       ignored by the Session-Reflector on receipt. The Session-Reflector MUST <bcp14>MUST</bcp14> fill it with the value of in-profile packets received.</t>
       <t>Session-Reflector received.</dd>
          <dt>Session-Reflector Tx counter  (R_TxC) is a (R_TxC):</dt><dd>A four-octet-long field. MUST It <bcp14>MUST</bcp14> be zeroed by the Session-Sender and ignored by the Session-Reflector on receipt.
       The Session-Reflector MUST <bcp14>MUST</bcp14> fill it with the value of the transmitted in-profile packets.</t>
       </list>
    </t> packets.</dd>
        </dl>
        <t>
    A Session-Sender MAY <bcp14>MAY</bcp14> include the Direct Measurement TLV in a STAMP test packet.
    If the received STAMP test packet includes the Direct Measurement TLV, the Session-Reflector MUST <bcp14>MUST</bcp14> include it in the reflected test packet.
    The Session-Reflector MUST <bcp14>MUST</bcp14> copy the value from the S_TxC field of the received test packet into the same field of the reflected packet before its transmission.
        </t>
      </section>
      <section anchor="access-avail-sec" title="Access numbered="true" toc="default">
        <name>Access Report TLV"> TLV</name>
        <t>
    A STAMP Session-Sender MAY <bcp14>MAY</bcp14> include an Access Report TLV (<xref target="access-tlv-fig"/>) target="access-tlv-fig" format="default"/>) to indicate
  changes to the access network status to the Session-Reflector. The
  definition of an access network is outside the scope of this document.
        </t>
    <t>
        <figure align="left" anchor="access-tlv-fig" title="Access anchor="access-tlv-fig">
          <name>Access Report TLV">
          <artwork><![CDATA[ TLV</name>
          <artwork name="" type="" align="left" alt=""><![CDATA[
     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |STAMP TLV Flags|Acc Report Type| Flags|     Type      |           Length              |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |   ID  |  Resv |  Return Code  |          Reserved             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
        </figure>
        where
        <t>
        The fields are defined as follows:
        <list style="symbols">
          <t>STAMP
        </t>
        <dl spacing="normal" newline="false">
          <dt>STAMP TLV Flags - is an Flags:</dt><dd>An eight-bit-long field. Its format is presented in <xref target="tlv-flags-format"/>.</t>
        <t>Access Report Type - is a target="tlv-flags-format" format="default"/>.</dd>
          <dt>Type:</dt><dd>A one-octet-long field, value TBA6 field. Value 6 has been allocated by IANA <xref target="iana-stamp-tlv-registry"/>.</t>
        <t>Length - (<xref target="iana-stamp-tlv-registry" format="default"/>).</dd>
          <dt>Length:</dt><dd>A two-octet-long field, set equal to the value 4.</t>
        <t>ID 4.</dd>
            <dt>ID (Access ID) - ID):</dt><dd><t>A four-bit-long field that identifies the access network,
     e.g., 3GPP (Radio Access Technologies specified by 3GPP) or Non-3GPP non-3GPP
     (accesses that are not specified by 3GPP) <xref target="TS23501"/>. target="TS23501" format="default"/>.
     The value is one of those listed below:
     <list>
     <t>1 - 3GPP Network</t>
     <t>2 - Non-3GPP Network</t>
     </list> the following:</t>
            <dl spacing="normal" newline="false">
              <dt>1:</dt><dd>3GPP Network</dd>
              <dt>2:</dt><dd>Non-3GPP Network</dd>
            </dl>
         <t>
     All other values are invalid and the invalid; a TLV that contains it MUST values other than '1' or '2' <bcp14>MUST</bcp14> be discarded.</t>
          <t>Resv -
      </dd>
          <dt>Resv:</dt><dd>A four-bit-long field, MUST field that <bcp14>MUST</bcp14> be zeroed on transmission
      and ignored on receipt.</t>
     <t>Return Code - receipt.</dd>
          <dt>Return Code:</dt><dd>A one-octet-long field that identifies the report signal,
     e.g., available or unavailable. The value is supplied to the STAMP
     end-point
     endpoint through some mechanism that is outside the scope of this document.
     The value is one of those listed in
<xref target="iana-return-code-reg"/>.</t>
     <t>Reserved - target="iana-return-code-reg" format="default"/> lists the possible values.</dd>
          <dt>Reserved:</dt><dd>A two-octet-long field, MUST field that <bcp14>MUST</bcp14> be zeroed on transmission
      and ignored on receipt.</t>
        </list>
        </t> receipt.</dd>
        </dl>
        <t>
           The STAMP Session-Sender that includes the Access Report TLV sets
   the value of the Access ID field according to the type of access network it reports on.
   Also, the Session-Sender sets the value of the Return Code field to reflect the operational state of the
   access network. The mechanism to determine the state of the access network is outside the scope
   of this specification.  A STAMP Session-Reflector
   that received the test packet with the Access Report TLV MUST <bcp14>MUST</bcp14> include
   the Access Report TLV in the reflected test packet.  The Session-
   Reflector MUST Session-Reflector <bcp14>MUST</bcp14> set the value of the Access ID and Return Code fields
   equal to the values of the corresponding fields from the test packet
   it has received.
        </t>
        <t>
   The Session-Sender MUST <bcp14>MUST</bcp14> also arm a retransmission timer after sending
   a test packet that includes the Access Report TLV.  This timer MUST <bcp14>MUST</bcp14>
   be disarmed upon reception of the reflected
   STAMP test packet that includes the Access Report TLV.
   In the event the timer expires before such a packet
   is received, the Session-Sender MUST <bcp14>MUST</bcp14> retransmit the STAMP test packet
   that contains the Access Report TLV. This retransmission SHOULD <bcp14>SHOULD</bcp14> be
   repeated up to four times before the procedure is aborted. Setting the value
   for the retransmission timer is based on local policies and the network environment.
   The default value of the retransmission timer for the Access Report TLV
   SHOULD
   <bcp14>SHOULD</bcp14> be three seconds. An implementation MUST <bcp14>MUST</bcp14> provide control
   of the retransmission timer value and the number of retransmissions.
        </t>
        <t>
  The Access Report TLV is used by the Performance Measurement
   Function (PMF) components of the Access Steering, Switching Switching, and
   Splitting feature for 5G networks <xref target="TS23501"/>. target="TS23501" format="default"/>.  The PMF
   component in the User Equipment acts as the STAMP Session-Sender,
   and the PMF component in the User Plane Function
   acts as the STAMP Session-Reflector.
        </t>
      </section>
      <section anchor="follow-up-tlv" title="Follow-up numbered="true" toc="default">
        <name>Follow-Up Telemetry TLV"> TLV</name>
        <t>
    A Session-Reflector might be able to put in the Timestamp field only an "SW Local"
    (see <xref target="timestamp-method-new-tbl"/>) timestamp. target="timestamp-method-new-tbl" format="default"/>) timestamp in the Follow-Up Timestamp field. But the hosting
    system might provide a timestamp closer to the start of the actual packet transmission
    even though it is not possible to deliver the information to the Session-Sender in time for the packet itself.
    This timestamp might nevertheless be important for the Session-Sender, as it
    improves the accuracy of measuring network delay measurement by minimizing the impact of egress queuing delays
    on the measurement.
        </t>

        <t>
  A STAMP Session-Sender MAY <bcp14>MAY</bcp14> include the Follow-up Follow-Up Telemetry TLV to
   request information from the Session-Reflector. The Session-Sender
   MUST
   <bcp14>MUST</bcp14> set the Follow-up Follow-Up Telemetry Type and Length fields to their appropriate values.
   The Sequence Number and Follow-Up Timestamp fields MUST <bcp14>MUST</bcp14> be zeroed on transmission by the Session-Sender
   and ignored by the Session-Reflector upon receipt of the STAMP test packet that includes the Follow-up Follow-Up Telemetry TLV.
   The Session-Reflector MUST <bcp14>MUST</bcp14> validate the Length value of the STAMP
   test packet.  If the value of the Length field is invalid, the
   Session-Reflector MUST <bcp14>MUST</bcp14> zero the Sequence Number and Follow-Up Timestamp fields and set the M flag in the STAMP TLV Flags field
   in the reflected packet. If the Session-Reflector is in the
   stateless mode (defined in Section 4.2 <xref target="RFC8762"/>), target="RFC8762" sectionFormat="of" section="4.2"/>),
   it MUST <bcp14>MUST</bcp14> zero the Sequence Number and Follow-Up Timestamp fields.
        </t>
    <t>
        <figure align="left" anchor="follow-up-tlv-fig" title="Follow-up anchor="follow-up-tlv-fig">
          <name>Follow-Up Telemetry TLV">
          <artwork><![CDATA[ TLV</name>
          <artwork name="" type="" align="left" alt=""><![CDATA[
     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |STAMP TLV Flags| Follow-up Type|      Type     |           Length              |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                        Sequence Number                        |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                      Follow-up                      Follow-Up Timestamp                      |
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |  Timestamp M  |                     Reserved                  |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
        </figure>
        where
        <t>
        The fields are defined as follows:
        <list style="symbols">
          <t>STAMP
        </t>
        <dl spacing="normal">
          <dt>STAMP TLV Flags - is an Flags:</dt><dd>An eight-bit-long field. Its format is presented in <xref target="tlv-flags-format"/>.</t>
        <t>Follow-up (Telemetry) Type - is a target="tlv-flags-format" format="default"/>.</dd>
          <dt>Type:</dt><dd>A one-octet-long field, value TBA7 field. Value 7 has been allocated by IANA <xref target="iana-stamp-tlv-registry"/>.</t>
        <t>Length - (<xref target="iana-stamp-tlv-registry" format="default"/>).</dd>
          <dt>Length:</dt><dd>A two-octet-long field, set equal to the value 16 octets.</t>
        <t> octets.</dd>
          <dt>
        Sequence Number - Number:</dt><dd>A four-octet-long field indicating the sequence
number of the last packet reflected in the same STAMP-test STAMP test session.
Since the Session-Reflector runs in the stateful mode
(defined in Section 4.2 <xref target="RFC8762"/>), target="RFC8762" sectionFormat="of" section="4.2"/>),
it is the Session-Reflector&#8217;s Session-Reflector's Sequence Number of the previous reflected packet.
</t>
<t>
     Follow-up Timestamp -
</dd>
          <dt>
     Follow-Up Timestamp:</dt><dd>An eight-octet-long field, with the format indicated by
      the Z flag of the Error Estimate field of the STAMP base packet, which is contained
      in this reflected test packet transmitted by a Session-Reflector,
      as described in Section 4.2.1 <xref target="RFC8762"/>. target="RFC8762" sectionFormat="of" section="4.2.1"/>.
      It carries the timestamp when the reflected packet with the
      specified sequence number was sent.
</t>
<t>
</dd>
          <dt>
Timestamp M(ode) - M(ode):</dt><dd>A one-octet-long field that characterizes the
method by which the entity that transmits a reflected STAMP packet obtained the Follow-up Follow-Up Timestamp.
The value is one of those listed in
<xref target="timestamp-method-new-tbl"/>.
</t>
<t> Reserved - target="timestamp-method-new-tbl" format="default"/> lists the possible values.
</dd>
          <dt>Reserved:</dt><dd>A three-octet-long field. Its value MUST <bcp14>MUST</bcp14> be zeroed on transmission and ignored on receipt.</t>
        </list>
    </t> receipt.</dd>
        </dl>
      </section>
      <section anchor="hmac-sec" title="HMAC TLV"> numbered="true" toc="default">
        <name>HMAC TLV</name>

        <t>
The STAMP authenticated mode protects the integrity of data collected in the STAMP base packet.
STAMP extensions are designed to provide valuable information about the condition of a network,
and protecting the integrity of that data is also essential.
All authenticated STAMP base packets (per Section 4.2.2 Sections <xref target="RFC8762"
sectionFormat="bare" section="4.2.2"/> and Section 4.3.2 <xref target="RFC8762"/>) target="RFC8762"
sectionFormat="bare" section="4.3.2"/> of <xref target="RFC8762" format="default"/>)
compatible with this specification MUST <bcp14>MUST</bcp14> additionally authenticate the
option
optional TLVs by including the keyed Hashed Message Authentication Code (HMAC) TLV, with the sole exception of when
there is only one TLV present, present and it is the Extended Padding TLV.
The HMAC TLV MUST <bcp14>MUST</bcp14> follow all TLVs included in a STAMP test packet, packet except for the Extra Padding TLV.
If the HMAC TLV appears in any other position in a STAMP extended test packet, then the situation
MUST
<bcp14>MUST</bcp14> be processed as HMAC verification failure, as defined below in this section, further below. section.
The HMAC TLV MAY <bcp14>MAY</bcp14> be used to protect the integrity of STAMP extensions in the STAMP unauthenticated mode.
An implementation of STAMP extensions MUST <bcp14>MUST</bcp14> provide controls to enable
the integrity protection of STAMP extensions in the STAMP unauthenticated mode.
</t>
        <t>
<!--
                <figure align="left" anchor="hmac-tlv-fig" title="HMAC TLV">
          <artwork><![CDATA[
    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            HMAC Type          |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          HMAC Key ID                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                       HMAC (Variable)                         ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
-->
        </t>
        <figure anchor="hmac-tlv-fig">
          <name>HMAC TLV</name>
          <artwork name="" type="" align="left" anchor="hmac-tlv-fig" title="HMAC TLV">
          <artwork><![CDATA[ alt=""><![CDATA[
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |STAMP TLV Flags|   HMAC      Type     |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   |                              HMAC                             |
   |                                                               |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
        </figure>
        where
        <t>
        The fields are defined as follows:
        <list style="symbols">
          <t>STAMP
        </t>
        <dl spacing="normal">
          <dt>STAMP TLV Flags - is an Flags:</dt><dd>An eight-bit-long field. Its format is presented in <xref target="tlv-flags-format"/>.</t>
        <t>HMAC Type - is a target="tlv-flags-format" format="default"/>.</dd>
          <dt>Type:</dt><dd>A one-octet-long field, value TBA8 field. Value 8 has been allocated by IANA <xref target="iana-stamp-tlv-registry"/>.</t>
        <t>Length - (<xref target="iana-stamp-tlv-registry" format="default"/>).</dd>
          <dt>Length:</dt><dd>A two-octet-long field, set equal to the value 16 octets.</t>
        <t>HMAC - is a octets.</dd>
          <dt>HMAC:</dt><dd>A 16-octet-long field that carries the HMAC digest of the text of all preceding TLVs.</t>
  </list>
</t> TLVs.</dd>
        </dl>
        <t>
As defined in <xref target="RFC8762"/>, target="RFC8762" format="default"/>, STAMP uses HMAC-SHA-256 truncated to 128 bits (<xref target="RFC4868"/>). (see <xref target="RFC4868" format="default"/>).
All considerations regarding using the key listed in Section 4.4 of <xref target="RFC8762"/> target="RFC8762" sectionFormat="of" section="4.4"/>
are fully applicable to the use of the HMAC TLV. Key management and the mechanisms to
distribute the HMAC key are outside the scope of this specification.
The HMAC TLV is anticipated to track updates in the base STAMP protocol <xref target="RFC8762"/>, target="RFC8762" format="default"/>,
including the use of more advanced cryptographic algorithms. HMAC is calculated as defined in <xref target="RFC2104"/> target="RFC2104" format="default"/>
over text as the concatenation of the Sequence Number field of the base STAMP packet and
all  preceding TLVs. The digest then MUST <bcp14>MUST</bcp14> be truncated to 128 bits and written into the HMAC field.
If the HMAC TLV is present in the extended STAMP test packet, e.g., in the authenticated mode,
HMAC MUST <bcp14>MUST</bcp14> be verified before using any data in the included STAMP TLVs. If HMAC verification
by the Session-Reflector fails, then the Session-Reflector MUST <bcp14>MUST</bcp14> stop processing the received extended STAMP test packet.
The Session-Reflector MUST <bcp14>MUST</bcp14> copy the TLVs from the received  STAMP test packet into the
reflected packet. The Session-Reflector MUST <bcp14>MUST</bcp14> set the I flag in each TLV copied over into
the reflected packet to 1 before transmitting the reflected test packet.
If the Session-Sender receives the extended STAMP test packet with I flag set to 1,
then the Session-Sender MUST <bcp14>MUST</bcp14> stop processing TLVs in the reflected test packet.
If HMAC verification by the Session-Sender fails, then the Session-Sender MUST <bcp14>MUST</bcp14>
stop processing TLVs in the reflected extended STAMP packet.
<!--
The Session-Sender MUST notify an operator of the failed HMAC verification.
Also, both the Session-Sender and Session-Reflector MAY log the notification that
HMAC verification of STAMP TLVs failed. Note that the system MUST control the rate of logging.
-->
</t>
      </section>
    </section>
    <section anchor="iana-consider" title="IANA Considerations"> numbered="true" toc="default">

      <name>IANA Considerations</name>
<t>IANA has created the following subregistries under the "Simple Two-way Active Measurement Protocol (STAMP) TLV Types" registry.</t>
      <section anchor="iana-stamp-tlv-registry" title="STAMP numbered="true" toc="default">
        <name>STAMP TLV Registry"> Types Subregistry</name>
        <t>
   IANA is requested to create has created the STAMP "STAMP TLV Type registry.
    All Types" subregistry. The code
   points in the range 1 through 175 in this registry shall be are allocated according to the "IETF Review" procedure as specified registration
   procedures <xref target="RFC8126" format="default"/> described in <xref target="RFC8126"/>.
    Code points in the range
     176 through 239 in this registry shall be allocated according to
   target="iana-stamp-type-tbl" format="default"/>.
        </t>
        <table anchor="iana-stamp-type-tbl" align="center">
          <name>Registration Procedures for the "First STAMP TLV Types Subregistry</name>
          <thead>
            <tr>
              <th align="left">Range</th>
              <th align="center">Registration Procedures</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td align="left">1 - 175</td>
              <td align="center">IETF Review</td>
            </tr>
            <tr>
              <td align="left">176 - 239</td>
              <td align="center">First Come First Served" procedure as
     specified in <xref target="RFC8126"/>.
         The remaining code points are Served</td>
            </tr>
            <tr>
              <td align="left">240 - 251</td>
              <td align="center">Experimental Use</td>
            </tr>
            <tr>
              <td align="left">252 - 254</td>
              <td align="center">Private Use</td>
            </tr>
          </tbody>
        </table>
        <t>Per this document, IANA has allocated according to <xref target="iana-stamp-type-tbl"/>:
     </t>
       <texttable anchor="iana-stamp-type-tbl" title="STAMP TLV Type Registry">
    <ttcol align="left">Value</ttcol>
    <ttcol align="center">Description</ttcol>
    <ttcol align="left">Reference</ttcol>
      <c>0</c>
    <c>Reserved</c>
    <c>This document</c>
     <c>1- 175</c>
    <c>Unassigned</c>
    <c>This document</c>
     <c>176 - 239</c>
         <c>Unassigned</c>
    <c>This document</c>
      <c>240 - 251</c>
    <c>Experimental</c>
    <c>This document</c>
     <c>252 - 254</c>
    <c>Private Use</c>
    <c>This document</c>
         <c>255</c>
    <c>Reserved</c>
    <c>This document</c>
   </texttable>

<t>This document defines the following new values in the IETF Review range of the STAMP "STAMP TLV Type registry:</t>
     <texttable Types" subregistry:
</t>

        <table anchor="stamp-new-type-tbl" title="STAMP align="center">
          <name>STAMP TLV Types">
    <ttcol align="left">Value</ttcol>
    <ttcol align="center">Description</ttcol>
    <ttcol align="left">Reference</ttcol>
    <c>TBA1</c>
    <c>Extra Padding</c>
    <c>This&nbsp;document</c>
        <c>TBA2</c>
    <c>Location</c>
    <c>This&nbsp;document</c>
        <c>TBA3</c>
    <c>Timestamp&nbsp;Information</c>
    <c>This&nbsp;document</c>
    <c>TBA4</c>
    <c>Class of&nbsp;Service</c>
    <c>This&nbsp;document</c>
        <c>TBA5</c>
    <c>Direct&nbsp;Measurement</c>
    <c>This&nbsp;document</c>
   <c>TBA6</c>
    <c>Access&nbsp;Report</c>
    <c>This&nbsp;document</c>
     <c>TBA7</c>
    <c>Follow-up&nbsp;Telemetry</c>
    <c>This&nbsp;document</c>
    <c>TBA8</c>
    <c>HMAC</c>
    <c>This&nbsp;document</c>
    </texttable> Types</name>
          <thead>
            <tr>
              <th align="left">Value</th>
              <th align="center">Description</th>
              <th align="left">Reference</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td align="left">0</td>
              <td align="center">Reserved</td>
              <td align="left">RFC 8972</td>
            </tr>
            <tr>
              <td align="left">1</td>
              <td align="center">Extra Padding</td>
              <td align="left">RFC 8972</td>
            </tr>
            <tr>
              <td align="left">2</td>
              <td align="center">Location</td>
              <td align="left">RFC 8972</td>
            </tr>
            <tr>
              <td align="left">3</td>
              <td align="center">Timestamp&nbsp;Information</td>
              <td align="left">RFC 8972</td>
            </tr>
            <tr>
              <td align="left">4</td>
              <td align="center">Class of&nbsp;Service</td>
              <td align="left">RFC 8972</td>
            </tr>
            <tr>
              <td align="left">5</td>
              <td align="center">Direct&nbsp;Measurement</td>
              <td align="left">RFC 8972</td>
            </tr>
            <tr>
              <td align="left">6</td>
              <td align="center">Access&nbsp;Report</td>
              <td align="left">RFC 8972</td>
            </tr>
            <tr>
              <td align="left">7</td>
              <td align="center">Follow-Up&nbsp;Telemetry</td>
              <td align="left">RFC 8972</td>
            </tr>
            <tr>
              <td align="left">8</td>
              <td align="center">HMAC</td>
              <td align="left">RFC 8972</td>
            </tr>
            <tr>
              <td align="left">255</td>
              <td align="center">Reserved</td>
              <td align="left">RFC 8972</td>
            </tr>
          </tbody>
        </table>
      </section>

      <section anchor="iana-tlv-flags-reg" title="STAMP numbered="true" toc="default">
        <name>STAMP TLV Flags Sub-registry"> Subregistry</name>
        <t>
      IANA is requested to create the STAMP TLV Flags sub-registry as part of has created the STAMP "STAMP TLV Type registry. Flags" subregistry.
      The registration procedure is "IETF Review" <xref target="RFC8126"/>. Flags target="RFC8126" format="default"/>. The flags are 8 bits.
      This document defines
      Per this document, IANA has allocated the following bit positions in the STAMP "STAMP TLV Flags sub-registry: Flags" subregistry.
        </t>
         <texttable
        <table anchor="tlv-flags-new-tbl" title="STAMP align="center">
          <name>STAMP TLV Flags">
    <ttcol Flags</name>
          <thead>
            <tr>
              <th align="center">Bit position</ttcol>
        <ttcol align="center">Symbol</ttcol>
    <ttcol align="center">Description</ttcol>
    <ttcol align="center">Reference</ttcol>
    <c>0</c>
    <c>U</c>
    <c>Unrecognized TLV</c>
    <c>This&nbsp;document</c>
        <c>1</c>
    <c>M</c>
    <c>Malformed TLV</c>
    <c>This&nbsp;document</c>
            <c>2</c>
    <c>I</c>
    <c>Integrity position</th>
              <th align="center">Symbol</th>
              <th align="center">Description</th>
              <th align="center">Reference</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td align="center">0</td>
              <td align="center">U</td>
              <td align="center">Unrecognized TLV</td>
              <td align="center">RFC 8972</td>
            </tr>
            <tr>
              <td align="center">1</td>
              <td align="center">M</td>
              <td align="center">Malformed TLV</td>
              <td align="center">RFC 8972</td>
            </tr>
            <tr>
              <td align="center">2</td>
              <td align="center">I</td>
              <td align="center">Integrity check failed</c>
    <c>This&nbsp;document</c>
    </texttable> failed</td>
              <td align="center">RFC 8972</td>
            </tr>
          </tbody>
        </table>
      </section>
      <section anchor="iana-sub-tlv-registry" title="Sub-TLV Type Sub-registry"> numbered="true" toc="default">
        <name>STAMP Sub-TLV Types Subregistry</name>
        <t>
   IANA is requested to create the sub-TLV Type sub-registry as part of has created the STAMP TLV Type registry.
    All "STAMP Sub-TLV Types" subregistry.
   The code points in the range 1 through 175 in this registry shall be are allocated according to the "IETF Review" procedure as specified in
   registration procedures <xref target="RFC8126"/>.
    Code points in the range
     176 through 239 in this registry shall be allocated according to the "First Come First Served" procedure as
     specified target="RFC8126" format="default"/> described
   in <xref target="RFC8126"/>.
         The remaining code points are allocated according to <xref target="iana-sub-type-tbl"/>: target="iana-sub-type-tbl" format="default"/>.
        </t>
       <texttable
        <table anchor="iana-sub-type-tbl" title="Location align="center">
          <name>Registration Procedures for the STAMP Sub-TLV Type Sub-registry">
    <ttcol align="left">Value</ttcol>
    <ttcol align="center">Description</ttcol>
    <ttcol align="left">Reference</ttcol>
      <c>0</c>
    <c>Reserved</c>
    <c>This document</c>
     <c>1- 175</c>
    <c>Unassigned</c>
    <c>This document</c>
     <c>176 - 239</c>
         <c>Unassigned</c>
    <c>This document</c>
      <c>240 - 251</c>
    <c>Experimental</c>
    <c>This document</c>
     <c>252 - 254</c>
    <c>Private Use</c>
    <c>This document</c>
         <c>255</c>
    <c>Reserved</c>
    <c>This document</c>
   </texttable>

<t>This document defines Types Subregistry</name>
          <thead>
            <tr>
              <th align="center">Range</th>
              <th align="center">Registration Procedures</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td align="left">1 - 175</td>
              <td align="center">IETF Review</td>
            </tr>
            <tr>
              <td align="left">176 - 239</td>
              <td align="center">First Come First Served</td>
            </tr>
            <tr>
              <td align="left">240 - 251</td>
              <td align="center">Experimental Use</td>
            </tr>
            <tr>
              <td align="left">252 - 254</td>
              <td align="center">Private Use</td>
            </tr>
          </tbody>
        </table>
        <t>Per this document, IANA has allocated the following new values in the IETF Review range of the Location sub-TLV Type sub-registry:</t>
     <texttable "STAMP Sub-TLV Types" subregistry:</t>
        <table anchor="sub-tlv-type-tbl" title="STAMP sub-TLV Types">
    <ttcol align="left">Value</ttcol>
    <ttcol align="center">Description</ttcol>
    <ttcol align="center">
          <name>STAMP Sub-TLV Types</name>
          <thead>
            <tr>
              <th align="center">Value</th>
              <th align="center">Description</th>
              <th align="left">TLV Used</ttcol>
    <ttcol align="left">Reference</ttcol>
    <c>TBA9</c>
    <c>Source Used</th>
              <th align="left">Reference</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td align="left">0</td>
              <td align="center">Reserved</td>
              <td></td>
              <td align="left">RFC 8972</td>
            </tr>
            <tr>
              <td align="left">1</td>
              <td align="center">Source MAC Address</c>
    <c>Location</c>
    <c>This&nbsp;document</c>
        <c>TBA10</c>
    <c>Source Address</td>
              <td align="left">Location</td>
              <td align="left">RFC 8972</td>
            </tr>
            <tr>
              <td align="left">2</td>
              <td align="center">Source EUI-48 Address</c>
     <c>Location</c>
    <c>This&nbsp;document</c>
        <c>TBA11</c>
    <c>Source Address</td>
              <td align="left">Location</td>
              <td align="left">RFC 8972</td>
            </tr>
            <tr>
              <td align="left">3</td>
              <td align="center">Source EUI-64 Address</c>
     <c>Location</c>
    <c>This&nbsp;document</c>
        <c>TBA12</c>
    <c>Destination Address</td>
              <td align="left">Location</td>
              <td align="left">RFC 8972</td>
            </tr>
            <tr>
              <td align="left">4</td>
              <td align="center">Destination IP Address</c>
     <c>Location</c>
    <c>This&nbsp;document</c>
        <c>TBA13</c>
            <c>Destination Address</td>
              <td align="left">Location</td>
              <td align="left">RFC 8972</td>
            </tr>
            <tr>
              <td align="left">5</td>
              <td align="center">Destination IPv4 Address</c>
             <c>Location</c>
    <c>This&nbsp;document</c>
        <c>TBA14</c>
            <c>Destination Address</td>
              <td align="left">Location</td>
              <td align="left">RFC 8972</td>
            </tr>
            <tr>
              <td align="left">6</td>
              <td align="center">Destination IPv6 Address</c>
             <c>Location</c>
    <c>This&nbsp;document</c>
        <c>TBA15</c>
    <c>Source&nbsp;IP Address</c>
     <c>Location</c>
    <c>This&nbsp;document</c>
            <c>TBA16</c>
    <c>Source&nbsp;IPv4 Address</c>
     <c>Location</c>
    <c>This&nbsp;document</c>
            <c>TBA17</c>
    <c>Source&nbsp;IPv6 Address</c>
     <c>Location</c>
    <c>This&nbsp;document</c>
    </texttable> Address</td>
              <td align="left">Location</td>
              <td align="left">RFC 8972</td>
            </tr>
            <tr>
              <td align="left">7</td>
              <td align="center">Source&nbsp;IP Address</td>
              <td align="left">Location</td>
              <td align="left">RFC 8972</td>
            </tr>
            <tr>
              <td align="left">8</td>
              <td align="center">Source&nbsp;IPv4 Address</td>
              <td align="left">Location</td>
              <td align="left">RFC 8972</td>
            </tr>
            <tr>
              <td align="left">9</td>
              <td align="center">Source&nbsp;IPv6 Address</td>
              <td align="left">Location</td>
              <td align="left">RFC 8972</td>
            </tr>
            <tr>
              <td align="left">255</td>
              <td align="center">Reserved</td>
              <td></td>
              <td align="left">RFC 8972</td>
            </tr>
          </tbody>
        </table>
      </section>
      <section anchor="iana-sync-source-reg" title="Synchronization Source Sub-registry"> numbered="true" toc="default">
        <name>STAMP Synchronization Sources Subregistry</name>
        <t>
   IANA is requested to create has created the "STAMP Synchronization Source sub-registry as part of the STAMP TLV Type registry.
    All Sources" subregistry.
The code points in the range 1 through 127 in this registry shall be are allocated according
   to the "IETF Review" procedure as specified in registration procedures
<xref target="RFC8126"/>.
    Code points in the range
     128 through 239 target="RFC8126" format="default"/> described in this registry shall be allocated according to
<xref target="iana-sync-source-tbl" format="default"/>.
        </t>
        <table anchor="iana-sync-source-tbl" align="center">
          <name>Registration Procedures for the "First STAMP Synchronization Sources Subregistry</name>
          <thead>
            <tr>
              <th align="left">Range</th>
              <th align="center">Registration Procedures</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td align="left">1 - 127</td>
              <td align="center">IETF Review</td>
            </tr>
            <tr>
              <td align="left">128 - 239</td>
              <td align="center">First Come First Served" procedure as
     specified in <xref target="RFC8126"/>.
         Remaining code points are Served</td>
            </tr>
            <tr>
              <td align="left">240 - 249</td>
              <td align="center">Experimental Use</td>
            </tr>
            <tr>
              <td align="left">250 - 254</td>
              <td align="center">Private Use</td>
            </tr>
          </tbody>
        </table>
        <t>Per this document, IANA has allocated according to <xref target="iana-sync-source-tbl"/>:
     </t>
       <texttable anchor="iana-sync-source-tbl" title="Synchronization Source Sub-registry">
    <ttcol align="left">Value</ttcol>
    <ttcol align="center">Description</ttcol>
    <ttcol align="left">Reference</ttcol>
     <c>0</c>
    <c>Reserved</c>
    <c>This document</c>
     <c>1- 127</c>
    <c>Unassigned</c>
    <c>This document</c>
     <c>128 - 239</c>
    <c>Unassigned</c>
    <c>This document</c>
     <c>240 - 249</c>
    <c>Experimental</c>
    <c>This document</c>
     <c>250 - 254</c>
    <c>Private Use</c>
    <c>This document</c>
         <c>255</c>
    <c>Reserved</c>
    <c>This document</c>
   </texttable>

<t>     This document defines the following new values in the "STAMP Synchronization Source sub-registry:</t>
     <texttable Sources" subregistry:
</t>
        <table anchor="ssync-source-new-tbl" title="Synchronization Sources">
    <ttcol align="left">Value</ttcol>
    <ttcol align="center">Description</ttcol>
    <ttcol align="left">Reference</ttcol>
    <c>1</c>
    <c>NTP</c>
    <c>This&nbsp;document</c>
        <c>2</c>
    <c>PTP</c>
    <c>This&nbsp;document</c>
        <c>3</c>
    <c>SSU/BITS</c>
    <c>This&nbsp;document</c>
    <c>4</c>
    <c>GPS/GLONASS/LORAN-C/BDS/Galileo</c>
    <c>This&nbsp;document</c>
        <c>5</c>
    <c>Local free-running</c>
    <c>This&nbsp;document</c>
    </texttable> align="center">
          <name>STAMP Synchronization Sources</name>
          <thead>
            <tr>
              <th align="left">Value</th>
              <th align="center">Description</th>
              <th align="left">Reference</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td align="left">0</td>
              <td align="center">Reserved</td>
              <td align="left">RFC 8972</td>
            </tr>

            <tr>
              <td align="left">1</td>
              <td align="center">NTP</td>
              <td align="left">RFC 8972</td>
            </tr>
            <tr>
              <td align="left">2</td>
              <td align="center">PTP</td>
              <td align="left">RFC 8972</td>
            </tr>
            <tr>
              <td align="left">3</td>
              <td align="center">SSU/BITS</td>
              <td align="left">RFC 8972</td>
            </tr>
            <tr>
              <td align="left">4</td>
              <td align="center">GPS/GLONASS/LORAN-C/BDS/Galileo</td>
              <td align="left">RFC 8972</td>
            </tr>
            <tr>
              <td align="left">5</td>
              <td align="center">Local free-running</td>
              <td align="left">RFC 8972</td>
            </tr>
            <tr>
              <td align="left">255</td>
              <td align="center">Reserved</td>
              <td align="left">RFC 8972</td>
            </tr>

          </tbody>
        </table>
      </section>
      <section anchor="iana-tiemstamp-methog-reg" title="Timestamping Method Sub-registry">
      <t>
   IANA is requested to create the Timestamping Method sub-registry as part of the STAMP TLV Type registry.
    All code points in the range 1 through 127 in this registry shall be allocated
    according to the "IETF Review" procedure as specified in <xref target="RFC8126"/>.
    Code points in the range
     128 through 239 in this registry shall be allocated according to the "First Come First Served" procedure as
     specified in <xref target="RFC8126"/>.
         Remaining code points are allocated according to <xref target="iana-timestamp-method-tbl"/>:
     </t>
       <texttable anchor="iana-timestamp-method-tbl" title="Timestamping Method Sub-registry">
    <ttcol align="left">Value</ttcol>
    <ttcol align="center">Description</ttcol>
    <ttcol align="left">Reference</ttcol>
    <c>0</c>
    <c>Reserved</c>
    <c>This document</c>
     <c>1- 127</c>
    <c>Unassigned</c>
    <c>This document</c>
     <c>128 - 239</c>
    <c>Unassigned</c>
    <c>This document</c>
     <c>240 - 249</c>
    <c>Experimental</c>
    <c>This document</c>
     <c>250 - 254</c>
    <c>Private Use</c>
    <c>This document</c>
         <c>255</c>
    <c>Reserved</c>
    <c>This document</c>
   </texttable>

<t>     This document defines the following new values in the numbered="true" toc="default">
        <name>STAMP Timestamping Methods sub-registry:</t>
     <texttable anchor="timestamp-method-new-tbl" title="Timestamping Methods">
    <ttcol align="left">Value</ttcol>
    <ttcol align="center">Description</ttcol>
    <ttcol align="left">Reference</ttcol>
    <c>1</c>
    <c>HW Assist</c>
    <c>This&nbsp;document</c>
        <c>2</c>
    <c>SW local</c>
    <c>This&nbsp;document</c>
        <c>3</c>
    <c>Control plane</c>
    <c>This&nbsp;document</c>
    </texttable>
     </section>

  <!--
       <section anchor="iana-access-report-reg" title="Access ID Sub-registry"> Subregistry</name>
        <t>
   IANA is requested to create Access ID sub-registry as part of STAMP TLV Type registry.
    All code points in the range 1 through 127 in this registry shall be allocated
    according to has created the "IETF Review" procedure as specified in <xref target="RFC8126"/>.
    Code "STAMP Timestamping Methods" subregistry.
The code points in the range
     128 through 239 in this registry shall be are allocated
   according to the "First Come First Served" procedure as
     specified in registration procedures
<xref target="RFC8126"/>.
         Remaining code points are allocated according to target="RFC8126" format="default"/>
described in
<xref target="iana-access-id-tbl"/>: target="iana-timestamp-method-tbl" format="default"/>.
        </t>
       <texttable anchor="iana-access-id-tbl" title="Access ID Sub-registry">
    <ttcol align="left">Value</ttcol>
    <ttcol align="center">Description</ttcol>
    <ttcol align="left">Reference</ttcol>
     <c>0</c>
    <c>Reserved</c>
    <c>This document</c>
     <c>1- 127</c>
    <c>Unassigned</c>
    <c>IETF Review</c>
     <c>128 - 239</c>
    <c>Unassigned</c>
    <c>First
        <table anchor="iana-timestamp-method-tbl" align="center">
          <name>Registration Procedures for the STAMP Timestamping Methods Subregistry</name>
          <thead>
            <tr>
              <th align="left">Range</th>
              <th align="center">Registration Procedures</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td align="left">1 - 127</td>
              <td align="center">IETF Review</td>
            </tr>
            <tr>
              <td align="left">128 - 239</td>
              <td align="center">First Come First Served</c>
     <c>240 - 249</c>
    <c>Experimental</c>
    <c>This document</c>
     <c>250 - 254</c>
    <c>Private Use</c>
    <c>This document</c>
         <c>255</c>
    <c>Reserved</c>
    <c>This document</c>
   </texttable>

<t>     This document defines Served</td>
            </tr>
            <tr>
              <td align="left">240 - 249</td>
              <td align="center">Experimental Use</td>
            </tr>
            <tr>
              <td align="left">250 - 254</td>
              <td align="center">Private Use</td>
            </tr>
          </tbody>
        </table>
        <t>Per this document, IANA has allocated the following new values in the Access ID sub-registry:</t>
     <texttable anchor="access-id-new-tbl" title="Access IDs">
    <ttcol align="left">Value</ttcol>
    <ttcol align="center">Description</ttcol>
    <ttcol align="left">Reference</ttcol>
    <c>1</c>
    <c>3GPP </c>
    <c>This&nbsp;document</c>
        <c>2</c>
    <c>Non-3GPP</c>
    <c>This&nbsp;document</c>
    </texttable> "STAMP Timestamping Methods" subregistry:</t>
        <table anchor="timestamp-method-new-tbl" align="center">
          <name>STAMP Timestamping Methods</name>
          <thead>
            <tr>
              <th align="left">Value</th>
              <th align="center">Description</th>
              <th align="left">Reference</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td align="left">0</td>
              <td align="center">Reserved</td>
              <td align="left">RFC 8972</td>
            </tr>

            <tr>
              <td align="left">1</td>
              <td align="center">HW Assist</td>
              <td align="left">RFC 8972</td>
            </tr>
            <tr>
              <td align="left">2</td>
              <td align="center">SW Local</td>
              <td align="left">RFC 8972</td>
            </tr>
            <tr>
              <td align="left">3</td>
              <td align="center">Control Plane</td>
              <td align="left">RFC 8972</td>
            </tr>
            <tr>
              <td align="left">255</td>
              <td align="center">Reserved</td>
              <td align="left">RFC 8972</td>
            </tr>
          </tbody>
        </table>
      </section>
-->
   <section anchor="iana-return-code-reg" title="Return Code Sub-registry"> numbered="true" toc="default">
        <name>STAMP Return Codes Subregistry</name>
        <t>
   IANA is requested to create has created the "STAMP Return Code sub-registry as part of the STAMP TLV Type registry.
    All Codes" subregistry.
The code points in the range 1 through 127 in this registry shall be are allocated
   according to the "IETF Review" procedure as specified in registration procedures <xref target="RFC8126"/>.
    Code points in the range
     128 through 239 target="RFC8126" format="default"/> described in this registry shall be allocated according to
<xref target="iana-return-code-tbl" format="default"/>.
        </t>
        <table anchor="iana-return-code-tbl" align="center">
          <name>Registration Procedures for the "First STAMP Return Codes Subregistry</name>
          <thead>
            <tr>
              <th align="left">Range</th>
              <th align="center">Registration Procedures</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td align="left">1 - 127</td>
              <td align="center">IETF Review</td>
            </tr>
            <tr>
              <td align="left">128 - 239</td>
              <td align="center">First Come First Served" procedure as
     specified in <xref target="RFC8126"/>.
         Remaining code points are Served</td>
            </tr>
            <tr>
              <td align="left">240 - 249</td>
              <td align="center">Experimental Use</td>
            </tr>
            <tr>
              <td align="left">250 - 254</td>
              <td align="center">Private Use</td>
            </tr>
          </tbody>
        </table>
        <t>Per this document, IANA has allocated according to <xref target="iana-return-code-tbl"/>:
     </t>
       <texttable anchor="iana-return-code-tbl" title="Return Code Sub-registry">
    <ttcol align="left">Value</ttcol>
    <ttcol align="center">Description</ttcol>
    <ttcol align="left">Reference</ttcol>
     <c>0</c>
    <c>Reserved</c>
    <c>This document</c>
     <c>1- 127</c>
    <c>Unassigned</c>
    <c>This document</c>
     <c>128 - 239</c>
    <c>Unassigned</c>
    <c>This document</c>
     <c>240 - 249</c>
    <c>Experimental</c>
    <c>This document</c>
     <c>250 - 254</c>
    <c>Private Use</c>
    <c>This document</c>
         <c>255</c>
    <c>Reserved</c>
    <c>This document</c>
   </texttable>

<t>     This document defines the following new values in the "STAMP Return Code sub-registry:</t>
     <texttable Codes" subregistry:</t>
        <table anchor="return-code-new-tbl" title="Return Codes">
    <ttcol align="left">Value</ttcol>
    <ttcol align="center">Description</ttcol>
    <ttcol align="left">Reference</ttcol>
    <c>1</c>
    <c>Network&nbsp;available</c>
    <c>This&nbsp;document</c>
        <c>2</c>
    <c>Network&nbsp;unavailable</c>
    <c>This&nbsp;document</c>
    </texttable> align="center">
          <name>STAMP Return Codes</name>
          <thead>
            <tr>
              <th align="left">Value</th>
              <th align="center">Description</th>
              <th align="left">Reference</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td align="left">0</td>
              <td align="center">Reserved</td>
              <td align="left">RFC 8972</td>
            </tr>
            <tr>
              <td align="left">1</td>
              <td align="center">Network&nbsp;available</td>
              <td align="left">RFC 8972</td>
            </tr>
            <tr>
              <td align="left">2</td>
              <td align="center">Network&nbsp;unavailable</td>
              <td align="left">RFC 8972</td>
            </tr>
            <tr>
              <td align="left">255</td>
              <td align="center">Reserved</td>
              <td align="left">RFC 8972</td>
            </tr>
          </tbody>
        </table>
      </section>
    </section>
    <section anchor="security" title="Security Considerations"> numbered="true" toc="default">
      <name>Security Considerations</name>
      <t>
This document defines extensions to STAMP <xref target="RFC8762"/> target="RFC8762" format="default"/> and inherits all the security considerations
applicable to the base protocol. Additionally, the HMAC TLV is defined in this document.
Though the HMAC TLV protects the integrity of STAMP extensions; extensions, it does not protect against a replay attack.
The use of the HMAC TLV is discussed in detail in <xref target="hmac-sec"/>. target="hmac-sec" format="default"/>.
      </t>
      <t>
     To protect against a malformed TLV TLV, an implementation of a Session-Sender and Session-Reflector MUST:
     <list style="symbols">
     <t>check <bcp14>MUST</bcp14>:
      </t>
      <ul spacing="normal">
        <li>check the setting of the M flag;</t>
     <t>validate flag and</li>
        <li>validate the Length field value.</t>
     </list>
     </t> value.</li>
      </ul>
      <t>
     As this specification defined defines the mechanism to test DSCP mapping,
   this document inherits all the security considerations discussed in <xref target="RFC2474"/>. target="RFC2474" format="default"/>.
   Monitoring and optional control of DSCP using the CoS TLV may be used across the Internet so that
     the Session-Sender and the Session-Reflector are located in domains that use different CoS profiles. Thus,
     it is essential that an operator verifies verify the set of CoS values that are is used in the Session-Reflector's domain.
     Also, an implementation of a Session-Reflector SHOULD <bcp14>SHOULD</bcp14> support a local policy to confirm whether the value sent by the Session-Sender
     can be used as the value of the DSCP field. <xref target="cos-info-section"/> target="cos-info-section" format="default"/> defines the use of that local policy.
      </t>
    </section>

      <section title="Acknowledgments">
         <t>
         Authors much appreciate the thorough review and thoughtful comments received from
         Tianran Zhou, Rakesh Gandhi, Yuezhong Song and Yali Wang.
         The authors express their gratitude to Al Morton for his comments and the most valuable suggestions.
         The authors greatly appreciate comments and thoughtful suggestions received from Martin Duke.
         </t>
      </section>

<section title="Contributors">
<t>
 The following people contributed text to this document:
         <figure align="left">
          <artwork><![CDATA[
   Guo Jun
   ZTE Corporation
   68# Zijinghua Road
   Nanjing, Jiangsu  210012
   P.R.China

   Phone: +86 18105183663
   Email: guo.jun2@zte.com.cn
]]></artwork>
        </figure>
</t>
</section>
  </middle>
  <back>
    <references title="Normative References">

  <?rfc include="reference.RFC.2119"?>
  <?rfc include="reference.RFC.8174"?>

  <?rfc include="reference.RFC.8126"?>

    <?rfc include="reference.RFC.8762"?>

    <?rfc include="reference.RFC.2104"?>

<displayreference target="I-D.irtf-pearg-numeric-ids-generation" to="NUM-IDS-GEN"/>

    <references>
      <name>References</name>
      <references>
        <name>Normative References</name>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.2119.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8174.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8126.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8762.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.2104.xml"/>
      </references>

  <references title="Informative References">
  <?rfc include="reference.RFC.5905"?>
  <?rfc include="reference.RFC.4868"?>

    <?rfc include="reference.RFC.2474"?>
    <?rfc include="reference.RFC.5357"?>
    <?rfc include="reference.I-D.gont-numeric-ids-generation"?>
      <references>
        <name>Informative References</name>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.5905.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.4868.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.2474.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.5357.xml"/>

        <xi:include href="https://datatracker.ietf.org/doc/bibxml3/reference.I-D.irtf-pearg-numeric-ids-generation-06.xml"/>

        <reference anchor="IEEE.1588.2008">
          <front>
<title>Standard
            <title>IEEE Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems</title>
            <author>
              <organization/>
            </author>
            <date month="March" month="July" year="2008"/>
          </front>
          <seriesInfo name="IEEE" value="Standard 1588"/> name="IEEE Std." value="1588-2008"/>
<seriesInfo name="DOI" value="10.1109/IEEESTD.2008.4579760"/>
        </reference>

        <reference anchor="TS23501">
          <front>
            <title>Technical
              Specification Group Services and System Aspects; System
              Architecture for the 5G System; System (5GS); Stage 2 (Release 16)</title>
            <author>
<organization>3GPP (3rd Generation Partnership Project)</organization>
              <organization>3GPP</organization>
            </author>
            <date year="2019"/>
          </front>
          <seriesInfo name="3GPP" value="TS23501"/> name="3GPP TS" value="23.501"/>
        </reference>

        <reference anchor="GPS">
          <front>
            <title>Global Positioning System (GPS) Standard Positioning Service (SPS) Performance Standard</title>
            <author>
              <organization/>
            </author>
            <date month="April" year="2020"/>
          </front>
          <seriesInfo name="GPS SPS" value="5th Edition"/>
        </reference>
      </references>
    </references>
    <section numbered="false" toc="default">
      <name>Acknowledgments</name>
      <t>
         The authors very much appreciate the thorough review and thoughtful comments received from <contact fullname="Tianran Zhou"/>, <contact fullname="Rakesh Gandhi"/>, <contact fullname="Yuezhong Song"/>, and <contact fullname="Yali Wang"/>.
         The authors express their gratitude to <contact fullname="Al Morton"/> for his comments and valuable suggestions.
         The authors greatly appreciate the comments and thoughtful suggestions received from <contact fullname="Martin Duke"/>.
      </t>
    </section>
    <section numbered="false" toc="default">
      <name>Contributors</name>
      <t>
 The following individual contributed text to this document:
      </t>
  <contact fullname="Guo Jun">
        <organization>ZTE Corporation</organization>
        <address>
          <postal>
            <street>68# Zijinghua Road</street>
            <city>Nanjing</city>
            <region>Jiangsu</region>
            <code>210012</code>
            <country>China</country>
          </postal>
<phone>+86 18105183663</phone>
       <email>guo.jun2@zte.com.cn</email>
        </address>
  </contact>
    </section>
  </back>

</rfc>