Internet Engineering Task Force (IETF)                         G. MirskyRequest for Comments: 8762                                        G. JunCategory: Standards Track                                      ZTE Corp.ISSN: 2070-1721                                                H. Nydell                                                       Accedian Networks                                                                R. Foote                                                                   Nokia                                                              March 2020               Simple Two-Way Active Measurement ProtocolAbstract   This document describes the Simple Two-way Active Measurement   Protocol (STAMP), which enables the measurement of both one-way and   round-trip performance metrics, like delay, delay variation, and   packet loss.Status of This Memo   This is an Internet Standards Track document.   This document is a product of the Internet Engineering Task Force   (IETF).  It represents the consensus of the IETF community.  It has   received public review and has been approved for publication by the   Internet Engineering Steering Group (IESG).  Further information on   Internet Standards is available in Section 2 of RFC 7841.   Information about the current status of this document, any errata,   and how to provide feedback on it may be obtained at   https://www.rfc-editor.org/info/rfc8762.Copyright Notice   Copyright (c) 2020 IETF Trust and the persons identified as the   document authors.  All rights reserved.   This document is subject to BCP 78 and the IETF Trust's Legal   Provisions Relating to IETF Documents   (https://trustee.ietf.org/license-info) in effect on the date of   publication of this document.  Please review these documents   carefully, as they describe your rights and restrictions with respect   to this document.  Code Components extracted from this document must   include Simplified BSD License text as described in Section 4.e of   the Trust Legal Provisions and are provided without warranty as   described in the Simplified BSD License.Table of Contents   1.  Introduction   2.  Conventions Used in This Document     2.1.  Terminology     2.2.  Requirements Language   3.  Operation and Management of Performance Measurement Based on           STAMP   4.  Theory of Operation     4.1.  UDP Port Numbers in STAMP Testing     4.2.  Session-Sender Behavior and Packet Format       4.2.1.  Session-Sender Packet Format in Unauthenticated Mode       4.2.2.  Session-Sender Packet Format in Authenticated Mode     4.3.  Session-Reflector Behavior and Packet Format       4.3.1.  Session-Reflector Packet Format in Unauthenticated Mode       4.3.2.  Session-Reflector Packet Format in Authenticated Mode     4.4.  Integrity Protection in STAMP     4.5.  Confidentiality Protection in STAMP     4.6.  Interoperability with TWAMP Light   5.  Operational Considerations   6.  IANA Considerations   7.  Security Considerations   8.  References     8.1.  Normative References     8.2.  Informative References   Acknowledgments   Authors' Addresses1.  Introduction   Development and deployment of the Two-Way Active Measurement Protocol   (TWAMP) [RFC5357] and its extensions (e.g., [RFC6038], which defines   Symmetrical Size for TWAMP) provided invaluable experience.  Several   independent implementations of both TWAMP and TWAMP Light exist, have   been deployed, and provide important operational performance   measurements.   At the same time, there has been noticeable interest in using a more   straightforward mechanism for active performance monitoring that can   provide deterministic behavior and inherent separation of control   (vendor-specific configuration or orchestration) and test functions.   Recent work on "Performance Measurement from IP Edge to Customer   Equipment using TWAMP Light" [BBF.TR-390] by the Broadband Forum   demonstrates that interoperability among implementations of TWAMP   Light is difficult because the composition and operation of TWAMP   Light were not sufficiently specified in [RFC5357].  According to   [RFC8545], TWAMP Light includes a subset of TWAMP-Test functions.   Thus, to have a comprehensive tool to measure packet loss and delay   requires support by other applications that provide, for example,   control and security.   This document defines an active performance measurement test   protocol, Simple Two-way Active Measurement Protocol (STAMP), that   enables measurement of both one-way and round-trip performance   metrics, like delay, delay variation, and packet loss.  Support of   some optional TWAMP extensions, e.g., [RFC7750], is discussed in   [STAMP-OPTION].2.  Conventions Used in This Document2.1.  Terminology   STAMP:      Simple Two-way Active Measurement Protocol   NTP:        Network Time Protocol   PTP:        Precision Time Protocol   HMAC:       Hashed Message Authentication Code   OWAMP:      One-Way Active Measurement Protocol   TWAMP:      Two-Way Active Measurement Protocol   MBZ:        Must be Zero   PDU:        Protocol Data Unit2.2.  Requirements Language   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and   "OPTIONAL" in this document are to be interpreted as described in   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all   capitals, as shown here.3.  Operation and Management of Performance Measurement Based on STAMP   Figure 1 presents the Simple Two-way Active Measurement Protocol   (STAMP) Session-Sender and Session-Reflector with a measurement   session.  In this document, a measurement session, also referred to   as a "STAMP session", is the bidirectional packet flow between one   specific Session-Sender and one particular Session-Reflector for a   time duration.  The configuration and management of the STAMP   Session-Sender, Session-Reflector, and sessions are outside the scope   of this document and can be achieved through various means.  A few   examples are Command Line Interface, telecommunication services'   Operational Support System (OSS) / Business Support System (BSS),   SNMP, and NETCONF/YANG-based Software-Defined Networking (SDN)   controllers.         o----------------------------------------------------------o         |                      Configuration and                   |         |                         Management                       |         o----------------------------------------------------------o                ||                                          ||                ||                                          ||                ||                                          ||     +----------------------+                +-------------------------+     | STAMP Session-Sender | <--- STAMP---> | STAMP Session-Reflector |     +----------------------+                +-------------------------+                      Figure 1: STAMP Reference Model4.  Theory of Operation   The STAMP Session-Sender transmits test packets over UDP transport   toward the STAMP Session-Reflector.  The STAMP Session-Reflector   receives the Session-Sender's packet and acts according to the   configuration.  Two modes of the STAMP Session-Reflector characterize   the expected behavior and, consequently, performance metrics that can   be measured:   Stateless:      The STAMP Session-Reflector does not maintain test state and will      use the value in the Sequence Number field in the received packet      as the value for the Sequence Number field in the reflected      packet.  As a result, values in the Sequence Number and Session-      Sender Sequence Number fields are the same, and only round-trip      packet loss can be calculated while the reflector is operating in      stateless mode.   Stateful:      STAMP Session-Reflector maintains the test state, thus allowing      the Session-Sender to determine directionality of loss using the      combination of gaps recognized in the Session Sender Sequence      Number and Sequence Number fields, respectively.  As a result,      both near-end (forward) and far-end (backward) packet loss can be      computed.  That implies that the STAMP Session-Reflector MUST      maintain a state for each configured STAMP-Test session, thereby      uniquely associating STAMP-Test packets with one such session      instance and, thus, enabling the addition of a sequence number in      the test reply that is individually incremented by one on a per-      session basis.   STAMP supports two authentication modes: unauthenticated and   authenticated.  Unauthenticated STAMP-Test packets, defined in   Sections 4.2.1 and 4.3.1, ensure interworking between STAMP and TWAMP   Light, as described in Section 4.6 regarding packet formats.   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.4.1.  UDP Port Numbers in STAMP Testing   A STAMP Session-Sender MUST use UDP port 862 (TWAMP-Test Receiver   Port) as the default destination UDP port number.  A STAMP   implementation of the Session-Sender MUST be able to be used as the   destination UDP port numbers from the User Ports (aka Registered   Ports) and Dynamic Ports (aka Private or Ephemeral Ports) ranges   defined in [RFC6335].  Before using numbers from the User Ports   range, the possible impact on the network MUST be carefully studied   and agreed on by all users of the network domain where the test has   been planned.   By default, an implementation of the STAMP Session-Reflector MUST   receive STAMP-Test packets on UDP port 862.  An implementation of the   Session-Reflector that supports this specification MUST be able to   define the port number to receive STAMP-Test packets from User Ports   and Dynamic Ports ranges, which are defined in [RFC6335].  STAMP   defines two different test packet formats: one for packets   transmitted by the STAMP Session-Sender and one for packets   transmitted by the STAMP Session-Reflector.4.2.  Session-Sender Behavior and Packet Format   A STAMP Session-Reflector supports the symmetrical size of test   packets, as defined in Section 3 of [RFC6038], as the default   behavior.  A reflected base test packet includes information from the   Session-Reflector and, thus, is larger.  To maintain the symmetry   between base STAMP packets, the base STAMP Session-Sender packet   includes the Must-Be-Zero (MBZ) field to match to the size of a base   reflected STAMP test packet.  Hence, the base STAMP Session-Sender   packet has a minimum size of 44 octets in unauthenticated mode (see   Figure 2) and 112 octets in the authenticated mode (see Figure 4).   Generating variable length of a test packet in STAMP is defined in   [STAMP-OPTION].4.2.1.  Session-Sender Packet Format in Unauthenticated Mode       0                   1                   2                   3       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |                        Sequence Number                        |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |                          Timestamp                            |      |                                                               |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |         Error Estimate        |                               |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +      |                                                               |      |                                                               |      |                        MBZ  (30 octets)                       |      |                                                               |      |                                                               |      |                                                               |      |                                                               |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+            Figure 2: STAMP Session-Sender Test Packet Format in                            Unauthenticated Mode   The fields are defined as following:   *  The Sequence Number field is four octets long.  For each new      session, its value starts at zero and is incremented by one with      each transmitted packet.   *  The Timestamp field is eight octets long.  The STAMP node MUST      support the Network Time Protocol (NTP) version 4 64-bit timestamp      format [RFC5905], the format used in [RFC5357].  The STAMP node      MAY support the IEEE 1588v2 Precision Time Protocol (PTP)      truncated 64-bit timestamp format [IEEE.1588.2008], the format      used in [RFC8186].  The use of the specific format, NTP or PTP, is      part of configuration of the Session-Sender or the particular test      session.   *  The Error Estimate field is two octets long with the format      displayed in Figure 3:               0                   1               0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5              +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+              |S|Z|   Scale   |   Multiplier  |              +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                       Figure 3: Error Estimate Format      The S, Scale, and Multiplier fields are interpreted as they are      defined in Section 4.1.2 of [RFC4656].  The Z field is interpreted      as it is defined in Section 2.3 of [RFC8186]:      0:  NTP 64-bit format of a timestamp      1:  PTPv2 truncated format of a timestamp      The default behavior of the STAMP Session-Sender and Session-      Reflector is to use the NTP 64-bit timestamp format (Z field value      of 0).  An operator using configuration/management function MAY      configure the STAMP Session-Sender and Session-Reflector to use      the PTPv2 truncated format of a timestamp (Z field value of 1).      Note that an implementation of a Session-Sender that supports this      specification MAY be configured to use the PTPv2 format of a      timestamp even though the Session-Reflector is configured to use      NTP format.   *  The MBZ field in the Session-Sender unauthenticated packet is 30      octets long.  It MUST be all zeroed on the transmission and MUST      be ignored on receipt.4.2.2.  Session-Sender Packet Format in Authenticated Mode     0                   1                   2                   3     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+    |                      Sequence Number                          |    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+    |                                                               |    |                      MBZ (12 octets)                          |    |                                                               |    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+    |                        Timestamp                              |    |                                                               |    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+    |        Error Estimate         |                               |    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +    ~                                                               ~    |                         MBZ (70 octets)                       |    ~                                                               ~    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+    |                                                               |    |                       HMAC (16 octets)                        |    |                                                               |    |                                                               |    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+            Figure 4: STAMP Session-Sender Test Packet Format in                             Authenticated Mode   The field definitions are the same as the unauthenticated mode,   listed in Section 4.2.1.  Also, MBZ fields are used to make the   packet length a multiple of 16 octets.  The value of the field MUST   be zeroed on transmission and MUST be ignored on receipt.  Note, that   both MBZ fields are used to calculate a key hashed message   authentication code (HMAC) [RFC2104] hash.  Also, the packet includes   an HMAC hash at the end of the PDU.  The detailed use of the HMAC   field is described in Section 4.4.4.3.  Session-Reflector Behavior and Packet Format   The Session-Reflector receives the STAMP-Test packet and verifies it.   If the base STAMP-Test packet is validated, the Session-Reflector   that supports this specification prepares and transmits the reflected   test packet symmetric to the packet received from the Session-Sender   copying the content beyond the size of the base STAMP packet (see   Section 4.2).4.3.1.  Session-Reflector Packet Format in Unauthenticated Mode     0                   1                   2                   3     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+    |                        Sequence Number                        |    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+    |                          Timestamp                            |    |                                                               |    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+    |         Error Estimate        |            MBZ                |    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+    |                          Receive Timestamp                    |    |                                                               |    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+    |                 Session-Sender Sequence Number                |    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+    |                  Session-Sender Timestamp                     |    |                                                               |    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+    | Session-Sender Error Estimate |            MBZ                |    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+    |Ses-Sender TTL |                      MBZ                      |    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+          Figure 5: STAMP Session-Reflector Test Packet Format in                            Unauthenticated Mode   Fields are defined as the following:   *  The Sequence Number field is four octets long.  The value of the      Sequence Number field is set according to the mode of the STAMP      Session-Reflector:      -  In the stateless mode, the Session-Reflector copies the value         from the received STAMP-Test packet's Sequence Number field.      -  In the stateful mode, the Session-Reflector counts the         transmitted STAMP-Test packets.  It starts with zero and is         incremented by one for each subsequent packet for each test         session.  The Session-Reflector uses that counter to set the         value of the Sequence Number field.   *  The Timestamp and Receive Timestamp fields are each eight octets      long.  The format of these fields, NTP or PTPv2, is indicated by      the Z field of the Error Estimate field, as described in      Section 4.2.1.  Receive Timestamp is the time the test packet was      received by the Session-Reflector.  Timestamp is the time taken by      the Session-Reflector at the start of transmitting the test      packet.   *  The Error Estimate field has the same size and interpretation as      described in Section 4.2.1.  It is applicable to both Timestamp      and Receive Timestamp.   *  The Session-Sender Sequence Number, Session-Sender Timestamp, and      Session-Sender Error Estimate fields are copies of the      corresponding fields in the STAMP-Test packet sent by the Session-      Sender.   *  The Session-Sender TTL field is one octet long, and its value is      the copy of the TTL field in IPv4 (or Hop Limit in IPv6) from the      received STAMP-Test packet.   *  The MBZ fields are used to achieve alignment of fields within the      packet on a four-octet boundary.  The value of each MBZ field MUST      be zeroed on transmission and MUST be ignored on receipt.4.3.2.  Session-Reflector Packet Format in Authenticated Mode      0                   1                   2                   3      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |                        Sequence Number                        |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |                        MBZ (12 octets)                        |      |                                                               |      |                                                               |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |                          Timestamp                            |      |                                                               |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |         Error Estimate        |                               |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +      |                        MBZ (6 octets)                         |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |                        Receive Timestamp                      |      |                                                               |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |                        MBZ (8 octets)                         |      |                                                               |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |                 Session-Sender Sequence Number                |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |                        MBZ (12 octets)                        |      |                                                               |      |                                                               |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |                 Session-Sender Timestamp                      |      |                                                               |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      | Session-Sender Error Estimate |                               |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +      |                        MBZ (6 octets)                         |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |Ses-Sender TTL |                                               |      +-+-+-+-+-+-+-+-+                                               +      |                                                               |      |                        MBZ (15 octets)                        |      |                                                               |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |                        HMAC (16 octets)                       |      |                                                               |      |                                                               |      |                                                               |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+          Figure 6: STAMP Session-Reflector Test Packet Format in                             Authenticated Mode   The field definitions are the same as the unauthenticated mode,   listed in Section 4.3.1.  Additionally, the MBZ field is used to make   the packet length a multiple of 16 octets.  The value of the field   MUST be zeroed on transmission and MUST be ignored on receipt.  Note   that the MBZ field is used to calculate the HMAC hash value.  Also,   the STAMP Session-Reflector test packet format in authenticated mode   includes the HMAC [RFC2104] hash at the end of the PDU.  The detailed   use of the HMAC field is in Section 4.4.4.4.  Integrity Protection in STAMP   Authenticated mode provides integrity protection to each STAMP   message by adding Hashed Message Authentication Code (HMAC).  STAMP   uses HMAC-SHA-256 truncated to 128 bits (similarly to the use of it   in IPsec defined in [RFC4868]); hence, the length of the HMAC field   is 16 octets.  In the authenticated mode, HMAC covers the first six   blocks (96 octets).  HMAC uses its own key, which may be unique for   each STAMP-Test session; key management and the mechanisms to   distribute the HMAC key are outside the scope of this specification.   One example is to use an orchestrator to configure the HMAC key based   on the STAMP YANG data model [STAMP-YANG].  HMAC MUST be verified as   early as possible to avoid using or propagating corrupted data.   Future specifications may define the use of other, more advanced   cryptographic algorithms, possibly providing an update to the STAMP   YANG data model [STAMP-YANG].4.5.  Confidentiality Protection in STAMP   If confidentiality protection for STAMP is required, a STAMP-Test   session MUST use a secured transport.  For example, STAMP packets   could be transmitted in the dedicated IPsec tunnel or share the IPsec   tunnel with the monitored flow.  Also, the Datagram Transport Layer   Security protocol would provide the desired confidentiality   protection.4.6.  Interoperability with TWAMP Light   One of the essential requirements to STAMP is the ability to   interwork with a TWAMP Light device.  Because STAMP and TWAMP use   different algorithms in authenticated mode (HMAC-SHA-256 versus HMAC-   SHA-1), interoperability is only considered for unauthenticated mode.   There are two possible combinations for such a use case:   *  STAMP Session-Sender with TWAMP Light Session-Reflector   *  TWAMP Light Session-Sender with STAMP Session-Reflector   In the former case, the Session-Sender might not be aware that its   Session-Reflector does not support STAMP.  For example, a TWAMP Light   Session-Reflector may not support the use of UDP port 862, as   specified in [RFC8545].  Thus, Section 4 permits a STAMP Session-   Sender to use alternative ports.  If any of STAMP extensions are   used, the TWAMP Light Session-Reflector will view them as the Packet   Padding field.   In the latter scenario, if a TWAMP Light Session-Sender does not   support the use of UDP port 862, the test management system MUST set   the STAMP Session-Reflector to use UDP port number, as permitted by   Section 4.  The Session-Reflector MUST be set to use the default   format for its timestamps, NTP.   A STAMP Session-Reflector that supports this specification will   transmit the base packet (Figure 5) if it receives a packet smaller   than the STAMP base packet.  If the packet received from the TWAMP   Session-Sender is larger than the STAMP base packet, the STAMP   Session-Reflector that supports this specification will copy the   content of the remainder of the received packet to transmit a   reflected packet of symmetrical size.5.  Operational Considerations   STAMP is intended to be used on production networks to enable the   operator to assess service level agreements based on packet delay,   delay variation, and loss.  When using STAMP over the Internet,   especially when STAMP-Test packets are transmitted with the   destination UDP port number from the User Ports range, the possible   impact of the STAMP-Test packets MUST be thoroughly analyzed.  The   use of STAMP for each case MUST be agreed by users of nodes hosting   the Session-Sender and Session-Reflector before starting the STAMP-   Test session.   Also, the use of the well-known port number as the destination UDP   port number in STAMP-Test packets transmitted by a Session-Sender   would not impede the ability to measure performance in an Equal-Cost   Multipath environment, and analysis in Section 5.3 of [RFC8545] fully   applies to STAMP.6.  IANA Considerations   This document has no IANA actions.7.  Security Considerations   [RFC5357] does not identify security considerations specific to   TWAMP-Test but refers to security considerations identified for OWAMP   in [RFC4656].  Since both OWAMP and TWAMP include control-plane and   data-plane components, only security considerations related to OWAMP-   Test discussed in Sections 6.2 and 6.3 of [RFC4656] apply to STAMP.   STAMP uses the well-known UDP port number allocated for the OWAMP-   Test/TWAMP-Test Receiver Port.  Thus, the security considerations and   measures to mitigate the risk of the attack using the registered port   number documented in Section 6 of [RFC8545] equally apply to STAMP.   Because of the control and management of a STAMP-Test being outside   the scope of this specification, only the more general requirement is   set:      To mitigate the possible attack vector, the control and management      of a STAMP-Test session MUST use the secured transport.      The load of the STAMP-Test packets offered to a network MUST be      carefully estimated, and the possible impact on the existing      services MUST be thoroughly analyzed before launching the test      session.  Section 3.1.5 of [RFC8085] provides guidance on handling      network load for UDP-based protocol.  While the characteristic of      test traffic depends on the test objective, it is highly      recommended to stay in the limits, as provided in [RFC8085].   Use of HMAC-SHA-256 in the authenticated mode protects the data   integrity of the STAMP-Test packets.8.  References8.1.  Normative References   [IEEE.1588.2008]              IEEE, "IEEE Standard for a Precision Clock Synchronization              Protocol for Networked Measurement and Control Systems",              IEEE Standard 1588, July 2008.   [RFC2104]  Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-              Hashing for Message Authentication", RFC 2104,              DOI 10.17487/RFC2104, February 1997,              <https://www.rfc-editor.org/info/rfc2104>.   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate              Requirement Levels", BCP 14, RFC 2119,              DOI 10.17487/RFC2119, March 1997,              <https://www.rfc-editor.org/info/rfc2119>.   [RFC4656]  Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M.              Zekauskas, "A One-way Active Measurement Protocol              (OWAMP)", RFC 4656, DOI 10.17487/RFC4656, September 2006,              <https://www.rfc-editor.org/info/rfc4656>.   [RFC5357]  Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J.              Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)",              RFC 5357, DOI 10.17487/RFC5357, October 2008,              <https://www.rfc-editor.org/info/rfc5357>.   [RFC5905]  Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch,              "Network Time Protocol Version 4: Protocol and Algorithms              Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010,              <https://www.rfc-editor.org/info/rfc5905>.   [RFC6038]  Morton, A. and L. Ciavattone, "Two-Way Active Measurement              Protocol (TWAMP) Reflect Octets and Symmetrical Size              Features", RFC 6038, DOI 10.17487/RFC6038, October 2010,              <https://www.rfc-editor.org/info/rfc6038>.   [RFC6335]  Cotton, M., Eggert, L., Touch, J., Westerlund, M., and S.              Cheshire, "Internet Assigned Numbers Authority (IANA)              Procedures for the Management of the Service Name and              Transport Protocol Port Number Registry", BCP 165,              RFC 6335, DOI 10.17487/RFC6335, August 2011,              <https://www.rfc-editor.org/info/rfc6335>.   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,              May 2017, <https://www.rfc-editor.org/info/rfc8174>.   [RFC8186]  Mirsky, G. and I. Meilik, "Support of the IEEE 1588              Timestamp Format in a Two-Way Active Measurement Protocol              (TWAMP)", RFC 8186, DOI 10.17487/RFC8186, June 2017,              <https://www.rfc-editor.org/info/rfc8186>.   [RFC8545]  Morton, A., Ed. and G. Mirsky, Ed., "Well-Known Port              Assignments for the One-Way Active Measurement Protocol              (OWAMP) and the Two-Way Active Measurement Protocol              (TWAMP)", RFC 8545, DOI 10.17487/RFC8545, March 2019,              <https://www.rfc-editor.org/info/rfc8545>.8.2.  Informative References   [BBF.TR-390]              Broadband Forum, "Performance Measurement from IP Edge to              Customer Equipment using TWAMP Light", TR-390 Issue 1, May              2017.   [RFC4868]  Kelly, S. and S. Frankel, "Using HMAC-SHA-256, HMAC-SHA-              384, and HMAC-SHA-512 with IPsec", RFC 4868,              DOI 10.17487/RFC4868, May 2007,              <https://www.rfc-editor.org/info/rfc4868>.   [RFC7750]  Hedin, J., Mirsky, G., and S. Baillargeon, "Differentiated              Service Code Point and Explicit Congestion Notification              Monitoring in the Two-Way Active Measurement Protocol              (TWAMP)", RFC 7750, DOI 10.17487/RFC7750, February 2016,              <https://www.rfc-editor.org/info/rfc7750>.   [RFC8085]  Eggert, L., Fairhurst, G., and G. Shepherd, "UDP Usage              Guidelines", BCP 145, RFC 8085, DOI 10.17487/RFC8085,              March 2017, <https://www.rfc-editor.org/info/rfc8085>.   [STAMP-OPTION]              Mirsky, G., Xiao, M., Nydell, H., Foote, R., Masputra, A.,              and E. Ruffini, "Simple Two-way Active Measurement              Protocol Optional Extensions", Work in Progress, Internet-              Draft, draft-ietf-ippm-stamp-option-tlv-03, 21 February              2020, <https://tools.ietf.org/html/draft-ietf-ippm-stamp-              option-tlv-03>.   [STAMP-YANG]              Mirsky, G., Xiao, M., and W. Luo, "Simple Two-way Active              Measurement Protocol (STAMP) Data Model", Work in              Progress, Internet-Draft, draft-ietf-ippm-stamp-yang-05,              25 October 2019, <https://tools.ietf.org/html/draft-ietf-              ippm-stamp-yang-05>.Acknowledgments   The authors express their appreciation to Jose Ignacio Alvarez-   Hamelin and Brian Weis for their great insights into the security and   identity protection as well as the most helpful and practical   suggestions.  Also, our sincere thanks to David Ball, Rakesh Gandhi,   and Xiao Min for their thorough reviews and helpful comments.Authors' Addresses   Greg Mirsky   ZTE Corp.   Email: gregimirsky@gmail.com   Guo Jun   ZTE Corp.   68# Zijinghua Road   Nanjing   Jiangsu, 210012   China   Phone: +86 18105183663   Email: guo.jun2@zte.com.cn   Henrik Nydell   Accedian Networks   Email: hnydell@accedian.com   Richard Foote   Nokia   Email: footer.foote@nokia.com