ZTE Corp.

gregimirsky@gmail.com

ZTE Corp.

68# Zijinghua Road Nanjing Jiangsu 210012 China +86 18105183663 guo.jun2@zte.com.cn

Accedian Networks

hnydell@accedian.com

Nokia

footer.foote@nokia.com

Transport Network Working Group IPPM Performance Measurement 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 .

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 () 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

• .  Introduction
• .  Conventions Used in This Document
  • .  Terminology
  • .  Requirements Language
• .  Operation and Management of Performance Measurement Based on STAMP
• .  Theory of Operation
  • .  UDP Port Numbers in STAMP Testing
  • .  Session-Sender Behavior and Packet Format
    • .  Session-Sender Packet Format in Unauthenticated Mode
    • .  Session-Sender Packet Format in Authenticated Mode
  • .  Session-Reflector Behavior and Packet Format
    • .  Session-Reflector Packet Format in Unauthenticated Mode
    • .  Session-Reflector Packet Format in Authenticated Mode
  • .  Integrity Protection in STAMP
  • .  Confidentiality Protection in STAMP
  • .  Interoperability with TWAMP Light
• .  Operational Considerations
• .  IANA Considerations
• .  Security Considerations
• .  References
  • .  Normative References
  • .  Informative References
• Acknowledgments
• Authors' Addresses

Introduction Development and deployment of the Two-Way Active Measurement Protocol (TWAMP) and its extensions (e.g., , 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" 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 . According to , 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., , is discussed in .

Conventions Used in This Document

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 Unit

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 when, and only when, they appear in all capitals, as shown here.

Operation and Management of Performance Measurement Based on STAMP 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.

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

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 and , ensure interworking between STAMP and TWAMP Light, as described in 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.

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 . 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 . 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.

Session-Sender Behavior and Packet Format A STAMP Session-Reflector supports the symmetrical size of test packets, as defined in , 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 ) and 112 octets in the authenticated mode (see ). Generating variable length of a test packet in STAMP is defined in .

Session-Sender Packet Format in Unauthenticated Mode

STAMP Session-Sender Test 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) | | | | | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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 , the format used in . The STAMP node MAY support the IEEE 1588v2 Precision Time Protocol (PTP) truncated 64-bit timestamp format , the format used in . 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 :

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

  The S, Scale, and Multiplier fields are interpreted as they are defined in . The Z field is interpreted as it is defined in :

  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.

Session-Sender Packet Format in Authenticated Mode

STAMP Session-Sender Test 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) | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

The field definitions are the same as the unauthenticated mode, listed in . 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) hash. Also, the packet includes an HMAC hash at the end of the PDU. The detailed use of the HMAC field is described in .

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 ).

Session-Reflector Packet Format in Unauthenticated Mode

STAMP Session-Reflector Test 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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 . 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 . 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.

Session-Reflector Packet Format in Authenticated Mode

STAMP Session-Reflector Test 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) | | | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

The field definitions are the same as the unauthenticated mode, listed in . 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 hash at the end of the PDU. The detailed use of the HMAC field is in .

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 ); 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 . 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 .

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.

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 . Thus, 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 . 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 () 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.

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 fully applies to STAMP.

IANA Considerations This document has no IANA actions.

Security Considerations does not identify security considerations specific to TWAMP-Test but refers to security considerations identified for OWAMP in . Since both OWAMP and TWAMP include control-plane and data-plane components, only security considerations related to OWAMP-Test discussed in Sections and of 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 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. 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 .

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

References Normative References IEEE This document describes HMAC, a mechanism for message authentication using cryptographic hash functions. HMAC can be used with any iterative cryptographic hash function, e.g., MD5, SHA-1, in combination with a secret shared key. The cryptographic strength of HMAC depends on the properties of the underlying hash function. This memo provides information for the Internet community. This memo does not specify an Internet standard of any kind In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. The One-Way Active Measurement Protocol (OWAMP) measures unidirectional characteristics such as one-way delay and one-way loss. High-precision measurement of these one-way IP performance metrics became possible with wider availability of good time sources (such as GPS and CDMA). OWAMP enables the interoperability of these measurements. [STANDARDS-TRACK] The One-way Active Measurement Protocol (OWAMP), specified in RFC 4656, provides a common protocol for measuring one-way metrics between network devices. OWAMP can be used bi-directionally to measure one-way metrics in both directions between two network elements. However, it does not accommodate round-trip or two-way measurements. This memo specifies a Two-Way Active Measurement Protocol (TWAMP), based on the OWAMP, that adds two-way or round-trip measurement capabilities. The TWAMP measurement architecture is usually comprised of two hosts with specific roles, and this allows for some protocol simplifications, making it an attractive alternative in some circumstances. [STANDARDS-TRACK] The Network Time Protocol (NTP) is widely used to synchronize computer clocks in the Internet. This document describes NTP version 4 (NTPv4), which is backwards compatible with NTP version 3 (NTPv3), described in RFC 1305, as well as previous versions of the protocol. NTPv4 includes a modified protocol header to accommodate the Internet Protocol version 6 address family. NTPv4 includes fundamental improvements in the mitigation and discipline algorithms that extend the potential accuracy to the tens of microseconds with modern workstations and fast LANs. It includes a dynamic server discovery scheme, so that in many cases, specific server configuration is not required. It corrects certain errors in the NTPv3 design and implementation and includes an optional extension mechanism. [STANDARDS-TRACK] This memo describes two closely related features for the core specification of the Two-Way Active Measurement Protocol (TWAMP): an optional capability where the responding host returns some of the command octets or padding octets to the sender, and an optional sender packet format that ensures equal test packet sizes are used in both directions. [STANDARDS-TRACK] This document defines the procedures that the Internet Assigned Numbers Authority (IANA) uses when handling assignment and other requests related to the Service Name and Transport Protocol Port Number registry. It also discusses the rationale and principles behind these procedures and how they facilitate the long-term sustainability of the registry. This document updates IANA's procedures by obsoleting the previous UDP and TCP port assignment procedures defined in Sections 8 and 9.1 of the IANA Allocation Guidelines, and it updates the IANA service name and port assignment procedures for UDP-Lite, the Datagram Congestion Control Protocol (DCCP), and the Stream Control Transmission Protocol (SCTP). It also updates the DNS SRV specification to clarify what a service name is and how it is registered. This memo documents an Internet Best Current Practice. RFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings. This document describes an OPTIONAL feature for active performance measurement protocols that allows use of the Precision Time Protocol timestamp format defined in IEEE 1588v2, as an alternative to the Network Time Protocol that is currently used. This memo explains the motivation and describes the reassignment of well-known ports for the One-Way Active Measurement Protocol (OWAMP) and the Two-Way Active Measurement Protocol (TWAMP) for control and measurement. It also clarifies the meaning and composition of these Standards Track protocol names for the industry. This memo updates RFCs 4656 and 5357, in terms of the UDP well-known port assignments, and it clarifies the complete OWAMP and TWAMP protocol composition for the industry. Informative References Broadband Forum This specification describes the use of Hashed Message Authentication Mode (HMAC) in conjunction with the SHA-256, SHA-384, and SHA-512 algorithms in IPsec. These algorithms may be used as the basis for data origin authentication and integrity verification mechanisms for the Authentication Header (AH), Encapsulating Security Payload (ESP), Internet Key Exchange Protocol (IKE), and IKEv2 protocols, and also as Pseudo-Random Functions (PRFs) for IKE and IKEv2. Truncated output lengths are specified for the authentication-related variants, with the corresponding algorithms designated as HMAC-SHA-256-128, HMAC-SHA-384-192, and HMAC-SHA-512-256. The PRF variants are not truncated, and are called PRF-HMAC-SHA-256, PRF-HMAC-SHA-384, and PRF-HMAC-SHA-512. [STANDARDS-TRACK] This document describes an optional extension for Two-Way Active Measurement Protocol (TWAMP) allowing the monitoring of the Differentiated Service Code Point and Explicit Congestion Notification fields with the TWAMP-Test protocol. The User Datagram Protocol (UDP) provides a minimal message-passing transport that has no inherent congestion control mechanisms. This document provides guidelines on the use of UDP for the designers of applications, tunnels, and other protocols that use UDP. Congestion control guidelines are a primary focus, but the document also provides guidance on other topics, including message sizes, reliability, checksums, middlebox traversal, the use of Explicit Congestion Notification (ECN), Differentiated Services Code Points (DSCPs), and ports. Because congestion control is critical to the stable operation of the Internet, applications and other protocols that choose to use UDP as an Internet transport must employ mechanisms to prevent congestion collapse and to establish some degree of fairness with concurrent traffic. They may also need to implement additional mechanisms, depending on how they use UDP. Some guidance is also applicable to the design of other protocols (e.g., protocols layered directly on IP or via IP-based tunnels), especially when these protocols do not themselves provide congestion control. This document obsoletes RFC 5405 and adds guidelines for multicast UDP usage. This document describes optional extensions to Simple Two-way Active Measurement Protocol (STAMP) which enable measurement performance metrics in addition to ones supported by the STAMP base specification. Work in Progress This document specifies the data model for implementations of Session-Sender and Session-Reflector for Simple Two-way Active Measurement Protocol (STAMP) mode using YANG. Work in Progress

Acknowledgments The authors express their appreciation to and for their great insights into the security and identity protection as well as the most helpful and practical suggestions. Also, our sincere thanks to , , and for their thorough reviews and helpful comments.

Authors' Addresses ZTE Corp.

gregimirsky@gmail.com

ZTE Corp.

68# Zijinghua Road Nanjing Jiangsu 210012 China +86 18105183663 guo.jun2@zte.com.cn

Accedian Networks

hnydell@accedian.com

Nokia

footer.foote@nokia.com