IP Performance Measurement G. White Internet-Draft CableLabs Intended status: Standards Track 10 December 2024 Expires: 13 June 2025 Simple Two-Way Active Measurement Protocol (STAMP) Extension for DSCP and ECN Traversal Measurement draft-white-ippm-stamp-ecn-00 Abstract The Simple Two-Way Active Measurement Protocol (STAMP) enables one- way and round-trip measurement of network metrics between IP hosts, and has a facility for defining optional extensions. This document defines a STAMP extension to enable the measurement of manipulation of the value of the explicit congestion notification (ECN) field of the IP header by middleboxes between two STAMP hosts, and to enable discovery and measurement of paths that provide differential treatment of packets depending on the value of their ECN field. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on 13 June 2025. Copyright Notice Copyright (c) 2024 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 White Expires 13 June 2025 [Page 1] Internet-Draft STAMP ECN December 2024 extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 2 2. DSCP and ECN Traversal STAMP Extension . . . . . . . . . . . 2 3. Implementation Status . . . . . . . . . . . . . . . . . . . . 4 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 5. Security Considerations . . . . . . . . . . . . . . . . . . . 4 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 6.1. Normative References . . . . . . . . . . . . . . . . . . 4 6.2. Informative References . . . . . . . . . . . . . . . . . 5 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 5 Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 6 1. Introduction Section 4.4 of [RFC8972] defines a "Class of Service TLV" extension for the STAMP protocol [RFC8762] which enables bi-directional measurement of manipulation of the differentiated services code point (DSCP) field of the IP header by middleboxes [RFC2474] but only allows one-way measurement of manipulation of the ECN field of the IP header by [RFC3168][RFC8311][RFC9331] middleboxes. Since the ECN field of the IP header is separately meaningful in each direction, it is valuable to have the capability to perform bi-directional measurements of ECN traversal and to have the abilty to measure path characteristics that depend on the value of the ECN codepoint. In addition, bi-directional measurements are important to isolate traversal issues so that remediation actions can be taken appropriately. 1.1. 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. 2. DSCP and ECN Traversal STAMP Extension The STAMP session-sender MAY include a DSCP and ECN TLV in the STAMP test packet. The format of the TLV is presented in Figure 1. White Expires 13 June 2025 [Page 2] Internet-Draft STAMP ECN December 2024 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | DSCP1 |EC1| DSCP2 |EC2| RP| Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1: DSCP and ECN Traversal TLV The fields are defined as follows. * STAMP TLV Flags: eight-bit field; format presented in [RFC8972]. * Type: one-octet field; value 179 allocated by this specification * Length: two-octet field; set equal to the value 4 octets * DSCP1: DSCP value intended by the session-sender to be used as the DSCP value of the reflected test packet * EC1: ECN value intended by the session-sender to be used as the ECN value of the reflected test packet * DSCP2: received value in the DSCP field at the ingress of the session-reflector * EC2: received value in the ECN field at the ingress of the session-reflector * RP (reverse path): two-bit field; a session-sender MUST set the value of the RP field to 0 on transmission * Reserved: fourteen-bit field to be zeroed on transmission and ignored on receipt A session-reflector that receives a test packet with the DSCP and ECN Traversal TLV MUST include the DSCP and ECN Traversal TLV in the reflected test packet. The session-reflector MUST copy the value of the DSCP and ECN fields of the IP header of the received STAMP test packet into the DSCP2 field and EC2 field in the reflected test packet. The session-reflector MUST set the value of the ECN field in the IP header of the reflected test packet equal to the value in the EC1 field of the received test packet. White Expires 13 June 2025 [Page 3] Internet-Draft STAMP ECN December 2024 Finally, the session-reflector MUST use the local policy to verify whether the CoS corresponding to the value of the DSCP1 field is permitted in the domain. If the corresponding CoS is permitted in the domain, the session-reflector MUST 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. If the corresponding CoS is not permitted in the domain, the session-reflector MUST 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. 3. Implementation Status The author is aware of two independent implementations of this STAMP Extension TLV, one of which is publicly available here (https://github.com/cerfcast/teaparty). 4. IANA Considerations Add this extension to the IANA STAMP TLV Types (https://www.iana.org/assignments/stamp-tlv-types/stamp-tlv- types.xhtml#stamp-tlv-types-1) Registry. * Value = 179 * Description = "DSCP and ECN Traversal" * Reference = this document 5. Security Considerations This document should not affect the security of the Internet. 6. References 6.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . White Expires 13 June 2025 [Page 4] Internet-Draft STAMP ECN December 2024 [RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black, "Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers", RFC 2474, DOI 10.17487/RFC2474, December 1998, . [RFC3168] Ramakrishnan, K., Floyd, S., and D. Black, "The Addition of Explicit Congestion Notification (ECN) to IP", RFC 3168, DOI 10.17487/RFC3168, September 2001, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC8762] Mirsky, G., Jun, G., Nydell, H., and R. Foote, "Simple Two-Way Active Measurement Protocol", RFC 8762, DOI 10.17487/RFC8762, March 2020, . [RFC8972] Mirsky, G., Min, X., Nydell, H., Foote, R., Masputra, A., and E. Ruffini, "Simple Two-Way Active Measurement Protocol Optional Extensions", RFC 8972, DOI 10.17487/RFC8972, January 2021, . 6.2. Informative References [RFC8311] Black, D., "Relaxing Restrictions on Explicit Congestion Notification (ECN) Experimentation", RFC 8311, DOI 10.17487/RFC8311, January 2018, . [RFC9331] De Schepper, K. and B. Briscoe, Ed., "The Explicit Congestion Notification (ECN) Protocol for Low Latency, Low Loss, and Scalable Throughput (L4S)", RFC 9331, DOI 10.17487/RFC9331, January 2023, . Acknowledgements TBD Contributors Karthik Sundaresan, William Hawkins III White Expires 13 June 2025 [Page 5] Internet-Draft STAMP ECN December 2024 Author's Address Greg White CableLabs 858 Coal Creek Circle Louisville, Colorado 80027 United States of America Email: g.white@cablelabs.com URI: http://www.cablelabs.com White Expires 13 June 2025 [Page 6]