Standard Communication with Network Elements R. Kejriwal Internet-Draft G. Fairhurst Intended status: Standards Track University of Aberdeen Expires: 27 April 2027 24 October 2026 QUIC Logging for the SCONE Protocol draft-kejriwal-scone-scone-qlog-00 Abstract This document defines qlog events for the Standard Communication with Network Elements (SCONE) protocol. The events record the sending and reception of SCONE packets and changes to throughput advice. About This Document This note is to be removed before publishing as an RFC. The latest revision of this draft can be found at https://RaghavKej.github.io/scone-qlog/draft-kejriwal-scone-scone- qlog.html. Status information for this document may be found at https://datatracker.ietf.org/doc/draft-kejriwal-scone-scone-qlog/. Discussion of this document takes place on the Standard Communication with Network Elements Working Group mailing list (mailto:scone@ietf.org), which is archived at https://mailarchive.ietf.org/arch/browse/scone. Subscribe at https://www.ietf.org/mailman/listinfo/scone/. Source for this draft and an issue tracker can be found at https://github.com/RaghavKej/scone-qlog. 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." Kejriwal & Fairhurst Expires 27 April 2027 [Page 1] Internet-Draft scone-qlog October 2026 This Internet-Draft will expire on 27 April 2027. Copyright Notice Copyright (c) 2026 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 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 2. Conventions and Definitions . . . . . . . . . . . . . . . . . 3 3. SCONE Rate Signal Data Type . . . . . . . . . . . . . . . . . 3 4. SCONE Event Schema Definition . . . . . . . . . . . . . . . . 4 4.1. Draft Event Schema Identification . . . . . . . . . . . . 4 5. SCONE Events . . . . . . . . . . . . . . . . . . . . . . . . 4 5.1. scone:packet_sent . . . . . . . . . . . . . . . . . . . . 4 5.2. scone:packet_received . . . . . . . . . . . . . . . . . . 5 5.3. scone:advice_updated . . . . . . . . . . . . . . . . . . 6 5.4. scone:advice_expired . . . . . . . . . . . . . . . . . . 7 6. Security Considerations . . . . . . . . . . . . . . . . . . . 7 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 8. Normative References . . . . . . . . . . . . . . . . . . . . 8 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 1. Introduction [SCONE] describes a protocol where on-path network elements can communicate their perspective on the maximum sustainable throughput for QUIC flows to endpoints. This throughput advice suggests an upper bound on long-term average throughput, independent of and complementary to real-time congestion control signals. This document defines the qlog namespace and events that record the sending and reception of SCONE packets and changes to throughput advice, allowing for debugging of implementations and reconstruction of the packets received. Kejriwal & Fairhurst Expires 27 April 2027 [Page 2] Internet-Draft scone-qlog October 2026 The event namespace with the identifier scone is defined in Section 4. Table 1 summarises the qlog events described in this document. +=======================+============+=============+ | Event Name | Importance | Definition | +=======================+============+=============+ | scone:packet_sent | Core | Section 5.1 | +-----------------------+------------+-------------+ | scone:packet_received | Core | Section 5.2 | +-----------------------+------------+-------------+ | scone:advice_updated | Base | Section 5.3 | +-----------------------+------------+-------------+ | scone:advice_expired | Base | Section 5.4 | +-----------------------+------------+-------------+ Table 1: Overview of SCONE qlog events. 2. Conventions and Definitions 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. The event and data structure definitions in this document are expressed in the Concise Data Definition Language [CDDL] and its extensions described in Section 1.2 of [QLOG-SCHEMA]. This document follows the language used in [SCONE]: * "Throughput advice" refers to the information communicated to endpoints by network elements in the form of a 7-bit rate signal * A "monitoring period" is the time over which rate signals apply (67 seconds [SCONE]). 3. SCONE Rate Signal Data Type A Rate Signal n in the range 0 to 126 maps to a ceiling bitrate of 100,000 * 10^(n/20) bits per second [SCONE]. The value 127 carries no throughput advice. SCONERateSignal = 0..127 SCONEKnownRateSignal = 0..126 Kejriwal & Fairhurst Expires 27 April 2027 [Page 3] Internet-Draft scone-qlog October 2026 Figure 1: CDDL Description of SCONE Rate Signal types. 4. SCONE Event Schema Definition This document describes how the SCONE protocol can be expressed in qlog using the event schema. Per the requirements in Section 8 of [QLOG-SCHEMA], this document registers the scone namespace. The event schema URI is urn:ietf:params:qlog:events:scone. 4.1. Draft Event Schema Identification RFC-Editor NOTE:: Please remove this section when this is published as an RFC. Only implementations of the final, published RFC can use the events belonging to the event schema with the URI urn:ietf:params:qlog:events:scone. Until such an RFC exists, implementations MUST NOT identify themselves using this URI. Implementations of draft versions of the event schema MUST append the string "-" and the corresponding draft number to the URI. For example, draft 00 of this document is identified using the URI urn:ietf:params:qlog:events:scone-00. The namespace identifier itself is not affected by this requirement. 5. SCONE Events SCONE events extend the $ProtocolEventData extension point defined in Section 8.2 of [QLOG-SCHEMA]. Additionally, they allow for direct extensibility by their use of per-event extension points via the $$ CDDL "group socket" syntax, as also described in Section 8.2 of [QLOG-SCHEMA]. SCONEEventData = SCONEPacketSent / SCONEPacketReceived / SCONEAdviceUpdated / SCONEAdviceExpired $ProtocolEventData /= SCONEEventData Figure 2: SCONEEventData definition and ProtocolEventData extension 5.1. scone:packet_sent Importance: Core Kejriwal & Fairhurst Expires 27 April 2027 [Page 4] Internet-Draft scone-qlog October 2026 The packet_sent event is emitted when an endpoint includes a SCONE packet in a datagram it sends. The event records the rate signal in the sent SCONE packet. SCONEPacketSent = { ? datagram_id: uint32 version: uint32 rate_signal: SCONERateSignal ; expected to be 127 when a packet is sent by an endpoint ? trigger: "loss_detected" ; indicates that the SCONE packet is being sent again ; because a coalesced QUIC packet was detected to be lost * $$scone-packetsent-extension } Figure 3: CDDL Description of the SCONEPacketSent Data. 5.2. scone:packet_received Importance: Core The packet_received event is emitted when an endpoint receives a datagram that begins with a SCONE packet, after the packet (and any subsequent coalesced packets) have been parsed to check validity [SCONE]. The event records the rate signal carried in the received SCONE packet and the outcome of processing it, regardless of whether the packet is accepted or discarded. Kejriwal & Fairhurst Expires 27 April 2027 [Page 5] Internet-Draft scone-qlog October 2026 SCONEPacketReceived = { ? datagram_id: uint32 version: uint32 rate_signal: SCONERateSignal ? throughput_advice: uint64 ; bits per second encoded by the rate_signal ; absent when rate_signal is 127 outcome: "accepted" / "discarded" ; accepted implies the packet was valid and contained a ; SCONEKnownRateSignal regardless of whether the advice was applied ? reason: "coalesced_packet_not_processed" / ; no coalesced packets were successfully processed "destination_connection_id_mismatch" / "source_connection_id_mismatch" / "multiple_scone_packets_received" / ; multiple scone packets were received in one datagram "unknown_rate_signal" ; rate signal was 127 * $$scone-packetreceived-extension } Figure 4: CDDL Description of the SCONEPacketReceived Data. The reason field MAY be omitted if the value of outcome is "discarded", and MUST NOT be present if the value of outcome is "accepted". 5.3. scone:advice_updated Importance: Base The advice_updated event is emitted by a SCONE-receiving endpoint when the effective throughput advice changes as a result of processing a received SCONE packet or applying the monitoring-period rules defined in [SCONE]. SCONEAdviceUpdated = { rate_signal: SCONEKnownRateSignal ; Rate signal corresponding to the effective advice throughput_advice: uint64 ; Effective throughput advice in bits per second * $$scone-adviceupdated-extension } Figure 5: CDDL Description of the SCONEAdviceUpdated Data. Kejriwal & Fairhurst Expires 27 April 2027 [Page 6] Internet-Draft scone-qlog October 2026 This event may be emitted in the following common cases (non- exhaustive): * When throughput advice first becomes effective, for example, after processing a SCONE packet carrying a known rate signal. * Processing a SCONE packet that lowers the effective throughput advice. * Advice from a previous monitoring period expires and advice from the current monitoring period becomes effective. This event SHOULD NOT be emitted when advice from a previous monitoring period expires, but the advice in the current monitoring period does not change the effective advice. 5.4. scone:advice_expired Importance: Base The advice_expired event is emitted by a SCONE-receiving endpoint when previously effective SCONE advice expires because no applicable throughput advice was received during the monitoring period, as defined in [SCONE]. SCONEAdviceExpired = { previous_throughput_advice: uint64 ; The effective previous advice in bits per second * $$scone-adviceexpired-extension } Figure 6: CDDL Description of the SCONEAdviceExpired Data. 6. Security Considerations The security and privacy considerations discussed in Section 14 of [QLOG-SCHEMA] apply to this document. 7. IANA Considerations This document registers a new entry in the "qlog event schema URIs" registry (created in Section 15 of [QLOG-SCHEMA]). Event schema URI: urn:ietf:params:qlog:events:scone Namespace scone Kejriwal & Fairhurst Expires 27 April 2027 [Page 7] Internet-Draft scone-qlog October 2026 Event Types packet_sent, packet_received, advice_updated, advice_expired Description: Event definitions related to the SCONE protocol. Reference: This Document 8. Normative References [CDDL] Birkholz, H., Vigano, C., and C. Bormann, "Concise Data Definition Language (CDDL): A Notational Convention to Express Concise Binary Object Representation (CBOR) and JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610, June 2019, . [QLOG-SCHEMA] Marx, R., Niccolini, L., Seemann, M., and L. Pardue, "qlog: Structured Logging for Network Protocols", Work in Progress, Internet-Draft, draft-ietf-quic-qlog-main- schema-14, 6 July 2026, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [SCONE] Thomson, M., Huitema, C., Oku, K., Joras, M., and L. M. Ihlar, "Standard Communication with Network Elements (SCONE) Protocol", Work in Progress, Internet-Draft, draft-ietf-scone-protocol-09, 24 September 2026, . Acknowledgments The authors thank the European Space Agency (ESA) for supporting the QUICOPTSAT project, under which an evaluation of SCONE over satellite networks was undertaken. Authors' Addresses Kejriwal & Fairhurst Expires 27 April 2027 [Page 8] Internet-Draft scone-qlog October 2026 Raghav Kejriwal University of Aberdeen Fraser Noble Building Aberdeen, AB24 3UE United Kingdom Email: ietf@raghavkejriwal.com Godred Fairhurst University of Aberdeen Fraser Noble Building Aberdeen, AB24 3UE United Kingdom Email: gorry@erg.abdn.ac.uk URI: https://www.erg.abdn.ac.uk Kejriwal & Fairhurst Expires 27 April 2027 [Page 9]