| Internet-Draft | scone-qlog | October 2026 |
| Kejriwal & Fairhurst | Expires 27 April 2027 | [Page] |
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.¶
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.¶
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[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.¶
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 |
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].¶
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
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.¶
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.¶
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 $$ CDDL "group socket" syntax, as also described in Section 8.2 of [QLOG-SCHEMA].¶
SCONEEventData = SCONEPacketSent /
SCONEPacketReceived /
SCONEAdviceUpdated /
SCONEAdviceExpired
$ProtocolEventData /= SCONEEventData
Importance: Core¶
The packet_sent event is emitted when an endpoint includes a SCONE packet in a datagram it sends. The event records the rate signal in the sent SCONE packet.¶
SCONEPacketSent = {
? datagram_id: uint32
version: uint32
rate_signal: SCONERateSignal
; expected to be 127 when a packet is sent by an endpoint
? trigger: "loss_detected"
; indicates that the SCONE packet is being sent again
; because a coalesced QUIC packet was detected to be lost
* $$scone-packetsent-extension
}
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.¶
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
* $$scone-packetreceived-extension
}
The reason field MAY be omitted if the value of outcome is "discarded", and MUST NOT be present if the value of outcome is "accepted".¶
Importance: Base¶
The advice_updated event is emitted by a SCONE-receiving endpoint when the effective throughput advice changes as a result of processing a received SCONE packet or applying the monitoring-period rules defined in [SCONE].¶
SCONEAdviceUpdated = {
rate_signal: SCONEKnownRateSignal
; Rate signal corresponding to the effective advice
throughput_advice: uint64
; Effective throughput advice in bits per second
* $$scone-adviceupdated-extension
}
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.¶
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
}
The security and privacy considerations discussed in Section 14 of [QLOG-SCHEMA] apply to this document.¶
This document registers a new entry in the "qlog event schema URIs" registry (created in Section 15 of [QLOG-SCHEMA]).¶
The authors thank the European Space Agency (ESA) for supporting the QUICOPTSAT project, under which an evaluation of SCONE over satellite networks was undertaken.¶