Fine-Grained QoS Optimization for QUIC Based on Connection ID Priority Mapping
draft-li-quic-qos-optimization-00

Network Working Group                                              Z. Li
Internet-Draft                                                     Z. Du
Intended status: Informational                              China Mobile
Expires: 5 January 2027                                          J. Wang
                                                                W. Cheng
                                                                G. Zhang
                                                                  Centec
                                                                  X. Sun
                                                                   Inesa
                                                                 C. Zhao
                                                                    SAIA
                                                             4 July 2026

 Fine-Grained QoS Optimization for QUIC Based on Connection ID Priority
                                Mapping
                   draft-li-quic-qos-optimization-00

Abstract

   This document defines a fine-grained, dynamically adaptive QoS
   mechanism for QUIC transport.  The mechanism encodes a priority
   mapping table index in the QUIC Destination Connection ID (DCID),
   enabling host NICs or user gateways to translate QUIC-layer service
   priority information into network-layer QoS mechanisms (DSCP/ToS per
   RFC 2474) and traffic engineering policies (SRv6 TE, MPLS TE, etc.)
   for end-to-end QoS enforcement.  Stream IDs carry endpoint priority
   information for local scheduling.  The mechanism supports host-side,
   network-side, and coordinated deployment modes with no intrusion into
   the host protocol stack.

Status of This Memo

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   This Internet-Draft will expire on 5 January 2027.

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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
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Problem Statement . . . . . . . . . . . . . . . . . . . . . .   4
     3.1.  QUIC Priorities Limited to Endpoints  . . . . . . . . . .   4
     3.2.  Datagram Priority Gap . . . . . . . . . . . . . . . . . .   4
     3.3.  Missing Network-Layer QoS Integration . . . . . . . . . .   4
   4.  Connection ID Priority Mapping Mechanism  . . . . . . . . . .   4
     4.1.  Architecture Overview . . . . . . . . . . . . . . . . . .   4
     4.2.  Destination Connection ID Encoding  . . . . . . . . . . .   4
     4.3.  Priority Mapping Table  . . . . . . . . . . . . . . . . .   5
     4.4.  Host-Side Workflow  . . . . . . . . . . . . . . . . . . .   5
     4.5.  Priority Controller . . . . . . . . . . . . . . . . . . .   5
     4.6.  Deployment Modes  . . . . . . . . . . . . . . . . . . . .   5
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   7.  Normative References  . . . . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   Vertical industry services (connected vehicles, remote healthcare,
   etc.) and AI-driven applications increasingly demand differentiated
   network service quality.  QUIC [RFC9000], as a modern transport
   protocol, provides encryption, multiplexing, and connection
   migration, but currently lacks mechanisms for end-to-end QoS
   enforcement across the network path.

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   QUIC's existing stream priority mechanism operates only at the
   endpoints.  Intermediate network devices (routers, switches) do not
   inspect or act on QUIC priority markings because they are encrypted
   within the QUIC payload.  Additionally, QUIC Datagrams [RFC9221] are
   typically excluded from priority scheduling mechanisms.

   This document proposes a mechanism that bridges the gap between QUIC
   transport-layer priorities and network-layer QoS enforcement by
   leveraging the Destination Connection ID field, which remains visible
   in the QUIC header even under encryption, as a carrier for priority
   mapping table indices.

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.  Terminology

   DCID (Destination Connection ID):  The Connection ID field in QUIC
      packet headers used to identify the destination endpoint of a
      connection.

   Stream:  A QUIC stream, an ordered byte-stream transport channel
      within a QUIC connection.

   Datagram:  A QUIC unreliable datagram as defined in [RFC9221].

   DSCP (Differentiated Services Code Point):  A field in the IP header
      for packet classification and per-hop behavior selection, defined
      in [RFC2474].

   TE Policy:  Traffic Engineering policy, including MPLS TE, SRv6 TE
      [RFC8754], SDN-based TE, and cross-layer coordination TE.

   Priority Mapping Table:  A lookup table that maps index Connection
      IDs to real Connection IDs and associated QoS parameters.

   Index Prefix:  A specific byte pattern (e.g., AAB00000, configurable)
      used to identify that a DCID is a mapping table index rather than
      a real Connection ID.

   Priority Controller:  A component responsible for generation, update,
      and management of the priority mapping table.

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3.  Problem Statement

3.1.  QUIC Priorities Limited to Endpoints

   QUIC stream priorities are enforced through application-layer
   marking, transport-layer scheduling, and congestion control
   coordination.  High-priority streams receive preferential packet
   encapsulation, loss retransmission, and potentially larger congestion
   windows.  However, these priorities are effective only at the
   endpoints.  Intermediate network devices do not process QUIC priority
   information, and the network layer has no awareness of QUIC-layer
   priorities, preventing end-to-end precise QoS enforcement.

3.2.  Datagram Priority Gap

   Per [RFC9000] and [RFC9221], QUIC priority mechanisms are primarily
   designed for streams.  Datagrams, as an unreliable transport mode,
   are typically not included in priority scheduling mechanisms.

3.3.  Missing Network-Layer QoS Integration

   QUIC transport-layer priority information cannot be directly mapped
   to network-layer DSCP/ToS mechanisms or traffic engineering policies,
   resulting in a broken end-to-end QoS enforcement chain.

4.  Connection ID Priority Mapping Mechanism

4.1.  Architecture Overview

   The core idea is to use the QUIC Destination Connection ID (DCID) as
   a carrier for priority information.  Service priority is encoded as
   an index value in the DCID.  A priority mapping table on the host NIC
   or user gateway translates this index into the real Connection ID and
   corresponding network-layer QoS parameters.

4.2.  Destination Connection ID Encoding

   The DCID is structured as follows: DCID = Index_Prefix | Frame_Type |
   Stream_ID | Priority.  Index Prefix: configurable byte pattern (e.g.,
   0xAAB00000) identifying this DCID as a mapping table index.  Frame
   Type: 0 = STREAM frame, 1 = DATAGRAM frame.  Stream ID: identifies
   the associated stream.  Priority: optional application-specified
   fine-grained priority (e.g., differentiating CSS, JS, HTML objects
   within a web page).

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4.3.  Priority Mapping Table

   An implementation MUST construct a priority mapping table.  The table
   deployment location depends on the deployment mode: on the host NIC
   for host-side deployment, or on the user gateway/router for network-
   side deployment.  Each mapping table entry contains: Index (the DCID
   index value); Real DCID (the actual Connection ID used in network
   transmission); ToS/DSCP (network-layer QoS marking per [RFC2474]); TE
   Policy (traffic engineering policy identifier); Reserved (set to 0,
   reserved for future finer-grained QoS constraints).

4.4.  Host-Side Workflow

   In host-side deployment mode: (1) The application issues a QUIC
   connection request via API, specifying service priority requirements.
   (2) Before the API request enters the host protocol stack, a mapping
   table index is generated and replaces the original DCID.  This step
   MUST NOT intrude upon the host protocol stack. (3) The host QUIC
   stack processes the connection normally; outbound QUIC packets carry
   the index value as DCID. (4) The host NIC (or NIC driver) intercepts
   outbound packets, looks up the priority mapping table using the DCID
   index: replaces the DCID with the real Connection ID, sets the IP
   header ToS/DSCP field, and selects the corresponding TE Policy path.
   (5) Packets traverse the network with QoS and TE enforcement.

4.5.  Priority Controller

   The Priority Controller is responsible for generation, update, and
   management of the priority mapping table.  It MAY be deployed as: a
   standalone component; a functional module within a network controller
   (e.g., SDN controller); integrated within the NIC or user gateway/
   router.  Applications MAY configure whether the ToS/TC/DSCP and TE
   Policy values in the mapping table are allowed to auto-adjust
   dynamically based on network quality feedback.

4.6.  Deployment Modes

   Host-Side Deployment: Priority mapping table resides on the host NIC;
   no network-side changes required.  Network-Side Deployment: Priority
   mapping table resides on the user gateway/router; no host-side
   changes required.  Coordinated Deployment: Host-side and network-side
   collaborate on priority mapping.

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5.  Security Considerations

   Mapping Table Confidentiality: The priority mapping table contains
   real Connection IDs and QoS policy information, which constitute
   sensitive data.  Storage and transmission of mapping table
   information MUST be encrypted.  Index Prefix Collision: If a third
   party can guess the index prefix, non-mechanism traffic could be
   incorrectly intercepted and processed.  The index prefix SHOULD have
   sufficient randomness or be negotiated out-of-band.  Priority
   Escalation Attack: Malicious applications may attempt to forge high-
   priority identifiers to obtain unwarranted QoS treatment.  The
   Priority Controller MUST authenticate and authorize application
   priority requests.  Stack Non-Intrusion Safety: The DCID replacement
   at the API layer SHOULD NOT introduce new attack surfaces.
   Implementations SHOULD ensure the security of the index generation
   process.

6.  IANA Considerations

   This document requests IANA consideration for: (1) If a standardized
   index prefix value is adopted, reserved space or a registered prefix
   within the QUIC Connection ID format may be needed. (2) If the DCID
   encoding format requires interoperation with the QUIC standard,
   registration of a new QUIC transport parameter type may be required.

7.  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,
              <https://www.rfc-editor.org/info/rfc2119>.

   [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,
              <https://www.rfc-editor.org/info/rfc2474>.

   [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>.

   [RFC8754]  Filsfils, C., Dukes, D., Previdi, S., Leddy, J.,
              Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header
              (SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020,
              <https://www.rfc-editor.org/info/rfc8754>.

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   [RFC9000]  Iyengar, J. and M. Thomson, "QUIC: A UDP-Based Multiplexed
              and Secure Transport", RFC 9000, DOI 10.17487/RFC9000, May
              2021, <https://www.rfc-editor.org/info/rfc9000>.

   [RFC9221]  Pauly, T., Kinnear, E., and D. Schinazi, "An Unreliable
              Datagram Extension to QUIC", RFC 9221,
              DOI 10.17487/RFC9221, March 2022,
              <https://www.rfc-editor.org/info/rfc9221>.

Authors' Addresses

   Zhiqiang Li
   China Mobile
   Beijing
   100053
   China
   Email: lizhiqiangyjy@chinamobile.com

   Zongpeng Du
   China Mobile
   Beijing
   100053
   China
   Email: duzongpeng@chinamobile.com

   Junjie Wang
   Centec
   Shanghai
   201203
   China
   Email: wangjj@centec.com

   Wei Cheng
   Centec
   Shanghai
   201203
   China
   Email: chengw@centec.com

   Guoying Zhang
   Centec
   Shanghai
   201203
   China

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   Email: zhanggy@centec.com

   Xun Sun
   Inesa
   Shanghai
   200030
   China
   Email: sunxun@inesa.com

   Chunhao Zhao
   SAIA
   Shanghai
   200125
   China
   Email: chunhao.zhao@sh-aia.com

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