



QUIC                                                           M. Kozuka
Internet-Draft                                        Okayama University
Intended status: Standards Track                         26 January 2026
Expires: 30 July 2026


        QUIC Extension for Server-Initiated Connection Migration
                 draft-kozuka-quic-server-migration-00

Abstract

   This document specifies an extension of QUIC that allows the server
   to initiate connection migration.

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://masa-
   koz.github.io/draft-kozuka-quic-server-migration/draft-kozuka-quic-
   server-migration.html.  Status information for this document may be
   found at https://datatracker.ietf.org/doc/draft-kozuka-quic-server-
   migration/.

   Discussion of this document takes place on the QUIC Working Group
   mailing list (mailto:quic@ietf.org), which is archived at
   https://mailarchive.ietf.org/arch/browse/quic/.  Subscribe at
   https://www.ietf.org/mailman/listinfo/quic/.

   Source for this draft and an issue tracker can be found at
   https://github.com/masa-koz/draft-kozuka-quic-server-migration.

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 30 July 2026.



Kozuka                    Expires 30 July 2026                  [Page 1]

Internet-Draft            QUIC Server Migration             January 2026


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 . . . . . . . . . . . . . . . . .   2
   3.  Motivation  . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   5.  Negotiating Extension Use . . . . . . . . . . . . . . . . . .   3
   6.  Connection Migration Procedure  . . . . . . . . . . . . . . .   4
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
     8.1.  QUIC Transport Parameter  . . . . . . . . . . . . . . . .   4
   9.  Normative References  . . . . . . . . . . . . . . . . . . . .   4
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .   5
   Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . .   5
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   RFC 9000 defines connection migration as a mechanism initiated by the
   client to change its IP address or network path without disrupting
   the QUIC connection.  This mechanism is based on the assumption that
   a client may be behind a NAT and a server has a public address.
   However, there is a reversed situation where a client has a public
   address and a server is behind a NAT.  This document specifies an
   extension that reverses this role: the server initiates migration.

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.




Kozuka                    Expires 30 July 2026                  [Page 2]

Internet-Draft            QUIC Server Migration             January 2026


3.  Motivation

   A key scenario is:

   *  The server is initially behind a NAT and cannot accept direct
      connections.

   *  The client has a public IP address.

   *  The server first establishes the QUIC connection via a relay
      server.

   *  Immediately after the handshake, the server migrates the
      connection to the client’s public address, reducing latency.

   This specification does not define how the server obtains the public
   address of the client.  Possible methods include application-level
   signaling or external mechanisms, but these are out of scope.

4.  Scope

   *  Reverse migration roles defined in RFC 9000.

   *  Maintain QUIC security guarantees.

   *  No new NAT traversal mechanism.

5.  Negotiating Extension Use

   allow_server_migration (0x3e764478):

   Clients advertise their support of this extension by sending the
   allow_server_migration (0x3e764478) transport parameter (Section 7.4
   of [QUIC-TRANSPORT]) with an empty value.  Sending this transport
   parameter signals to the server that the client will accept the
   server-initiated migration.

   Servers also send this parameter with an empty value.  The server
   informs the client that it will initiate the connection migration by
   sending this parameter.

   When this extension is negotiated, the server-initiated migration is
   only permitted and the client-initiated migration is prohibited.

   An implementation that understands this transport parameter MUST
   treat the receipt of a non-empty value as a connection error of type
   TRANSPORT_PARAMETER_ERROR.




Kozuka                    Expires 30 July 2026                  [Page 3]

Internet-Draft            QUIC Server Migration             January 2026


   Endpoints MUST NOT remember the value of this extension for 0-RTT.

6.  Connection Migration Procedure

   The connection migration procedure is the same as (Section 9 of
   [QUIC-TRANSPORT]) except that the roles between the client and the
   server are reversed.

7.  Security Considerations

   TODO Security

8.  IANA Considerations

8.1.  QUIC Transport Parameter

   This document registers the allow_server_migration transport
   parameter in the "QUIC Transport Parameters" registry established in
   Section 22.3 of [QUIC-TRANSPORT].  The following fields are
   registered:

   Value:  0x3e764478

   Parameter Name:  allow_server_migration

   Status:  Provisional

   Specification:  This document

   Change Controller:  IETF (iesg@ietf.org)

   Contact:  Masahiro Kozuka (kozuka@okayama-u.ac.jp)

9.  Normative References

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

   [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/rfc/rfc2119>.






Kozuka                    Expires 30 July 2026                  [Page 4]

Internet-Draft            QUIC Server Migration             January 2026


   [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/rfc/rfc8174>.

Acknowledgments

   TODO acknowledge.

Questions

   *  Sould we extend this extension to allow both clients and servers
      to initiate connection migration?

   *  Any new security conserations from allowing servers to initiate
      connection migration?

Author's Address

   Masahiro Kozuka
   Okayama University
   Email: kozuka@okayama-u.ac.jp






























Kozuka                    Expires 30 July 2026                  [Page 5]
