RFC 9959 - Careful Resume: Convergence of Congestion Control from Retained State

• Status: Proposed Standard
• Published: May 2026
• Stream: IETF
• Core Method: Careful Resume

Abstract

Careful Resume reuses saved congestion-control parameters from a previously observed path so a later connection can get up to speed faster while still confirming path validity and retreating safely on congestion.

Contents

• 1. Introduction
• 2. Language, Notation, and Terms
• 3. Careful Resume Phases
• 4. Implementation Notes
• 5. Operational Considerations
• 6. IANA Considerations
• 7. Security Considerations
• 8. References
• Appendix A. Notes on the Careful Resume Phases
• Appendix B. Examples of the Careful Resume Phases
• Appendix C. Implementation Notes for Using BBR

Related Resources

• Official Text: RFC 9959
• Official Page: RFC 9959 DataTracker
• Errata: RFC Editor Errata