QUIC Loss Detection and Congestion Control
draft-ietf-quic-recovery-34
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Document | Type | Active Internet-Draft (quic WG) | |
---|---|---|---|
Authors | Jana Iyengar , Ian Swett | ||
Last updated | 2021-02-03 (latest revision 2021-01-14) | ||
Replaces | draft-iyengar-quic-loss-recovery | ||
Stream | Internent Engineering Task Force (IETF) | ||
Intended RFC status | Proposed Standard | ||
Formats | plain text html xml pdf htmlized (tools) htmlized bibtex | ||
Reviews | |||
Stream | WG state | Submitted to IESG for Publication (wg milestone: Jul 2020 - Loss detection and C... ) | |
Document shepherd | Lars Eggert | ||
Shepherd write-up | Show (last changed 2020-09-25) | ||
IESG | IESG state | Approved-announcement to be sent | |
Action Holders |
(None)
|
||
Consensus Boilerplate | Yes | ||
Telechat date | |||
Responsible AD | Magnus Westerlund | ||
Send notices to | quic-chairs@ietf.org | ||
IANA | IANA review state | IANA OK - No Actions Needed |
QUIC J. Iyengar, Ed. Internet-Draft Fastly Intended status: Standards Track I. Swett, Ed. Expires: 19 July 2021 Google 15 January 2021 QUIC Loss Detection and Congestion Control draft-ietf-quic-recovery-34 Abstract This document describes loss detection and congestion control mechanisms for QUIC. Note to Readers Discussion of this draft takes place on the QUIC working group mailing list (quic@ietf.org (mailto:quic@ietf.org)), which is archived at https://mailarchive.ietf.org/arch/ search/?email_list=quic. Working Group information can be found at https://github.com/quicwg; source code and issues list for this draft can be found at https://github.com/quicwg/base-drafts/labels/-recovery. 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 19 July 2021. Copyright Notice Copyright (c) 2021 IETF Trust and the persons identified as the document authors. All rights reserved. Iyengar & Swett Expires 19 July 2021 [Page 1] Internet-Draft QUIC Loss Detection January 2021 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 Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Conventions and Definitions . . . . . . . . . . . . . . . . . 4 3. Design of the QUIC Transmission Machinery . . . . . . . . . . 5 4. Relevant Differences Between QUIC and TCP . . . . . . . . . . 6 4.1. Separate Packet Number Spaces . . . . . . . . . . . . . . 6 4.2. Monotonically Increasing Packet Numbers . . . . . . . . . 6 4.3. Clearer Loss Epoch . . . . . . . . . . . . . . . . . . . 7 4.4. No Reneging . . . . . . . . . . . . . . . . . . . . . . . 7 4.5. More ACK Ranges . . . . . . . . . . . . . . . . . . . . . 7 4.6. Explicit Correction For Delayed Acknowledgments . . . . . 7 4.7. Probe Timeout Replaces RTO and TLP . . . . . . . . . . . 7 4.8. The Minimum Congestion Window is Two Packets . . . . . . 8 5. Estimating the Round-Trip Time . . . . . . . . . . . . . . . 8 5.1. Generating RTT samples . . . . . . . . . . . . . . . . . 8 5.2. Estimating min_rtt . . . . . . . . . . . . . . . . . . . 9 5.3. Estimating smoothed_rtt and rttvar . . . . . . . . . . . 10 6. Loss Detection . . . . . . . . . . . . . . . . . . . . . . . 12 6.1. Acknowledgment-Based Detection . . . . . . . . . . . . . 12 6.1.1. Packet Threshold . . . . . . . . . . . . . . . . . . 13 6.1.2. Time Threshold . . . . . . . . . . . . . . . . . . . 13 6.2. Probe Timeout . . . . . . . . . . . . . . . . . . . . . . 14 6.2.1. Computing PTO . . . . . . . . . . . . . . . . . . . . 14 6.2.2. Handshakes and New Paths . . . . . . . . . . . . . . 16 6.2.3. Speeding Up Handshake Completion . . . . . . . . . . 17 6.2.4. Sending Probe Packets . . . . . . . . . . . . . . . . 18 6.3. Handling Retry Packets . . . . . . . . . . . . . . . . . 19 6.4. Discarding Keys and Packet State . . . . . . . . . . . . 19 7. Congestion Control . . . . . . . . . . . . . . . . . . . . . 20 7.1. Explicit Congestion Notification . . . . . . . . . . . . 20 7.2. Initial and Minimum Congestion Window . . . . . . . . . . 21 7.3. Congestion Control States . . . . . . . . . . . . . . . . 21 7.3.1. Slow Start . . . . . . . . . . . . . . . . . . . . . 22 7.3.2. Recovery . . . . . . . . . . . . . . . . . . . . . . 22 7.3.3. Congestion Avoidance . . . . . . . . . . . . . . . . 23Show full document text