QUIC Loss Detection and Congestion Control
draft-ietf-quic-recovery-16

Document Type Active Internet-Draft (quic WG)
Last updated 2018-10-23
Replaces draft-iyengar-quic-loss-recovery
Stream IETF
Intended RFC status Proposed Standard
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Stream WG state WG Document (wg milestone: Jul 2019 - Loss detection and C... )
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QUIC                                                     J. Iyengar, Ed.
Internet-Draft                                                    Fastly
Intended status: Standards Track                           I. Swett, Ed.
Expires: April 26, 2019                                           Google
                                                        October 23, 2018

               QUIC Loss Detection and Congestion Control
                      draft-ietf-quic-recovery-16

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), which is archived at
   https://mailarchive.ietf.org/arch/search/?email_list=quic [1].

   Working Group information can be found at https://github.com/quicwg
   [2]; source code and issues list for this draft can be found at
   https://github.com/quicwg/base-drafts/labels/-recovery [3].

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 April 26, 2019.

Copyright Notice

   Copyright (c) 2018 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

Iyengar & Swett          Expires April 26, 2019                 [Page 1]
Internet-Draft             QUIC Loss Detection              October 2018

   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
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   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 . . . . . . . . . .   4
     3.1.  Relevant Differences Between QUIC and TCP . . . . . . . .   5
       3.1.1.  Separate Packet Number Spaces . . . . . . . . . . . .   5
       3.1.2.  Monotonically Increasing Packet Numbers . . . . . . .   6
       3.1.3.  No Reneging . . . . . . . . . . . . . . . . . . . . .   6
       3.1.4.  More ACK Ranges . . . . . . . . . . . . . . . . . . .   6
       3.1.5.  Explicit Correction For Delayed ACKs  . . . . . . . .   6
   4.  Loss Detection  . . . . . . . . . . . . . . . . . . . . . . .   7
     4.1.  Computing the RTT estimate  . . . . . . . . . . . . . . .   7
     4.2.  Ack-based Detection . . . . . . . . . . . . . . . . . . .   7
       4.2.1.  Fast Retransmit . . . . . . . . . . . . . . . . . . .   7
       4.2.2.  Early Retransmit  . . . . . . . . . . . . . . . . . .   8
     4.3.  Timer-based Detection . . . . . . . . . . . . . . . . . .   9
       4.3.1.  Crypto Retransmission Timeout . . . . . . . . . . . .   9
       4.3.2.  Tail Loss Probe . . . . . . . . . . . . . . . . . . .  10
       4.3.3.  Retransmission Timeout  . . . . . . . . . . . . . . .  11
     4.4.  Generating Acknowledgements . . . . . . . . . . . . . . .  12
       4.4.1.  Crypto Handshake Data . . . . . . . . . . . . . . . .  13
       4.4.2.  ACK Ranges  . . . . . . . . . . . . . . . . . . . . .  13
       4.4.3.  Receiver Tracking of ACK Frames . . . . . . . . . . .  13
     4.5.  Pseudocode  . . . . . . . . . . . . . . . . . . . . . . .  14
       4.5.1.  Constants of interest . . . . . . . . . . . . . . . .  14
       4.5.2.  Variables of interest . . . . . . . . . . . . . . . .  14
       4.5.3.  Initialization  . . . . . . . . . . . . . . . . . . .  16
       4.5.4.  On Sending a Packet . . . . . . . . . . . . . . . . .  16
       4.5.5.  On Receiving an Acknowledgment  . . . . . . . . . . .  17
       4.5.6.  On Packet Acknowledgment  . . . . . . . . . . . . . .  19
       4.5.7.  Setting the Loss Detection Timer  . . . . . . . . . .  19
       4.5.8.  On Timeout  . . . . . . . . . . . . . . . . . . . . .  20
       4.5.9.  Detecting Lost Packets  . . . . . . . . . . . . . . .  21
     4.6.  Discussion  . . . . . . . . . . . . . . . . . . . . . . .  22
   5.  Congestion Control  . . . . . . . . . . . . . . . . . . . . .  22
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