The QUIC Loss Bits
draft-ferrieux-hamchaoui-quic-lossbits-00

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QUIC                                                    A. Ferrieux, Ed.
Internet-Draft                                         I. Hamchaoui, Ed.
Intended status: Experimental                                Orange Labs
Expires: October 11, 2019                                  April 9, 2019

                           The QUIC Loss Bits
               draft-ferrieux-hamchaoui-quic-lossbits-00

Abstract

   This document specifies the addition of loss bits to the QUIC
   transport protocol and describes how to use them to measure and
   locate packet loss.

Note to Readers

   This document specifies an experimental delta to the QUIC transport
   protocol.

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
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   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
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   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 October 11, 2019.

Copyright Notice

   Copyright (c) 2019 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
   (http://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

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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  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Passive Loss measurement  . . . . . . . . . . . . . . . . . .   3
     2.1.  Proposed Short Header Format Including Loss Bits  . . . .   3
     2.2.  Semantics . . . . . . . . . . . . . . . . . . . . . . . .   3
       2.2.1.  Setting the sQuare Bit on Outgoing Packets  . . . . .   3
       2.2.2.  Setting the Retransmit Bit on Outgoing Packets  . . .   3
       2.2.3.  Resetting state on CID change . . . . . . . . . . . .   4
   3.  Using the loss bits for Passive Loss Measurement  . . . . . .   4
     3.1.  End-to-end loss . . . . . . . . . . . . . . . . . . . . .   4
     3.2.  Upstream loss . . . . . . . . . . . . . . . . . . . . . .   4
     3.3.  Downstream loss . . . . . . . . . . . . . . . . . . . . .   5
     3.4.  Bidirectional flows . . . . . . . . . . . . . . . . . . .   5
   4.  Security and Privacy Considerations . . . . . . . . . . . . .   6
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   6.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   6
   7.  Normative References  . . . . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   Packet loss is a hard and pervasive problem of day-to-day network
   operation, and locating them is crucial to timely resolution of
   crippling end-to-end throughput issues.  To this effect, in a TCP-
   dominated world, network operators have been heavily relying on
   information present in clear in TCP headers: sequence and
   acknowledgement numbers, and SACK when enabled.  By passive on-path
   observation, these allow for quantitative estimation of packet loss.
   Additionally, the lossy segment (upstream or downstream from the
   observation point) is unambiguous; this is crucial as it gives the
   ability to quickly home in on the offending segment, by moving the
   passive observer around.

   In the QUIC context, the equivalent transport headers being
   encrypted, such observation is not possible.  To restore network
   operators' ability to maintain QUIC clients experience, this document
   adds two explicit loss bits to the QUIC short header, named "Q"
   (sQuare signal) and "R" (Retransmit).  Together, these bits allow the
   observer to estimate upstream and downstream loss, enabling the same
   dichotomic search as with TCP.

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2.  Passive Loss measurement

   The proposed mechanisms enable loss measurement from observation
   points on the network path throughout the lifetime of a connection.
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