Performance Metrics Subprotocol for QUIC
draft-kazuho-quic-perf-metrics-00

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Network Working Group                                             K. Oku
Internet-Draft                                                    Fastly
Intended status: Standards Track                       February 12, 2018
Expires: August 16, 2018

                Performance Metrics Subprotocol for QUIC
                   draft-kazuho-quic-perf-metrics-00

Abstract

   This memo proposes a subprotocol that can be used to query the
   performance metrics of a QUIC path.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on August 16, 2018.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Overview  . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  METRICS Packet  . . . . . . . . . . . . . . . . . . . . . . .   3
     3.1.  REQUEST Subtype . . . . . . . . . . . . . . . . . . . . .   5
     3.2.  RESPONSE Subtype  . . . . . . . . . . . . . . . . . . . .   6
     3.3.  DENY Subtype  . . . . . . . . . . . . . . . . . . . . . .   7
   4.  Server Behavior . . . . . . . . . . . . . . . . . . . . . . .   7
     4.1.  Server State  . . . . . . . . . . . . . . . . . . . . . .   8
   5.  Normative References  . . . . . . . . . . . . . . . . . . . .   8
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   Observation of upstream loss, reorder, and round-trip time is crucial
   to diagnosing issues on the network.  With TCP, it is possible for an
   on-path device to make estimation of such metrics by observing the
   sequence number and the ACK packets being sent in clear.  But with
   QUIC, packet number is never used twice and ACK is encrypted, hence
   such on-path observation has become difficult.  There is also an
   ongoing discussion about encrypting the packet numbers to avoid
   ossification and also to miminize privacy concern.  Such change will
   make observation even more challenging.

   There have been proposals to include signals in each QUIC packet that
   conveys enough information for diagnosis but does not cause
   ossification nor privary issues.  However, it is difficult if not
   impossible to figure out an approach that will work well for the
   lifetime of a transport protocol.

   This memo proposes an alternative solution.  In the proposal, an on-
   path device willing to obtain the performance metrics of a QUIC path
   sends a query to the server, and the server responds with the
   necessary information to calculate such metrics.

   There are three primary benefits in the approach:

   o  Observation becomes an active action rather than passive, giving
      the endpoints a chance to record observation attempts as well as
      rejecting undesirable ones.

   o  Observation becomes accurate due to the endpoints' knowledge of
      what is being exchanged encypted.

   o  Flexibility against issues (both performance- and privacy-related)
      that might arise in the future, since bits for observation no

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      longer exists hard-coded in each packet.  The metrics protocol can
      evolve indenpendently to the QUIC transport protocol.

2.  Overview

   An on-path device that is willing to query the performance metrics of
   a QUIC path sends a METRICS packet of subtype REQUEST to the server-
   side endpoint of the path.

   When receiving the request packet, A QUIC server sends a response to