The Transport-Info Response Header
draft-ohanlon-transport-info-header-00

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HTTP                                                         P. O'Hanlon
Internet-Draft                                              J. Gruessing
Intended status: Standards Track        British Broadcasting Corporation
Expires: May 20, 2020                                  November 17, 2019

                   The Transport-Info Response Header
                 draft-ohanlon-transport-info-header-00

Abstract

   The Transport-Info header provides a mechanism to inform a client of
   the last-mile server's view of the network transport related
   information such as current delivery rate and round-trip time.  This
   information has a wide range of uses such as client monitoring and
   diagnostics, or allowing a client to adapt to current network
   conditions.

Note to Readers

   _RFC Editor: please remove this section before publication_

   Source code and issues for this draft can be found at
   https://github.com/bbc/draft-ohanlon-transport-info-header [1].

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
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   This Internet-Draft will expire on May 20, 2020.

Copyright Notice

   Copyright (c) 2019 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   This document is subject to BCP 78 and the IETF Trust's Legal
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   (https://trustee.ietf.org/license-info) in effect on the date of
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Motivation  . . . . . . . . . . . . . . . . . . . . . . .   3
     1.2.  Notational Conventions  . . . . . . . . . . . . . . . . .   3
   2.  The Transport-Info Response Header  . . . . . . . . . . . . .   3
     2.1.  Utilisation of Transport-Info header metrics  . . . . . .   5
   3.  Server side behaviour . . . . . . . . . . . . . . . . . . . .   6
   4.  Client side proxy considerations  . . . . . . . . . . . . . .   6
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   8
     7.3.  URIs  . . . . . . . . . . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   The Transport-Info header provides for relaying of transport protocol
   related information from a last-mile edge server entity to a client
   with the aim of informing the client of the server's view on the
   transport state.  The state of a connection is dependent upon
   information based upon packet exchanges during the transport
   processes.  Firstly, there is information that is common to both
   client and server, such as the calculated round-trip time (RTT),
   although it may be measured using different packets at each end.
   Secondly, there is state information that exists only at each
   endpoint, such as the size of the congestion, and receive windows.
   Thus certain transport state information is only available at the
   server which can be useful to the client, for example, to calculate
   the current transport rate.  This information may then be used to
   better inform a client of the state of the network path and make
   appropriate adaptations.

   The information can also be utilised by a client to provide for
   application level client oriented metric logging to back-end systems

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   for monitoring and analysis purposes.  Such data could be utilised in
   a manner not unlike that proposed in [RFC4898].