Communication Units Granularity Considerations for Multi-Path Aware Transport Selection
draft-tiesel-taps-communitgrany-02

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TAPS Working Group                                             P. Tiesel
Internet-Draft                                               T. Enghardt
Intended status: Informational                                 TU Berlin
Expires: November 3, 2018                                   May 02, 2018

  Communication Units Granularity Considerations for Multi-Path Aware
                          Transport Selection
                   draft-tiesel-taps-communitgrany-02

Abstract

   This document provides an approach how to reason about the
   composition of multi-path aware transport stacks.  It discusses how
   to compose the functionality needed by stacking existing internet
   protocols and the fundamental mechanisms that are used in multi-path
   systems and the consequences of applying them to different
   granularities of communication units, e.g, on a message or stream
   granularity.  This document is targeted as guidance for automation of
   destination selection, path selection, and transport protocol
   selection.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
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   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on November 3, 2018.

Copyright Notice

   Copyright (c) 2018 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
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents

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   carefully, as they describe your rights and restrictions with respect
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Communication Units vs. Layering  . . . . . . . . . . . .   3
   2.  Abstract Hierarchy of Communication Units . . . . . . . . . .   4
     2.1.  Message . . . . . . . . . . . . . . . . . . . . . . . . .   4
     2.2.  Stream  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     2.3.  Association / Connection Group  . . . . . . . . . . . . .   5
     2.4.  Association Set / Flow-Group  . . . . . . . . . . . . . .   5
   3.  Mechanisms Used in Multi-Path Systems . . . . . . . . . . . .   5
     3.1.  Destination Selection . . . . . . . . . . . . . . . . . .   5
     3.2.  Path Selection  . . . . . . . . . . . . . . . . . . . . .   6
     3.3.  Chunking  . . . . . . . . . . . . . . . . . . . . . . . .   7
     3.4.  Scheduling  . . . . . . . . . . . . . . . . . . . . . . .   7
   4.  Cost of Transport Option Selection  . . . . . . . . . . . . .   8
   5.  Involvement of On-Path Elements . . . . . . . . . . . . . . .   8
   6.  Overview of Mechanisms provided by selected IETF Protocols  .   9
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  10
   8.  Informative References  . . . . . . . . . . . . . . . . . . .  11
   Appendix A.  Changes  . . . . . . . . . . . . . . . . . . . . . .  12
     A.1.  Since -00 . . . . . . . . . . . . . . . . . . . . . . . .  12
     A.2.  Since -01 . . . . . . . . . . . . . . . . . . . . . . . .  12
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  12

1.  Introduction

   Today's Internet architecture faces a communication endpoint with a
   set of choices, including choosing a transport protocol and picking
   an IP protocol version.  In many cases, e.g., when fetching data from
   a CDN, an endpoint has also the choice of which endpoint instance,
   [I-D.brunstrom-taps-impl] calls these instances "Derived Endpoint",
   to contact as DNS can return multiple alternative addresses.

   If endpoints want to take advantage of multiple available paths,
   there is another bunch of, partially interdependent, choices:

   o  Which path(s) between the endpoints could be used?

   o  Which path(s) between the endpoints should be used?

   o  Should the paths be used in an active/active way or only as
      active/fallback?

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