LOOPS Generic Information Set
draft-welzl-loops-gen-info-03

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TSVWG                                                           M. Welzl
Internet-Draft                                        University of Oslo
Intended status: Standards Track                         C. Bormann, Ed.
Expires: September 10, 2020                      Universitaet Bremen TZI
                                                          March 09, 2020

                     LOOPS Generic Information Set
                     draft-welzl-loops-gen-info-03

Abstract

   LOOPS (Local Optimizations on Path Segments) aims to provide local
   (not end-to-end but in-network) recovery of lost packets to achieve
   better data delivery in the presence of losses.
   [I-D.li-tsvwg-loops-problem-opportunities] provides an overview over
   the problems and optimization opportunities that LOOPS could address.

   The present document is a strawman for the set of information that
   would be interchanged in a LOOPS protocol, without already defining a
   specific data packet format.

   The generic information set needs to be mapped to a specific
   encapsulation protocol to actually run the LOOPS optimizations.  The
   current version of this document contains sketches of bindings to GUE
   [I-D.ietf-intarea-gue] and Geneve [I-D.ietf-nvo3-geneve].

Status of This Memo

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   This Internet-Draft will expire on September 10, 2020.

Welzl & Bormann        Expires September 10, 2020               [Page 1]
Internet-Draft                    LOOPS                       March 2020

Copyright Notice

   Copyright (c) 2020 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
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   5
   2.  Challenges  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     2.1.  No Access to End-to-End Transport Information . . . . . .   6
     2.2.  Path Asymmetry  . . . . . . . . . . . . . . . . . . . . .   6
     2.3.  Reordering vs. Spurious Retransmission  . . . . . . . . .   7
     2.4.  Informing the End-to-End Transport  . . . . . . . . . . .   7
     2.5.  Congestion Detection  . . . . . . . . . . . . . . . . . .   8
   3.  Simplifying assumptions . . . . . . . . . . . . . . . . . . .   9
   4.  LOOPS Architecture  . . . . . . . . . . . . . . . . . . . . .   9
   5.  LOOPS Generic Information Set . . . . . . . . . . . . . . . .  10
     5.1.  Setup Information . . . . . . . . . . . . . . . . . . . .  10
     5.2.  Forward Information . . . . . . . . . . . . . . . . . . .  11
     5.3.  Reverse Information . . . . . . . . . . . . . . . . . . .  11
   6.  LOOPS General Operation . . . . . . . . . . . . . . . . . . .  12
     6.1.  Initial Packet Sequence Number  . . . . . . . . . . . . .  12
       6.1.1.  Minimizing collisions . . . . . . . . . . . . . . . .  13
       6.1.2.  Optional Initial PSN procedure  . . . . . . . . . . .  13
     6.2.  Acknowledgement Generation  . . . . . . . . . . . . . . .  14
     6.3.  Measurement . . . . . . . . . . . . . . . . . . . . . . .  14
       6.3.1.  Ingress-relative timestamps . . . . . . . . . . . . .  15
       6.3.2.  ACK generation  . . . . . . . . . . . . . . . . . . .  15
     6.4.  Loss detection and Recovery . . . . . . . . . . . . . . .  16
       6.4.1.  Local Retransmission  . . . . . . . . . . . . . . . .  16
       6.4.2.  FEC . . . . . . . . . . . . . . . . . . . . . . . . .  16
     6.5.  Discussion  . . . . . . . . . . . . . . . . . . . . . . .  16
   7.  Sketches of Bindings to Tunnel Protocols  . . . . . . . . . .  17
     7.1.  Embedding LOOPS in Geneve . . . . . . . . . . . . . . . .  17
     7.2.  Embedding LOOPS in GUE  . . . . . . . . . . . . . . . . .  17
     7.3.  Embedding LOOPS in SRv6 . . . . . . . . . . . . . . . . .  18