Datagram PLPMTUD for UDP Options
draft-fairhurst-tsvwg-udp-options-dplpmtud-00

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Internet Engineering Task Force                             G. Fairhurst
Internet-Draft                                                  T. Jones
Intended status: Standards Track                  University of Aberdeen
Expires: October 27, 2019                                 April 25, 2019

                    Datagram PLPMTUD for UDP Options
             draft-fairhurst-tsvwg-udp-options-dplpmtud-00

Abstract

   This document describes how a UDP Options sender may implement
   Datagram Packetization Layer Path Maximum Transmission Unit Discovery
   (DPLPMTUD) as a robust method for Path Maximum Transmission Unit
   Discovery.

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 October 27, 2019.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  DPLPMTUD for UDP Options  . . . . . . . . . . . . . . . . . .   3
     3.1.  Sending Packet Probes using Control Information . . . . .   4
     3.2.  Sending Packet Probes using Application Data  . . . . . .   5
     3.3.  Validating the Path with UDP Options  . . . . . . . . . .   5
     3.4.  Handling of PTB Messages by UDP Options . . . . . . . . .   5
   4.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   6
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   7
   Appendix A.  Revision Notes . . . . . . . . . . . . . . . . . . .   7
   Appendix B.  Informative Description of new UDP Options . . . . .   7
     B.1.  UDP Probe Request Option  . . . . . . . . . . . . . . . .   7
     B.2.  UDP Probe Response Option . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   The User Datagram Protocol [RFC0768] offers a minimal transport
   service on top of IP and is frequently used as a substrate for other
   protocols.  Applications using UDP frequently have to implement basic
   transport services such as Path Maximum Transmission Unit Discovery
   (PMTUD) themselves.  Section 3.5 of UDP Guidelines ([RFC8085])
   recommends that applications implement some form of Path MTU
   Discovery to avoid the generation of IP fragments:

   "Consequently, an application SHOULD either use the path MTU
   information provided by the IP layer or implement Path MTU Discovery
   (PMTUD)".

   The UDP API [RFC8304] offers calls for applications to receive ICMP
   Packet Too Big (PTB) messages and to control the size of messages
   that are sent, but does not offer any automatic mechanisms for an
   application to discover the maximum packet size supported by a path.
   Applications and upper layer protocols are left to implement robust
   PMTUD mechanisms of their own.

   Packetization Layer PMTUD (PLPMTUD) [RFC4821] describes a method for
   a Packetization Layer (such as UDP with options) to search for the
   largest MTU supported on a path in the absence of ICMP PTB messages.
   Datagram PLPMTUD [I-D.ietf-tsvwg-datagram-plpmtud] describes PMTUD
   probing and search algorithms for datagram transports that does not
   solely rely on ICMP PTB messages.  This allows the Packetization

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