Packetization Layer Path MTU Discovery for Datagram Transports
draft-ietf-tsvwg-datagram-plpmtud-00

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Document Type Active Internet-Draft (tsvwg WG)
Last updated 2018-01-22
Replaces draft-fairhurst-tsvwg-datagram-plpmtud
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Internet Engineering Task Force                             G. Fairhurst
Internet-Draft                                                  T. Jones
Intended status: Standards Track                  University of Aberdeen
Expires: July 24, 2018                                         M. Tuexen
                                                            I. Ruengeler
                                 Muenster University of Applied Sciences
                                                        January 22, 2018

     Packetization Layer Path MTU Discovery for Datagram Transports
                  draft-ietf-tsvwg-datagram-plpmtud-00

Abstract

   This document describes a robust method for Path MTU Discovery
   (PMTUD) for datagram Packetization layers.  The method allows a
   Packetization layer (or a datagram application that uses it) to probe
   an network path with progressively larger packets to determine a
   maximum packet size.  The document describes as an extension to RFC
   1191 and RFC 8201, which specify ICMP-based Path MTU Discovery for
   IPv4 and IPv6.  This provides functionally for datagram transports
   that is equivalent to the Packetization layer PMTUD specification for
   TCP, specified in RFC4821.

   When published, this specification updates RFC4821.

Status of this Memo

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   This Internet-Draft will expire on July 24, 2018.

Copyright Notice

   Copyright (c) 2018 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

Fairhurst, Jones, Tuexen ExpireseJuly 24, 2018                  [Page 1]
Internet-Draft              Datagram PLPMTUD                January 2018

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (http://trustee.ietf.org/
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   Please review these documents carefully, as they describe your rights
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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  5
   3.  Features required to provide Datagram PLPMTUD  . . . . . . . .  6
     3.1.  PMTU Probe Packets . . . . . . . . . . . . . . . . . . . .  8
     3.2.  Validation of the current effective PMTU . . . . . . . . .  9
     3.3.  Reduction of the effective PMTU  . . . . . . . . . . . . . 10
   4.  Datagram Packetization Layer PMTUD . . . . . . . . . . . . . . 10
     4.1.  Probing  . . . . . . . . . . . . . . . . . . . . . . . . . 10
     4.2.  Selecting the Size of a Probe Message  . . . . . . . . . . 11
     4.3.  Verification and use of PTB messages . . . . . . . . . . . 11
     4.4.  Timers . . . . . . . . . . . . . . . . . . . . . . . . . . 12
     4.5.  Constants  . . . . . . . . . . . . . . . . . . . . . . . . 12
     4.6.  Variables  . . . . . . . . . . . . . . . . . . . . . . . . 13
     4.7.  Selecting Probe Size . . . . . . . . . . . . . . . . . . . 13
     4.8.  State Machine  . . . . . . . . . . . . . . . . . . . . . . 14
   5.  Specification of Protocol-Specific Methods . . . . . . . . . . 16
     5.1.  DPLPMTUD for UDP and UDP-Lite  . . . . . . . . . . . . . . 16
       5.1.1.  UDP Options  . . . . . . . . . . . . . . . . . . . . . 16
       5.1.2.  UDP Options required for PLPMTUD . . . . . . . . . . . 16
         5.1.2.1.  Echo Request Option  . . . . . . . . . . . . . . . 16
         5.1.2.2.  Echo Response Option . . . . . . . . . . . . . . . 17
       5.1.3.  Sending UDP-Option Probe Packets . . . . . . . . . . . 17
       5.1.4.  Validating the Path with UDP Options . . . . . . . . . 17
       5.1.5.  Handling of PTB Messages by UDP  . . . . . . . . . . . 17
     5.2.  DPLPMTUD for SCTP  . . . . . . . . . . . . . . . . . . . . 17
       5.2.1.  SCTP/IP4 and SCTP/IPv6 . . . . . . . . . . . . . . . . 18
         5.2.1.1.  Sending SCTP Probe Packets . . . . . . . . . . . . 18
         5.2.1.2.  Validating the Path with SCTP  . . . . . . . . . . 18
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