Destination Originates Internet Control Message Protocol (ICMP) Packet Too Big (PTB) Messages
draft-leddy-6man-truncate-03

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Last updated 2018-06-11
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6man                                                            J. Leddy
Internet-Draft                                                   Comcast
Intended status: Standards Track                               R. Bonica
Expires: December 13, 2018                              Juniper Networks
                                                           June 11, 2018

 Destination Originates Internet Control Message Protocol (ICMP) Packet
                         Too Big (PTB) Messages
                      draft-leddy-6man-truncate-03

Abstract

   This document defines procedures that enhance Path MTU Discovery
   (PMTUD), so that it no longer relies on the network's ability to
   deliver an ICMP Packet Too Big (PTB) message from a downstream router
   to an IPv6 source node.  According to these procedures, selected
   packets carry a new IPv6 Destination option.  When a downstream
   router cannot forward one of these packets because of MTU issues, it
   truncates the packet, marks it to indicate that it has been
   truncated, and forwards it towards the destination node.

   When the destination node receives a packet that has been truncated,
   it sends an ICMP PTB message to the source node.  The source node
   uses MTU information contained by the ICMP PTB message to update its
   PMTU estimate.

   The destination node also examines the new Destination option to
   determine whether it should discard the truncated packet or deliver
   it to an upper-layer protocol.

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
   Task Force (IETF).  Note that other groups may also distribute
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   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
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   This Internet-Draft will expire on December 13, 2018.

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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
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   publication of this document.  Please review these documents
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   4
   3.  Operational Considerations  . . . . . . . . . . . . . . . . .   4
   4.  Reference Topology  . . . . . . . . . . . . . . . . . . . . .   5
   5.  Truncation Option . . . . . . . . . . . . . . . . . . . . . .   6
   6.  PMTU Signaling Procedures . . . . . . . . . . . . . . . . . .   7
   7.  Truncation Considerations . . . . . . . . . . . . . . . . . .   8
   8.  ICMP Considerations . . . . . . . . . . . . . . . . . . . . .   9
   9.  Delivering Truncated Packets  . . . . . . . . . . . . . . . .   9
   10. Backward Compatibility  . . . . . . . . . . . . . . . . . . .  10
   11. Optimizations . . . . . . . . . . . . . . . . . . . . . . . .  11
   12. Upper-Layer Considerations  . . . . . . . . . . . . . . . . .  11
   13. Encapsulating Security Payload Considerations . . . . . . . .  11
   14. Extension Header Considerations . . . . . . . . . . . . . . .  12
   15. Security Considerations . . . . . . . . . . . . . . . . . . .  12
   16. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  13
   17. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  13
   18. References  . . . . . . . . . . . . . . . . . . . . . . . . .  13
     18.1.  Normative References . . . . . . . . . . . . . . . . . .  13
     18.2.  Informative References . . . . . . . . . . . . . . . . .  14
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  14

1.  Introduction

   An Internet path connects a source node to a destination node.  A
   path can contain links and routers.

   Each link is constrained by the number of bytes that it can convey in
   a single IP packet.  This constraint is called the link Maximum
   Transmission Unit (MTU).  IPv6 [RFC8200] requires every link to have

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