Reaction of Stateless Address Autoconfiguration (SLAAC) to Renumbering Events
draft-gont-6man-slaac-renum-01

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IPv6 Maintenance (6man) Working Group                            F. Gont
Internet-Draft                                    SI6 Networks / UTN-FRH
Updates: 4861, 4862 (if approved)                                J. Zorz
Intended status: Standards Track                       February 18, 2019
Expires: August 22, 2019

 Reaction of Stateless Address Autoconfiguration (SLAAC) to Renumbering
                                 Events
                     draft-gont-6man-slaac-renum-01

Abstract

   In scenarios where network configuration information related to IPv6
   prefixes becomes invalid without any explicit signaling of that
   condition (such as when a CPE crashes and reboots without knowledge
   of the previously-employed prefixes), nodes on the local network will
   continue using stale prefixes for an unacceptably long period of
   time, thus resulting in connectivity problems.  This document
   analyzes these problem scenarios, and proposes workarounds to improve
   network robustness.  This document updates RFC4861 and RFC4862 to
   allow for a more robust reaction to network configuration changes.

Status of This Memo

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   Copyright (c) 2019 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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   (https://trustee.ietf.org/license-info) in effect on the date of

Gont & Zorz              Expires August 22, 2019                [Page 1]
Internet-Draft       Reaction to Renumbering Events        February 2019

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Analysis of the Problem . . . . . . . . . . . . . . . . . . .   4
     3.1.  Inappropriate Default Timer Values in IPv6 Stateless
           Address Autoconfiguration (SLAAC) . . . . . . . . . . . .   4
     3.2.  Inability of SLAAC Hosts to Recover from Stale Network
           Configuration Information . . . . . . . . . . . . . . . .   5
     3.3.  Lack of Explicit Signaling about Stale Information  . . .   6
     3.4.  Under-specified Interaction Between DHCPv6-PD and SLAAC .   6
   4.  Use of Dynamic Prefixes . . . . . . . . . . . . . . . . . . .   7
   5.  Possible workarounds  . . . . . . . . . . . . . . . . . . . .   8
     5.1.  Improvements to SLAAC . . . . . . . . . . . . . . . . . .   8
       5.1.1.  Default Timer Values  . . . . . . . . . . . . . . . .   8
       5.1.2.  Signaling Stale Configuration Information . . . . . .   9
       5.1.3.  Recovery from Stale Configuration Information . . . .  10
     5.2.  Interaction Between DHCPv6-PD and SLAAC . . . . . . . . .  13
     5.3.  Improved CPE behavior . . . . . . . . . . . . . . . . . .  13
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  14
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  14
   8.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  14
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  15
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  15
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  15
   Appendix A.  Flowchart for Host Processing of RAs . . . . . . . .  17
   Appendix B.  Sample Timeline for Host Processing of RAs . . . . .  18
   Appendix C.  Analysis of Some Suggested Workarounds . . . . . . .  19
     C.1.  On a Possible Reaction to ICMPv6 Error Messages . . . . .  20
     C.2.  On a Possible Improvement to Source Address Selection . .  20
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  22

1.  Introduction

   In scenarios where network configuration information related to IPv6
   prefixes becomes invalid without any explicit signaling of that
   condition, nodes on the local network will continue using stale
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