Reaction of Stateless Address Autoconfiguration (SLAAC) to Renumbering Events
draft-gont-v6ops-slaac-renum-00

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IPv6 Operations Working Group (v6ops)                            F. Gont
Internet-Draft                                              SI6 Networks
Intended status: Informational                                   J. Zorz
Expires: January 7, 2020
                                                            R. Patterson
                                                                  Sky UK
                                                            July 6, 2019

 Reaction of Stateless Address Autoconfiguration (SLAAC) to Renumbering
                                 Events
                    draft-gont-v6ops-slaac-renum-00

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 discusses operational
   workarounds to improve network robustness.

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Gont, et al.             Expires January 7, 2020                [Page 1]
Internet-Draft       Reaction to Renumbering Events            July 2019

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Analysis of the Problem . . . . . . . . . . . . . . . . . . .   4
     2.1.  Default Timer Values in IPv6 Stateless Address
           Autoconfiguration (SLAAC) . . . . . . . . . . . . . . . .   5
     2.2.  Recovering from Stale Network Configuration Information .   5
     2.3.  Lack of Explicit Signaling about Stale Information  . . .   6
     2.4.  Interaction Between DHCPv6-PD and SLAAC . . . . . . . . .   6
     2.5.  Use of Dynamic Prefixes . . . . . . . . . . . . . . . . .   6
   3.  Possible workarounds  . . . . . . . . . . . . . . . . . . . .   7
     3.1.  SLAAC Parameter Tweaking  . . . . . . . . . . . . . . . .   7
     3.2.  Improved CPE behavior . . . . . . . . . . . . . . . . . .   8
       3.2.1.  Signaling Stale Configuration Information . . . . . .   9
       3.2.2.  Interaction Between DHCPv6-PD and SLAAC . . . . . . .  10
   4.  Summary of Operational Mitigations  . . . . . . . . . . . . .  10
     4.1.  Networks  . . . . . . . . . . . . . . . . . . . . . . . .  10
     4.2.  CPE routers . . . . . . . . . . . . . . . . . . . . . . .  11
   5.  Future Work . . . . . . . . . . . . . . . . . . . . . . . . .  11
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  11
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  11
   8.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  11
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  12
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  12
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  12
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  14

1.  Introduction

   IPv6 largely assumes prefix stability, with network renumbering only
   taking place in a planned manner, with old/stale prefixes being
   phased-out via reduced prefix lifetimes, and new prefixes (with
   longer lifetimes) being introduced at the same time.  However, there
   are a number of scenarios that may lead to the so-called "flash-
   renumbering", where the prefix being employed on a network suddenly
   becomes invalid and replaced by a new prefix.  In some of these
   scenarios, the local router producing the network renumbering may be
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