Recommendations for Prefix Binding in the Softwire DS-Lite Context
draft-vinapamula-softwire-dslite-prefix-binding-11

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Network Working Group                                      S. Vinapamula
Internet-Draft                                          Juniper Networks
Intended status: Informational                              M. Boucadair
Expires: February 22, 2016                                France Telecom
                                                         August 21, 2015

   Recommendations for Prefix Binding in the Softwire DS-Lite Context
           draft-vinapamula-softwire-dslite-prefix-binding-11

Abstract

   This document discusses issues induced by the change of the Dual-
   Stack Lite (DS-Lite) Basic Bridging BroadBand (B4) IPv6 address and
   sketches a set of recommendations to solve those issues.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
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   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on February 22, 2016.

Copyright Notice

   Copyright (c) 2015 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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   described in the Simplified BSD License.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   2
   2.  The Problem . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Introducing Subscriber-Mask . . . . . . . . . . . . . . . . .   4
   4.  Recommendations . . . . . . . . . . . . . . . . . . . . . . .   4
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   6.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .   6
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     8.1.  Normative references  . . . . . . . . . . . . . . . . . .   7
     8.2.  Informative references  . . . . . . . . . . . . . . . . .   7
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   IPv6 deployment models assume IPv6 prefixes are delegated by Service
   Providers to the connected CPEs (Customer Premises Equipments) or
   hosts, which in turn derive IPv6 addresses from that prefix.  In the
   case of Dual-Stack Lite (DS-Lite) [RFC6333], which is an IPv4 service
   continuity mechanism over an IPv6 network, the Basic Bridging
   BroadBand (B4) element derives an IPv6 address for the IPv4-in-IPv6
   softwire setup purposes.

   The B4 element might obtain a new IPv6 address, for a variety of
   reasons that include (but are not limited to) a reboot of the CPE,
   power outage, DHCPv6 lease expiry, or other actions undertaken by the
   Service Provider.  If this occurs, traffic forwarded to a B4's
   previous IPv6 address may never reach its destination or be delivered
   to another B4 that now uses the address formerly assigned to the
   original B4.  This situation affects all mapping types, both implicit
   (e.g., by sending a TCP SYN) and explicit (e.g., using Port Control
   Protocol (PCP) [RFC6887]).  The problem is further elaborated in
   Section 2.

   This document proposes recommendations to soften the impact of such
   renumbering issues (Section 4).

   This document complements [RFC6908].

1.1.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

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2.  The Problem

   Since private IPv4 addresses assigned to hosts serviced by a B4
   element overlap across multiple CPEs, the IPv6 address of a B4