Softwire Provisioning Using DHCPv4 over DHCPv6
RFC 8539

Document Type RFC - Proposed Standard (March 2019; No errata)
Updates RFC 7598
Last updated 2019-03-15
Replaces draft-fsc-softwire-dhcp4o6-saddr-opt
Stream IETF
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Reviews
Stream WG state Submitted to IESG for Publication
Document shepherd Bernie Volz
Shepherd write-up Show (last changed 2018-06-21)
IESG IESG state RFC 8539 (Proposed Standard)
Consensus Boilerplate Yes
Telechat date
Responsible AD Suresh Krishnan
Send notices to Bernie Volz <volz@cisco.com>
IANA IANA review state IANA OK - Actions Needed
IANA action state RFC-Ed-Ack
Internet Engineering Task Force (IETF)                         I. Farrer
Request for Comments: 8539                           Deutsche Telekom AG
Updates: 7598                                                     Q. Sun
Category: Standards Track                                         Y. Cui
ISSN: 2070-1721                                                   L. Sun
                                                     Tsinghua University
                                                              March 2019

             Softwire Provisioning Using DHCPv4 over DHCPv6

Abstract

   DHCPv4 over DHCPv6 (RFC 7341) is a mechanism for dynamically
   configuring IPv4 for use as an over-the-top service in an IPv6-only
   network.  Softwires are an example of such a service.  For DHCPv4
   over DHCPv6 (DHCP 4o6) to function with some IPv4-over-IPv6 softwire
   mechanisms and deployment scenarios (e.g., RFC 7596 or RFC 7597), the
   operator needs to know the IPv6 address that the client will use as
   the source of an IPv4-in-IPv6 softwire tunnel.  This address, in
   conjunction with the client's IPv4 address, and (in some deployments)
   the Port Set ID are used to create a binding table entry in the
   operator's softwire tunnel concentrator.  This memo defines a DHCPv6
   option to convey IPv6 parameters for establishing the softwire tunnel
   and a DHCPv4 option (to be used only with DHCP 4o6) to communicate
   the source tunnel IPv6 address between the DHCP 4o6 client and
   server.  It is designed to work in conjunction with the IPv4 address
   allocation process.

   "DHCPv6 Options for Configuration of Softwire Address and Port-Mapped
   Clients" (RFC 7598) describes a deterministic DHCPv6-based mechanism
   for provisioning softwires.  This document updates RFC 7598, allowing
   OPTION_S46_BR (90) to be enumerated in the DHCPv6 client's Option
   Request Option (ORO) request and to appear directly within subsequent
   messages sent by the DHCPv6 server.

Farrer, et al.               Standards Track                    [Page 1]
RFC 8539           Softwire Provisioning with DHCP 4o6        March 2019

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8539.

Copyright Notice

   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
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Farrer, et al.               Standards Track                    [Page 2]
RFC 8539           Softwire Provisioning with DHCP 4o6        March 2019

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Applicability . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Requirements Language . . . . . . . . . . . . . . . . . . . .   4
   4.  Solution Overview . . . . . . . . . . . . . . . . . . . . . .   5
     4.1.  Updating RFC 7598 to Permit the Reuse of
           OPTION_S46_BR (90)  . . . . . . . . . . . . . . . . . . .   5
   5.  DHCP 4o6 IPv6/IPv4 Binding Message Flow . . . . . . . . . . .   6
   6.  DHCP Options  . . . . . . . . . . . . . . . . . . . . . . . .   7
     6.1.  DHCPv6 Softwire Source Binding Prefix Hint Option . . . .   7
     6.2.  DHCP 4o6 Softwire Source Address Option . . . . . . . . .   8
   7.  Client Behavior . . . . . . . . . . . . . . . . . . . . . . .   9
     7.1.  Client Initialization . . . . . . . . . . . . . . . . . .   9
     7.2.  Renewing or Rebinding the IPv4 Address Lease and
           Softwire Source Address . . . . . . . . . . . . . . . . .  10
       7.2.1.  Changing the Bound IPv6 Softwire Source Address . . .  10
     7.3.  Releasing the IPv4 Address Lease and Softwire
           Source Address  . . . . . . . . . . . . . . . . . . . . .  11
     7.4.  OPTION_S46_BIND_IPV6_PREFIX Validation Behavior . . . . .  11
     7.5.  Client and Server Softwire Source Address Mismatch  . . .  11
     7.6.  Use with Dynamic, Shared IPv4 Addresses . . . . . . . . .  12
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