IKEv2 Notification Status Types for IPv4/IPv6 Coexistence
draft-ietf-ipsecme-ipv6-ipv4-codes-02

Network Working Group                                       M. Boucadair
Internet-Draft                                                    Orange
Updates: 7296 (if approved)                            November 08, 2018
Intended status: Standards Track
Expires: May 12, 2019

       IKEv2 Notification Status Types for IPv4/IPv6 Coexistence
                 draft-ietf-ipsecme-ipv6-ipv4-codes-02

Abstract

   This document specifies new IKEv2 notification status types to better
   manage IPv4 and IPv6 co-existence.

   This document updates RFC7296.

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
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on May 12, 2019.

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
   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.

Boucadair                 Expires May 12, 2019                  [Page 1]
Internet-Draft            An Update to RFC7296             November 2018

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Why Not INTERNAL_ADDRESS_FAILURE? . . . . . . . . . . . . . .   3
   4.  IP6_ONLY_ALLOWED and IP4_ONLY_ALLOWED Status Types  . . . . .   4
   5.  An Update to RFC7296  . . . . . . . . . . . . . . . . . . . .   4
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   As described in [RFC7849], if the subscription data or network
   configuration allows only one IP address family (IPv4 or IPv6), the
   cellular host must not request a second PDP-Context to the same APN
   for the other IP address family.  The Third Generation Partnership
   Project (3GPP) network informs the cellular host about allowed Packet
   Data Protocol (PDP) types by means of Session Management (SM) cause
   codes.  In particular, the following cause codes can be returned:

   o  cause #50 "PDP type IPv4 only allowed": This cause code is used by
      the network to indicate that only PDP type IPv4 is allowed for the
      requested Public Data Network (PDN) connectivity.

   o  cause #51 "PDP type IPv6 only allowed": This cause code is used by
      the network to indicate that only PDP type IPv6 is allowed for the
      requested PDN connectivity.

   o  cause #52 "single address bearers only allowed": This cause code
      is used by the network to indicate that the requested PDN
      connectivity is accepted with the restriction that only single IP
      version bearers are allowed.

   If the requested IPv4v6 PDP-Context is not supported by the network
   but IPv4 and IPv6 PDP types are allowed, then the cellular host will
   be configured with an IPv4 address or an IPv6 prefix by the network.
   It must initiate another PDP-Context activation of the other address
   family in addition to the one already activated for a given Access
   Point Name (APN).  The purpose of initiating a second PDP-Context is
   to achieve dual-stack connectivity by means of two PDP-Contexts.

   When the UE attaches the network using a WLAN access by means of
   IKEv2 capabilities [RFC7296], there are no equivalent notification

Boucadair                 Expires May 12, 2019                  [Page 2]
Internet-Draft            An Update to RFC7296             November 2018

   codes to inform the User Equipment (UE) why an IP address family is
   not assigned or whether that UE should retry with another address
   family.

   This document fills that void by introducing new IKEv2 notification
   status types for the sake of deterministic UE behaviors (Section 4).

   These notification status types are not specific to 3GPP
   architectures, but can be used in other deployment contexts.
   Cellular networks are provided as an illustration example.

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119][RFC8174] when, and only when, they appear in all
   capitals, as shown here.

   This document makes use of the terms defined in [RFC7296].  In
   particular, readers should be familiar with "initiator" and
   "responder" terms used in that document.

3.  Why Not INTERNAL_ADDRESS_FAILURE?

   The following address assignment failures may be encountered when an
   initiator requests assignment of IP addresses/prefixes:

   o  An initiator asks for IPvx, but IPvx address assignment is not
      supported by the responder.

   o  An initiator requests both IPv4 and IPv6 addresses, but only IPv4
      address assignment is supported by the responder.

   o  An initiator requests both IPv4 and IPv6 addresses, but only IPv6
      prefix assignment is supported by the responder.

   o  An initiator asks for both IPv4 and IPv6 addresses, but only one
      address family can be assigned by the responder for policy
      reasons.

   Section 3.15.4 of [RFC7296] defines a generic notification error type
   that is related to a failure to handle an internal address failure.
   That error type does not explicitly allow an initiator to determine
   why a given address family is not assigned, nor whether it should try
   using another address family.  INTERNAL_ADDRESS_FAILURE is a catch-
   all error type when an address-related issue is encountered by an
   IKEv2 responder.

Boucadair                 Expires May 12, 2019                  [Page 3]
Internet-Draft            An Update to RFC7296             November 2018

   INTERNAL_ADDRESS_FAILURE does not provide sufficient hints to the
   IKEv2 initiator to adjust its behavior.

4.  IP6_ONLY_ALLOWED and IP4_ONLY_ALLOWED Status Types

   IP6_ONLY_ALLOWED and IP4_ONLY_ALLOWED status types (see Section 7)
   are defined to inform the initiator about the responser's address
   family assignment support capabilities, and to report to the
   initiator the reason why an address assignment failed.  These
   notifications are used by the initiator to adjust its behavior
   accordingly (Section 5).

   No data is associated with these notifications.

5.  An Update to RFC7296

   If the initiator is dual-stack, it MUST include both address families
   in its request (absent explicit policy/configuration otherwise).

   The responder MUST include IP6_ONLY_ALLOWED (or IP4_ONLY_ALLOWED)
   status type in a response to an address assignment request in the
   following cases:

   1.  The responder only supports IPv6 (or IPv4) address assignment, or

   2.  The responder supports both IPv4 and IPv6 address assignments,
       but it is configured to reply to requests asking for both address
       families with only an IPv6 prefix (or an IPv4 address).

       The address family preference is defined by a policy that is
       local to the responder.

   If the initiator receives IP6_ONLY_ALLOWED or IP4_ONLY_ALLOWED
   notification from the responder, the initiator MUST NOT send a
   request for an alternate address family not supported by the
   responder.

   If a dual-stack initiator requests only an IPv6 prefix (or an IPv4
   address) but receives IP4_ONLY_ALLOWED (or IP6_ONLY_ALLOWED)
   notification from the responder, the initiator MUST send a request
   for IPv4 address(es) (or IPv6 prefix(es)).

   For other address-related error cases that have not been covered by
   the aforementioned notification status types, the repsonder/initiator
   MUST follow the procedure defined in Section 3.15.4 of [RFC7849].

Boucadair                 Expires May 12, 2019                  [Page 4]
Internet-Draft            An Update to RFC7296             November 2018

6.  Security Considerations

   This document adheres to the security considerations defined in
   [RFC7296].

7.  IANA Considerations

   This document requests IANA to update the "IKEv2 Notify Message Types
   - Status Types" registry available at:
   https://www.iana.org/assignments/ikev2-parameters/
   ikev2-parameters.xhtml with the following status types:

   Value           NOTIFY MESSAGES - STATUS TYPES        Reference
    TBD                   IP6_ONLY_ALLOWED           [This-Document]
    TBD                   IP4_ONLY_ALLOWED           [This-Document]

8.  Acknowledgements

   Many thanks to Christian Jacquenet for the review.

   Thanks to Paul Wouters, Yaov Nir, Valery Smyslov, Daniel Migault, and
   Tero Kivinen for the comments.

9.  References

9.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC7296]  Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T.
              Kivinen, "Internet Key Exchange Protocol Version 2
              (IKEv2)", STD 79, RFC 7296, DOI 10.17487/RFC7296, October
              2014, <https://www.rfc-editor.org/info/rfc7296>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

9.2.  Informative References

   [RFC7849]  Binet, D., Boucadair, M., Vizdal, A., Chen, G., Heatley,
              N., Chandler, R., Michaud, D., Lopez, D., and W. Haeffner,
              "An IPv6 Profile for 3GPP Mobile Devices", RFC 7849,
              DOI 10.17487/RFC7849, May 2016,
              <https://www.rfc-editor.org/info/rfc7849>.

Boucadair                 Expires May 12, 2019                  [Page 5]
Internet-Draft            An Update to RFC7296             November 2018

Author's Address

   Mohamed Boucadair
   Orange
   Rennes  35000
   France

   Email: mohamed.boucadair@orange.com

Boucadair                 Expires May 12, 2019                  [Page 6]