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Versions: (draft-binet-v6ops-cellular-host-requirements) 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 RFC 7849

V6OPS Working Group                                             D. Binet
Internet-Draft                                              M. Boucadair
Intended status: Informational                            France Telecom
Expires: March 2, 2015                                         A. Vizdal
                                                     Deutsche Telekom AG
                                                                 G. Chen
                                                            China Mobile
                                                         August 29, 2014


 An Internet Protocol Version 6 (IPv6) Profile for 3GPP Mobile Devices
               draft-ietf-v6ops-mobile-device-profile-10

Abstract

   This document defines an IPv6 profile that a number of operators
   recommend in order to connect 3GPP mobile devices to an IPv6-only or
   dual-stack wireless network (including 3GPP cellular network and IEEE
   802.11 network).

   This document defines a different profile than the one for general
   connection to IPv6 cellular networks defined in the IPv6 for Third
   Generation Partnership Project (3GPP) Cellular Hosts document.  In
   particular, this document identifies also features to deliver IPv4
   connectivity service over an IPv6-only transport.

   Both hosts and devices with capability to share their WAN (Wide Area
   Network) connectivity are in scope.

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 http://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 March 2, 2015.






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Copyright Notice

   Copyright (c) 2014 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
   (http://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.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   4
     1.2.  Scope . . . . . . . . . . . . . . . . . . . . . . . . . .   4
     1.3.  Language Considerations . . . . . . . . . . . . . . . . .   4
   2.  Connectivity Recommendations  . . . . . . . . . . . . . . . .   5
     2.1.  WLAN Connectivity Recommendations . . . . . . . . . . . .   8
   3.  Advanced Recommendations  . . . . . . . . . . . . . . . . . .   9
   4.  Recommendations for Cellular Devices with LAN Capabilities  .  12
   5.  APIs & Applications Recommendations . . . . . . . . . . . . .  14
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  14
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  14
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  14
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  15
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  15
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  16

1.  Introduction

   IPv6 deployment in 3GPP mobile networks is the only perennial
   solution to the exhaustion of IPv4 addresses in those networks.
   Several mobile operators have already deployed IPv6 [RFC2460] or are
   in the pre-deployment phase.  One of the major hurdles encountered by
   mobile operators is the availability of non-broken IPv6
   implementation in mobile devices.

   [RFC7066] lists a set of features to be supported by cellular hosts
   to connect to 3GPP mobile networks.  In the light of recent IPv6
   production deployments, additional features to facilitate IPv6-only
   deployments while accessing IPv4-only service are to be considered.





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   This document defines a different profile than the one for general
   connection to IPv6 mobile networks defined in [RFC7066]; in
   particular:

   o  It lists an extended list of features while [RFC7066] identifies
      issues and explains how to implement basic IPv6 features in a
      cellular context.

   o  It identifies also features to ensure IPv4 service delivery over
      an IPv6-only transport.

   This document defines an IPv6 profile for mobile devices listing
   specifications produced by various Standards Developing Organizations
   (in particular 3GPP and IETF).  The objectives of this effort are:

   1.  List in one single document a comprehensive list of IPv6 features
       for a mobile device, including both IPv6-only and dual-stack
       mobile deployment contexts.  These features cover various network
       types such as GPRS (General Packet Radio Service), EPC (Evolved
       Packet Core) or IEEE 802.11 network.

   2.  Help Operators with the detailed device requirement list
       preparation (to be exchanged with device suppliers).  This is
       also a contribution to harmonize Operators' requirements towards
       device vendors.

   3.  Vendors to be aware of a set of features to allow for IPv6
       connectivity and IPv4 service continuity (over an IPv6-only
       transport).

   Pointers to some requirements listed in [RFC6434] are included in
   this profile.  The justification for using a stronger language
   compared to what is specified in [RFC6434] is provided for some
   recommendations.

   The recommendations do not include 3GPP release details.  For more
   information on the 3GPP releases detail, the reader may refer to
   Section 6.2 of [RFC6459].

   Some of the features listed in this profile document require to
   activate dedicated functions at the network side.  It is out of scope
   of this document to list these network-side functions.

   A detailed overview of IPv6 support in 3GPP architectures is provided
   in [RFC6459].






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1.1.  Terminology

   This document makes use of the terms defined in [RFC6459].  In
   addition, the following terms are used:

   o  "3GPP cellular host" (or cellular host for short) denotes a 3GPP
      device which can be connected to 3GPP mobile networks or IEEE
      802.11 networks.

   o  "3GPP cellular device" (or cellular device for short) refers to a
      cellular host which supports the capability to share its WAN (Wide
      Area Network) connectivity.

   o  "Cellular host" and "mobile host" are used interchangeably.

   o  "Cellular device" and "mobile device" are used interchangeably.

   PREFIX64 denotes an IPv6 prefix used to build IPv4-converted IPv6
   addresses [RFC6052].

1.2.  Scope

   A 3GPP mobile network can be used to connect various user equipments
   such as a mobile telephone, a CPE (Customer Premises Equipment) or a
   M2M (machine-to-machine) device.  Because of this diversity of
   terminals, it is necessary to define a set of IPv6 functionalities
   valid for any node directly connecting to a 3GPP mobile network.
   This document describes these functionalities.

   This document is structured to provide the generic IPv6
   recommendations which are valid for all nodes, whatever their
   function (e.g., host or CPE) or service (e.g., Session Initiation
   Protocol (SIP, [RFC3261])) capability.  The document also contains
   sections covering specific functionalities for devices providing some
   LAN functions (e.g., mobile CPE or broadband dongles).

   The recommendations listed below are valid for both 3GPP GPRS and
   3GPP EPS (Evolved Packet System) access.  For EPS, PDN-Connection
   term is used instead of PDP-Context.

   This document identifies also some WLAN-related IPv6 recommendations.
   Other non-3GPP accesses [TS.23402] are out of scope of this document.

1.3.  Language Considerations

   The key words "must", "must not", "should", "should not", and "may"
   in this document are to be interpreted as described in RFC 2119
   [RFC2119].



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   This document is not a standard, and conformance with it is not
   required in order to claim conformance with IETF standards for IPv6.
   The support of the full set of features may not be required in some
   deployment contexts.  The authors believe that the support of a
   subset of the features included in this protocol may lead to degraded
   level of service in some deployment contexts.

   This document uses these keywords only for precision.

2.  Connectivity Recommendations

   This section identifies the main connectivity recommendations to be
   followed by a cellular host to attach to a network using IPv6.  Both
   dual-stack and IPv6-only deployment models are considered.  IPv4
   service continuity features are listed in this section because these
   are critical for Operators with an IPv6-only deployment model.

   C_REC#1:   The cellular host must be compliant with Section 5.9.1
              (IPv6 Addressing Architecture) and Section 5.8 (ICMPv6
              support) of [RFC6434].

   C_REC#2:   In order to allow each operator to select their own
              strategy regarding IPv6 introduction, the cellular host
              must support both IPv6 and IPv4v6 PDP-Contexts [TS.23060].
              Both IPv6 and IPv4v6 PDP-Contexts must be supported.
              IPv4, IPv6 or IPv4v6 PDP-Context request acceptance
              depends on the cellular network configuration.

   C_REC#3:   The cellular host must comply with the behavior defined in
              [TS.23060] [TS.23401] [TS.24008] for requesting a PDP-
              Context type.  In particular, the cellular host must
              request by default an IPv6 PDP-Context if the cellular
              host is IPv6-only and requesting an IPv4v6 PDP-Context if
              the cellular host is dual-stack or when the cellular host
              is not aware of connectivity types requested by devices
              connected to it (e.g., cellular host with LAN capabilities
              as discussed in Section 4):

              *  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 in addition to
                 the one already activated for a given APN (Access Point
                 Name).

              *  If the requested PDP type and subscription data allows
                 only one IP address family (IPv4 or IPv6), the cellular



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                 host must not request a second PDP-Context to the same
                 APN for the other IP address family.

              The text above focuses on the specification part which
              explains the behavior for requesting IPv6-related PDP-
              Context(s).  Understanding this behavior is important to
              avoid having broken IPv6 implementations in cellular
              devices.

   C_REC#4:   The cellular host must support the PCO (Protocol
              Configuration Options) [TS.24008] to retrieve the IPv6
              address(es) of the Recursive DNS server(s).

                 In-band signaling is a convenient method to inform the
                 cellular host about various services, including DNS
                 server information.  It does not require any specific
                 protocol to be supported and it is already deployed in
                 IPv4 cellular networks to convey such DNS information.

   C_REC#5:   The cellular host must support IPv6 aware Traffic Flow
              Templates (TFT) [TS.24008].

                 Traffic Flow Templates are employing a packet filter to
                 couple an IP traffic with a PDP-Context.  Thus a
                 dedicated PDP-Context and radio resources can be
                 provided by the cellular network for certain IP
                 traffic.

   C_REC#6:   The cellular host must support the Neighbor Discovery
              Protocol ([RFC4861] and [RFC5942]).

                 This is a stronger form compared to what is specified
                 in Section 5.2 and Section 12.2 of [RFC6434].

                 The support of Neighbor Discovery Protocol is mandatory
                 in 3GPP cellular environment as it is the only way to
                 convey IPv6 prefix towards the 3GPP cellular device.

                 In particular, MTU (Maximum Transmission Unit)
                 communication via Router Advertisement must be
                 supported since many 3GPP networks do not have a
                 standard MTU setting.

   C_REC#7:   The cellular host must comply with Section 5.6.1 of
              [RFC6434].  If the MTU used by cellular hosts is larger
              than 1280 bytes, they can rely on Path MTU discovery
              function to discover the real path MTU.




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   C_REC#8:   The cellular host must support IPv6 Stateless Address
              Autoconfiguration ([RFC4862]) apart from the exceptions
              noted in [TS.23060] (3G) and [TS.23401] (LTE):

                 Stateless mode is the only way to configure a cellular
                 host.  The GGSN/PGW must allocate a prefix that is
                 unique within its scope to each primary PDP-Context.

                 To configure its link local address, the cellular host
                 must use the Interface Identifier conveyed in 3GPP PDP-
                 Context setup signaling received from a GGSN/PGW.  The
                 cellular host may use a different Interface Identifiers
                 to configure its global addresses (see also A_REC#1
                 about privacy addressing recommendation).

                 For more details, refer to [RFC6459] and [RFC7066].

   C_REC#9:   The cellular host must comply with Section 7.3 of
              [RFC6434].

   C_REC#10:  The cellular host must comply with Section 7.2.1 of
              [RFC6434].

                 Stateless DHCPv6 is useful to retrieve other
                 information than DNS.

                 If [RFC6106] is not supported at the network side, the
                 cellular host should retrieve DNS information using
                 stateless DHCPv6 [RFC3736].

   C_REC#11:  If the cellular host receives the DNS information in
              several channels for the same interface, the following
              preference order must be followed:

                 1.  PCO

                 2.  RA

                 3.  DHCPv6

   C_REC#12:  The cellular host must be able to be configured to limit
              PDP type(s) for a given APN.  The default mode is to allow
              all supported PDP types.  Note, C_REC#3 discusses the
              default behavior for requesting PDP-Context type(s).

                 This feature is useful to drive the behavior of the UE
                 to be aligned with: (1) service-specific constraints
                 such as the use of IPv6-only for VoLTE (Voice over



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                 LTE), (2) network conditions with regards to the
                 support of specific PDP types (e.g., IPv4v6 PDP-Context
                 is not supported), (3) IPv4 sunset objectives, (4)
                 subscription data, etc.

   C_REC#13:  Because of potential operational deficiencies to be
              experienced in some roaming situations, the cellular host
              must be able to be configured with a home IP profile and a
              roaming IP profile.  The aim of the roaming profile is to
              limit the PDP type(s) requested by the cellular host when
              out of the home network.  Note, distinct PDP type(s) can
              be configured for home and roaming cases.

   C_REC#14:  In order to ensure IPv4 service continuity in an IPv6-only
              deployment context, the cellular host should support a
              method to locally construct IPv4-embedded IPv6 addresses
              [RFC6052].  A method to learn PREFIX64 should be supported
              by the cellular host.

                 This solves the issue when applications use IPv4
                 referrals on IPv6-only access networks.

                 In PCP-based environments, cellular hosts should follow
                 [RFC7225] to learn the IPv6 Prefix used by an upstream
                 PCP-controlled NAT64 device.  If PCP is not enabled,
                 the cellular host should implement the method specified
                 in [RFC7050] to retrieve the PREFIX64.

   C_REC#15:  In order to ensure IPv4 service continuity in an IPv6-only
              deployment context, the cellular host should implement the
              Customer Side Translator (CLAT, [RFC6877]) function which
              is compliant with [RFC6052][RFC6145][RFC6146].

                 CLAT function in the cellular host allows for IPv4-only
                 application and IPv4-referals to work on an IPv6-only
                 connectivity.  CLAT function requires a NAT64
                 capability [RFC6146] in the core network.

                 The IPv4 Service Continuity Prefix used by CLAT is
                 defined in [RFC7335].

2.1.  WLAN Connectivity Recommendations

   It is increasingly common for cellular hosts have a WLAN interface in
   addition to their cellular interface.  These hosts are likely to be
   connected to private or public hotspots.  Below are listed some
   generic recommendations:




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   W_REC#1:  IPv6 must be supported on the WLAN interface.  In
             particular, WLAN interface must behave properly when only
             an IPv6 connectivity is provided.

                Some tests revealed that IPv4 configuration is required
                to enable IPv6-only connectivity.  Indeed, some cellular
                handsets can access a WLAN IPv6-only network by
                configuring first a static IPv4 address.  Once the
                device is connected to the network and the wlan0
                interface got an IPv6 global address, the IPv4 address
                can be deleted from the configuration.  This avoids the
                device to ask automatically for a DHCPv4 server, and
                allows to connect to IPv6-only networks.  Failing to
                configure an IPv4 address on the interface must not
                prohibit using IPv6 on the same interface.

                IPv6 Stateless Address Autoconfiguration ([RFC4862])
                must be supported.

   W_REC#2:  DHCPv6 client should be supported on WLAN interface.

                Refer to Section 7.2.1 of [RFC6434].

   W_REC#3:  WLAN interface should support Router Advertisement Options
             for DNS configuration (See Section 7.3 of [RFC6434]).

   W_REC#4:  If the device receives the DNS information in several
             channels for the same interface, the following preference
             order must be followed:

                1.  RA

                2.  DHCPv6

3.  Advanced Recommendations

   This section identifies a set of advanced recommendations to meet
   regulatory constraints in some countries, fulfill requirements of
   critical services such as VoLTE, or enforce policies such as traffic
   offload.

   A_REC#1:  The cellular host must be able to generate IPv6 addresses
             which preserve privacy.

                The activation of privacy extension (e.g., using
                [RFC4941] or [RFC7217]) makes it more difficult to track
                a host over time when compared to using a permanent
                Interface Identifier.  Note, [RFC4941] does not require



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                any DAD mechanism to be activated as the GGSN/PGW must
                not configure any global address based on the prefix
                allocated to the cellular host.

                Tracking a host is still possible based on the first 64
                bits of the IPv6 address.  Means to prevent against such
                tracking issues may be enabled in the network side.

                Privacy extensions are required by regulatory bodies in
                some countries.

   A_REC#2:  The cellular host must support ROHC RTP Profile (0x0001)
             and ROHC UDP Profile (0x0002) for IPv6 ([RFC5795]).  Other
             ROHC profiles may be supported.

                Bandwidth in cellular networks must be optimized as much
                as possible.  ROHC provides a solution to reduce
                bandwidth consumption and to reduce the impact of having
                bigger packet headers in IPv6 compared to IPv4.

                "RTP/UDP/IP" ROHC profile (0x0001) to compress RTP
                packets [RFC3550] and "UDP/IP" ROHC profile (0x0002) to
                compress RTCP packets [RFC3550] are required for Voice
                over LTE (VoLTE) by IR.92.4.0 section 4.1 [IR92].  Note,
                [IR92] indicates also the host must be able to apply the
                compression to packets that are carried over the radio
                bearer dedicated for the voice media.

   A_REC#3:  The cellular host should support PCP [RFC6887].

                The support of PCP is seen as a driver to save battery
                consumption exacerbated by keepalive messages.  PCP also
                gives the possibility of enabling incoming connections
                to the cellular device.  Indeed, because several
                stateful devices may be deployed in wireless networks
                (e.g., NAT and/or Firewalls), PCP can be used by the
                cellular host to control network-based NAT and Firewall
                functions which will reduce per-application signaling
                and save battery consumption.

                According to [Power], the consumption of a cellular
                device with a keep-alive interval equal to 20 seconds
                (that is the default value in [RFC3948] for example) is
                29mA (2G)/34mA (3G).  This consumption is reduced to
                16mA (2G)/24mA (3G) when the interval is increased to 40
                seconds, to 9.1mA (2G)/16mA (3G) if the interval is
                equal to 150s, and to 7.3mA (2G)/14mA (3G) if the
                interval is equal to 180s.  When no keep-alive is



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                issued, the consumption would be 5.2mA (2G)/6.1mA (3G).
                The impact of keepalive messages would be more severe if
                multiple applications are issuing those messages (e.g.,
                SIP, IPsec, etc.).

   A_REC#4:  In order for host-based validation of DNS Security
             Extensions (DNSSEC) to continue to function in an IPv6-only
             with NAT64 deployment context, the cellular host should
             embed a DNS64 function ([RFC6147]).

                This is called "DNS64 in stub-resolver mode" in
                [RFC6147].

                As discussed in Section 5.5 of [RFC6147], a security-
                aware and validating host has to perform the DNS64
                function locally.

                Because synthetic AAAA records cannot be successfully
                validated in a host, learning the PREFIX64 used to
                construct IPv4-converted IPv6 addresses allows the use
                of DNSSEC [RFC4033] [RFC4034], [RFC4035].  Means to
                configure or discover a PREFIX64 are required on the
                cellular device as discussed in C_REC#14.

                [RFC7051] discusses why a security-aware and validating
                host has to perform the DNS64 function locally and why
                it has to be able to learn the proper PREFIX64(s).

   A_REC#5:  When the cellular host is dual-stack connected (i.e.,
             configured with an IPv4 address and IPv6 prefix), it should
             support means to prefer native IPv6 connection over
             connection established through translation devices (e.g.,
             NAT44 and NAT64).

                When both IPv4 and IPv6 DNS servers are configured, a
                dual-stack host must contact first its IPv6 DNS server.

                Cellular hosts should follow the procedure specified in
                [RFC6724] for source address selection.

   A_REC#6:  The cellular host should support Happy Eyeballs procedure
             defined in [RFC6555].

   A_REC#7:  The cellular host must comply with Section 5.3 of [RFC6434]
             and should support Router Advertisement extension for
             communicating default router preferences and more-specific
             routes as described in [RFC4191].




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                This function can be used for instance for traffic
                offload.

4.  Recommendations for Cellular Devices with LAN Capabilities

   This section focuses on cellular devices (e.g., CPE, smartphones, or
   dongles with tethering features) which provide IP connectivity to
   other devices connected to them.  In such case, all connected devices
   are sharing the same 2G, 3G or LTE connection.  In addition to the
   generic recommendations listed in Section 2, these cellular devices
   have to meet the recommendations listed below.

   L_REC#1:  The cellular device must support Prefix Delegation
             capabilities [RFC3633] and must support Prefix Exclude
             Option for DHCPv6-based Prefix Delegation as defined in
             [RFC6603].  Particularly, it must behave as a Requesting
             Router.

                Cellular networks are more and more perceived as an
                alternative to fixed networks for home IP-based services
                delivery; especially with the advent of smartphones and
                3GPP data dongles.  There is a need for an efficient
                mechanism to assign shorter prefix than /64 to cellular
                hosts so that each LAN segment can get its own /64
                prefix and multi-link subnet issues to be avoided.

                In case a prefix is delegated to a cellular host using
                DHCPv6, the cellular device will be configured with two
                prefixes:

                   (1) one for 3GPP link allocated using SLAAC mechanism
                   and

                   (2) another one delegated for LANs acquired during
                   Prefix Delegation operation.

                Note that the 3GPP network architecture requires both
                the WAN (Wide Area Network) and the delegated prefix to
                be aggregatable, so the subscriber can be identified
                using a single prefix.

                Without the Prefix Exclude Option, the delegating router
                (GGSN/PGW) will have to ensure [RFC3633] compliancy
                (e.g., halving the delegated prefix and assigning the
                WAN prefix out of the 1st half and the prefix to be
                delegated to the terminal from the 2nd half).





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   L_REC#2:  The cellular CPE must be compliant with the requirements
             specified in [RFC6204].

                There are several deployments, particularly in emerging
                countries, that relies on mobile networks to provide
                broadband services (e.g., customers are provided with
                mobile CPEs).

   L_REC#3:  For deployments requiring to share the same /64 prefix, the
             cellular device should support [RFC7278] to enable sharing
             a /64 prefix between the 3GPP interface towards the GGSN/
             PGW (WAN interface) and the LAN interfaces.

   L_REC#4:  In order to ensure IPv4 service continuity in an IPv6-only
             deployment context, the cellular device should support the
             Customer Side Translator (CLAT) [RFC6877].

                Various IP devices are likely to be connected to
                cellular device, acting as a CPE.  Some of these devices
                can be dual-stack, others are IPv6-only or IPv4-only.
                IPv6-only connectivity for cellular device does not
                allow IPv4-only sessions to be established for hosts
                connected on the LAN segment of cellular devices.

                In order to allow IPv4 sessions establishment initiated
                from devices located on LAN segment side and target IPv4
                nodes, a solution consists in integrating the CLAT
                function in the cellular device.  As elaborated in
                Section 2, the CLAT function allows also IPv4
                applications to continue running over an IPv6-only host.

                The IPv4 Service Continuity Prefix used by CLAT is
                defined in [RFC7335].

   L_REC#5:  If a RA MTU is advertised from the 3GPP network, the
             cellular device should relay that upstream MTU information
             to the downstream attached LAN devices in RA.

                Receiving and relaying RA MTU values facilitates a more
                harmonious functioning of the mobile core network where
                end nodes transmit packets that do not exceed the MTU
                size of the mobile network's GTP tunnels.

                [TS.23060] indicates providing a link MTU value of 1358
                octets to the 3GPP cellular device will prevent the IP
                layer fragmentation within the transport network between
                the cellular device and the GGSN/PGW.




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5.  APIs & Applications Recommendations

   The use of address family dependent APIs (Application Programming
   Interfaces) or hard-coded IPv4 address literals may lead to broken
   applications when IPv6 connectivity is in use.  This section
   identifies a set of recommendations aiming to minimize broken
   applications when the cellular device is attached to an IPv6 network.

   APP_REC#1:  Name resolution libraries must support both IPv4 and
               IPv6.

                  In particular, the cellular host must support
                  [RFC3596].

   APP_REC#2:  Applications provided by the mobile device vendor must be
               independent of the underlying IP address family.

                  This means applications must be IP version agnostic.

   APP_REC#3:  Applications provided by the mobile device vendor that
               use Uniform Resource Identifiers (URIs) must follow
               [RFC3986].  For example, SIP applications must follow the
               correction defined in [RFC5954].

6.  Security Considerations

   The security considerations identified in [RFC7066] and [RFC6459] are
   to be taken into account.

   Security-related considerations that apply when the cellular device
   provides LAN features are specified in [RFC6092].

   Address privacy considerations are discussed in [RFC4941] [RFC7217].

7.  IANA Considerations

   This document does not require any action from IANA.

8.  Acknowledgements

   Many thanks to C.  Byrne, H.  Soliman, H.  Singh, L.  Colliti, T.
   Lemon, B.  Sarikaya, M.  Mawatari, M.  Abrahamsson, P.  Vickers, V.
   Kuarsingh, N.  Heatley, E.  Kline, S.  Josefsson, A.  Baryun, J.
   Woodyatt, and R.  Chandler for the discussion in the v6ops mailing
   list.

   Special thanks to T.  Savolainen, J.  Korhonen, and J.  Jaeggli for
   their detailed reviews and comments.



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9.  References

9.1.  Normative References

   [IR92]     GSMA, "IR.92.V4.0 - IMS Profile for Voice and SMS", March
              2011, <http://www.gsma.com/newsroom/
              ir-92-v4-0-ims-profile-for-voice-and-sms>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2460]  Deering, S. and R. Hinden, "Internet Protocol, Version 6
              (IPv6) Specification", RFC 2460, December 1998.

   [RFC3596]  Thomson, S., Huitema, C., Ksinant, V., and M. Souissi,
              "DNS Extensions to Support IP Version 6", RFC 3596,
              October 2003.

   [RFC3633]  Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic
              Host Configuration Protocol (DHCP) version 6", RFC 3633,
              December 2003.

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66, RFC
              3986, January 2005.

   [RFC4861]  Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
              "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
              September 2007.

   [RFC4862]  Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
              Address Autoconfiguration", RFC 4862, September 2007.

   [RFC5795]  Sandlund, K., Pelletier, G., and L-E. Jonsson, "The RObust
              Header Compression (ROHC) Framework", RFC 5795, March
              2010.

   [RFC5942]  Singh, H., Beebee, W., and E. Nordmark, "IPv6 Subnet
              Model: The Relationship between Links and Subnet
              Prefixes", RFC 5942, July 2010.

   [RFC5954]  Gurbani, V., Carpenter, B., and B. Tate, "Essential
              Correction for IPv6 ABNF and URI Comparison in RFC 3261",
              RFC 5954, August 2010.

   [RFC6052]  Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X.
              Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052,
              October 2010.



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   [RFC6603]  Korhonen, J., Savolainen, T., Krishnan, S., and O. Troan,
              "Prefix Exclude Option for DHCPv6-based Prefix
              Delegation", RFC 6603, May 2012.

   [RFC7066]  Korhonen, J., Arkko, J., Savolainen, T., and S. Krishnan,
              "IPv6 for Third Generation Partnership Project (3GPP)
              Cellular Hosts", RFC 7066, November 2013.

   [TS.23060]
              3GPP, "General Packet Radio Service (GPRS); Service
              description; Stage 2", September 2011,
              <http://www.3gpp.org/DynaReport/23060.htm>.

   [TS.23401]
              3GPP, "General Packet Radio Service (GPRS) enhancements
              for Evolved Universal Terrestrial Radio Access Network
              (E-UTRAN) access", September 2011,
              <http://www.3gpp.org/DynaReport/23401.htm>.

   [TS.24008]
              3GPP, "Mobile radio interface Layer 3 specification; Core
              network protocols; Stage 3", June 2011,
              <http://www.3gpp.org/DynaReport/24008.htm>.

9.2.  Informative References

   [Power]    Haverinen, H., Siren, J., and P. Eronen, "Energy
              Consumption of Always-On Applications in WCDMA Networks",
              April 2007, <http://ieeexplore.ieee.org/xpl/
              articleDetails.jsp?arnumber=4212635>.

   [RFC3261]  Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
              A., Peterson, J., Sparks, R., Handley, M., and E.
              Schooler, "SIP: Session Initiation Protocol", RFC 3261,
              June 2002.

   [RFC3550]  Schulzrinne, H., Casner, S., Frederick, R., and V.
              Jacobson, "RTP: A Transport Protocol for Real-Time
              Applications", STD 64, RFC 3550, July 2003.

   [RFC3736]  Droms, R., "Stateless Dynamic Host Configuration Protocol
              (DHCP) Service for IPv6", RFC 3736, April 2004.

   [RFC3948]  Huttunen, A., Swander, B., Volpe, V., DiBurro, L., and M.
              Stenberg, "UDP Encapsulation of IPsec ESP Packets", RFC
              3948, January 2005.





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   [RFC4033]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
              Rose, "DNS Security Introduction and Requirements", RFC
              4033, March 2005.

   [RFC4034]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
              Rose, "Resource Records for the DNS Security Extensions",
              RFC 4034, March 2005.

   [RFC4035]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
              Rose, "Protocol Modifications for the DNS Security
              Extensions", RFC 4035, March 2005.

   [RFC4191]  Draves, R. and D. Thaler, "Default Router Preferences and
              More-Specific Routes", RFC 4191, November 2005.

   [RFC4941]  Narten, T., Draves, R., and S. Krishnan, "Privacy
              Extensions for Stateless Address Autoconfiguration in
              IPv6", RFC 4941, September 2007.

   [RFC6092]  Woodyatt, J., "Recommended Simple Security Capabilities in
              Customer Premises Equipment (CPE) for Providing
              Residential IPv6 Internet Service", RFC 6092, January
              2011.

   [RFC6106]  Jeong, J., Park, S., Beloeil, L., and S. Madanapalli,
              "IPv6 Router Advertisement Options for DNS Configuration",
              RFC 6106, November 2010.

   [RFC6145]  Li, X., Bao, C., and F. Baker, "IP/ICMP Translation
              Algorithm", RFC 6145, April 2011.

   [RFC6146]  Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful
              NAT64: Network Address and Protocol Translation from IPv6
              Clients to IPv4 Servers", RFC 6146, April 2011.

   [RFC6147]  Bagnulo, M., Sullivan, A., Matthews, P., and I. van
              Beijnum, "DNS64: DNS Extensions for Network Address
              Translation from IPv6 Clients to IPv4 Servers", RFC 6147,
              April 2011.

   [RFC6204]  Singh, H., Beebee, W., Donley, C., Stark, B., and O.
              Troan, "Basic Requirements for IPv6 Customer Edge
              Routers", RFC 6204, April 2011.

   [RFC6434]  Jankiewicz, E., Loughney, J., and T. Narten, "IPv6 Node
              Requirements", RFC 6434, December 2011.





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   [RFC6459]  Korhonen, J., Soininen, J., Patil, B., Savolainen, T.,
              Bajko, G., and K. Iisakkila, "IPv6 in 3rd Generation
              Partnership Project (3GPP) Evolved Packet System (EPS)",
              RFC 6459, January 2012.

   [RFC6555]  Wing, D. and A. Yourtchenko, "Happy Eyeballs: Success with
              Dual-Stack Hosts", RFC 6555, April 2012.

   [RFC6724]  Thaler, D., Draves, R., Matsumoto, A., and T. Chown,
              "Default Address Selection for Internet Protocol Version 6
              (IPv6)", RFC 6724, September 2012.

   [RFC6877]  Mawatari, M., Kawashima, M., and C. Byrne, "464XLAT:
              Combination of Stateful and Stateless Translation", RFC
              6877, April 2013.

   [RFC6887]  Wing, D., Cheshire, S., Boucadair, M., Penno, R., and P.
              Selkirk, "Port Control Protocol (PCP)", RFC 6887, April
              2013.

   [RFC7050]  Savolainen, T., Korhonen, J., and D. Wing, "Discovery of
              the IPv6 Prefix Used for IPv6 Address Synthesis", RFC
              7050, November 2013.

   [RFC7051]  Korhonen, J. and T. Savolainen, "Analysis of Solution
              Proposals for Hosts to Learn NAT64 Prefix", RFC 7051,
              November 2013.

   [RFC7217]  Gont, F., "A Method for Generating Semantically Opaque
              Interface Identifiers with IPv6 Stateless Address
              Autoconfiguration (SLAAC)", RFC 7217, April 2014.

   [RFC7225]  Boucadair, M., "Discovering NAT64 IPv6 Prefixes Using the
              Port Control Protocol (PCP)", RFC 7225, May 2014.

   [RFC7278]  Byrne, C., Drown, D., and A. Vizdal, "Extending an IPv6
              /64 Prefix from a Third Generation Partnership Project
              (3GPP) Mobile Interface to a LAN Link", RFC 7278, June
              2014.

   [RFC7335]  Byrne, C., "IPv4 Service Continuity Prefix", RFC 7335,
              August 2014.

   [TS.23402]
              3GPP, "Architecture enhancements for non-3GPP accesses",
              September 2011,
              <http://www.3gpp.org/DynaReport/23402.htm>.




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Authors' Addresses

   David Binet
   France Telecom
   Rennes
   France

   EMail: david.binet@orange.com


   Mohamed Boucadair
   France Telecom
   Rennes  35000
   France

   EMail: mohamed.boucadair@orange.com


   Ales Vizdal
   Deutsche Telekom AG

   EMail: ales.vizdal@t-mobile.cz


   Gang Chen
   China Mobile

   EMail: phdgang@gmail.com























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