Network Working Group                                            G. Chen
Internet-Draft                                                   H. Deng
Intended status: Informational                              China Mobile
Expires: January 5, 2015                                      D. Michaud
                                                   Rogers Communications
                                                             J. Korhonen
                                                          Renesas Mobile
                                                            M. Boucadair
                                                          France Telecom
                                                               A. Vizdal
                                                     Deutsche Telekom AG
                                                            July 4, 2014

                     IPv6 Roaming Behavior Analysis


   This document identifies a set of failure cases encountered by an
   IPv6-enabled IPv6 customers in roaming scenarios.  The investigations
   on those failed cases reveal the causes in order to notice improper
   configurations, equipment's incomplete functions or inconsistent IPv6
   introduction strategy.

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
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   Drafts is at

   Internet-Drafts are draft documents valid for a maximum of six months
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   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 January 5, 2015.

Copyright Notice

   Copyright (c) 2014 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   ( 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
   2.  Roaming Architecture Description  . . . . . . . . . . . . . .   3
   3.  Roaming Scenario  . . . . . . . . . . . . . . . . . . . . . .   5
   4.  Failure Case in Attachment Stage  . . . . . . . . . . . . . .   6
   5.  Failure Cases in PDP/PDN Creation . . . . . . . . . . . . . .   7
     5.1.  Case 1: Splitting Dual-stack Bearer . . . . . . . . . . .   7
     5.2.  Case 2: Lack of IPv6 support in applications  . . . . . .   8
     5.3.  Case 3: Fallback Incapability . . . . . . . . . . . . . .   8
     5.4.  Case 4: 464xlat Support . . . . . . . . . . . . . . . . .   9
   6.  Discussions . . . . . . . . . . . . . . . . . . . . . . . . .   9
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  10
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  11
     10.2.  Informative References . . . . . . . . . . . . . . . . .  11
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  13

1.  Introduction

   Many Mobile Operators deployed or are in a per-deployment stage of
   IPv6 in their operational networks.  Customers will be delivered with
   IPv6 connectivity if their User Equipment (UE) are IPv6-compliant.  A
   detailed overview of IPv6 support in 3GPP architectures is provided
   in [RFC6459].  Operators may adopt various approaches to deploy IPv6
   in mobile networks, for example the solutions described in
   [TR23.975]).  Dual-stack or IPv6 single-stack has been selected
   depending on network's conditions.  It has been observed that a
   mobile subscriber roaming around different operator's areas may
   experience service degradations or interruptions due to the
   inconsistent configurations and incomplete functions on the networks

   This memo intends to document the observed failed cases and analyze
   the causes.

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2.  Roaming Architecture Description

   The roaming process has been occurred in the following scenarios:

   o  International roaming: a mobile UE may entry a visited network,
      where different Public Land Mobile Network (PLMN) identity is
      used.  UEs could, either in an automatic mode or a manual mode,
      attach to the visited PLMN.

   o  Intra-PLMN mobility: a UE moves to a visited network as that of
      the Home Public Land Mobile Network (HPLMN).  However, the
      subscriber profiles may not be stored in the area.  Once the
      subscriber attached to the network, the subscriber profile should
      be extracted from the home network for the network attachment.

   When a UE is turned on or is transferred via a handover to a visited
   network, the mobile device will scan all radio channels and find
   available Public Land Mobile Networks (PLMNs) to attach.  Serving
   GPRS Support Node (SGSN) or Mobility Management Entity (MME) in the
   visited networks must contact the Home Location Register(HLR) or Home
   Subscriber Server(HSS) and obtain the subscriber profile.  Once the
   authentication and registration process is completed, the Packet Data
   Protocol (PDP) or Packet Data Networks (PDN) activation and traffic
   flows may be operated differently according to the subscriber profile
   stored in HLR or HSS.  Two modes have been shown at the figure to
   illustrate, that are "Home routed traffic" (Figure 1) and "Local
   breakout" (Figure 2).

+---------------------------------+             +------------------------+
|Visited Network                  |             |Home Network            |
|  +----+           +--------+    |             |    +--------+ Traffic Flow
|  | UE |==========>|SGSN/MME|======================>|GGSN/PGW|============>
|  +----+           +--------+    | Signaling   |    +--------+          |
|                        |-------------------------->+--------+          |
|                                 |             |    |HLR/HSS |          |
|                                 |             |    +--------+          |
+---------------------------------+             +------------------------+

                       Figure 1: Home Routed Traffic

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+---------------------------------+             +------------------------+
|Visited Network                  |             |Home Network            |
|  +----+           +--------+    | Signaling   |    +--------+          |
|  | UE |==========>|SGSN/MME|---------------------->|HLR/HSS |          |
|  +----+           +--------+    |             |    +--------+          |
|                       ||        |             |                        |
|                   +--------+    |             |                        |
|                   |GGSN/PGW|    |             |                        |
|                   +--------+    |             |                        |
|         Traffic Flow  ||        |             |                        |
+-----------------------||--------+             +------------------------+

                         Figure 2: Local Breadkout

   In the home routed mode, subscribers will activate the PDP/PDN
   context and get address from the home network.  All traffic would be
   routed back to the home networks.  It's likely most cases for
   international roaming of Internet data services to facilitate the
   charging process between two operators.

   In the local breakout mode, the subscriber address will be assigned
   from the visited network.  The traffic flow is directly offloaded
   locally at a network node close to that device's point of attachment
   in the visited networks.  Therefore, more efficient route is
   achieved.  The international roaming of IP Multimedia Subsystem (IMS)
   based services, e.g.  Voice over LTE (VoLTE)[IR.92] , is claimed to
   select the local breakout mode in [IR.65].  Data service roaming
   across different areas within a operator network could use local
   breakout mode in order to get efficient traffic route.  The local
   breakout mode could be also applied to an operators alliance for
   international roaming of data service.  EU Roaming Regulation
   III[EU-Roaming-III] involves local breakout mode allowing european
   subscribers roaming in european 2G/3G networks can choose to have
   their Internet data routed directly to the Internet from their
   current VPLMN.  The following enumerates the more specific
   configuration considerations.

   o  Operators may add the APN-OI-Replacement flag defined in 3GPP
      [TS29.272] into user's subscription-data.  The visited network
      indicates a local domain name to replace the user requested Access
      Point Name (APN).  As the consequence, the traffic would be
      steered to the visited network.  Those functions are normally
      deployed for the Intra-PLMN mobility cases.

   o  Operators could also configure VPLMN-Dynamic-Address-Allowed
      flag[TS29.272] in the user profile to enable local breakout mode
      in Visited Public Land Mobile Networks (VPLMNs).

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   o  3GPP specified Selected IP Traffic Offload (SIPTO)
      function[TS23.401] since Release 10 in order to get efficient
      route paths.  It enables an operator to offload certain types of
      traffic at a network node close to that device's point of
      attachment to the access network.

   o  GSMA has defined RAVEL[IR.65] as IMS international roaming
      architecture.  Local breakout mode has been adopted for the
      roaming architecture.

3.  Roaming Scenario

   There are two stages happened when a subscriber roams to a visited
   network and intends to start data services.

   o  Nework attachment: it's occurred once the subsriber enters a
      visited network.  During an attachment, the visited network should
      authenticate the subsriber and make location update to the HSS/HLR
      in the home network of the subsriber.  Accordingly, the subscriber
      profile is offered from the HSS/HLR.  The subscriber profile
      contains the allowed Access Point Names (APN), allowed PDP/PDN
      Types and rules regarding the routing of data sessions (i.e. home
      routed or local breakout mode) [TS29.272].  SGSN/MME in the
      visited network could use those informaiton to facilitate the
      subsequent PDP/PDN session creation.

   o  PDP/PDN context creation: it's occurred after the subsriber makes
      a sucessful attachment.  It's worth nothing that this stage is
      integrated with the attachment stage in the case of 4G, but a
      seperated process in 2/3G. 3GPP specifies three types of Packet
      Data Protocol (PDP)/Packet Data Networks (PDN) to describe
      connections, i.e., PDP/PDN Type IPv4, PDP/PDN Type IPv6 and PDP/
      PDN Type IPv4v6.  When a subsriber creates a data session, a user
      device is configured to request a particular PDP/PDN Type.  The
      allowed PDP/PDN types for the subscriber are learned from the
      attachment stage.  Hence, SGSN/MME could initiate PDP/PDN request
      to GGSN/PGW if the subscription profile is allowed.

   The failures are likely happened in both stages due to an incompliant
   implementation or mismatch between the subscriber requested and the
   visited network capability.  The failures in the attachment stage is
   independent with home routed and local breakout mode, while most
   failure cases in the PDP/PDN context creation stage are appeared in
   the local breakout cases.  Section 4 and 5 make further descriptions
   for each cases.  The below table lists the several cases regarding
   the PDP/PDN creation stage.

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   | UE request  |  PDN/PDP IP Type  |Local breakout|
   |             |     permitted     |              |
   | IPv4v6      |  IPv4 or IPv6     |Failure case 1|
   | IPv4v6      |      IPv6         |Failure case 2|
   | IPv6        |      IPv4         |Failure case 3|
   | IPv6        |       IPv6        |Failure case 4|
   | with 464xlat|   without NAT64   |              |

                  Table 1: Roaming Scenario Descriptions

4.  Failure Case in Attachment Stage

   3GPP specified PDP/PDN type IPv4v6 in order to allow a UE requesting
   both IPv4 and IPv6 within a single PDP/PDN request.  This feature is
   stored as a part of subscription data for a subscriber in the HLR/
   HSS.  PDP/PDN type IPv4v6 is introduced since the inception of
   Evolved Packet System (EPS) in 4G network.  The nodes in 4G networks
   should no issues with the handling of this PDN type.  However, it's
   of varing supports in 2/3G networks denpending on Serving GPRS
   Support Node (SGSN) software version.  In theory, S4-SGSN (i.e., the
   SGSN with S4 interface) support the PDP/PDN type IPv4v6 since
   Release8 and Gn-SGSN (i.e., the SGSN with Gn interface) support it
   since Release 9.  In most cases, operators normally use Gn-SGSN to
   connect either GGSN in 3G or Packet Data Network Gateway (PGW) in 4G.
   The MAP (Mobile Application Part) protocol, as defined in 3GPP
   [TS29.002], is used over the Gr interface between SGSN and HLR.  The
   MAP Information Element (IE) "ext-pdp-Type" contains the IPv4v6 PDP
   Type is conveyed to SGSN from HLR within the Insert Subscriber Data
   (ISD) MAP operation.  If the SGSN does not support the IPv4v6 PDP
   Type, it will not support the "ext-pdp-Type" IE and consequently must
   silently discard that IE and continue processing of the rest of the
   ISD MAP message.  The issue we observe is that multiple SGSNs will be
   unable to correctly process a subscriber data received in the Insert
   Subscriber Data procedure[TS23.060].  As a consequence , it will
   likely refuse the subscriber attach request, which is erroneous
   behaviour as they are not 3GPP compliant.

   Operators may have to remove the PDP/PDN type IPv4v6 from HLR/HSS in
   the home network, that will restrict UEs only initiates IPv4 PDP or
   IPv6 PDP activation.  In order to avoid this situation, operators
   should make a comprehensive roaming agreement to support IPv6 and
   ensure that aligns with GSMA document, e.g [IR.33], [IR.88] and

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   [IR.21].  The agreement requires visited operators to get necessary
   patch on all SGSN nodes to support PDP/PDN type IPv4v6.

   There are some specific implementation in HLS/HSS of home network as
   an alternative solution.  Once the HLR/HSS receives an Update
   Location message from visited SGSN known to not support the PDP type
   IPv4v6, only the subscription data with PDP/PDN type IPv4 will be
   sent to SGSN in the Insert Subscriber Data procedure.  It guarantee
   the user profile could compatible with visited SGSN/MME capability.

5.  Failure Cases in PDP/PDN Creation

   Once a subscriber succeed in the attach stage, IP allocation process
   is taken place to allocate IP addresses to the subscriber.  This
   section has summarized several failures in the break-out cases.

5.1.  Case 1: Splitting Dual-stack Bearer

   Dual-stack capability can be provided using separate PDP/PDN
   activations.  That means only a single IPv4 and IPv6 PDP/PDN is
   allowed to be initiated to allocate IPv4 and IPv6 address separately.
   The below lists the cases.

   o  The SGSN/MME returns Session Manamgement (SM) Cause #52, "Single
      address bearers only allowed", or SM Cause #28 "Unknown PDP
      address or PDP type" as per[TS24.008] and [TS24.301].

   o  The SGSN/MME does not set the Dual Address Bearer Flag due to the
      operator using single addressing per bearer to support
      interworking with nodes of earlier releases

   A roaming subscriber with IPv4v6 PDP/PDN type have to change the
   request into two separated PDP/PDN requests with single IP version in
   order to achieve equivalent results.  Some drawbacks in this case are
   listed as following:

   o  The parallel PDP/PDN activations would likely double PDP/PDN
      resources consumptions.  It impacts the capacity of GGSN/PGW,
      since a certain amount of PDP/PDN activations are only allowed on
      those nodes.

   o  Some networks may only allow one PDP/PDN is alive for each
      subscriber.  For example, IPv6 PDP/PDN will be rejected if the
      subscriber has an active IPv4 PDP/PDN.  Therefore, the subscriber
      will lost IPv6 connection in the visited network.  It's even worse
      that it may have a risk of losing all data connectivity if the
      IPv6 PDP gets rejected with a permanent error at the APN-level and
      not specific to the PDP-Type IPv6 requested.

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   o  Additional correlations between those two PDP/PDN contexts are
      required on the charging system.

   o  Policy and Charging Rules Function(PCRF)/Policy and Charging
      Enforcement Function (PCEF) treat IPv4 and IPv6 session as
      independent and perform different Quality of Service (QoS)
      policies.  The subscriber may have unstable experiences due to
      different behaviors on each IP version connection.

   o  Mobile devices may have the limitation of allowed simultaneous
      PDP/PDN activations.  Overmuch PDP/PDN activation may result in
      other unrelated services broken.

   Operators may have to disable the local-break mode to avoid the
   risks.  Another approach is to set a dedicated Access Point Name
   (APN) profile to only request PDP/PDN type IPv4 in the roaming

5.2.  Case 2: Lack of IPv6 support in applications

   Some operators may adopt IPv6-only configuration for the IMS service,
   e.g.  Voice over LTE (VoLTE)[IR.92] or Rich Communication Suite
   (RCS)[RCC.07].  Since IMS roaming architecture will offload all
   traffic in the visited network, a dual-stack subscriber can only be
   assigned with IPv6 address and no IPv4 address returned.  It requires
   all the IMS based applications should be IPv6 capable.  A
   translation-based method, for example Bump-in-the-host (BIH)[RFC6535]
   or 464xlat [RFC6877] may help to address the issue if there are IPv6
   compatibility problems.  Those functions could be automatically
   enabled in an IPv6-only network and disabled in a dual-stack or IPv4

5.3.  Case 3: Fallback Incapability

   3GPP specified the PDP/PDN type IPv6 as early as PDP/PDN type IPv4.
   Therefore, the IPv6 single PDP/PDN type has been well supported and
   interpretable in the 3GPP network nodes.  Roaming to IPv4-only
   networks with IPv6 PDP/PDN request could guarantee the subscription
   data is compatible with the visited pre-Release 9 SGSN.  When a
   subscriber requests PDP/PDN type IPv6, the network should only return
   the expected IPv6 address.  The mobile device may be failed to get IP
   address if the visited network only allocates an IPv4 address to a
   subscriber.  In that case, the request will be dropped and the cause
   code should be sent to the user.

   A proper fallback is desirable however the behavior is implementation
   specific.  There are some mobile devices have the ability to provide
   a different configuration for home network and visited network

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   respectively.  Android system solves the issue by setting the roaming
   Access Point Name(APN).  It guarantees UE will always initiate PDP/
   PDN type IPv4 in the roaming area.

5.4.  Case 4: 464xlat Support

   464xlat[RFC6877] is proposed to address IPv4 compatibility issue in a
   IPv6 single-stack environment.  The function on a mobile terminal
   likely gets along with PDP/PDN IPv6 type request to cooperate with a
   remote NAT64[RFC6146] gateway.  464xlat may use the mechanism defined
   in [RFC7050] to automatically detect the presence of DNS64 and learn
   the IPv6 prefix used for protocol translation.  When a mobile device
   with 464xlat function roams to an IPv6 visited network without the
   presence of NAT64 or DNS64, 464xlat may get failed to perform if
   traffic is undergoing the local breakout approach.

   The issue has been found mostly in a intra-PLMN mobility case for the
   time being.  Considering the various network's situations, operators
   may turn off the local breakout and take home routed mode to perform
   464xlat.  Some devices may support the configuration to adopt 464xlat
   in the home networks and use IPv4-only in the visited networks with
   different roaming profile configurations.  It could also be a
   solution to address this issue.

6.  Discussions

   Several failure cases have been discussed in this document.  It has
   been testified the major issues are occurred at the two stages, i.e.,
   the initial network attach and the IP allocation process.

   During the initial network attach, PDP/PDN type IPv4v6 is major
   concern to the visited pre-Release 9 SGSN.  The dual-stack deployment
   is recommended in most cases.  However, it may take some times in a
   mobile environment. 3GPP didn't specify PDP/PDN type IPv4v6 in the
   early release.  Such PDP/PDN type is supported in new-built EPS
   network, but didn't support well in the third generation network.
   The situations may cause the roaming issues dropping the attach
   request from dual-stack subscribers.  Operators may have to adopt
   temporary solution unless all the interworking nodes(i.e.  SSGN) in
   the visited network have been upgraded to support ext-PDP-Type

   The issues in the IP address allocation process are caused due to the
   local breakout policy.  Since the IP address is allocated by the
   visited GGSN or PGW, the mismatch is found in the following aspects.

   o  The mismatch between requested PDP/PDN type and permitted PDP/PDN

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   o  The mismatch between application capability and allowed network

   o  The mismatch between mobile device function (e.g., 464xlat) and
      particular network deployment status

   There are some solutions to overcome the issue.  Those solutions can
   be done either in the network side or mobile device side.  The below
   lists potential workarounds.

   o  Change local breakout to the home routed mode

   o  A dedicated roaming APN profile is implemented for roamer.  When a
      subscriber roams to a visited network, PDP/PDN type IPv4 is always
      be selected for session activation.

   o  Networks could deploy AAA server to coordinate the mobile device
      capability.  Once the GGSN/PGW receive the session creation
      requests, it will initiate an Access-Request to an AAA server in
      the home land via the Radius protocol.  The Access-Request
      contains subscriber and visited network information, e.g.  PDP/PDN
      Type, International Mobile Equipment Id (IMEI), Software
      Version(SV) and visited SGSN/MME location code, etc.  The AAA
      server could take mobile device capability combining with the
      visited network information to ultimately determine the type of
      session to be created, i.e.  IPv4, IPv6 or IPv4v6.

7.  IANA Considerations

   This document makes no request of IANA.

8.  Security Considerations

   Even if this document does not define a new architecture nor a new
   protocol, it is encouraged to refer to [RFC6459] for a generic
   discussion on IPv6-related security considerations.

9.  Acknowledgements

   Many thanks to F.  Baker and J.  Brzozowski for their support.

   This document is the result of the IETF v6ops IPv6-Roaming design
   team effort.

   The authors would like to thank Mikael Abrahamsson, Victor Kuarsingh,
   Heatley Nick, Alexandru Petrescu, Tore Anderson and Cameron Byrne for
   their helpful comments.

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10.  References

10.1.  Normative References

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

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

   [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.

   [RFC6535]  Huang, B., Deng, H., and T. Savolainen, "Dual-Stack Hosts
              Using "Bump-in-the-Host" (BIH)", RFC 6535, February 2012.

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

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

10.2.  Informative References

              amdocs-eu-roaming-regulation-III-solution.pdf", July 2013.

   [IR.21]    Global System for Mobile Communications Association,
              GSMA., "Roaming Database, Structure and Updating
              Procedures", July 2012.

   [IR.33]    Global System for Mobile Communications Association,
              GSMA., "GPRS Roaming Guidelines", July 2012.

   [IR.65]    Global System for Mobile Communications Association,
              GSMA., "IMS Roaming & Interworking Guidelines", May 2012.

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   [IR.88]    Global System for Mobile Communications Association,
              GSMA., "LTE Roaming Guidelines", January 2012.

   [IR.92]    Global System for Mobile Communications Association
              (GSMA), , "IMS Profile for Voice and SMS Version 7.0",
              March 2013.

   [RCC.07]   Global System for Mobile Communications Association
              (GSMA), , "Rich Communication Suite 5.1 Advanced
              Communications Services and Client Specification Version
              4.0", November 2013.

   [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.

   [RFC6586]  Arkko, J. and A. Keranen, "Experiences from an IPv6-Only
              Network", RFC 6586, April 2012.

              3rd Generation Partnership Project, 3GPP., "IPv6 migration
              guidelines", June 2011.

              3rd Generation Partnership Project, 3GPP., "General Packet
              Radio Service (GPRS); Service description; Stage 2 v9.00",
              March 2009.

              3rd Generation Partnership Project, 3GPP., "General Packet
              Radio Service (GPRS) enhancements for Evolved Universal
              Terrestrial Radio Access Network (E-UTRAN) access v9.00",
              March 2009.

              3rd Generation Partnership Project, 3GPP., "Mobile radio
              interface Layer 3 specification; Core network protocols;
              Stage 3 v9.00", September 2009.

              3rd Generation Partnership Project, 3GPP., "Non-Access-
              Stratum (NAS) protocol for Evolved Packet System (EPS) ;
              Stage 3 v9.00", September 2009.

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              3rd Generation Partnership Project, 3GPP., "Mobile
              Application Part (MAP) specification v9.00", December

              3rd Generation Partnership Project, 3GPP., "Mobility
              Management Entity (MME) and Serving GPRS Support Node
              (SGSN) related interfaces based on Diameter protocol
              v9.00", September 2009.

Authors' Addresses

   Gang Chen
   China Mobile
   53A,Xibianmennei Ave.,
   Xuanwu District,
   Beijing  100053


   Hui Deng
   China Mobile
   53A,Xibianmennei Ave.,
   Xuanwu District,
   Beijing  100053


   Dave Michaud
   Rogers Communications
   8200 Dixie Rd.
   Brampton, ON L6T 0C1


   Jouni Korhonen
   Renesas Mobile
   Porkkalankatu 24
   FIN-00180 Helsinki, Finland


Chen, et al.             Expires January 5, 2015               [Page 13]

Internet-Draft            IPv6 Roaming Analysis                July 2014

   Mohamed Boucadair
   France Telecom


   Vizdal Ales
   Deutsche Telekom AG
   Tomickova 2144/1
   Prague 4,  149 00
   Czech Republic


Chen, et al.             Expires January 5, 2015               [Page 14]