Internet DRAFT - draft-xue-fmc-ps


Network Working Group                                             L. Xue
Internet-Draft                                               B. Sarikaya
Intended status: Informational                                    Huawei
Expires: April 25, 2013                                      D. von Hugo
                                         Telekom Innovation Laboratories
                                                        October 22, 2012

             Problem Statement for Fixed Mobile Convergence


   The purpose of this document is to analyze the issues that have
   arisen so far and to propose several use cases for the Fixed Mobile
   Convergence.  This document gives a brief overview of the assumed
   Fixed Mobile Convergence architecture and related works and then
   introduces several Intarea type of use cases based on the partnership
   in Fixed Mobile Convergence architecture, such as group
   identification, mobility consideration, such as mobility status
   reporting in Wi-Fi network.

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

   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 April 25, 2013.

Copyright Notice

   Copyright (c) 2012 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
   ( in effect on the date of
   publication of this document.  Please review these documents

Xue, et al.              Expires April 25, 2013                 [Page 1]
Internet-Draft                 PS for FMC                   October 2012

   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 . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Conventions and Terminology  . . . . . . . . . . . . . . . . .  6
   3.  Key Issues in Fixed Mobile Converged Interworking  . . . . . .  7
   4.  Group Id in Fixed Broadband Network  . . . . . . . . . . . . .  7
   5.  UE Mobility in Fixed Broadband Network . . . . . . . . . . . . 10
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 12
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 12
   8.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
     9.1.  Normative References . . . . . . . . . . . . . . . . . . . 12
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 13
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13

Xue, et al.              Expires April 25, 2013                 [Page 2]
Internet-Draft                 PS for FMC                   October 2012

1.  Introduction

   Growing availability of intelligent mobile devices and mature
   networks of operators providing both reliable carrier grade
   connectivity and affordable high bandwidth access offer to the
   customer a nice climate of mobile broadband.  With widespread
   availability and easy usability of mobile broadband, mobile broadband
   applications become more ubiquitous.  Subscribers demand for various
   service applications, especially Internet applications, such as
   mobile Internet video, mobile Internet real-time communication, etc.

   The subscribers requirements lay the foundation of mobile broadband.
   On the other hand, simultaneously, the subscribers' services promote
   the evolution of mobile broadband, which will impact the network
   architecture.  The flourishing mobile applications demand more and
   more bandwidth offered by the operators.  Even with wireless networks
   becoming mature, such as 3G and LTE, the average bandwidth offered is
   not comparable to data rates offered by fixed networks.  With data
   services rapidly increasing, the traditional cellular network
   operating at a shared medium and thus being limited in transmission
   rate often becomes the bottle-neck of mobile broadband.  In addition
   radio network technology generally requires high capital investment
   and operational expenditures.  Cellular network operators are facing
   the challenge of increasing traffic demand at decreasing revenue and
   have to provide means of more cost efficient access technology in a
   highly competitive environment.  With parallel availability of
   different access technologies such as cellular and local wireless
   networks a selection of the most (e.g. resource) efficient technology
   is advantageous for both user and operator.  Mobile industry has
   specified functionalities to offload the data traffic to the fixed
   broadband (FBB) network, via WLAN or a Home (e)NodeB (HNB or eNodeB,
   aka.  Femtocell) [TR23.829], which could alleviate traffic pressure
   on the mobile network.  That is to say, today, operators are able to
   employ mechanisms to manage the subscriber service over both the
   mobile and the fixed broadband network.  We can say, FMC is emerging
   on the basis of subscribers and operators requirements.

   Fixed Mobile Convergence is a technology trend which aims to provide
   the subscribers access to services regardless of the access network
   type they are connecting to and provide the operators with the
   flexibility to ensure transparency of services to the end user.  For
   a mobile subscriber to access services over both mobile and fixed
   broadband networks seamlessly, additionally, the subscriber's end-to-
   end service level agreement (SLA) must be maintained.  This is
   achieved by interworking between the control planes of the fixed
   broadband network and the mobile network.

   In the FMC interworking scenario addressed here, the fixed broadband

Xue, et al.              Expires April 25, 2013                 [Page 3]
Internet-Draft                 PS for FMC                   October 2012

   network must partner with the mobile network to perform
   authorisation, authentication, and accounting (AAA) and acquire the
   policies for the mobile subscriber.  Please note, a single converged
   control plane, used for both the fixed broadband and the mobile
   network, may be used in a truely converged, i.e. integrated
   convergence scenario.  This document only focuses on the interworking
   scenario in this version.  The convergence scenario is for further

   Figure 1 shows the assumed reference architecture of Fixed Mobile
   Convergence Interworking for a Mobile (3GPP) Network and a fixed non-
   3GPP access network as proposed by 3GPP and BroadBand Forum (BBF) as
   an example in document [TR203].

Xue, et al.              Expires April 25, 2013                 [Page 4]
Internet-Draft                 PS for FMC                   October 2012

                      | Mobile Network                       |
                      |                                ----  |
                      |                    +------+  /      \|
                      |                +---+ PCRF | |Operator|
                      |                |   +---+--+ | Service|
                      |                |       |     \      /|
                      |                |       |       --+-  |
  +------+  +------+  | +------+   +---+--+    |         |   |
  |  UE  |  | eNB  +----+ SGW  +---+ PGW  +----|---------+----------+
  +------+  +------+  | +------+   +--+---+--+ |     +------+|      |
                      |            +--+---+  +-|-----+M AAA ||    --+-
                      |            | ePDG +--+ |     +---+--+|  /      \
                      +------------+------+----|---------|---+ |Internet
                                      |        |         |     | Service
                      +---------------|--------|---------|---+  \      /
                      | Fixed Network |     +---+--+ +---+--+|    --+-
                      |               | +---+ BPCF | |F AAA ||      |
                      |            +--+-+-+ +------+ +---+--+|      |
            +------+  |            | BNG  +--------------+   |      |
            | Femto+----------+    +--+-+-+                  |      |
            +------+  |       |       | +---------------------------+
  +------+            |       |    +--+---+                  |
  |  UE  |            |       +----+  AN  |                  |
  +------+  +------+  |            +--+---+                  |
            |WiFiAP|------------------+                      |
            |  CPE |  |                                      |
            +------+  |                                      |
   M AAA   Authentication Authorization Accounting in Mobile Network
   F AAA   Authentication Authorization Accounting in Fixed Network
   AN      Access Node
   BPCF    Broadband Policy Control Function
   BNG     Broadband Network Gateway
   ePDG    evolved Packet Data Gateway
   PCRF    Policy Charging Rule Function
   PGW     Packet Data Network Gateway
   SGW     Serving Gateway
   UE      User Equipment
   CPE     Customer Premises Equipment

       Figure 1: Reference Architecture of Fixed Mobile Convergence

   The policy and charging control (PCC) system is an important element
   in FMC architecture.  PCC system of FMC consists of policy decision
   point (PCRF in the mobile network and BPCF in the fixed broadband
   network) and the policy enforcement point (PGW and BNG,

Xue, et al.              Expires April 25, 2013                 [Page 5]
Internet-Draft                 PS for FMC                   October 2012

   respectively), shown in Figure 1.  PCC should support for controlling
   the QoS (e.g., QoS class and bit rates) authorized for service, and
   IP flow based charging.  In FMC interworking scenario, these services
   can be divided into four types.

   1.  Service via macrocell wireless network

   2.  Service via WiFi/Femtocell access routed back to 3GPP Evolved
       Packet Core (EPC), where the fixed broadband network is used as
       the access network,

       *  The service from a mobile UE is connected to WiFi or to
          Femtocell Access Point (FAP) at the residential gateway (RG),
          routed back to 3GPP Evolved Packet Core (EPC).

   3.  Services via WiFi access only fixed broadband routed

       *  The service from a mobile UE is connected to WiFi without
          traversing the mobile network.

       *  In this scenario, the UE service may be guaranteed based on
          subscriber's policy from the mobile network.

   4.  LIPA/SIPTO traffic

       *  Support of Local IP access (LIPA) and of Selected IP traffic
          offload (SIPTO) for the Home (e)NodeB Subsystem and for the
          macro layer network include a more integrated FMC scenario and
          thus are for further study.

   As for the services stated above, only the second and the third type
   are related to FMC, where both the fixed broadband and the mobile
   network are involved.  The FMC architecture shall be capable to set
   operator policies to support simultaneous access to these service.

   In the network today, deploying FMC is a worthy way for operators to
   satisfy subscriber's requirement and ease pressure from bandwidth.
   In the following sections, we first describe the motivation and then
   discuss the key issues that are at this time limited to the Intarea
   and to FMC interworking scenario.

2.  Conventions and Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in RFC 2119 [RFC2119].

Xue, et al.              Expires April 25, 2013                 [Page 6]
Internet-Draft                 PS for FMC                   October 2012

3.  Key Issues in Fixed Mobile Converged Interworking

   There is a need to highlight and discuss the issues when facilitating
   FMC.  We systematically analyze the issues that have been proposed so
   far and briefly assess the possible protocol extensions which could
   solve the problems.  In the network architecture, we target and limit
   the scope to the interworking architecture for FMC.

   Regarding the traffic management and control requirements in FMC
   interworking scenario, these are the issues from an IETF Internet
   Area and fixed broadband network point of view.

   1.  Group Id in fixed broadband network,

   2.  UE mobility status reporting in fixed broadband network.

   There are many standardization issues related to FMC and protocol
   extension work needed.  If these issues are fixed, the advantages
   brought out will be:

   1.  Optimize traffic management (per-UE granularity in the fixed
       broadband network)

   2.  Enhance device management (via IP address synchronization between
       fixed broadband network and mobile network)

   3.  Quick Responsiveness based on UE status

   These issues are elaborated in the sections that follow.

4.  Group Id in Fixed Broadband Network

   Consumers in a fixed mobile convergence scenario nowadays are not
   being limited by a single device such as only smart phone in
   connecting to fixed broadband network.  Increasingly, portable media
   players, PCs, tablet, and mobile phones all belonging to the same
   subscriber are being used.  It is reported that more than 90
   percentage of video streaming customers own more than one device.
   Therefore, the same set of devices owned by one subscriber will have
   the same personalized requirement.  For example, one subscriber may
   order the highest priority video streaming service from the operator,
   an instant bandwidth tune service, security control, etc.

   It is expected for consumers to receive network services seamlessly
   in a convenient and economic way, irrespective of access
   technologies.  For example, consumers prefer to connect to the
   Internet service via WiFi, instead of cellular access technology when

Xue, et al.              Expires April 25, 2013                 [Page 7]
Internet-Draft                 PS for FMC                   October 2012

   moving into a Wi-Fi hotspot, if their mobile device is equipped with
   WiFi (IEEE 802.11-based) interface.

   Users must be able to access to services irrespective of the access
   network.  Operators need to have suitable user management ability, to
   reduce the CAPEX and OPEX.  For example, operators could apply the
   unified policy control, and accounting control to the multiple
   devices owned by one subscriber, or devices with multiple interfaces,
   etc.  This brings the need to identify each subscriber as one group
   and given a group identifier.

   Consider Figure 2 where several hosts are connected to the same RG in
   a fixed broadband network.  These hosts belong to different
   subscribers.  One of the subscribers has only one device shown as UE
   in the figure.  The second subscriber has multiple devices, one Pad,
   one smart phone and a personal computer (PC).  Each subscriber is
   assigned a group id by the operator.  Group Identifier (GroupId)
   needs to be communicated to fixed broadband network nodes such as the
   edge router (BNG).

   A subscriber signs in the services of an operator.  This subscriber
   has several devices, e.g., two phones and one pad.  She/he wishes to
   share the subscription with these three devices.  The operator could
   assign a group id to the costumer, and any of the devices belonging
   to the customer can be authenticated with this Id.  Then all the
   other devices can access the service - either in parallel or
   sequentially - with unified policy control without additional

   A subscriber owns one pad and one Phone.  This subscriber may take
   photos on his trip away from home.  It would be desirable that the
   other device(s) which are left at home to be immediately syncronized
   with these pictures in order to share them with the family.  The
   operator could ensure the device discovery belonging to one
   subscriber by keeping an unified subscriber database in the network
   containing all group ids of the subscribers.

   Group id based traffic management changes the granularity of traffic
   management that is currently in effect in cellular networks which is
   based on per-UE or per-contract level.  In current FMC procedures,
   the broadband network can be made known of per-phone level traffic
   control by way of the IP-CAN session [TS23.203] which denotes the
   association between a UE and an IP network.  The operator now will be
   in a position to provide unified service to all the devices that
   belong to the same group id, possibly carrying over UE's downloaded
   traffic quality of service requirements to all other devices.

   If several devices access service via multiple access technologies,

Xue, et al.              Expires April 25, 2013                 [Page 8]
Internet-Draft                 PS for FMC                   October 2012

   the access technologies could belong to different network operators.
   For example, WiFi network could be deployed by a different operator.
   In this scenario, the subscriber ID semantics must be consistent
   among these two operators.  This can be achieved by agreement between
   different operators.

   Another problem that arises is efficient packet inspection.
   Operators expect the fixed broadband network could be configured in
   such a way that the traffic subject to packet inspection is routed
   via the Traffic Detection Function (TDF) [TS29.212] usually
   collocated with the edge router.  Traffic inspection and then traffic
   redirection that follows can be facilitated with group id.  The same
   inspection and redirection (to the local home network, to the mobile
   network or to the Internet) rules can be applied in a unified manner
   to all devices belonging to the same group.

 Group  +----+
   Id   | UE |                                                  Internet
    1   +----+                                                     /
               W                                               ^ Mobile
 Group  +----+ i                                               | Network
   Id   | PC | F +----+                                        |
    2   +----+ i | AP |   +----------+                     +----------+
        +----+   |  & |   |          |                     |          |
        |Pad | L | RG |---|          |   +-------------+   |          |
        +----+ i +----+   | Access   |---| Aggregation |   |  Edge    |
       +-----+ n          |  Node    |   |   Network   |---|  Router  |
       |Phone| k          |          |   +-------------+   |          |
       +-----+            +----------+                     +----------+

            Figure 2: Group Identification in Broadband Network

   As discussed before, there are many drivers for the identification of
   GroupId when the same subscriber accesses the broadband network using
   several devices.  They include efficient packet inspection, QoS
   enforcement, charging.  We can note that all these functions in FMC
   depend on being able to identify the subscriber to which the device
   belongs, i.e. group identification.

   The subscriber ID must be contained in the traffic packet of the
   subscriber in order to achieve policy enforcement in the device node
   in the network.  Currently the group id is not being communicated in
   an IP packet.  There are several possibilities which provide
   solutions.  IP (v4 or v6) level solution would call for including
   group identifier in every packet the user sends.  Such an approach
   facilitates packet inspection to provide required Quality of Service

Xue, et al.              Expires April 25, 2013                 [Page 9]
Internet-Draft                 PS for FMC                   October 2012

   since by looking at each packet the subscriber can be identified.

   ICMP (both v4 and v6) or TCP/UDP protocol extensions can also be
   other solution approaches.  In this case the group id sent at the
   beginning needs to be paired with the IP address of the device.
   Packet inspection can then be conducted by first detecting the
   address and then identifying the subscriber followed by enforcement
   specific to this subscriber.  It is difficult to foresee which is the
   suitable solution among the various possibilities, more work needs to
   be done.

5.  UE Mobility in Fixed Broadband Network

   The users are the mobile subscribers in FMC.  Note that all the
   services depend on the substantive character of subscriber's
   mobility.  It is important for operators to capture the user device
   when it is moving into or outside the network, even in WiFi access.
   Besides, the application and service from the subscriber must be
   guaranteed based on the policy of operators.

   In mobile network today, there are many mature solutions offered for
   user's mobility already.  Herein, only mobility in fixed access,
   i.e., WiFi access, will be considered.  For example, the user device
   is attached to the home LAN (e.g., WiFi ) network, and establishes a
   connection back to the subscriber's mobile service provider network
   via the fixed broadband network.  The mobile operator should
   cooperate with the broadband access operator to deliver proper policy
   for the service from UE.

   +----+  +------+    +----------+
   | UE1|  |AP&RG |----|          |
   +----+  +------+    |          |
          W            |    AN    |\
   +----+ i+------+    |          | \
   | UE2| F|AP&RG |----|          |  \
   +----+ i+------+    +----------+   \                    +----------+
                                       \                   |          |
          L                          +-------------+       |          |
          i                          | Aggregation |       |  Edge    |
          n                          |   Network   |-------|  Router  |
          k                          +-------------+       |          |
                      +----------+   /                     +----------+
   +----+  +-----+    |          | /
   | UE3|  |AP&RG|----|    AN    |/
   +----+  +-----+    |          |

Xue, et al.              Expires April 25, 2013                [Page 10]
Internet-Draft                 PS for FMC                   October 2012

                Figure 3: UE Mobility in Broadband Network

   The mobility considered in the fixed access does not consider the use
   of a mobility protocol.  Consider Figure 3 where there are many
   mobile nodes, i.e.  UEs connected to the fixed broadband network.
   Status of these nodes at a given time needs to be communicated to the
   network by the access points.  In this section, we divide the
   mobility status reporting capability into two cases:

   1.  UE is moving into or outside the coverage area of WiFi AP

   2.  UE's WiFi access is dormant or not.

   Figure 3 shows an example of the scenario where mobile UEs are served
   in WiFi deployment over the fixed broadband network.  RG embeds WiFi
   AP.  Each UE is provided with an IPv4/IPv6 address assigned within
   the local network.  A point-to-point link is established between the
   UE and the edge router.

   BPCF in fixed broadband network must have partnership with PCRF in
   mobile network in order to maintain the service level agreement
   (SLA).  In order to allow the PCRF to retrieve the UE's policy to be
   passed onto the BPCF in the fixed broadband network, it is mainly
   concerned about the traffic and UE identification binding used to
   achieve the actual traffic control.  The BPCF/BNG will perform the
   policy control based on the binding.

   Since plenty of UEs may move into the coverage of WiFi AP, it is
   possible that large amount of resources will be needed at the BPCF/
   BNG.  For optimum operation, the resources need to be released when
   the UE goes out of the coverage of WiFi AP.  So timely detection of
   UE detachments is crucial in fixed mobile convergence environments.

   That is to say the configuration must be updated regularly to satisfy
   that the WiFi AP can serve thousands of UEs and proper resource
   allocation at the BPCF/BNG.

   Possible solutions approaches include extending the Control And
   Provisioning of Wireless Access Points (CAPWAP) architecture RFC 5415
   [RFC5415].  Access Controllers using an extended protocol can be
   charged to keep track of the mobility status of the UEs that are
   connected to the fixed broadband network using IEEE 802.11 links.
   However, in Fixed Mobile Convergence, this information is needed by
   entities not necessarily co-located with the Access Controller.

   In some cases, e.g. home networks, CAPWAP protocol is not commonly
   used.  In such cases, it becomes even more challenging to keep track
   of the UE mobility status.  Protocol solutions need to be developed

Xue, et al.              Expires April 25, 2013                [Page 11]
Internet-Draft                 PS for FMC                   October 2012

   to solve this problem.  During the solution process, CAPWAP protocol
   could be used as an example.

6.  IANA Considerations

   This document makes no request to IANA.

7.  Security Considerations

   Serious concern of mobile operators towards FMC approaches has been
   the customer access via networks not under control of the operator.
   Operators would like to keep their own high security measures to
   prevent various kinds of fraud or attack to the operators services
   and network entities.  Well known risks and vulnerabilities involved
   in using IEEE 802.11 with the CAPWAP protocol are documented in
   [RFC5416].  Any additional security considerations arising from FMC
   are TBD.

8.  Acknowledgements

   Many people provided comments that have been incorporated into this
   document including Mohamed Boucadair, David Binet, Pierrick Seite,
   Daniel Park and Cameron Byrne.

9.  References

9.1.  Normative References

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

   [RFC5415]  Calhoun, P., Montemurro, M., and D. Stanley, "Control And
              Provisioning of Wireless Access Points (CAPWAP) Protocol
              Specification", RFC 5415, March 2009.

   [RFC5416]  Calhoun, P., Montemurro, M., and D. Stanley, "Control and
              Provisioning of Wireless Access Points (CAPWAP) Protocol
              Binding for IEEE 802.11", RFC 5416, March 2009.

   [RFC5996]  Kaufman, C., Hoffman, P., Nir, Y., and P. Eronen,
              "Internet Key Exchange Protocol Version 2 (IKEv2)",
              RFC 5996, September 2010.


Xue, et al.              Expires April 25, 2013                [Page 12]
Internet-Draft                 PS for FMC                   October 2012

              "3GPP TR23.829, Local IP Access and Selected IP Traffic
              Offload (LIPA-SIPTO)", October 2011.

              "3GPP TS23.203, Policy and Charging control architecture",
              September 2012.

              "3GPP TS29.212, Policy and Charging Control (PCC) over
              Gx/Sd reference point", September 2012.

9.2.  Informative References

   [TR203]    "Broadband Forum Technical Report TR-203, Interworking
              between Next Generation Fixed and 3GPP Wireless Access",
              August 2012.

              "3GPP TS24.302, Access to the 3GPP Evolved Packet Core
              (EPC) via non-3GPP access networks", September 2012.

   [WT146]    "Broadband Forum Working Text WT-146, Subscriber
              Sessions", June 2012.

Authors' Addresses

   Li Xue
   No.156 Beiqing Rd. Z-park, Shi-Chuang-Ke-Ji-Shi-Fan-Yuan,
   Beijing, HaiDian District  100095


   Behcet Sarikaya
   5340 Legacy Dr.
   Plano, TX  75024


Xue, et al.              Expires April 25, 2013                [Page 13]
Internet-Draft                 PS for FMC                   October 2012

   Dirk von Hugo
   Telekom Innovation Laboratories
   Deutsche-Telekom-Allee 7
   D-64295 Darmstadt


Xue, et al.              Expires April 25, 2013                [Page 14]