Network Working Group                                             D. Liu
Internet-Draft                                              China Mobile
Intended status: Informational                                   H. Chan
Expires: September 4, 2014                           Huawei Technologies
                                                                 H. Deng
                                                            China Mobile
                                                           March 3, 2014


           Cloud Based Mobile Core Network Problem Statement
                  draft-liu-dmm-deployment-scenario-01

Abstract

   This document discusses the deployment scenario of distributed
   mobility management.  The purpose of this document is to trigger the
   discussion in the group to understnad the DMM deployment scenario and
   consideration from the operator's perspective.

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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.


Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Conventions used in this document . . . . . . . . . . . . . . . 3
   3.  Deployment Scenario and Model of DMM  . . . . . . . . . . . . . 3
   4.  Network Function Virtualization . . . . . . . . . . . . . . . . 3
     4.1.  Network Function Virtualization Scenario  . . . . . . . . . 4
     4.2.  Control and data plane separation . . . . . . . . . . . . . 4
     4.3.  Mobility management functions . . . . . . . . . . . . . . . 5
   5.  SIPTO deployment scenario . . . . . . . . . . . . . . . . . . . 6
   6.  Conclusion  . . . . . . . . . . . . . . . . . . . . . . . . . . 6
   7.  Security Considerations . . . . . . . . . . . . . . . . . . . . 6
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
   9.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . . . 7
   10. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 7
   11. Normative References  . . . . . . . . . . . . . . . . . . . . . 7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 7






























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1.  Introduction

   Distributed mobility management aims at solving the centralized
   mobility anchor problems of the tranditional mobility management
   protocol.  The benefit of DMM solution is that the data plane traffic
   does not need to traverse the centralized anchoring point.  This
   document discusses the potential deployment scenario of DMM.  The
   purpose of this document is to help the group to reach consensus
   regarding the deployment model of DMM and then develop the DMM
   solution based on the deployment model.


2.  Conventions used in this document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL","SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].


3.  Deployment Scenario and Model of DMM

   As discussed in the DMM requirement document, the centralized
   mobility management has several drawbacks.  The main problem of the
   centralized mobility management protocols is that all the traffic
   need to anchor to a centralized anchor point.  This approach does not
   cause any problem in current mobile network deployment but in the
   scenario that will be discussed later in this document, centralized
   mobility management protocols will have many drawbacks and it is
   believed that DMM is more suitable in that scenario.

   The main deployment scenario discussed in this document is divided
   into two types.  The first one is the network function virtualization
   scenario.  In this scenario, the mobile core network's control plane
   function is centralized in the mobile cloud.  Apparently, deploying
   the data plane function also in the same centralized mobile cloud is
   not optimized from the traffic routing's perspective.  Another
   deployment scenario is the SIPTO/LIPA scenario which is discussed in
   3GPP.  In this scenario, DMM can provide optimized traffic offloading
   solution.


4.  Network Function Virtualization

   This section discusses network function virtualization scenario, the
   associated control - data plane separation and the possible mobility
   management functions to support this scenario.





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4.1.  Network Function Virtualization Scenario

   The network function virtualization scenario is shown in Figure 1.

                Mobile Cloud
                 ...........
               ('             ')
             (                )))
            (((  +-----------+ )))
           ((    |Mobile Core|    )))
           (((   +-----------+   )))
              ('..............')
                               |
                       | IP Transit Network
                   (.........)
                 (           )) MN-Internet communication
                (           ^ ))
         ^ > > >(           ^  ))> > > > > > > > >
         ^       ((         ^  )                  v
         ^        (.........^.)                   v
         ^ +-------|     |  ^|                    v
         ^ |             |  ^+--------------+     v
         ^ |             |  < <             |     v  MN-MN communication
         ^ |             |    ^             |     v
   +--------------+    +--------------+    +--------------+
   |Access Network|    |Access Network|    |Access Network|
   +--------------+    +--------------+    +--------------+
         ^                    ^                   v
         ^                    ^                   v
     +---------+         +---------+         +---------+
     |   MN    |         |    MN   |         |   MN    |
     +---------+         +---------+         +---------+

   Figure 1: Network function virtualization deployment architecture

   In this architecture, the mobile core network is located in the cloud
   /data center, which can be the operator's private cloud.  The access
   network is connected through an IP transit network.  The mobile core
   network can run in a virtualized platform in the cloud/datacenter.

4.2.  Control and data plane separation

   The cloud based mobile core network architecture implies separation
   of the control and data plane.  The control plane is located in the
   cloud and the data plane should be distributed.  Otherwise, all the
   data traffic will go through the cloud which is obviously not
   optimized for the mobile node to mobile node communication.




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   For the mobile node to Internet communication, the Internet access
   point is normally located in the metro IP transit network.  In this
   case, the mobile node to Internet traffic should also go through the
   Internet access point instead of the mobile core in the cloud.

   However, in some deployment scenario, the operator may choose to put
   the mobile core cloud in the convergence layer of IP metro network.
   In this case, the Internet access point may co-located with the
   mobile core cloud.  In this case, the mobile node to Internet traffic
   may go through the mobile core cloud.

4.3.  Mobility management functions

   Since the control plane and data plane are separated and the data
   plane is distributed, traditional mobility management cannot meet
   this requirement.

   Distributed mobility management or SDN based mobility management may
   be used in this architecture to meet the traffic routing requirement
   (e.g.  MN to MN and MN to Internet traffic should not go through from
   the mobile core cloud.).

   The traditional mobility management functions is not separating the
   data plane from the control plane.  Basic mobility management
   functions include location management (LM) and Routing management
   (RM).  The former is a control plane function.  The latter can be
   separated into data plane routing management (RM-DP) and control
   plane routing management (RM-CP).

   The data plane function is RM-DP which may also be called a Data
   Plane Anchor (DPA).  The control plane functions include RM-CP and LM
   and may be called a Control Plane Anchor (CPA).  Then the control
   plane functions in the cloud-based mobile core includes LM and RM-CP
   or CPA.  They are of cause other functions in the control plane such
   as policy function.  The distributed data plane may have multiple
   instances of RM-DP / DPA in the network.

                  core network controller
                     +---------------+
                     |LM, RM-CP / CPA|
                     +---------------+



     +-------------+  +-------------+  +-------------+
     | RM-DP / DPA |  | RM-DP / DPA |  | RM-DP / DPA |
     +-------------+  +-------------+  +-------------+




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   Figure 2: Mobility management functions with data plane - control
   plane separation under one controller

   When the control of the access network is separate from that of the
   core, there will be separate controllers as shown in Figure 3.

    Access network controller               Core network controller
        +---------------+                      +---------------+
        |LM, RM-CP / CPA|                      |LM, RM-CP / CPA|
        +---------------+                      +---------------+



 +-------------+  +-------------+       +-------------+  +-------------+
 | RM-DP / DPA |  | RM-DP / DPA |       | RM-DP / DPA |  | RM-DP / DPA |
 +-------------+  +-------------+       +-------------+  +-------------+

   Figure 2: Mobility management functions with data plane - control
   plane separation with separate control in core and in access.


5.  SIPTO deployment scenario

   Another deployment scenario is the SIPTO scenario which is discussed
   in 3GPP.  DMM is believed to be able to provide dynamic anchoring.
   It allows the mobile node to have several anchoring points and to
   change the anchoring point according to the requirment of
   application.  In SIPTO scenario, the gateway function is located very
   near to the access network and to the user.  If using current
   centralized mobility management, the traffic will need to tunnel back
   to the previous anchor point even when the mobile node has changed
   the point of attachment to a new one.


6.  Conclusion

   This document discusses the deployment scenario of DMM.  Two types of
   deployment scenario is discussed in this document.  Further types of
   deployment scenario can be added to this document according to the
   progress of the group's discussion.


7.  Security Considerations

   N/A.






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8.  IANA Considerations

   N/A.


9.  Contributors


10.  Acknowledgements


11.  Normative References

   [IEEE-802.11.2012]
              "", March 2012.

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


Authors' Addresses

   Dapeng Liu
   China Mobile
   No.32 Xuanwumen West Street
   Beijing  100053
   China

   Email: liudapeng@chinamobile.com


   H Anthony Chan
   Huawei Technologies
   5340 Legacy Dr. Building 3
   Plano, TX 75024
   USA

   Email: h.a.chan@ieee.org


   Hui Deng
   China Mobile
   No.32 Xuanwumen West Street
   Beijing  100053
   China

   Email: denghui@chinamobile.com




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