Internet DRAFT - draft-fu-dmm-vcpe-models

draft-fu-dmm-vcpe-models







Internet Engineering Task Force                               Q. Fu, Ed.
Internet-Draft                                                   H. Deng
Intended status: Informational                              China Mobile
Expires: April 21, 2016                                 October 19, 2015


                Motivations, usecases and Models of VCPE
                      draft-fu-dmm-vcpe-models-01

Abstract

   This document introduces the concept of Virtual Customer Premises
   Equipment (VCPE).  Such concept was first proposed in Broadband Forum
   (BBF) as Network Enhanced Residential Gateway (NERG).  The concept is
   further expanded as not only referring to virtual CPE of residential
   network, but all the virtual network and service functions shifted
   from the customer side to the operator side.  Deployment of VCPE in
   some typical DMM (Distributed Mobility Management) scenarios brings
   specific requirements and even protocol extension in DMM.  In this
   document, we will first explain the motivation and advantages of
   VCPE.  A usecases of VCPE in the community Wi-Fi deployment is
   further discussed so as to explain the deployment of VCPE in a DMM
   scenario.  Three models of field deployment of VCPE are discussed
   afterwards to indicate the possible CP/DP decomposition requirement
   and protocol extension.

Status of This Memo

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   This Internet-Draft will expire on April 21, 2016.

Copyright Notice

   Copyright (c) 2015 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
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Motivation and Advantage of VCPE  . . . . . . . . . . . . . .   3
   4.  Use case of VCPE  . . . . . . . . . . . . . . . . . . . . . .   4
   5.  Models of VCPE Deployment . . . . . . . . . . . . . . . . . .   5
   6.  VCPE Deployment for Community Wi-Fi . . . . . . . . . . . . .   8
   7.  Conclusion  . . . . . . . . . . . . . . . . . . . . . . . . .   9
   8.  Informative References  . . . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   This document introduces the concept of VCPE.  The concept of VCPE is
   to shift most of the networking and service functionalities from the
   customer side to the network side.  In this way, the customer side's
   equipment, that is the pCPE (Physical Customer Premises Equiptment),
   can be simplified.  The VCPE refers to one or a set of equipments at
   the network side to execute the networking and service
   functionalities used to be executed at the CPE.  In such
   architecture, the CPE can be a simple L2 switch, which is only
   responsible for forwarding packets to a certain next hop.  The
   concept of VCPE was first introduced in BBF as NERG (WT-317), which
   mainly focuses on shifting some of the functionalities of a
   residential gateway to the operator's network, for enabling network
   based features.  The aim is to facilitate the deployment, maintenance
   and evolution of both existing and new capabilities without adding
   complexity to the RG and/or the home network.

   Figure 1 shows the architecture of the pCPE and the VCPE.










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                    ...............         ..............
                    :Customer side:         :Network side:
                    :   +-----+   :         :  +-----+   :
                    :   |pCPE |================|VCPE |   :
                    :   +-----+   :         :  +-----+   :
                    ..............:         .............:

                        Figure 1: VCPE Architecture

   In this document, we would like to further propose such concept in
   the following aspects:

   (1) Motivation and advantages of VCPE.

   (2) Usecases of VCPE.  A usecase of VCPE in the community Wi-Fi is
   explained in detail.

   (3) Models of VCPE deployment.  We propose three models for the field
   deployment of VCPE.

2.  Terminology

   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.  Motivation and Advantage of VCPE

   The motivation and advantage of introduting VCPE can be concluded as
   follows:

   (1) It will greatly speed up the service launching period.  Since
   most of the complicated functions are located at the VCPE in the
   network side, operators have more power over services.  Benefitting
   from the recent NFV (Network Function Virtualization) and cloud
   technologies, VCPE can be accomplished using SFC in the virtual
   network, where different services can act as different VNFs (Virtual
   Network Functions).  Operators only need to add new VNFs on the VCPE
   side to launch new services to the customers.  In this way, Operators
   can provide a variety of services through the network.

   (2) It will reduce the cost of the pCPE.  By shifting most of the
   complicated functions from the customer's side to the operator's
   side, the cost of the pCPE can be reduced significantly.  Such
   redunction can be remarkable in the enterprise network, since network
   functions, such as Firewall and NAT(Network Address Translator) at
   the customer side can be expensive.  In the meantime, the cost of




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   upgrading tens of thousands of pCPE when launching new services can
   be saved, since only software upgrade at the VCPE side is required.

   (3) It will simplify the maintainance of the pCPE.  Since most of the
   complicated functionalities are shifted to the network side, the
   maintainance of the pCPE can be greatly simplified.  On-line
   maintainance is possible in lots of cases since the pCPE is only a L2
   devices and can be considered transparent to the operators.

   (4) It will provide user-define-network experience.  By introducing
   SFC concept into the VCPE, users can define his own service order and
   sequence.  Therefore, customers can enjoy the self-defined services
   over the public network.

4.  Use case of VCPE

   The concept of VCPE can be used in multiple scenarios.  In this
   section, we will propose a usecase of VCPE when deploying community
   Wi-Fi.

   The community Wi-Fi is a new service that operators provide to
   leverage unused capacity on existing residential Wi-Fi infrastructure
   to offer Wi-Fi network access to visitors and passers by near the
   neighbourhood.  An operator can also use this excess capacity to
   offer services to retail and roaming-parter operators' subscribers.
   The residential subscribers accessing the network from inside their
   homes have prioritized access to the Wi-Fi resources.  The
   residential Wi-Fi infrastructure is configured in a manner that
   allows for a secure and independent access channel to retain service
   quality, safety, and privacy for both residential and visitor
   customers.  Roaming users are only allowed to use the Wi-Fi network
   capacity that is not currently used by the subscriber at home.

   Basically, the wireless Access Point (AP) in the home will provide
   two networks: a private one for the home owner/subscriber, and a
   community network for on-the-go subscribers passing through the
   neighborhood.  Home users can have all of their Wi-Fi devices
   (smartphone, tablet, etc.) automatically connect to the private
   network.  In the meantime users travel outside can connect to the
   community network, and can roaming through different APs supporting
   community Wi-Fi as he/she is moving.  The community Wi-Fi service is
   a typical usecase of DMM.

   Deploying community Wi-Fi on the pCPE means upgrading tens of
   thousands of existing pCPE devices at the customer side, which is not
   cost-effective and may bring extra complexity for maintainance.
   Therefore VCPE becomes an optimized solution for such deployment.  In
   such deployment, the private users access to the pCPE (which is the



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   AP at home) as usual.  The public users are roaming through different
   pCPEs.  The traffic all goes though the tunnel from the pCPE to the
   VCPE.  The deployment of VCPE in the community Wi-Fi sencario brings
   specific requirement and protocol extensions to DMM.  The deployment
   model of VCPE and its possible influence to DMM is further discussed
   in the following section.

5.  Models of VCPE Deployment

   There are multiple models when deploying VCPE in use cases as are
   discussed in the previous section.  In this document, we conclude the
   deployment of VCPE into three models.  In the first model, a logical
   instance of VCPE is deployed in the cloud for each pCPE instance.
   That is, the pCPE and VCPE is deployed in an 1:1 manner.  All traffic
   from pCPE goes through the vCPE.


            +------+     +------+
            | pCPE +-----| VCPE |-----+
            +------+     +------+     |
                                      |         +------+     ________
            +------+     +------+   +-+---+     |SFC in|    /        \
            | pCPE +-----+ VCPE +---+ BNG +-----+WAN DC+---+ Internet |
            +------+     +------+   +-+---+     +------+    \________/
                                      |
            +------+     +------+     |
            | pCPE +-----| VCPE |-----+
            +------+     +------+

      Figure 2: VCPE deployment model NO.1: Logical Instance of VCPE

   In the second model, vCPE is modeled service function chains in Gi-
   LAN.  BNG knows how to classify the traffic from a given CPE with the
   help of the control plane, and run it through the service chain.  In
   such model, the CP/DP interface should be used between the control
   plane (which might be the controller) and the pCPE.















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             +----------+
             +Controller|
             +--+-------+
                +CP/DP interface        .......................
                +                       :VCPE                 :
                +  +---+--+             : +-----------------\ :
                ++++ pCPE +--------+    :|SFP1:DPI->FW->NAT + :
                +  +------+        |    : +-----------------/ :
                +                  |    :                     :
                +  +------+     +--+--+ : +------------\      :
                ++++ pCPE +-----+ BNG +---+SFP2:FW->NAT +     :
                +  +------+     +--+--+ : +------------/      :
                +                  |    :                     :
                + +------+        |    : +--------\          :
                ++++ pCPE +--------+    : |SFP3:NAT +         :
                   +------+             : +--------/          :
                                        .......................

             Figure 3: VCPE deployment model NO.2: VCPE as SFC

   The third model is almost the same with the second one, except that
   the BNG is also CP/DP decomposed.  In this model, The control plane
   is composed of the controller of the pCPE and the control plane of
   the BNG.  The CP/DP interface is used between the controller and the
   pCPE, and between the control plane and the data plane of the BNG.
   Both of model No.2 and No.3 may have specific requirement and protoco
   extensions for the CP/DP interface due to the usecase of VCPE.
























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            .................................
            : Control Plane                 :
            :       +----------+  +------+  :
            : +++++++Controller|  |BNG CP|  :
            : +     +----------+  +--+---+  :
            ..+......................+......:
              +   CP/DP interface    +    .......................
              +                      +    :VCPE                 :
              +  +---+--+            +    : +-----------------\ :
              ++++ pCPE +-------+    +    :|SFP1:DPI->FW->NAT + :
              +  +------+       |    +    : +-----------------/ :
              +                 |    +    :                     :
              +  +------+     +-+----+-+  : +------------\      :
              ++++ pCPE +-----+ BNG DP +----+SFP2:FW->NAT +     :
              +  +------+     +-+------+  : +------------/      :
              +                 |         :                     :
              +  +------+       |         : +--------\          :
              ++++ pCPE +-------+         : |SFP3:NAT +         :
                 +------+                 : +--------/          :
                                          .......................

       Figure 4: VCPE deployment model NO.3: VCPE as SFC, with CP/DP
                           decomposition of BNG

   SDN (Software Define Network) controllers can also be introduced in
   the third model.  In which case, all of the pCPEs and the BNG data
   plane (BNG DP) can be controlled by the SDN-controller.  When the
   customer selects a set of services, the SDN-controller will inform
   the pCPE and the BNG DP to direct the traffic flow to a certain SFC.






















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            .................................
            : Control Plane                 :
            :       +--------------+        :
            : +++++++SDN Controller|++      :
            : +     +--------------+ +      :
            ..+......................+......:
              +   CP/DP interface    +    .......................
              +                      +    :VCPE                 :
              +  +---+--+            +    : +-----------------\ :
              ++++ pCPE +-------+    +    :|SFP1:DPI->FW->NAT + :
              +  +------+       |    +    : +-----------------/ :
              +                 |    +    :                     :
              +  +------+     +-+----+-+  : +------------\      :
              ++++ pCPE +-----+ BNG DP +----+SFP2:FW->NAT +     :
              +  +------+     +-+------+  : +------------/      :
              +                 |         :                     :
              +  +------+       |         : +--------\          :
              ++++ pCPE +-------+         : |SFP3:NAT +         :
                 +------+                 : +--------/          :
                                          .......................

    Figure 5: VCPE deployment model NO.3: SFC realization of VCPE, with
                      SDN controller as control plane

6.  VCPE Deployment for Community Wi-Fi

   In this section, we will discuss about the VCPE deployment for
   Community Wi-Fi in detail.  In the following deployment, we assume
   the VCPE is deployed following the third model we discussed in
   section 5.  That is, the VCPE is a bounch of SFCs at the operator
   side behind the BNG.  The pCPEs and BNG-DP are all controlled by a
   mutual control plane.  The FPC protocol is used between the control
   plane and the pCPEs, and that and the BNG-DP.

   As we discussed in section 4, Community Wi-Fi can be deployed with
   the help of deploying VCPE.  In order to provide the Community Wi-Fi
   service, the pCPE should provide two SSIDs, one for the pubic Wi-Fi
   users, and the other for the private Wi-Fi users.  Packets from
   different SSID are marked with different VLAN ID.  The VCPE should
   know of the corresponding relation between the SSID and the VLAN ID,
   so as to provide distinguished services to the publice users and the
   private users.  For instance, the private users should experience a
   better QoS than the publice ones.  In the meantime, the private users
   and the public users may choose different SFC in the VCPE.  All of
   these different services are classified based on the VLAN ID.

   Such deployment requirs the FPC client to support the following task:




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   1) The FPC client should be able to set specific VLAN to each SSID.

   2) The FPC client should be able to set the QoS for specific VLAN ID.

   3) The FPC client should be able to inform the agent the specific SFC
   for each VLAN ID.

   4) The FPC client should be capable of instruct the agent to handle
   the MN hand-over of the public Wi-Fi users.

   In the meantime, such deployment requirs the FPC agent to support the
   following task:

   1) The FPC agent should be able to set specific VLAN to each SSID
   following the command from the client.

   2) The FPC agent should be able to set the QoS for specific VLAN ID
   following the command from the client.

   3) The FPC agent should be able to direct the traffic for specific
   VLAN ID to a certain SFC following the command of the client.

   4) The FPC agent should be able to handle the MN hand-over of the
   public Wi-Fi users.

7.  Conclusion

   In this document, the concept of VCPE is illustrated in detail.  The
   basic concept of VCPE is to shift the complicated functions from the
   pCPE at the customer side to the VCPE at the service provider side.
   The motivation of such shifting can be concluded as providing quick
   launched customer defined services, reducing the Capex and Opex of
   the pCPE, and simlify the maintainance of both pCPE and VCPE.  A use
   cases of community Wi-Fi is proposed for VCPE, which is a typical
   scenario for DMM.  Three models are then discussed for the field
   deployment of VCPE.  And CP/DP interface is suggested to be utilized
   in the deployment models.

8.  Informative References

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







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Authors' Addresses

   Qiao Fu (editor)
   China Mobile
   Xuanwumenxi Ave. No.32
   Beijing
   China

   Email: fuqiao1@outlook.com


   Hui Deng
   China Mobile
   Xuanwumenxi Ave. No.32
   Beijing
   China

   Email: denghui@chinamobile.com

































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