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rtgwg                                                              R. Gu
Internet-Draft                                                     S. Hu
Intended status: Informational                              China Mobile
Expires: May 1, 2018                                       Michael. Wang
                                                                  Huawei
                                                        October 28, 2017


    Deployment Model of Control Plane and User Plane Separation BNG
           draft-cuspdt-rtgwg-cu-separation-bng-deployment-00

Abstract

   This document introduces deployment model of BNG device with Control
   Plane and User Plane separation in order to give guidance of the
   deployment of CP and UP separation BNG devices in operators' 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
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   This Internet-Draft will expire on May 1, 2018.

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   Copyright (c) 2017 IETF Trust and the persons identified as the
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   described in the Simplified BSD License.



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Table of Contents

   1.  Introduction and Overview . . . . . . . . . . . . . . . . . .   2
   2.  Concept and Terminology . . . . . . . . . . . . . . . . . . .   3
     2.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Deployment Model of BNG with CP and UP Separation . . . . . .   4
     3.1.  CP and UP of BNG deployment within only one district  . .   4
     3.2.  CP and UP of BNG deployment within different districts  .   5
   4.  The Process of BNG with CP and UP in Home Broadband Service .   6
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   7.  Normative References  . . . . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction and Overview

   BNG is an Ethernet-centric IP edge router and acts as the aggregation
   point for the user traffic with some additional functions such as
   address management, AAA and Radius cooperating with AAA and Radius
   systems and subscriber management.  According to the rapid
   development of new services, such as 4K, IoT, etc. and the increasing
   numbers of distributed home broadband service users, high resource
   utilization, management of high-efficiency, and fast service
   provision are required.  Thus a new architecture of BNG with CP and
   UP separation which is also called Cloud BNG is proposed in [BBF-
   CloudCO] and [I-D.draft-gu-nfvrg-cloud-bng-architecture].

   The bandnew CP and UP separation architecture of BNG is constructed
   by Control Plane and Uer Plane, with concentrated CP responsible for
   control and management of UP's resrouces and subscribers' informaiton
   while distributed UP taking charge of policy implementation and
   traffic forwarding.  The obvious advantages of this new architecture
   can be listed as belows.

   Resource Utilization Improvement: Centralized Control Plane provides
   the capability of unitfied management of network resources and users
   information.  CP has an overview of all the resources and can
   distribute resources as specific user required, thus resources can be
   totally controlled and balances.

   Management with High Effiency: Centralized CP provides unified
   management interface to the outside systems such as EMS, DHCP Server,
   Radius Server and etc.  In this situation, management can be much
   easier for centralized CP is the only device facing to the outside
   systems.

   Dynamic and Flexibility: CP can be virtualized as a VNF with MANO
   management in NFV, while UP can be a virtual machine or physical



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   device as demand.  Software-oriented CP can be designed with
   flexibility.  CP can handle all the situations dynamically such as
   few users accessing and large numbers of users access.

   Fast TTM: CP and UP can be deployed separately with CP deployed
   centrally and UP deployed in distribution closing to users.  Thus
   according to different situations such as session overload or
   extremely high throughput, CP and UP can be extended separately as
   well.  It can help shorten the time to marketing.

   As noted that the new architecture of BNG consists with CP and UP
   separation, CP and UP are deployed due to practical requiement.  This
   document gives out CU separation BNG deployment model according to
   the actual deployment.

2.  Concept and 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].

2.1.  Terminology

   BNG: Broadband Network Gateway.  A broadband remote access server
   (BRAS, B-RAS or BBRAS) routes traffic to and from broadband remote
   access devices such as digital subscriber line access multiplexers
   (DSLAM) on an Internet service provider's (ISP) network.  BRAS can
   also be referred to as a Broadband Network Gateway (BNG).

   CP: Control Plane.  The CP is a user control management component
   which support to manage UP's resources such as the user entry and
   user's QoS policy

   UP: User Plane.  UP is a network edge and user policy implementation
   component.  The traditional router's Control Plane and forwarding
   plane are both preserved on BNG devices in the form of a user plane.

   TTM: Time to Market.  It is the length of time it takes from a
   product or a service being conceived until its being available for
   sale.

   MANO: Management and Orchestration.  Functions are collectively
   provided by NFVO, VNFM and VIM.

   VNF: Virtual Network Function.  Implementation of a Network Function
   that can be deployed on a Network Function Virtualization
   Infrastructure (NFVI).




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   PNF: Physical Network Function

   AAA: Authentication Authorization Accounting

   DHCP: Dynamic Host Configuration Protocol

   PPPoE: Point to Point Protocol over Ethernet

   IPoE: Internet Protocol over Ethernet

3.  Deployment Model of BNG with CP and UP Separation

3.1.  CP and UP of BNG deployment within only one district

   +-------------------+
   |                   |
   |       Internet    |
   |                   |
   +---------^---------+
             |
         +---+---+
         |       |              +------------------------+
         |   CR  |              |                        |
         |       |              |            +--------+  |
         +---^---+              |     +------+ Radius |  |
             |                  |     |      +--------+  |
             |                  |  +--+---+              |
         +---+---+              |  |      |  +--------+  |
         |       +---SERVICE----+  |      +--+  DHCP  |  |
         | BNG-UP+---CONTROL----+  | BNG  |  +--------+  |
         |VNF/PNF+----MGNT------+  | -CP  |              |
         +---^---+              |  |  VNF |  +--------+  |
             |                  |  |      +--+   EMS  |  |
             |                  |  |      |  +--------+  |
         +---+---+              |  +--+---+              |
         |       |              |     |      +--------+  |
         |  OLT  |              |     +------+  MANO  |  |
         |       |              |            +--------+  |
         +---^---+              |   Management Network   |
             |                  +------------------------+
         +---+---+
         |  USER |
         +-------+

               Figure 1: Cloud BNG Deployed in One Disctict

   Take one district as an example, here BNG-CP and BNG-UP are separated
   deployed.  As CP is computational intensive, virtualized CP acting as



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   a VNF can meet the requirement of flexibility and fast calculation.
   UP is traffic intensive, which can be virtualized or stay physical
   depending on traffic.  The virtualized UP with low expcense and high
   flexibility can be suitable in light traffic.  In hugh traffic,
   special hardware is needed with high traffic forwarding performance.

   In order to fulfill the function of BNG, BNG-CP needs to communicate
   with outside systems such as Radius and many others in the management
   network.  In addition, BNG-CP has different interfaces with BNG-UP
   including service interface, control interface and management
   interface, seeing in [I-D.draft-gu-nfvrg-cloud-bng-architecture]and
   [I-D.draft-wcg-i2rs-cu-separation-infor-model-01].

3.2.  CP and UP of BNG deployment within different districts

               +-------------------+
               |                   |
               |       Internet    |
               |                   |
               +---------^---------+
                         |               +------+ +----+ +---+ +----+
                     +---+---+           |Radius| |DHCP| |EMS| |MANO|
                     |       |           +---+--+ +--+-+ +-+-+ +-+--+
                     |       |               |       |     |     |
                 +---+   CR  +-----+     +---+-------+-----+-----+--+
                 |   |       |     |     |         BNG-CP           |
                 |   |       |     |     +---.--.------------.------+
                 |   +---^---+     +---------.--.--+         .
                 |   ....|....................  .  |         .
                 |   .   |           ............  |         .
                 |   .   +-------+   .             | .........
               +-+---.-+       +-+---.-+       +---+-.-+
               |       |       |       |       |       |
               | BNG-UP|       | BNG-UP|       | BNG-UP|
               |VNF/PNF|       |VNF/PNF|       |VNF/PNF|
               +---^---+       +---^---+       +---^---+
                   |               |               |
                   |               |               |
               +---+---+       +---+---+       +---+---+
               |  OLT  |       |  OLT  |       |  OLT  |
               +---+---+       +---+---+       +---+---+
             +-----|-----+         |         +-----|-----+
         +---+---+   +---+---+ +---+---+ +---+---+   +---+---+
         |USER A1|   |USER A2| |USER B1| |USER C1|   |USER C2|
         +-------+   +-------+ +-------+ +-------+   +-------+

             Figure 2: Cloud BNG Deployed in Several Discticts




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   If scubscribers are distributed in serveral districts, CP is deployed
   centrally with UP deployed in different districts closing to
   subscribers.  Take three districts A B C for example.  Here three UPs
   are placed which share one CP.  CP is usually deployed in Core Date
   Center with UP in edge Date Centers.  In the Data Centers design, we
   have core data centers and edge data centers according to their
   location and responsibility.  Core datacenters are often planned in
   province for the control and management , while edge datacenters in
   cities or towns for easy service access.

   In this scenario, centralized CP faces to the subsystems outside and
   communicate with all these UPs for the control and management.

   Under the CP's control, the corresponding traffic is forwarded by UP
   to the Internet.

4.  The Process of BNG with CP and UP in Home Broadband Service

   Take a user Bob accessing to the Internet by Home Broadband Service
   as an example.  The process includs the service traffic from user to
   the internet and signaling traffic between BNG-UP and BNG-CP.  Below
   is the whole process.

   (1)User Bob dialups with packets of PPPoE or IPoE from BNG-UP which
   will send to BNG-CP with its information.  This belongs to signaling
   traffic.

   (2)BNG-CP processes the dialup packets.  Confirming with the outside
   neighboring systems in the management network, BNG-CP makes the
   decision to permit or deny of the dial through certification.  In
   this step, BNG-CP manages resources and generates tables with
   information such as User Infor, IP Infor, QoS Info and etc.  This
   belongs to signaling traffic.

   (3)BNG-CP sends tables to the corresponding UP or choose one UP in
   corresponding UPs.  This belongs to signaling traffic.

   (4)BNG-UP receives the tables, matches rules and performs
   corresponding actions.

   (5)If Bob is certificated and permitted, the UP forwards the traffic
   into the Internet with related policies such as limited bandwidth,
   etc.  Otherwise, Bob is denied to access the Internet.  This belongs
   to service traffic.

   From Step 2 to Step 4, the information model defined in [I-D.draft-
   wcg-i2rs-cu-separation-infor-model-01] can be used.




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5.  Security Considerations

   None.

6.  IANA Considerations

   None.

7.  Normative References

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

Authors' Addresses

   Rong Gu
   China Mobile
   32 Xuanwumen West Ave, Xicheng District
   Beijing, Beijing  100053
   China

   Email: gurong_cmcc@outlook.com


   Sujun Hu
   China Mobile
   32 Xuanwumen West Ave, Xicheng District
   Beijing, Beijing  100053
   China

   Email: shujun_hu@outlook.com


   Michael Wang
   Huawei
   101 Software Avenue, Yuhua District
   Nanjing, Jiangsu  210012
   China

   Email: wangzitao@huawei.com









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