rtgwg R. Gu Internet-Draft S. Hu Intended status: Informational China Mobile Expires: August 30, 2018 Michael. Wang Huawei Fangwei. Hu ZTE Corporation February 26, 2018 Deployment Model of Control Plane and User Plane Separated BNG draft-cuspdt-rtgwg-cu-separation-bng-deployment-01 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 separated 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 Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. 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 August 30, 2018. Copyright Notice Copyright (c) 2018 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 (https://trustee.ietf.org/license-info) 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 Gu, et al. Expires August 30, 2018 [Page 1] Internet-Draft Deployment Model of CU separated BNG February 2018 the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. 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 . 6 4. The Process of BNG with CP and UP in Home Broadband Service . 7 5. High Availability Consideration . . . . . . . . . . . . . . . 7 6. Security Considerations . . . . . . . . . . . . . . . . . . . 8 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 8. Normative References . . . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 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 and Radius cooperating with 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][TR-384]. The brandnew CP and UP separation architecture of BNG is constructed by Control Plane and User 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 unified 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 balanced. 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 as it's the only device facing to the outside systems. Gu, et al. Expires August 30, 2018 [Page 2] Internet-Draft Deployment Model of CU separated BNG February 2018 Dynamic and Flexibility: CP can be virtualized as a VNF with MANO management in NFV, while UP can be a virtual machine or physical 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 accessing. 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 (TTM). As noted that the new architecture of BNG consists with CP and UP separation, CP and UP are deployed due to practical requirements. 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. 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. Gu, et al. Expires August 30, 2018 [Page 3] Internet-Draft Deployment Model of CU separated BNG February 2018 VNF: Virtual Network Function. Implementation of a Network Function that can be deployed on a Network Function Virtualization Infrastructure (NFVI). PNF: Physical Network Function 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 Gu, et al. Expires August 30, 2018 [Page 4] Internet-Draft Deployment Model of CU separated BNG February 2018 Take one district as an example, here BNG-CP and BNG-UP are separated deployed. As CP is computational intensive, virtualized CP acting as a VNF can meet the requirements of flexibility and fast calculation. UP is traffic intensive, which can be virtualized or stay physical depending on traffic. The virtualized UP with low expense 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. There are three kinds of interfaces between BNG-CP and BNG-UP according to its traffic catergories: Service Interface, Control Interface, and Management Interface. +----------------------------------+ | | | BNG-CP | | | +--+--------------+--------------+-+ | | | 1.Service | 2.Control | 3.Management| Interface | Interface | Interface | | | | +--+--------------+--------------+-+ | | | BNG-UP | | | +----------------------------------+ Internal interfaces between the CP and UP of the BNG device Service interface: The CP and UP use this interface to establish VXLAN tunnels with each other and transmit PPPoE and IPoE packets over the VXLAN tunnels for the authentication. Control interface: The CP uses this interface to deliver service entries, and the UP uses this interface to report service events to the CP. Management interface: The CP uses this interface to deliver basic configurations to the UP. This interface runs on NETCONF. Several related drafts describing these interfaces in details exist. VXLAN-GPE extention draft for C/U separated BNG is related with Servie Interface in [I-D.draft-huang-nov3-vxlan-gpe-extension-for- vbng]. The draft YANG data model for CU separated BNG focuses on Management Interface, seeing in [I-D.draft-hu-rtgwg-cu-separation- Gu, et al. Expires August 30, 2018 [Page 5] Internet-Draft Deployment Model of CU separated BNG February 2018 yang-model]. Another two drafts [I-D.draft-cuspdt-rtgwg-cusp- requirements] and [I-D.draft-cuspdt-rtgwg-cu-separation-infor-model] are related with control interface with information model abstraction and suitable protocol discussion. 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 If scubscribers are distributed in serveral districts, CP is deployed centrally with UP deployed in different districts closing to subscribers. Thus the deployment model can be a few complex. 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 such as in the province datacenter with UP in edge Date Centers such as datacenter in cities. In the Data Centers design, we have core data centers and edge data centers according to their location and Gu, et al. Expires August 30, 2018 [Page 6] Internet-Draft Deployment Model of CU separated BNG February 2018 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- cuspdt-rtgwg-cu-separation-infor-model] can be used. 5. High Availability Consideration As the BNG-CP takes the responsibility of control and management such as communicating with outside systems, generating flow tables and managing UP's resources, high availability of the key component should be considered. Some technology is adopted to ensure the Gu, et al. Expires August 30, 2018 [Page 7] Internet-Draft Deployment Model of CU separated BNG February 2018 reliability, such as N+N or N+K active standby BNG-CP. N+N active standby means 1:1 backup for example, while N+K active standby means N:1 backup for example. When active CP fails, standby CP should take the role of active according to some mechanism. Actually in the deployment, resources should be reserved for the backup BNG-CP VNF. 6. Security Considerations None. 7. IANA Considerations None. 8. 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, . 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 Gu, et al. Expires August 30, 2018 [Page 8] Internet-Draft Deployment Model of CU separated BNG February 2018 Fangwei Hu ZTE Corporation No.889 Bibo Rd Shanghai 201203 China Phone: +86 21 68896273 Email: hu.fangwei@zte.com.cn Gu, et al. Expires August 30, 2018 [Page 9]