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Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year == The document doesn't use any RFC 2119 keywords, yet seems to have RFC 2119 boilerplate text. -- The document date (December 12, 2018) is 1249 days in the past. Is this intentional? Checking references for intended status: Informational ---------------------------------------------------------------------------- == Missing Reference: 'BBF-CloudCO' is mentioned on line 80, but not defined Summary: 0 errors (**), 0 flaws (~~), 3 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 INTERNET-DRAFT R. Gu 2 Intended status: Informational S. Hu 3 China Mobile 4 M. Wang 5 D. Eastlake 6 Huawei 7 F. Hu 8 ZTE 9 Expires: June 11, 2019 December 12, 2018 11 Control Plane and User Plane Separated BNG Deployment Model 12 draft-cuspdt-rtgwg-cu-separation-bng-deployment-02 14 Abstract 16 This document describes the deployment model for a Broadband Network 17 Gateway (BNG) device with Control Plane (CP) and User Plane(UP) 18 separation. It is intended to give guidance for the deployment of CP 19 and UP separated BNG devices in an operators' network. 21 Status of This Memo 23 This Internet-Draft is submitted in full conformance with the 24 provisions of BCP 78 and BCP 79. 26 Distribution of this document is unlimited. Comments should be sent 27 to the authors or the BESS working group mailing list: bess@ietf.org. 29 Internet-Drafts are working documents of the Internet Engineering 30 Task Force (IETF), its areas, and its working groups. Note that 31 other groups may also distribute working documents as Internet- 32 Drafts. 34 Internet-Drafts are draft documents valid for a maximum of six months 35 and may be updated, replaced, or obsoleted by other documents at any 36 time. It is inappropriate to use Internet-Drafts as reference 37 material or to cite them other than as "work in progress." 39 The list of current Internet-Drafts can be accessed at 40 http://www.ietf.org/1id-abstracts.html. The list of Internet-Draft 41 Shadow Directories can be accessed at 42 http://www.ietf.org/shadow.html. 44 * 46 Table of Contents 48 1. Introduction and Overview...............................3 50 2. Concept and Terminology.................................5 51 2.1 Terminology............................................5 53 3. BNG with CP and UP Separation Deployment Model..........6 54 3.1 CP and UP of BNG Deployment Within One District........6 55 3.2. CP and UP of BNG Deployment in Multiple Districts.....7 57 4. The Process of BNG with CUPS in Home Service...........10 59 5. High Availability Considerations.......................11 61 6. Security Considerations................................12 62 7. IANA Considerations....................................12 64 Normative References......................................13 65 Informative References....................................13 67 Authors' Addresses........................................14 68 < 69 1. Introduction and Overview 71 A Broadband Network Gateway (BNG) is an Ethernet-centric IP edge 72 router and acts as the aggregation point for the user traffic with 73 some additional functions such as address management and cooperating 74 with AAA (Radius/Diameter) systems and subscriber management. Because 75 of the rapid development of new services, such as 4K, IoT, etc. and 76 the increasing numbers of distributed home broadband service users, 77 high resource utilization, high-efficiency management, and fast 78 service provisioning are required. This calls for a new BNG 79 architecture with CP and UP separation, which is also called Cloud 80 BNG, as proposed in [BBF-CloudCO] [TR-384]. 82 The CP and UP separation architecture of the BNG is composed of a 83 Control Plane and a User Plane, with the concentrated CP responsible 84 for control and management of the UP's resources and subscribers' 85 information, and with the distributed UP taking charge of policy 86 implementation and traffic forwarding. The obvious advantages of this 87 new architecture are listed below. 89 Resource Utilization Improvement: A centralized Control Plane 90 provides unified management capability for network 91 resources and users information. The CP has an overview of 92 all the resources and can distribute resources as specific 93 users require, thus resources can be totally controlled and 94 balanced. 96 Management with High Efficiency: A centralized CP provides a unified 97 management interface to the outside systems such as EMS, 98 DHCP Server, AAA Server, etc. In this situation, management 99 can be easier for the centralized CP as it's the only 100 device interfacing with the outside systems. 102 Dynamic and Flexible: The CP can be virtualized as a VNF with MANO 103 management in an NFVI, while the UP can be a virtual 104 machine or physical device as needed. A software-oriented 105 CP can be designed with flexibility. The CP can handle all 106 the situations dynamically over a wide range from few users 107 accessing to large numbers of users accessing. 109 Fast TTM: The CP and UP can be deployed separately with the CP 110 deployed centrally and the UP deployed in distribution 111 closer to users. Thus, according to different situations 112 such as session overload or extremely high throughput, the 113 CP and UP can be extended separately. This can help shorten 114 the time to market (TTM). 116 As noted, the new BNG architecture has CP and UP separation. The CP 117 and UP are deployed with separation due to practical requirements. 118 This document gives the CU separation BNG deployment model for actual 119 deployments. 121 2. Concept and Terminology 123 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 124 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 125 "OPTIONAL" in this document are to be interpreted as described in BCP 126 14 [RFC2119] [RFC8174] when, and only when, they appear in all 127 capitals, as shown here. 129 2.1 Terminology 131 BNG: Broadband Network Gateway. A broadband remote access server 132 (BRAS, B-RAS or BBRAS) routes traffic to and from broadband 133 remote access devices such as digital subscriber line access 134 multiplexers (DSLAM) on an Internet service provider's (ISP) 135 network. BRAS can also be referred to as a Broadband Network 136 Gateway (BNG). 138 CP: Control Plane. The CP is a user control management component 139 which manages UP's resources such as the user entry and user's 140 QoS policy 142 CUPS: Control/User Plane Separation 144 UP: User Plane. The UP is a network edge and user policy 145 implementation component. The traditional router's Control Plane 146 and forwarding plane are both preserved on BNG devices in the 147 form of a user plane. 149 TTM: Time to Market. It is the length of time it takes from a product 150 or a service being conceived until it is available for sale. 152 MANO: Management and Orchestration. Functions are collectively 153 provided by NFVO, VNFM and VIM. 155 VNF: Virtual Network Function. Implementation of a Network Function 156 that can be deployed on a Network Function Virtualization 157 Infrastructure (NFVI). 159 PNF: Physical Network Function 161 DHCP: Dynamic Host Configuration Protocol 163 PPPoE: Point-to-Point Protocol over Ethernet 165 IPoE: Internet Protocol over Ethernet 167 3. BNG with CP and UP Separation Deployment Model 169 3.1 CP and UP of BNG Deployment Within One District 171 +-------------------+ 172 | | 173 | Internet | 174 | | 175 +---------^---------+ 176 | 177 +---+---+ 178 | | +------------------------+ 179 | CR | | | 180 | | | +--------+ | 181 +---^---+ | +------+ AAA | | 182 | | | +--------+ | 183 | | +--+---+ | 184 +---+---+ | | | +--------+ | 185 | +---SERVICE----+ | +--+ DHCP | | 186 | BNG-UP+---CONTROL----+ | BNG | +--------+ | 187 |VNF/PNF+----MGNT------+ | -CP | | 188 +---^---+ | | VNF | +--------+ | 189 | | | +--+ EMS | | 190 | | | | +--------+ | 191 +---+---+ | +--+---+ | 192 | | | | +--------+ | 193 | OLT | | +------+ MANO | | 194 | | | +--------+ | 195 +---^---+ | Management Network | 196 | +------------------------+ 197 +---+---+ 198 | USER | 199 +-------+ 201 Figure 1: Cloud BNG Deployed in One District 203 Take a one district example as in Figure 1. Here BNG-CP and BNG-UP 204 are separated as deployed. Since the CP is computationally intensive, 205 a virtualized CP acting as a VNF can meet the requirements of 206 flexibility and fast calculation. The UP is traffic intensive, which 207 can be virtualized or stay physical depending on traffic. The 208 virtualized UP with low expense and high flexibility can be suitable 209 for light traffic. In high traffic, special hardware is needed with 210 high traffic forwarding performance. 212 In order to fulfill the function of a BNG, the BNG-CP needs to 213 communicate with outside systems such as a AAA (Radius/Diameter) 214 server and many others in the management network. In addition, the 215 BNG-CP has three interfaces with the BNG-UP separated by their 216 traffic categories: Service Interface, Control Interface, and 217 Management Interface. 219 +-------------------------------------+ 220 | | 221 | BNG-CP | 222 | | 223 +--+--------------+----------------+--+ 224 | | | 225 1. Service | 2. Control | 3. Management | 226 Interface | Interface | Interface | 227 | | | 228 +--+--------------+----------------+--+ 229 | | 230 | BNG-UP | 231 | | 232 +-------------------------------------+ 234 Figure 2. Internal Interfaces Between the BNG CP and UP 236 The functions of the three interfaces are as follows: 238 Service Interface: The CP and UP use this interface to establish 239 VXLAN tunnels with each other and transmit PPPoE and IPoE 240 packets over the VXLAN tunnels for authentication. 242 Control Interface: The CP uses this interface to deliver service 243 entries to the UP, and the UP uses this interface to report 244 service events to the CP. 246 Management Interface: The CP uses this interface to deliver basic 247 configurations to the UP. This interface uses NETCONF. 249 Several related drafts exist describing these interfaces in detail. 250 The VXLAN-GPE extension draft for C/U separated BNG is related to the 251 Service Interface [huang-nov3-vxlan-gpe-extension-for-vbng]. The 252 draft YANG data model for CU separated BNG focuses on Management 253 Interface, seeing in [cuspdt-rtgwg-cu-separation-yang-model]. Another 254 two drafts [cuspdt-rtgwg-cusp-requirements] and [cuspdt-rtgwg-cu- 255 separation-infor-model] are related to the control interface giving 256 an information model abstraction and suitable protocol. 258 3.2. CP and UP of BNG Deployment in Multiple Districts 259 +-------------------+ 260 | | 261 | Internet | 262 | | 263 +---------^---------+ 264 | +------+ +----+ +---+ +----+ 265 +---+---+ |Radius| |DHCP| |EMS| |MANO| 266 | | +---+--+ +--+-+ +-+-+ +-+--+ 267 | | | | | | 268 +---+ CR +-----+ +---+-------+-----+-----+--+ 269 | | | | | BNG-CP | 270 | | | | +---.--.------------.------+ 271 | +---^---+ +---------.--.--+ . 272 | ....|.................... . | . 273 | . | ............ | . 274 | . +-------+ . | ......... 275 +-+---.-+ +-+---.-+ +---+-.-+ 276 | | | | | | 277 | BNG-UP| | BNG-UP| | BNG-UP| 278 |VNF/PNF| |VNF/PNF| |VNF/PNF| 279 +---^---+ +---^---+ +---^---+ 280 | | | 281 | | | 282 +---+---+ +---+---+ +---+---+ 283 | OLT | | OLT | | OLT | 284 +---+---+ +---+---+ +---+---+ 285 +-----|-----+ | +-----|-----+ 286 +---+---+ +---+---+ +---+---+ +---+---+ +---+---+ 287 |USER A1| |USER A2| |USER B1| |USER C1| |USER C2| 288 +-------+ +-------+ +-------+ +-------+ +-------+ 290 Figure 3: Cloud BNG Deployed in Several Districts 292 If subscribers are distributed in several districts, the CP can be 293 deployed centrally with the UP deployed in different districts close 294 to subscribers as shown in Figure 3. Thus the deployment model can be 295 a bit complex. 297 Take three districts A, B. and C for example. Here three UPs are 298 placed with one shared CP. The CP is usually deployed in a Core Data 299 Center such as in a provincial datacenter with UPs in edge Date 300 Centers such as city datacenters. In this Data Centers design, we 301 have core data centers and edge data centers according to their 302 location and responsibility. Core data centers are often planned in 303 provinces for control and management, while edge data centers are in 304 cities or towns for easy service access. 306 In this scenario, a centralized CP interfaces to the subsystems 307 outside and communicate with all these UPs for control and 308 management. 310 Under the CP's control, the corresponding traffic is forwarded by UP 311 to the Internet. 313 4. The Process of BNG with CUPS in Home Service 315 Take a user Bob accessing to the Internet using Home Broadband 316 Service as an example. The process includes the service traffic from 317 user to the internet and signaling traffic between BNG-UP and BNG-CP. 318 Below is the whole process. 320 (1) User Bob dials up with packets of PPPoE or IPoE from BNG-UP which 321 will be sent to the BNG-CP with the user's information. This is 322 signaling traffic. 324 (2) The BNG-CP processes the dialup packets. Confirming with the 325 outside neighboring systems in the management network, the BNG-CP 326 makes the decision to permit or deny of the dial access through 327 certification. In this step, the BNG-CP manages resources and 328 generates tables with information such as User Info, IP Info, QoS 329 Info, etc. This is signaling traffic. 331 (3) The BNG-CP sends tables to the corresponding UP or to one UP it 332 chooses from the corresponding UPs. This is signaling traffic. 334 (4) The BNG-UP receives the tables, matches rules and performs 335 corresponding actions. 337 (5) If Bob is certificated and permitted, the UP forwards their 338 traffic into the Internet with related policies such as limited 339 bandwidth, etc. Otherwise, Bob is denied to access the Internet. 340 This is service traffic. 342 From Step 2 to Step 4, the information model defined in 343 [cuspdt-rtgwg-cu-separation-infor-model] can be used. 345 5. High Availability Considerations 347 As the BNG-CP takes responsibility for control and management, such 348 as communicating with outside systems, generating flow tables, and 349 managing the UP's resources, high availability of this key component 350 should be considered. Some redundancy should be adopted for 351 reliability, such as N+N or N+K active standby BNG-CPs. N+N standby 352 means 1:1 backup for each BNG-CP, which enables easy rapid switch of 353 any number of BNG-CP to their backup but is expensive because it 354 requires a large number of backup CPs. N+K means a smaller number of 355 backup CPs, for example N2:1 backup where N2. 374 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 375 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 376 2017, .in -10 378 Informative References 380 [hu-nov3-vxlan-gpe-extension-for-vbng] Huang, L., "VXLAN GPE 381 Extension for Packets Exchange Between Control and User 382 Plane of vBNG", draft-hu-nvo3-vxlan-gpe-extension-for-vbrg, 383 work in progress, 2017. 385 [cuspdt-rtgwg-cu-separation-yang-model] Hu, F., "YANG Data Model for 386 Configuration Interface of Control-Plane and User-Plane 387 separation BNG", draft-cuspdt-rtgwg-cu-separation-yang- 388 model, work in progress, 2018. 390 [cuspdt-rtgwg-cusp-requirements] Hu, S., "Requirements for Control 391 Plane and User Plane Separated BNG Protocol", draft-cuspdt- 392 rtgwg-cusp-requirements, work in progress, 2018. 394 [cuspdt-rtgwg-cu-separation-infor-model] Wang, Z., "Information Model 395 of Control-Plane and User- Plane separation BNG", draft- 396 cuspdt-rtgwg-cu-separation-infor-model, work in progress, 397 2018. 399 [TR-384] BroadBand Forum, "Cloud Central Office Reference 400 Architectural Framework", January 2018. 402 Authors' Addresses 404 Rong Gu 405 China Mobile 406 32 Xuanwumen West Ave, Xicheng District 407 Beijing, Beijing 100053 408 China 410 Email: gurong_cmcc@outlook.com 412 Sujun Hu 413 China Mobile 414 32 Xuanwumen West Ave, Xicheng District 415 Beijing, Beijing 100053 416 China 418 Email: shujun_hu@outlook.com 420 Michael Wang 421 Huawei Technologies 422 101 Software Avenue, Yuhua District 423 Nanjing, Jiangsu 210012 424 China 426 Email: wangzitao@huawei.com 428 Donald Eastlake, 3rd 429 Huawei Technologies 430 1424 Pro Shop Court 431 Davenport, FL 33896 432 USA 434 Phone: +1-508-333-2270 435 Email: d3e3e3@gmail.com 437 Fangwei Hu 438 ZTE Corporation 439 No.889 Bibo Rd 440 Shanghai 201203 441 China 443 Phone: +86 21 68896273 444 Email: hu.fangwei@zte.com.cn 446 Copyright, Disclaimer, and Additional IPR Provisions 448 Copyright (c) 2018 IETF Trust and the persons identified as the 449 document authors. 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