Requirements for Control Plane and User Plane Separated BNG Protocol
draft-cuspdt-rtgwg-cusp-requirements-00
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Authors | Sujun Hu , Lu Huang , Rong Gu , Victor Lopez , Jun Song , Zitao Wang | ||
Last updated | 2017-10-26 | ||
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draft-cuspdt-rtgwg-cusp-requirements-00
rtgwg S. Hu Internet-Draft L. Huang Intended status: Informational R. Gu Expires: April 29, 2018 China Mobile Victor. Lopez Telefonica Jun. Song Michael. Wang Huawei October 26, 2017 Requirements for Control Plane and User Plane Separated BNG Protocol draft-cuspdt-rtgwg-cusp-requirements-00 Abstract This document introduces the Control Plane and User Plane separated BNG architecture and defines a set of associated terminology. This document also defines a set of protocol requirements to Control Plane and User Plane Separated BNG (CUSP). 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 April 29, 2018. Copyright Notice Copyright (c) 2017 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 Hu, et al. Expires April 29, 2018 [Page 1] Internet-Draft Requirements for CUSP October 2017 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 the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Concept and Terminology . . . . . . . . . . . . . . . . . . . 3 2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 3. CU Separated BNG Model . . . . . . . . . . . . . . . . . . . 3 3.1. Internal interfaces between the CP and UP . . . . . . . . 5 4. The usage of CU separation BNG protocol . . . . . . . . . . . 6 5. Control Plane and User Plane Separation Protocol Requirements 7 5.1. Transmit information tables . . . . . . . . . . . . . . . 7 5.2. Scalability . . . . . . . . . . . . . . . . . . . . . . . 7 5.3. Message Priority . . . . . . . . . . . . . . . . . . . . 8 5.4. Reliability . . . . . . . . . . . . . . . . . . . . . . . 8 5.5. Support for Secure Communication . . . . . . . . . . . . 8 5.6. Version negotiation . . . . . . . . . . . . . . . . . . . 8 5.7. Capability Exchange . . . . . . . . . . . . . . . . . . . 9 5.8. CP primary/backup capability . . . . . . . . . . . . . . 9 5.9. Event Notification . . . . . . . . . . . . . . . . . . . 9 5.10. Query Statistics . . . . . . . . . . . . . . . . . . . . 10 6. Security Considerations . . . . . . . . . . . . . . . . . . . 10 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 8. Normative References . . . . . . . . . . . . . . . . . . . . 10 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 1. Introduction BNG is an Ethernet-centric IP edge router, and the aggregation point for the user traffic. To provide centralized session management, flexible address allocation, high scalability for subscriber management capacity, and cost-efficient redundancy, the CU separated BNG is introduced [BBF-CloudCO]. The CU separated Service Control Plane could be virtualized and centralized, which is responsible for user access authentication and setting forwarding entries of user plane. The routing control and forwarding plane, i.e. BNG user plane (local), could be distributed across the infrastructure. This document introduces the Control Plane and User Plane separated BNG architecture and modeling. This document also defines the protocol requirements to Control Plane and User Plane Separated BNG (CUSP). Hu, et al. Expires April 29, 2018 [Page 2] Internet-Draft Requirements for CUSP October 2017 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. 3. CU Separated BNG Model The following figure describes the architecture of CU separation BNG Hu, et al. Expires April 29, 2018 [Page 3] Internet-Draft Requirements for CUSP October 2017 +------------------------------------------------------------------+ | Neighboring policy and resource management systems | | | | +-------------+ +-----------+ +---------+ +----------+ | | |Radius Server| |DHCP Server| | EMS | | MANO | | | +-------------+ +-----------+ +---------+ +----------+ | +------------------------------------------------------------------+ +------------------------------------------------------------------+ | CU-separated BNG system | | +--------------------------------------------------------------+ | | |+----------+ +----------+ +------++------++-----------+ | | | || Address | |Subscriber| |Radius||PPPoE/|| UP | | | | ||management| |management| | ||IPoE ||management | | | | |+----------+ +----------+ +------++------++-----------+ | | | |+----------+ +----------+ +------++------++-----------+ | | | | CP | | | +--------------------------------------------------------------+ | | +---------------------------+ +--------------------------+ | | | +------------------+ | | +------------------+ | | | | | Routing control | | | | Routing control | | | | | +------------------+ | ... | +------------------+ | | | | +------------------+ | | +------------------+ | | | | |Forwarding engine | | | |Forwarding engine | | | | | +------------------+ UP | | +------------------+ UP| | | +---------------------------+ +--------------------------+ | +------------------------------------------------------------------+ Architecture of CU Separation BNG Briefly, a CU separated BNG is made up of a Control Plane (CP) and a set of User Planes (UPs) [BBF-CloudCO], [I-D.draft-gu-nfvrg-cloud- bng-architecture]. The Control Plane is a user control management component which support to manage UP's resources such as the user entry and user's QoS policy, for example, the access bandwidth and priority management. This Control Plane could be virtualized and centralized. The functional components inside the BNG Service Control Plane can be implemented as VNFs and hosted in a NFVI. The User Plane Management module in the BNG control plane centrally manages the distributed BNG user planes (e.g. load balancing), as well as the setup, deletion, maintenance of channels between control planes and user planes [BBF-CloudCO], [I-D.draft-gu-nfvrg-cloud-bng- architecture]. And the User Plane (UP) is a network edge and user policy implementation component. It can support the forwarding plane functions on traditional BNG devices, such as traffic forwarding, QoS, and traffic statistics collection, and it can also support the control plane functions on traditional BNG devices, such as routing, Hu, et al. Expires April 29, 2018 [Page 4] Internet-Draft Requirements for CUSP October 2017 multicast, etc.[BBF-CloudCO],[I-D.draft-gu-nfvrg-cloud-bng- architecture] 3.1. Internal interfaces between the CP and UP To support the communication between the Control Plane and User Plane, several interfaces are involved. The Figure 2 illustrates the internal interfaces of CU Separated BNG. +----------------------------------+ | | | BRAS-CP | | | +--+--------------+--------------+-+ | | | Service | Control | Management | Interface | Interface | Interface | | | | +--+--------------+--------------+-+ | | | BRAS-UP | | | +-----------------+----------------+ | | +--------+--------+ | | | Access Network | | | +--------+--------+ | +----+----+ | | | User | | | +---------+ Internal interfaces between the CP and UP 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. Hu, et al. Expires April 29, 2018 [Page 5] Internet-Draft Requirements for CUSP October 2017 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 configurations to the UP. This interface runs NETCONF. 4. The usage of CU separation BNG protocol ----------------- //// \\\\ //// \\\\ // Cloud \\ | | | | | | | | | +-----------------+ | | | Control Plane | | \\ | | // \\\\ +------+----------+ //// \\\\ | //// ----------------- | +--------+----------+-------------+-----+ | | | | User's information IP ddress QoS: ....... May Including: | CIR; : User ID; | PIR; | User MAC; | CBS; | Access method(PPPoE, | PBS; | IPoE, etc) | ...... ..... | | | +-------------------V--------------+ | +-----------+ | ------- | /// \\\ +------+ +-------v---------+ +--------+ | | | OLT | | User Plane | | Core | | Internet | +-------+ +-------+ Routing-----+ | +------+ +-----------------+ +--------+ \\\ /// ------- CU Separation BNG Hu, et al. Expires April 29, 2018 [Page 6] Internet-Draft Requirements for CUSP October 2017 As shown in above figure, when users access to the BNG network, the control plane solicits these users' information (such as user's ID, user's MAC, user's access methods, for example via PPPoE/IPoE), associates them with available bandwidth which are reported by User planes, and based on the service's requirement to generate a set of tables, which may include user's information, UP's IP segment, and QoS, etc. Then the control plane can transmit these tables to the User planes. User planes receive these tables, parses it, matches these rules, and then performs corresponding actions. 5. Control Plane and User Plane Separation Protocol Requirements This section specifies some of the requirements that the CU separation protocol SHOULD support. 5.1. Transmit information tables The Control Plane and User Plane Separation Protocol MUST allow the CP to send tables to each User Plane device. a) The current BNG service requires that the UP should support at least 2000 users being accessed every second. And every user requires at least 2000 bytes. To achieve high performance, the CU Separation protocol SHOULD be lightweight. b) CU separation protocol should support XML/binary data which serves as the encoding format. It allows user information data be read, saved, and manipulated with tools specific to XML/binary. c) Furthermore, in order to provide centralized session management, high scalability for subscriber management capacity, and cost-efficient redundancy, batching ability should be involved. The CU Separation protocol should be able to group an ordered set of commands to a UP device. Each such group of commands SHOULD be sent to the UP in as few messages as possible. Furthermore, the protocol MUST support the ability to specify if a command group MUST have all-or-nothing semantics. 5.2. Scalability The CU Separation protocol SHOULD be able to supporting at least hundreds of UP devices and tens of thousands of ports. For example, the protocol field sizes corresponding to UP or port numbers SHALL be large enough to support the minimum required numbers. This requirement does not relate to the performance of the system as the number of UPs or ports in the system grows. Hu, et al. Expires April 29, 2018 [Page 7] Internet-Draft Requirements for CUSP October 2017 5.3. Message Priority The CU Separation protocol MUST provide a means to express the protocol message priorities. 5.4. Reliability In Network, a heartbeat is a periodic signal generated by hardware or software to indicate normal operation or to synchronize other parts of network system. In CU separation BNG, the heartbeat is sent between CP and UPs at a regular interval in the order of seconds. If the CP/UP does not receive a heartbeat for a time--usually a few heartbeat intervals-- the CP/UP that should have sent the heartbeat is assumed to have failed. The CU separation protocol should support some kind of heartbeat monitor mechanism. And this mechanism should have ability to distinguish whether the interruption is an actual failure. For example, in some scenarios (i.e. CP/UP update, etc), the connection between the UP and CP need to be interrupted. In this case, the interruption should not be reported. 5.5. Support for Secure Communication As mentioned above, CP may send some information tables to the UP which may critical to the functioning of a network (e.g, User Information, IPv4/IPv6 information) and may reflect the business relationships (e.g, QoS, service level agreements, etc). Therefore, it MUST be supported to ensure the integrity of all CU Separation protocol messages and protect against man-in-the-middle attacks. And the CP Separation protocol should support multiple security mechanisms to satisfy various scenarios. For example, when the special lines are implemented between the CP and UPs, the key chain SHOULD be supported. And if some VPNs are deployed between the CP and UPS, the TLS SHOULD be supported. In case of the CP and UPs cross several domains (i.e. cross third-party network), the IPsec SHOULD be supported. 5.6. Version negotiation The CU separation BNG may consist of different vendor's devices. Since different vendors' device may implement different version of protocol, therefore, the CU separation protocol should provide some mechanisms to perform the version negotiation. Hu, et al. Expires April 29, 2018 [Page 8] Internet-Draft Requirements for CUSP October 2017 The version negotiation is the process that the CU separation BNG's Control-Plane uses to evaluate the protocol versions that are supported by the control-plane and the user-plane devices, and select the protocol version it will use when communicating with the exchange user-plane devices. The process is a "negotiation" because it requires identifying the most recent protocol version that is supported by both the control-plane and the user-plane devices. 5.7. Capability Exchange The UP Capability Report displays the devices profile, service capability, and other assigned capabilities within the CU separation BNG. The CU separation protocol should provide some mechanism to exchange the UP device's capability 5.8. CP primary/backup capability A backup CP for disaster recovery is required for the CU separation BNG network. And the CUSP should provide some mechanism to implement the backup CP: a) In some scenarios, there are maybe two CP devices which declare that they are the primary CP. In this situation, the CUSP should support or associate with some mechanisms to determine which CP is the primary device. b) In the some scenarios the primary CP downs, the CUSP should support to switching between primary and backup CP. 5.9. Event Notification The CUSP protocol SHOULD be able to asynchronously notify the CP of events on the UP such as failures or change in available resources or capabilities. There are some scenarios may initiate the event notification: a) Sending response message: As mentioned above, the control plane solicits these users' information, associates them with available bandwidth, and based on the service's requirement to generate a set of tables. Then the control plane transmit these tables to the User planes. The UPs should respond with an event notification to inform the CP that the tables are received. b) User trace: The user trace mechanism can support the Control Plane to trace and monitor the network state for users (for example the real-time bandwidth, etc) , debug the user's application. Therefore, the UPs SHOULD be able to notify the CP with the User trace message. Hu, et al. Expires April 29, 2018 [Page 9] Internet-Draft Requirements for CUSP October 2017 c) Sending statistics parameters: In CU separation BNG, the User- plane will report the traffic statistics parameters to the Control-plane, such as the ingress packets, ingress bytes, egress packets, egress bytes, etc. These parameters can help to measurement the BNG network status. The Control-Plane can base on the statistics parameters to allocate available network resources. Therefore, the UPs SHOULD be able to notify the CP with statistics parameters. d) Report the result of User Detect: "User Detect" message will be send periodically to detect user dial-up and disconnect. The UPs SHOULD be able to notify the CP with the result of User Detect. 5.10. Query Statistics The CUSP protocol MUST provide a means for the CP to be able to query statistics (monitor performance) from the UP. 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, <https://www.rfc-editor.org/info/rfc2119>. Authors' Addresses Sujun Hu China Mobile 32 Xuanwumen West Ave, Xicheng District Beijing, Beijing 100053 China Email: shujun_hu@outlook.com Hu, et al. Expires April 29, 2018 [Page 10] Internet-Draft Requirements for CUSP October 2017 Lu Huang China Mobile 32 Xuanwumen West Ave, Xicheng District Beijing, Beijing 100053 China Email: hlisname@yahoo.com Rong Gu China Mobile 32 Xuanwumen West Ave, Xicheng District Beijing, Beijing 100053 China Email: gurong_cmcc@outlook.com Victor Lopez Telefonica Sur 3 building, 3rd floor, Ronda de la Comunicacion s/n Madrid 28050 Spain Email: victor.lopezalvarez@telefonica.com Jun Song Huawei 101 Software Avenue, Yuhua District Nanjing, Jiangsu 210012 China Email: song.jun@huawei.com Michael Wang Huawei 101 Software Avenue, Yuhua District Nanjing, Jiangsu 210012 China Email: wangzitao@huawei.com Hu, et al. Expires April 29, 2018 [Page 11]