Carrier-Grade vBRAS: Key to the Cloud MAN

By Chen Chixin, ZTE Corporation

In 2017, the wait-and-see period of NFV of the telecommunications industry comes to an end. NFV is substantively introduced. As the preferred scenario for the NFV transformation of fixed network services, the vBRAS separates the control plane from the forwarding plane to remedy the defects of traditional BRAS equipment, including the uneven resource usage, long deployment period of new services and heavy workload of decentralized configurations and O&M. Laboratory proof of concept is finished and the MAN is ready to stand up to live service operation. The network service is one of the most basic services of the information society. Carrier networks provide services for individuals, governments and enterprises. As a gateway to a variety of MAN services, the vBRAS should have “carrier-grade” operation capabilities.

Meeting the Needs for Large Scale, High Bandwidth and Strong Expansion of Carrier Networks

• A vBRAS instance can support the access of millions of users. The dial-up Internet access rate can be higher than 10 kb/s.
• The forwarding plane meets the high-bandwidth requirements for the large-scale deployment of MAN FE/GE optical bandwidth services and 4K-dominated IPTV services.
• With the fully distributed architecture, dynamic scale-in and scale-out can be achieved automatically in accordance with the defined scaling policy.

Providing Service-Level High Reliability and High Availability

• At present, if the VM corresponding to the vBRAS fails and the VM live migration technology is adopted, the switching rate cannot guarantee the continuity of services or meet the carrier-grade reliability requirement. Therefore, the reliability of the vBRAS is mainly guaranteed through the redundancy of NEs. You can split the control plane functions of the vBRAS into different components deployed on different VMs to achieve the redundancy of all the functional components in a vBRAS instance. In addition, multi-instance inter-site vBRAS backup is supported to maximize service-level reliability.
• When a MAN carries a variety of services, the services can still operate stably, and the packet loss rate can reach the carrier-grade standard (10^(-6)) defined by operators.

Carrying All Types of Services of the MAN

• Provides PPPoE, IPoE, and IPTV multicast, covering the home triple-play service and personal Wi-Fi service.
• Provides IP Host, L2/L3 VPN, and L2TP access, covering the government and enterprise dedicated Internet access and VPN services.
• Powerful CGN function and perfect CGN protection solution, ensuring the development and reliability of the private network IPv4 service.
• High-performance QoS/H-QoS capability, assisting in the elaborate operation and traffic operation of fixed network broadband services.

Smooth Network Evolution Protects Existing Assets

• Most operators have completed MAN flattening. The level-2 network architecture significantly enhances network efficiency. The vBRAS should be deployed based on the existing MAN architecture, and should be able to seamlessly evolve into the future network after CO re-architecting.
• The traditional BRAS equipment in the existing networks achieves high-performance forwarding based on hardware NP. Pure X86 forwarding cannot reach this forwarding performance at the current stage. For operators’ investment, the existing network equipment must be fully used to introduce the new vBRAS technology to protect existing assets.

Standard Interfaces and More Open Network Capabilities

• In most cases, a carrier network involves multiple vendors and multiple domains. The provisioning and management of end-to-end services requires the collaboration of multi-vendor NEs. The vBRAS should be able to provide standardized and open northbound interfaces to achieve the orchestration, collaboration, and control of end-to-end network resources and services.
• Through open network capabilities and based on the cooperation with third-party application platforms, functions can be used flexibly and users can customize networks and services as required. This propels broadband service innovation.

ZTE has been working in the carrier MAN field for many years. With a deep understanding of the status and development of MANs, ZTE has put forward a carrier-grade vBRAS product solution for carrier networks in 2016. Based on the core idea of SDN and NFV, this solution achieves control and forwarding separation through SDN, and achieves control plane software and hardware decoupling through NFV. This solution not only has the advantages of SDN and NFV technologies, but also meets all the above “carrier-grade” needs. ZTE’s vBRAS focuses on the needs of carrier networks. The control plane (vBRAS-C) achieves software virtualization for service control. The forwarding plane (vBRAS-U) provides two forwarding pools: NP-based high-performance forwarding pool and common X86–based pure virtual forwarding pool. These two forwarding pools use a unified vBRAS control plane. This can coordinate networking to achieve the collaboration and optimization of services and resources. The high-performance forwarding pool provides a Tbit-level forwarding capability and can easily achieve a packet loss rate lower than 10^(-7) in environments where complex services are provided. Big video services hold no fear for this pool and it can carry high-bandwidth services and services that require high-QoS (such as HSI, IPTV, and OTT). The X86 forwarding pool can be used to carry low-bandwidth and low-QoS services (such as TR069, VOIP, and WLAN) to help share user sessions and reduce the flow table overhead of the high-performance forwarding pool. In addition, the existing traditional BRAS equipment can be used as the high-performance forwarding pool through software upgrade. This can fully protect operators’ original assets.

Over the past year, ZTE has actively participated in the vBRAS tests and pilot verification of major carriers. ZTE entered into in-depth partnerships with carriers, third-party applications and platform vendors, and they explored together the development and evolution of the vBRAS technology in order to promote the standardization process of the NFV industry.

• ZTE is the industry’s first manufacturer who has completed the vBRAS technical verification test of the C/U separation architecture in the laboratories of China Mobile and China Telecom, and then ZTE has completed pilot verification in China Mobile’s and China Telecom’s existing networks in a number of provinces.
• ZTE, together with China Mobile Research Institute and other manufacturers in the industry, developed CCSA industry standards for the forwarding-control separation vBRAS technology, and specified detailed technical specifications and test specifications for equipment, promoting the industry standardization of the vBRAS
• In the first global open source project Open-O led by China, ZTE’s vBRAS and vCPE products provide home scenario solutions based on third-party platforms, helping complete the first release of the “SUN”.

ZTE is deeply concerned about the characteristics of carrier networks and services, and launched the innovative carrier-grade vBRAS product solution. In addition to all the advantages of the NFV technology, the product can overcome the performance weaknesses of the X86 and meet the high concurrent sessions, high bandwidth, high reliability, and high efficiency requirements for carrier-level operation, helping build intelligent, agile, and elastic next-generation cloud MANs.