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SDN: Driving Cloud Networks

By Yin Yuanbin, SDN Controller Solutions Architect, Network Product Line, Huawei Technologies Co., Ltd.

As our society becomes ever more information driven, there is a general trend toward digital transformation in all sectors and convergence across industries. The next five to ten years is a critical period for the digital transformation of traditional industries that are compelled to promote service innovation and growth. It is very clear that traditional network architectures are no longer able to support the development of contemporary services. The creation of agile, intelligent, and open cloud networks is essential to meet the requirements of the intelligent digital industries of the immediate future — and Software-Defined Networking (SDN) is the key to implementing the cloud networks needed for industrial growth.

Agile, Intelligent Open Networks

Traditional networks use a distributed architecture in which each network device has an independent on-board control plane. In other words, there is no centralized controller on a legacy network. Administrators provisioned network services through the command-line interface or a network management system that communicated with each device individually. With the advent of SDN technology, based on off-board, networked control, it is evident that traditional network architectures are no longer able to satisfy today’s requirements for the rapid deployment of new services for the Internet and cloud computing. It is simply not possible for a traditional architecture to keep up with the rates of development expected by enterprises and telecommunication carriers. A truth of the modern age is that both carriers and enterprises require SDNs that are agile, intelligent, and open.

  • Agility: Networks must be able to integrate and provision new services to shorten the time-to-market for launch. For example, in the past it would take months for a carrier to provision a leased-line service to an enterprise site. Deployment times are now reduced to hours and sometimes even minutes. Providers of public cloud services must offer fast, on-demand provisioning of many types of cloud services to remain competitive and accommodate customer requirements.
  • Intelligence: Flexible scheduling must be implemented network-wide to enable intelligent planning, provisioning, resource scheduling, and Operations and Maintenance (O&M) without the need for manual interaction. For example, carriers must increase bandwidth utilization on network links to reduce costs; and enterprises must be able to configure and modify user security policies for mobile office scenarios in real time, based on changes to user locations and roles.
  • Openness: Networks must have fully open capabilities and provide programming interfaces so that network applications can be quickly updated to match the latest service requirements. This is necessary to support rapid service innovations. For example, carriers must update their service packages based on customer preferences and competitive offerings; these can include bandwidth or traffic-priority modifications within a service package.
  • Basic SDN architecture

    A new network architecture was needed to meet the needs of agile, intelligent open networks and SDN is the best choice currently accepted by the ICT industry. SDN architectures include five components (from upper level to lower): SDN network applications, northbound interface, SDN controller, southbound interface, and the SDN data plane for packet switching.

    The SDN architecture is divided into three layers: application, control, and forwarding. The core of the architecture is the control plane where the controller is the ‘brain’ of the network. The controller provides many levels of programmable capabilities to network applications. In addition, the controller converts the network services received from the upper layers into terms understandable by network devices.

    Through southbound interfaces, the controller unifies the configuration, management, and control of the SDN data plane and provides the services requested by network applications. When required by services, the application layer invokes the northbound interface of the controller, and through the southbound interface, configures the data plane to fulfill the assigned service functions. The forwarding layer is populated with the actual network devices that carry out the configuration instructions for routes and flow tables as delivered by the controller through its southbound interfaces. An expansive future is ahead for industry, as there are multitudes of SDN applications that will be developed to meet specific, customized service requirements.

    Use Case 1: Cloud Data Center Networks

    SDN was originally developed and brought into commercial use for Data Center Networks (DCNs). Data centers consist of storage, computing, and network resources. The network resources enable interconnection among computing and storage resources, and the Internet. With the rapid development of cloud services and mobile applications, data center servers have become massive in scale and, as a result, much more difficult to operate and maintain. Most critically for the business prospects of all stakeholders, data centers must support the rapid deployment of new, innovative services; for example, cloud data centers must be able to deploy new tenant networks within several minutes.

    To solve such challenges, DCNs must offer management and O&M capabilities that are agile, open, and centralized. SDN technology has been designed to provide exactly these capabilities. In particular, the Huawei CloudFabric solution has been developed specifically to enable SDN-based data center networks. The Huawei solution offers the following benefits:

  • Agility: Tenant networks can be automatically provisioned, and tenants can orchestrate their own value-added services.
  • Intelligence: Service, logical, and physical network topologies are automatically interconnected. The service paths between Virtual Machines (VMs) are automatically detected; access switches and interfaces are automatically found based on the IP and MAC addresses of VMs.
  • Openness: VMware vCenter, Microsoft System Center, and other major cloud platforms are supported. An interoperability framework for third-party value-added services provides quick interconnection.
  • These capabilities help CloudFabric-based data center networks accommodate the future development of many varied services.

    Use Case 2: Enterprise Network Interconnections

    Traditionally, interconnections between the branch offices of an enterprise relied on dedicated network devices on enterprise premises and leased-lines provided by carriers. One downside is that leased-line services were and remain expensive, and enterprises constantly need to add interconnect bandwidth to guarantee application performance. These factors resulted in enterprises incurring high interconnection costs. The rise of cloud computing and mobile office capabilities has brought major changes to enterprise application deployment, including the gradual migration of applications to public clouds and the introduction of an increasing number of Software-as-a-Service applications. The result is that the requirements for enterprise network connectivity have become exceedingly complex. Traditional passive interconnections cannot meet the dynamic needs of enterprise applications because old school deployment methods rely on skilled network engineers who need too much time to complete their assignments.

    The Huawei CloudEPN solution uses SDN to alleviate these problems. The SD-WAN controller interfaces with Customer Premises Equipment (CPEs) at the enterprise egress and offers the following:

  • Agility: CPE plug-and-play is supported, including email, USB, and DHCP. Network connections among branch offices, or between branch offices and headquarters can be automatically provisioned. Full-mesh and star topologies are supported, and enterprises can provision new branch office connections in real time. In addition, all enterprise gateways are operated, managed, and maintained by the controller.
  • Intelligence: Paths can be selected automatically based on quality requirements by application and the actual quality of the link. Services are provided over the most economical paths possible.
  • Openness: The controller has open northbound interfaces to interconnect with customer service systems.
  • The CloudEPN SD-WAN solution has the following advantages over traditional offerings:

  • On-demand service provisioning: The CloudEPN controller provides value-added services as well as common network connection services. The controller enables the real-time provisioning of enterprise services, including node addition, public cloud access, firewalls, and anti-Distributed Denial of Services (anti-DDoS) security protection.
  • Reduces enterprise cost: The CloudEPN controller can automatically select connections that meet the quality requirements of applications, and therefore provide services through the most cost-efficient connections possible. In addition, the SD-WAN controller allows the centralized management of WAN edge devices, which reduces O&M costs.
  • Working toward Intelligent Networks

    Since inception, the goals of SDN have been to make networks more agile, intelligent, and open — the very characteristics that are most essential to cloud networks. Huawei uses SDN to create cloud solutions such as CloudFabric, CloudEPN, and CloudCampus, and will continue to innovate DCNs by focusing on real-world customer scenarios. Huawei is committed to perfecting its SDN-based solutions, advancing network cloudification, and providing its customers with agile and efficient open networks.

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