Table of Contents
On September 17, 2014, AT&T announced its Network on Demand offering that will allow its business customers to order, add, and change network services on-demand, via a self-service portal. The offering uses software defined networking (SDN) technology architecture to simplify provisioning of services and ports, and to enable enterprises to procure bandwidth in a flexible manner.
AT&T’s announcement is the result of a proof of concept project that the company has been operating at University of Texas, in Austin, Texas. The company plans a commercial rollout of the capability over AT&T’s switched Ethernet services, to businesses in Austin, TX by end of 2014. Future deployments will include rollout of Network on Demand-enabled services in additional markets; as well as with additional wide area networking (WAN) technologies, such as Internet services and multiprotocol label switching virtual private network (MPLS VPN) services, along with Ethernet. The capability will also be extended to business services such as Business Voice over IP (BVoIP), network-based firewalls, and distributed denial of service (DDoS).
SDN has seen some traction in data center transformation use cases, largely owing to virtualization and cloud computing, but the technology architecture is new to service provider networks. With the introduction of AT&T’s Network on Demand offering, SDN could be finally getting its due in the service provider network.
In this SPIE, we evaluate the SDN reference architecture and its significance in communication service provider (CSP) networks. We take a close look at AT&T’s SDN-based Network on Demand offering and the value it provides to the company and to the market.
What is SDN?
SDN is a technology architecture that decouples the network control from the forwarding functions of the physical infrastructure. In an SDN architecture, a controller determines how packets are forwarded by networking elements, separating the control and data planes within switches and routers. SDN technology does for network services what virtual machines (VM) do for servers—it enables physical network resources to be pooled together and consumed on-demand.
As shown in Figure 1, below, the infrastructure layer (data plane) comprises network elements, which expose their capabilities toward the control layer (controller plane) via interfaces southbound from the controller. The applications exist in the application layer (plane), and communicate their network requirements toward the controller plane via northbound interfaces. In the middle, the SDN controller translates the applications’ requirements, and exerts low-level control over the network elements, while providing relevant information up to the applications. An SDN controller may orchestrate competing application demands for limited network resources, according to policy.
OpenFlow, a protocol that became an industry standard in 2011, is the primary southbound interface between the control and infrastructure layers. Along with new protocols in development, OpenFlow is designed to facilitate open communication between different vendor devices, the rest of the network, and third-party applications. The application layer is home to legacy Operations Support Systems (OSS) and Business Support Systems (BSS), other network and business applications, and the orchestration function.
Network Function Virtualization, or NFV, is a related network architecture that proposes virtualization technology to networks. The aim of NFV is to replace the multitude of proprietary network elements—hardware-based switches and routers usually contained within a CSP network—with industry standard, centrally managed commodity-based servers. In the network, NFV allows routers, switches, firewalls, load balancers, content delivery systems, end-user devices, IMS nodes, and almost any other network function to be run as software on virtual machines—ultimately, on shared servers, using shared storage.
While SDN and NFV are complementary and mutually beneficial, they are not inter-dependent. SDN can improve NFV performance (simplify compatibility, ease operations); NFV enhances SDN via virtualization, IT orchestration and management techniques. Stratecast uses the term “Virtual Network” as the ideal combined future network comprised of elements from both NFV and SDN. Although we agree with the industry consensus that NFV and SDN are not inextricably linked at this stage in their development, Stratecast believes that the long-term and best use of these technology architectures is as complements to each other.2
Why is SDN Important for Service Providers?
Networks are the crux of everything that CSPs do. The physical network infrastructure is the underlying infrastructure on top of which CSPs layer all the services and solutions they provide to their customers—enterprises, consumers, cloud service providers and wholesale channels. CSP networks are highly dependent on hardware from multiple vendors, and are static by nature; thus making it challenging for CSPs to provision services to existing customers, and roll out new solutions. Any change to the network takes weeks or even months—to add and configure new switches and routers, define a service offering, establish the appropriate pricing strategies, ensure performance, and apply consistent management policies across the board.
The “slow to define a new service configuration” nature of the network elements and nodes, which define a physical network, was successful in the past when enterprises’ network traffic (predominantly voice and data) patterns were predictable, and a need for change in bandwidth requirements occurred at a much slower rate. However, the current enterprise WAN architecture is predominantly IP/MPLS based, with voice, data and video traffic running across this converged network. In a highly IP-centric world, not only does the bandwidth requirement vary based on the application that corporate users are trying to run; but those applications are increasingly accessed via mobile devices—making it challenging for the network managers to ensure availability and reliability of network resources.
Increased adoption of cloud computing (data center resources) among enterprises is another key factor expected to drive CSP deployment of SDN and NFV technology architectures. The servers in data centers are now virtualized to increase utilization rates and achieve cost efficiencies; and customers can procure storage and computing resources in a utility-based consumption model. However, network services continue to be sold in a fixed model, due to the limiting nature of the physical network architecture. For CSPs to take advantage of the growth coming from cloud networking, their networks need to be capable of changing in real time, in order to be more cloud-centric for satisfying enterprise customer demand for dynamic bandwidth capacity.
SDN can enable network resource management to be automated by separation of the control functions from the actual data plane or the infrastructure elements, to provision network resources and services based on traffic patterns and customer requirements. APIs are used to query the available network resources, and allocate them as demanded by the application.
Get Industry Insights. Simply.
Talk to Ahmad
+1 718 618 4302
“The increasing need for simplified network architecture and enhanced security is expected to drive the growth of the software-defined everything and networking technologies” The top 10 Software-Defined ...
"CSPs are focusing on WAN SDN in a bid to deliver new revenue and reduce opex, which is unleashing a ‘land grab’ among vendors that want to take a share of this emerging and lucrative market." This ...
Software defined networking (SDN) is the organization of network services by lower level functionality abstraction and is a major shift in network architecture paving way for unified communications and ...