Going Beyond SDN and NFV for WAN



altby Steve Woo

At the macro level, new innovations in wide area networking (WAN) are being triggered by at least four broad-based trends:

  1. 1. Migration of business-critical applications to the cloud (SaaS, PaaS, IaaS, etc.);
  2. Increase in the number and distribution of branch offices, the number of mobile workers, and the speed of deployment desired;
  3. Expectation by employees that they will have high-quality anywhere, anytime access to enterprise and cloud applications, with high bandwidth; and
  4. Concerns about security by IT administrators who are losing visibility and policy control over network traffic being routed over public broadband links.

Software-defined networking (SDN) and network functions virtualization (NFV) have been touted as new ways to address these macro trends. Although often used in conjunction with one another, SDN and NFV are not joined at the hip technologically; they can be applied independently. For the vast majority of enterprises, however, SDN and NFV—separately or together—are not sufficient to adequately address the trends pressuring today’s distributed enterprises.

At first, SDN was applied to the datacenter to improve flexibility and reduce costs in the datacenter network. The focus of SDN is to separate the control plane from the data plane, which provides cost-efficiency benefits—at least for very large installations. By using SDN approaches to replace large, expensive, intelligent switches with simpler L2 switches, online services providers can build their datacenters at one-third the cost of using non-SDN approaches.

NFV has also been focused primarily on the datacenter, but it is more narrowly of interest to those datacenters operated by service providers. The promise of NFV is greater agility in provisioning additional network services, such as network services, security, and routing. Today, NFV is primarily used to increase the flexibility of service delivery within service provider datacenters.

In general, then, the benefits of SDN and NFV remain far less meaningful outside the realms of datacenter networks operated by service providers and large online services providers.

Extending the concept of SDN and NFV to the enterprise WAN can benefit a far broader spectrum of mid-tier to large enterprises. SDN and NFV principles can reduce the cost and complexity of provisioning traditional networking gear both at the branch and in the datacenter of more typical enterprises. However, next-generation WAN designs should strive to incorporate but also go significantly beyond the application of SDN and NFV design principles.

Leveraging the Cloud for WAN Design
Driven by the key business demands toward mobility and migration to the cloud, next-generation WAN designs must leverage the cloud itself. In other words, the new WAN architecture will not only be software-defined and use virtualized services, but also be cloud-delivered.

This new WAN approach adds two important components:

1. The network must be deployed in the cloud as well as on premise, to support the migration to cloud datacenters and applications.

Along with the migration of applications to the cloud is the move toward migrating the entire datacenter to the cloud. How do you deploy a traditional WAN with cloud applications or cloud datacenter, if you no longer control your datacenter equipment? The answer is, you don’t deploy a traditional WAN. You deploy a different kind of WAN.

Trying to use traditional WANs with cloud datacenters requires backhauling application traffic via a private WAN to on-premise datacenter network equipment before forwarding it to the cloud datacenter. This backhauling extracts a significant performance penalty on the application traffic.

Some traditional WAN vendors have attempted to offer virtual-appliance versions of their datacenter network appliances, but this approach does not address the most difficult requirement of being able to locate the services in the optimal paths for many distributed cloud applications and datacenters. It also puts the burden on the enterprise to distribute the network widely throughout the cloud; if this is not done, the backhaul issue still exists. Finally, the use of virtual appliances does not address the upfront capital expenses, nor the complexity of deploying datacenter services. It’s not the same as true cloud service delivery.

A cloud-deployed network provides the right architecture to support direct access to cloud applications. In addition, it makes it easy to deploy network services. These benefits should also be extended to the branch by enabling branch-office WANs to use NFV principles to deploy virtual services.

Instead of delivering services individually via multiple fixed-function appliances, necessitating service-provider truck rolls and IT effort to install and provision services, virtual delivery benefits must be extended to multiple distributed branches within an enterprise. In this way, branch networks would gain the same agility that datacenter networks have enjoyed.

2. The WAN architecture must leverage broadband Internet access to support faster branch deployment, direct access to cloud applications, and dramatically improved economics.

Traditional WANs have relied on private lines such as T1 with MPLS services. When the goal is fast branch deployment, private links are a serious impediment. It can take two to six months to provision and deploy a new private line. Wired broadband takes much less time to deploy, and wireless broadband—crucial for supporting mobility—is the fastest to deploy.

Private circuits are best suited for on-premise datacenters, not cloud datacenters. Internet broadband links can provide direct access to cloud datacenters—but at a cost of losing IT visibility and control as well as predictable performance. Any next-generation WAN approach needs to enable the use of Internet broadband while retaining enterprise-grade performance, security, and IT control.

Toward a New WAN Design
In summary, WAN innovations are being pushed by changing expectations: Enterprise applications and datacenters are being migrated to the cloud. Enterprises expect to be able to set up and manage their branch-office networks quickly, easily, and affordably. The increasing number of branch-office and mobile workers expect the same high-bandwidth, low-latency network experience as they enjoy with their broadband connections at home. IT admins expect to be able to control WANs with the same enterprise-grade qualities as their headquarters networks.

Meeting these expectations is the role of a next-generation WAN. Key elements of such a WAN include:

  • Cloud network. Delivering network services from the cloud achieves flexibility and ease of deployment, as well as the massive scale and coverage of a cloud-based solution. It also puts the services into the right place, allowing for the most optimal direct access to cloud applications. An SDN architecture—enabling the control plane to manage the distributed cloud network—is an ideal complement to cloud-based deployment.
  • Enterprise-grade Internet. Branch offices are being held back by the expense, complexity, and lengthy provisioning times of private lines, yet moving WAN traffic to public links has meant loss of crucial security, control, and predictable performance. The answer is to make Internet links function with enterprise-grade quality.
  • Virtualized services. Branch offices need to be freed from the hassle and ongoing costs of gaining acc
    ess to vital networking services through fixed-use hardware boxes. Applying virtualized service agility to the branch premise as well as the headend services is important for meeting the needs and lean IT staffing of today’s increasingly distributed enterprises.

Steve Woo is the co-founder and vice president of products at VeloCloud.

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