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Introduction to Cisco Software-Defined Wide Area Networking (SD-WAN)

Chapter Description

In this sample chapter from Cisco Software-Defined Wide Area Networks: Designing, Deploying and Securing Your Next Generation WAN with Cisco SD-WAN, you will explore the technologies and challenges of today’s networks, the benefits and drivers of Cisco SD-WAN, high-level design considerations, building an ROI to identify cost savings, and more.

Common Desired Benefits

This section of this chapter will cover some of the most common benefits that businesses are looking for from their network and WAN. Designing and deploying the next-generation WAN is about taking advantage of some very useful benefits and the impact they have on the network environment and overall user experience. Here is each of the benefits we will discuss:

  • Prioritize and secure traffic with granular control

  • Reduce costs and lower operational complexity

  • Augment or replace premium WAN bandwidth

  • Provide a consistent, high-quality user experience

  • Offload guest and public cloud traffic

  • Ensure remote site uptime

Oftentimes businesses want to augment or replace premium bandwidth services and move from active/standby WAN transport models to active/active models. This alone will help them to reduce costs. However, the challenge becomes that augmentation of services can increase operational complexity. Complexity is something that must be avoided as businesses look to simplify IT and create a consistent operational model. Ensuring remote site uptime to support business continuity is about more than simply protecting against blackout situations. Critical applications that are impacted by conditions such as latency, jitter, and loss can ultimately render the applications unusable. This is analogous to the applications being completely unavailable. These are called brownouts. Providing a consistent high-quality application experience is top of mind for most businesses today. Because not all applications are created equal, each organization or department might have its own applications that are critical to it and are required to support its business. Voice and video, for example, may be the most critical applications for one business, such as a contact center. However, in the retail vertical, the point of sales (PoS) system or online marketplace may be more critical. It comes down to the level of importance each application plays within a specific organization. Businesses demand the flexibility and power to prioritize applications with granular control. There is a shift to take back control and not have to rely on the service provider for making changes and for ensuring connectivity. This goes beyond typical routing or QoS and extends into application experience and availability. Many businesses are still not comfortable with the Internet edge moving into their remote site edge. This is necessary to more effectively support the rollout of public cloud applications such as Software as a Service (SaaS) and productivity applications. This is also needed for more optimized access to Infrastructure as a Service (IaaS). However, many businesses are interested in offloading guest traffic to directly attached Internet connectivity in remote branches. This is because it is better to offload this traffic locally rather than consume WAN bandwidth by routing it through a centralized data center for Internet services. This is not efficient and wastes expensive WAN bandwidth.

Networks of today cannot scale at the speed necessary to address the changing needs that the businesses require. Hardware-centric networks are traditionally more expensive and have fixed capacity. They are also more difficult to support due to the box-by-box configurations approach, siloed management tools, and lack of automated provisioning. Conflicting policies between domains and different configurations between services make them inflexible, static, expensive, and cumbersome to maintain. This leads to the network being more prone to misconfigurations and security vulnerabilities. It is important to shift from a connectivity-centric architecture to an application- or service-centric infrastructure that focuses on user experience and simplicity. Figure 1-2 shows the key factors affecting critical service level agreements (SLAs) that can disrupt business continuity.

FIGURE 1.2

FIGURE 1.2 Issues That Impact Critical SLAs

The solution required to support today’s cloud-enabled enterprise needs to be complete and comprehensive. It should be based on the software-defined approach mentioned earlier by leveraging the controller concept. The solution must also include a robust set of capabilities that reduce cost and complexity as well as promote business continuity and rapid innovation. These capabilities should include the separation of the management plane, control plane, and data plane. This will provide more horizontal scaling capabilities and the security of knowing where the data is at all times.

It should provide various consumption models, such as being hosted in the cloud or being managed on-premises, with complete redundancy between the two. The solution must also provide a complete set of network visibility and troubleshooting tools that are all accessible from a single place. Having this type of solution would assist in providing the following business outcomes and use cases:

  • Faster branch deployment with no operational interaction

  • Complete end-to-end network segmentation for enhanced security and privacy

  • Increased WAN performance

  • Topology independence

  • Better user experience

All of the things mentioned thus far are critical in terms of what businesses are demanding to drive their network into becoming an asset that truly sets them apart from their industry peers. Many organizations rely on the network to function at its best to provide value and competitive differentiation so their businesses can excel. This is what is driving the industry to these types of technologies. This is also why the industry has increased the speed of adoption and deployment of these solutions.

4. High-Level Design Considerations | Next Section Previous Section

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