Understanding SD-WAN's Deployment Imperative
What enterprises need to consider before taking the software-defined plunge
Enterprise interest in software-defined WAN (SD-WAN) technology is blazing hot, with the technology enabling rapid evolution of legacy WANs and accommodating a cost-effective shift to cloud-based architectures by leveraging software-defined networking principles. Enterprises expect a huge uptick in service agility, an operational model that is extremely efficient and scalable, and bulletproof security that protects each application and its associated network resources.
But with most SD-WAN vendors claiming to provide all the same benefits to prospective enterprise customers, marketplace confusion is no surprise. In many cases, the final decision comes down to price, with enterprises disregarding critical considerations that, when overlooked, can have dire consequences on SD-WAN success. In the end, many enterprises fail to take into account their ability to integrate and deploy the solution flexibly and efficiently into an existing WAN environment even though this should be an essential decision criterion.
SD-WAN Deployment Considerations
IT professionals responsible for transforming their company's WAN to SD-WAN technology should consider various deployment options to assure they take the right approach.
Multi-cloud Deployment Flexibility
For one, IT needs to take current and future cloud strategies into consideration. For example, in order to support a UC-as-a-service (UCaaS) migration, the SD-WAN needs to extend to and integrate with the UCaaS point of presence. IT might also need to consider an infrastructure-as-a-service (IaaS) model for applications the company wants to continue managing but may not have the resources with which to accommodate their growth. For all of these reasons, the SD-WAN solution needs the deployment flexibility to support multiple public clouds and a multi-cloud deployment model.
Deployment Flexibility to Transform WAN Transport
IT needs to consider the following WAN deployment scenarios that the SD-WAN solution will need to seamlessly manage:
- Hybrid WAN -- The ability of a branch to leverage multiple underlay transport networks (e.g., IP/MPLS, Internet broadband, LTE) to carry traffic governed by a centralized policy defined to optimize the cost per bit transported
- LTE backup -- The ability to protect essential traffic on the IP/MPLS transport links by provisioning LTE backup transport for resiliency governed by a centralized policy
- Disjointed transport -- Since some branches are not homogeneously connected by the underlay transport network, the SD-WAN solution will need to support a specialized routing capability that will seamlessly connect disjointed underlay transport segments. For example, several remote branches may only be connected by Internet transport, but will need to communicate to some branches that are only connected through IP/MPLS.
Deployment Flexibility to Transform the Branch and Data Center
IT will have to select an SD-WAN solution that is flexible enough to support various deployment scenarios at the branch and data center:
- SDN and SD-WAN -- The current SDN vendor's support for an SD-WAN solution under the same management system should be another consideration, since seamless support for both SDN at the data center and SD-WAN at the branches would greatly simplify IT operations for years to come
- Physical and virtual options -- Some branches will require a vendor-branded SD-WAN physical device that offers a range of different bandwidth and port requirements. At other sites, the SD-WAN software will need to be deployed as a virtualized network function (VNF) on existing x86 servers
- LTE and Wi-Fi -- For the sites that deploy a physical SD-WAN device, support for Wi-Fi access and LTE uplink is essential
- Routing compatibility -- If the SD-WAN branch software doesn't provide a comprehensive and proven routing stack, there's a strong possibility that upon deployment existing customer routers would need to be reconfigured -- thus introducing increased risk, cost, and delay
- Brownfield deployment -- A small portion of the branches won't be migrated to SD-WAN and there'll be a continuation of "brownfield deployments" in certain countries. To meet these realities, the SD-WAN solution must be compatible with legacy deployments
Deployment Flexibility to Support Value-Added Services
IT should want a solution that supports multiple deployment options to support value-added services (VAS):
- Embedded -- Some services are best suited to be embedded within the SD-WAN function itself (e.g. NAT/PAT, DHCP, ACLs, IPS/IDS, URL filtering, etc.)
- Branch-in-a-box -- Multiple VNFs representing the services can be hosted on the physical SD-WAN device itself. This deployment model will reduce the physical, electrical, and cooling footprint required while simplifying the operational model and adding service agility
- Service chaining -- With this deployment model, VNFs representing the services can be deployed in the cloud and are dynamically attached to the SD-WAN network via service chaining rules. With this model, new functionality can be delivered from the cloud, simplifying the operational model while allowing for easy deployment of best-of-breed solutions
After taking the time to thoroughly examine the different deployment criteria required for the company's SD-WAN implementation, the path forward for IT should become clearer. All enterprises must engage in this exercise before migrating to a cloud environment. An SD-WAN solution built with deployment flexibility and support for open standards will help unleash the power of the cloud.
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