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What Today’s SDN Is Not Doing for Distributed Enterprises
The SDN industry is still evolving, but when considering virtual networking solutions, think beyond the data center
By: Dave Corley
Dec. 3, 2013 09:00 AM
Today's software-defined networking (SDN) and virtualized networking solutions focus on virtualizing network functionality within the data center and the metropolitan area network (MAN). But for typical enterprises, and those managed and cloud service providers that cater to them, these solutions are not optimized for local area network (LAN) and wide area network (WAN) edge environments within today's highly distributed infrastructures.
Where the Problem Resides
A 50-Site Distributed Enterprise Network
Each site's LAN provides access connectivity to a site's users and devices. The LAN, while a shared resource, is normally implemented through highly available, high-bandwidth layer 2 and layer 3 switches and wireless access points. Bandwidth into and out of the WAN edge is normally much more expensive and, therefore, constrained, requiring resource sharing and prioritization of the services delivered over the edge router. Each of the edge routers depicted in the diagram above is normally managed as an autonomous device, meaning that any other edge router has no awareness of the configuration of service state of every other router.
Today's legacy, hardware-based SDN approach for the distributed enterprises does not address the following requirements:
The problems that arise from not meeting these requirements boil down to higher costs and a lack of flexibility, agility and control required in today's dynamic distributed networking environments, including:
Comparative: Legacy Routed Network versus Distributed SDN
Significant Cost Savings from Distributed SDN
The virtual components in this approach are distributed among the various sites. A single virtual controller, with closely coupled virtual routing, firewall and tunneling functions, is hosted on a commodity server at a head-end facility. The data plane component, a virtual switch, is hosted on an inexpensive server at each site, inheriting layer 2/3 forwarding, routing, firewall, and tunneling functions from its parent virtual controller. A web-based lifecycle management application, running on a standard server in the enterprise headquarters, can provide authenticated access through a browser. To simplify management, it is best to have the management UI administer all workflows through an intuitive web-based GUI, rather a command-line interface (CLI).
This distributed SDN scenario realized an Opex savings of 10:1 in installation and provisioning costs and a 4:1 reduction in operations policy and management costs. Over 3 years, the average TCO savings in this environment was 4:1. These savings are realized through multiple efficiencies. All administration can be done through the GUI across the distributed enterprise, and not a CLI, with no need for on-site staff at each branch or more expensive expert support staff at the enterprise headquarters. In addition, more flexible SDN solutions can allow you to use either secure MPLS networks or less expensive end-to-end security with fully-meshed IPsec tunnels between sites.
SDN solutions that provide interoperability with legacy router components through routing protocols (e.g., OSPF/BGP/static/default) are important because they allow you to plan an at-your-pace, site-to-site infrastructure migration schedule. Also, SDN solutions to support this type of environment should have a full range of these automated features: policy-based end-to-end QoS, priority queuing, rate limiting, edge routing, and LAN features (including network address translation, port forwarding, and network access control).
Benefits to MSPs and CSPs Who Serve Enterprise Networks
The SDN industry is still evolving, but when considering virtual networking solutions, think beyond the data center - weigh both the short- and long-term costs and benefits behind deploying SDN in a real-world distributed enterprise environment.
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