Some enterprise customers may wonder why they need network virtualization (SDN) when they already have plenty of VLANs. They might further argue that once they put an application into production, that environment remains very static and, as such, agile policy-based virtual network management is not a solution that they need.
Here is the problem with this logic: Although enterprises have largely virtualized their application workloads to consolidate server resources, they still need to provision enough servers for a particular application’s peak usage. Repeated across many applications that make an enterprise run, this translates to an overall 30-40% server utilization rate. Clearly, this is far better than the 5-10% utilization rates before virtualization, but it is a far cry from the 80-90% potential that is required of a lean and efficient operations.
Stated another way, enterprise data centers are built around peak loads of individual applications instead of the peak load of the entire data center. If the data center infrastructure were nimble enough, such that the network infrastructure were virtualized and as fungible as compute resources, computation resources would quickly shift from hour to hour to respond to peak application usage while keeping the required network policies (QoS, security, compliance, etc.) in tact.
The chart above tells the story of three applications with varying CPU loads in a 24-hour period. In today’s data center design with a rigid network infrastructure, total data center capacity is the total of the peak capacity for all applications. However, the optimal capacity is for the peak data center load. In the example above, there is a 25% difference. In other words, 25% of the enterprise data center operational expense is wasted with excess, unneeded capacity imposed upon the business because the networks are not flexible enough.
In the old data center model, servers were isolated islands dutifully serving up applications in a relatively immutable environment for some four years. Inflexibility and waste were afterthoughts. Server virtualization began to change the game. It inspired the notion of cloud computing, which made far more flexible and efficient operations possible. Inside the enterprise, the promise of the cloud computing has hit the “last mile” network snag. Network virtualization through the proper use of SDN eliminates this “last mile” problem. The flexibility and efficiency of the enterprise private cloud are within reach.
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