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Two standard design approaches ( Multi-Tiered Design and Server Cluster Design ) are often used when designing a Data Center and are based on tried and proven design methodologies tested in some of the largest Data Centers Cisco has had the opportunity to work with . This prevents TCAM starving that can occur due to a denial of service attack or by enabling too many services concurrently . The media loves a horse race and if you can position yourself as the noble underdog it 's easy to get attention . Power-on self test ( POST ) and online diagnostics provide proactive health monitoring . Virtualization is being embraced on many fronts , and adoption of server virtualization is one such example that is high on the agenda of many Data Centers . Although each of these reasons is a valid reason for building out separate fabrics , doing so can become quite wasteful . The Multi-Tiered Design for the Data Center is the first of these design options and is geared to support a tiered approach to serving HTTP applications . This application-optimized approach to port deployment can reduce the number of switches and ISLs required in a storage network , in many cases eliminating the need for core-edge network topologies . " Many firms , particularly those that understand the game of capitalizing on bureaucratic ineptitude , hunt for customers who are weak but adequately funded . Many Data Centers run their switches for an indefinite period of time , so the inability to run boot-up diagnostics reduces the chance of detecting potential hardware issues that might otherwise arise .