Cisco Advanced Services has been involved in quite a few Data Center Migration projects over last couple of years. One common theme in most of these migrations was that the projects were never limited to infrastructure migration to shiny new devices. Statements of work almost always included improvements and customization to routing, configuration of QoS across the Data Center Interconnect and the WAN circuits, and to provide some level of instrumentation to validate the traffic flow across multiple different paths. While these requirements seem like a logical extension of any Data Center migration project, fulfilling these requirements was never straightforward.
In most of the customer environments, by looking at the Network topology, we could easily determine safe upper limits of client to server traffic. The real challenge was to determine traffic between the web front-end servers and the application and/or database servers – the east/west traffic. Some wild assumptions were made in some cases since the data was either not available or was inadequate. This lack of network traffic profiling made QoS provisioning very difficult on WAN circuits and almost impossible on the Inter Data Center links.