I helped several customers design scale-out private or public cloud infrastructure. In every case, I tried to start with a reasonably small pod (based on what they’d consider acceptable loss unit – another great term I inherited from Chris Young), connected them to a shared L3 backbone (either within a data center or across multiple data centers), and then tried to address the inevitable desire for stretched layer-2 connectivity.

You’ll find a summary of these designs in my next ExpressExpress case study: Scale-Out Private Cloud Infrastructure, and if you need more details, I’m usually available for online consulting.