Good post by Enrico Signoretti (thank you)
Bandwidth, throughput, and latency aren’t issues when you are within the boundaries of a data center, but things drastically change when you have to move data over a distance. Applications are designed to process data and provide results as fast as possible, because users and business processes now require instant access to resources of all kinds. This is not easy to accomplish when data is physically far from where it is needed.
Read on here (needs registration)