Internet-based content pouring through your pipes is certain to increase; the only question is by how much? And the answer is: to just under trillions of hours a year by 2015.

That according to Cisco, whose latest traffic forecast is contained in its inaugural Global Cloud Index. While Cisco does get to use the buzzword du jour in the title, it says this projection differs from its series of Visual Networking Indexes (VNI) in that it breaks out traffic patterns of specific interest to organizations that run cloud data centers.

That could include multichannel video programming distributors (MVPDs), content delivery networks (CDNs) and others running cloud services, such as Amazon, Apple and Google.

Concurrent with the increase in traffic moving through data centers, there is an evolution in the way data centers process not only data, but applications, more typically referred to as workloads. Originally, servers had one workload, Cisco explained. Today, traditional servers typically run 1.4 workloads, while the number of workloads per cloud server is 3.8. Cisco estimates that by 2015, cloud servers will be handling 7.8 workloads.

Cisco estimates that annual global data center IP traffic will reach 4.8 zettabytes by the end of 2015. Overall, data center IP traffic will grow at a compound annual growth rate (CAGR) of 33 percent from 2010 to 2015.

Cisco says 1.6 zettabytes is approximately equivalent to 22 trillion hours of streaming music, or 5 trillion hours of business Web conferencing with a webcam, or 1.6 trillion hours of online high-definition (HD) video streaming.

That said, the vast majority of data center traffic will remain within and among data centers – think of reading/writing to a database, or database backup.