In the inaugural Cisco Global Cloud Index, Cisco estimates global cloud computing traffic will grow 12-fold from 130 exabytes to reach a total of 1.6 zettabytes annually by 2015, a 66 percent compound annual growth rate (CAGR. One zettabyte is equal to a sextillion bytes or a trillion gigabytes―1.6 zettabytes is approximately equivalent to:

Cloud is the fastest growing component of data center traffic, which itself will grow 4-fold at a 33 percent CAGR to reach 4.8 zettabytes annually by 2015. Cloud is also estimated today to be 11 percent of data center traffic, growing to more than 33 percent of the total by 2015. Cloud is becoming a critical element for the future of information technology (IT) and delivery of video and content.

The vast majority of the data center traffic is not caused by end users but by the data centers and clouds themselves undertaking activities that are largely non-transparent to end users – like backup and replication. By 2015, 76 percent of data center traffic will remain within the data center itself as workloads migrate between various virtual machines and background tasks take place, 17 percent of the total traffic leaves the data center to be delivered to the end user, while an additional 7 percent of total traffic is generated between data centers through activities such as cloud-bursting, data replication and updates.

The transition to cloud services is driving global cloud traffic at a growth rate that is twice as great as global data center traffic. Global data center traffic will grow fourfold (a 33 percent CAGR) from 2010 to 2015, while global cloud traffic will grow 12-fold (a 66 percent CAGR) over the same period.

Cloud data centers offer better performance, higher utilization and greater ease of management than traditional data centers. Virtualization serves as a major catalyst in enabling hardware and software consolidation, greater automation and an integrated security approach.

Data center traffic is forecast to more than quadruple from 1.1 zettabytes in 2010 to 4.8 zettabytes annually in 2015, representing a 33 percent CAGR.

Data center traffic sources: Most stays within the data center itself Of the data center traffic in 2015, 76 percent stays within the data center itself, through such activities as storage and authentication across virtual machines.

Due predominately to the rise in video-based consumer services, data-center-to-user traffic has some significant peaks in activity. Much like prime time viewing hours, average amount of data center traffic per hour during peak periods is expected to rise up to 2.5 times, requiring the need to plan for additional capacity from data centers and the cloud as well as from the network. The on-demand model of cloud is perfectly suited to serve this type of variable demand.

2014 is the first year where the balance of workloads shifts toward the cloud for the first time – 51 percent of total workloads will be in a cloud environment versus 49 percent in the traditional IT space.
Overall, the data center workload from 2010 – 2015 is growing 2.7-fold; however, the cloud workload from 2010 – 2015 is growing more than 7-fold over the forecast period.

"Cloud and data center traffic is exploding, driven by user demand to access volumes of content on the devices of their choice. The result: greater data center virtualization and relevance of the network for cloud applications and the need to make sense of a dynamically evolving situation. The Cisco Global Cloud Index provides insight into this traffic growth and trends so that organizations can make strategic long-term decisions. We will continue to develop and release the Cisco Global Cloud Index on a regular and ongoing annual basis, contributing to ‘cloud readiness' efforts worldwide," says Suraj Shetty, vice president of product and solutions marketing, Cisco