The Cisco Global Cloud Index: Forecast and Methodology, 2010-2015 is chock full of data, projections and trends from the networking giant. Cisco describes the document as "an ongoing effort to forecast the growth of global data center and cloud-based IP traffic." The current version is 26 pages in length.
Among the projections within it is: "The year 2014 is expected to be a pivotal year - when workloads processed in cloud data centers (51 percent) will exceed those processed in traditional data centers (49 percent) for the first time." The report adds that, "we expect cloud-processed workloads to dominate at 57 percent by 2015."
The index defines a workload as "the amount of processing a server undertakes to execute an application and support a number of users interacting with the application."
Another fact of note from the index is that most data center traffic stays within the data center from which it originated, rather than flowing from one data center to another or flowing from a data center to end users through the Internet or IP wide area network.
"In 2010, 77 percent of traffic remains within the data center, and this will decline only slightly to 76 percent by 2015," the index says. (A chart from the index appears at the bottom of this page.) It cites the following three factors as primary contributors to traffic remaining within data centers.
- Functional separation of application servers and storage, which requires all replication and backup traffic to traverse the data center
- Functional separation of database and application servers, such that traffic is generated whenever an application reads from or writes to a central database
- Parallel processing, which divides tasks into multiple smaller tasks and sends them to multiple servers, contributing to internal data center traffic
According to Cisco, virtualization offsets video, thereby maintaining the high level of internal data center traffic. The index reports specifically: "The ratio of traffic exiting the data center to traffic remaining within the data center might be expected to increase over time, because video files are bandwidth-heavy and do not require database or processing traffic commensurate with their file size. However, the ongoing virtualization of data centers offsets this trend. Virtualization of storage, for example, increases traffic within the data center because virtualized storage is no longer local to a rack or server."
Image source: Cisco Global Cloud Index Forecast and Methodology, 2010-2015