Cloud Traffic Growing Fast Inside the Data Center

Cisco today announced their inaugural Global Cloud Index report, providing statistics and forecasts on both the current and future use of the cloud.

While Cisco has been predicting for years the growth of the network by way of their Visual Networking Index, the Cloud Index takes a look at traffic both inside and outside of the data center. Among the key forecasts from the new Cloud report is that overall data center IP traffic will grow between 2010 and 2015 at a compound annual growth rate of 33 percent. Overall traffic will grow from 1.1 Zettabytes in 2010 to 4.8 Zettabytes in 2015.

“The interesting part about the 4.8 Zettabyte figure is that it is higher than what we forecast in the Visual Networking Index for the network itself and this caught us by surprise,” Doug Webster, Sr. Director of SP Marketing at Cisco told “The vast majority of traffic is staying within the data center itself.”

Webster noted that approximately 76 percent of traffic stays within the data center as virtual machines migrate from one server to another. Data center to data center traffic is also on the rise, accounting for as much as 17 percent of total traffic.

Cisco analyst Shruti Jain added that many people don’t realize how much supplementary data is generated for different types of transactions. For example, Jain told that if you send a 1 MB email to four people, you’d expect to have used 5 MB of data. As it turns out according to Cisco’s findings, that transaction can generate as much as 30 MB of data due to all the storage, replication and backup that goes on.

Looking specifically at cloud traffic, according to Cisco, the cloud represents only 11 percent of data center traffic today. That number will grow to 34 percent by 2015. Overall cloud traffic is set to increase as well, growing from 130 Exabytes today to 1.6 Zettabytes in 2015.

In terms of defining the cloud, Cisco is using the NIST definition of cloud, which isn’t just about virtualization, but also includes the idea of elastic services that are billed on a usage basis.

“We’re aligning with a broader view than just saying that anything that is virtualized is cloud,” Jain said. “We’re not equating cloud to virtualization and we’re making sure we include things like usage based pricing.”

From a workload perspective, only 21 percent of workloads were cloud based in 2010. Cisco expects that number to grow to 51 percent by 2014. While cloud will represent the majority of workloads in 2014, it will not represent the majority of data center traffic.

“That is due to more efficiency on the cloud side,” Jain said. “Also there is the fact that some workloads are less traffic intensive to begin with.”

Sean Michael Kerner is a senior editor at, the news service of, the network for technology professionals. Follow him on Twitter @TechJournalist

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