Cisco Blogs

Networking Forecast: Cloudy with Increasing Zettabytes

November 29, 2011 - 2 Comments

With the onset of cloud, we’re being asked more and more by our customers about the architectural requirements that result from it.  While the customers have an instinct as to what’s needed, there seems to be less actual data to that effect than what they would like.  When confronted with a similar situation over 5 years ago about the network, we developed the Cisco Visual Networking Index which focuses on the amount of traffic carried across the network to the end user to help gauge the extent of infrastructure needed to support the data deluge.  Now with the network becoming inextricably linked to the data center and cloud, we realized we need to look at the other half of the equation as well to get a truly comprehensive architectural view.  To achieve this, we reviewed 30Tb of data each month, more than 45 million speed tests, analyst forecasts, and inputs from our customers.  The result?  The inaugural Cisco Global Cloud Index, released today.

Here are a few takeaways to consider:

  • Global data center traffic is estimated to grow four-fold to reaching a total of 4.8 zettabytes annually by 2015.
  • The vast majority of the traffic – 76% — surprisingly, doesn’t even hit the network but instead stays within the data center itself, as workloads are constantly being migrated to different virtual servers.
  • Of the total data center traffic, about 11%, or 130 exabytes of annual data center traffic in 2010 is considered part of the cloud  – however that amount is going to grow significantly in the next half decade, reaching more than a third of data center traffic, or 1.6 zettabytes annually, by 2015.

Cloud may be the concept-of-the-day for the industry, but with growth like that, it shouldn’t be discounted as a passing fad but rather a lasting trend whose impact will fundamentally affect network architectures going forward.

When both the network and data center/cloud are taken into effect, it is pretty amazing how our individual activities can add to the overall traffic load far more than we realize.  Here are a few examples:

  • If you send a web email 1 Mb in size to four people, what would the resulting traffic impact be?  4-5 Mb?  In actuality, it’s more like 50 Mb by the time you take into account the virtual machines migration impact in the data center, the data is replicated in another data center, etc.  Little things can add a lot.
  • Searching for gifts on  (Hypothetically as I did during lunch on Cyber Monday… Amazon Prime service rocks, btw) With their cloud infrastructure, a single search on their site could end up touching more than 100 servers or virtual machines to get a distributed and comprehensive search results page back to you in a blink of an eye… and resulting in much more of a traffic impact than just the text page you see.
  • What about the buying process… say of a cupcake?  Fortunately, our social media team put together a short and “sweet” video showing just that.

The Cisco Global Cloud Index has a lot more detail – from the extent of peak traffic loads should be factored into architectural requirements, to how much workloads will be supported by cloud vs. traditional data centers, even to the readiness of geographic regions to support cloud – which I’ll go into more details in future posts.  But in the interim, I encourage you to read all the detail here.

Just as we do with VNI, there is a paper discussing the results as well as our methodology, and even an infographic for the visual oriented ones out there, you know who you are… (just click on the image above)

I hope you find this data useful, look for more to come on this in the future, and thanks, as always, for following us on SP360.

In an effort to keep conversations fresh, Cisco Blogs closes comments after 60 days. Please visit the Cisco Blogs hub page for the latest content.


  1. With the number of people geometrically increasing online, will cloud computing ( with respect to Cisco) provide robust architecture that can withstand daily demand.

    I have been noticing usually behavior of websites of reputable companies and I paused to ask a question of networking platform/architecture.

    I think cloud servers should be given due attention in design and implementation.

    • Thanks for the comment. Cloud is certainly booming and we believe, yes, it absolutely will provide a robust enough architecture to withstand the future dramatic growth, assuming a couple of key requirements are met:
      Active deployment of the right kind of servers that are able to adopt a greater number of workloads, and arguably even more importantly,thorough integration of the cloud datacenter components and their servers with a network that understands the types of traffic that the cloud is attempting to delivery.

      Far too often, when people think of clouds, they only think of servers or data centers. Rather, we believe that those are inextricably linked to the network as a whole. This combination will great the Next Generation Internet that we believe will help make the network experiences that we all have on the network all the more visual, mobile, and on-demand with a quality level we would expect.