Data Center Traffic Drives WAN Capacity, But Most Traffic is Inside the Building

Global Internet traffic volume forecasts historically have been tricky, and on occasion have been wildly too optimistic.

Forecasts also are complicated by the new reality that so much Internet traffic is exchanged inside data centers, and does not cross the wide area network. That has implications for any company investing in, operating or selling wide area network infrastructure and services.

A further complication is that “data center traffic” often includes both traffic that crosses wide area networks and traffic that is exchanged solely within a data center.

The fact of note is that traffic carried inside a data center exceeds global wide area network traffic volume. The implication is that forecasters will have to be careful when dealing with concepts such as “data center IP traffic.”

Some of that traffic will drive demand for local access, metro and long-haul capacity. Some will not.

The analogy is to today’s data networks, which include WAN and local access connections and revenue, as well as local area network data transfers (Wi-Fi, for example) that do not represent revenue for service providers.

And inside-the-data-center traffic is a huge deal.

By 2018, as much as 75 percent of all IP traffic will occur within data centers, and will not cross the WAN, about even with the 2013 estimate that 77 percent of total IP traffic actually remains within a data center, Cisco predicts.

Although the amount of global traffic crossing the Internet and IP WAN networks is projected to reach 1.6 ZB per year, by 2018, the amount of annual global data center traffic in 2013 is already estimated to be 3.1 ZB, and by 2018, will triple to reach 8.6 ZB per year, according to Cisco.

Traffic between data centers is growing faster than either traffic to end-users or traffic within the data center, though, and by 2018, traffic between data centers will account for almost nine percent of total data center traffic, up from nearly seven percent at the end of 2013.

The high growth of this segment is due to the increasing prevalence of content distribution networks, the proliferation of cloud services and the need to shuttle data between clouds, and the growing volume of data that needs to be replicated across data centers.

Over the next five years, the study projects data center traffic to nearly triple, with cloud representing 76 percent of total data center traffic.

In 2013, cloud accounted for 54 percent of total data center traffic. By 2018, cloud will account for 76 percent of total data center traffic.

(Data center traffic includes data center-to-user traffic along with data center-to-data center traffic and traffic that remains within data centers.)

The study predicts that global data center traffic will nearly triple from 2013 to 2018 with a combined annual growth rate of 23 percent.

A few clear observations can be made about what drives global Internet traffic. It has been clear for some time that content bits--especially entertainment video--is the primary driver of volume across global and access networks.

It has been clear for some time that consumer-facing Internet apps likewise drive traffic, not enterprise traffic.

Most Internet traffic has originated or terminated in a data center since 2008, according to Cisco.

Now there is one more assumption we can make: data center traffic will continue to dominate Internet traffic for the foreseeable future, and will be driven by cloud applications, services, and infrastructure.

By 2018 76 percent of data center traffic, will be cloud traffic, Cisco now says.

source: Cisco Global Cloud Index