Traffic patterns are rapidly shifting from the traditional north-south client server model to an east-west server to server, said Jayshree Ullal, Arista president and CEO.
What that implies is a shift of data traffic. “We found that most of the server generated trafﬁc in
the cloud data centers stays within a rack, while the opposite is truefor campus data centers,” say Theophilus Benson and Aditya Akella of the University of Wisconsin–Madison and David A. Maltz of Microsoft Research–Redmond.
And make no mistake, traffic generated by cloud computing increasingly dominates the pattern of global wide area network, metro and data center traffic. Data center traffic, as measured by Cisco, includes data center-to-user traffic along with data center-to-data center traffic and traffic that remains within data centers.
Cisco’s latest Global Cloud Index estimates that global data center traffic will grow nearly 300 percent between 2013 and 2018.
By 2018, 76 percent of all data center traffic will come from the cloud, while 75 percent of data center workloads will be processed in the cloud.
But that might not even be the most significant prediction. Quantitatively, the impact of cloud computing on data center traffic is clear, Cisco argues.
Most Internet traffic has originated or terminated in a data center since 2008.
Where in the past most traffic (voice) functionally originated and terminate at a central office, though that traffic was passively transmitted to an end user telephone, now most global traffic originates and terminates at a data center.
And Cisco means that literally. Most traffic that ultimately traverses the WAN will follow communication within a data center between co-located servers.
The whole rest of the communications network essentially becomes a passive connection between an edge device requesting some operation, and the server that processes and serves up the result.
So in a meaningful sense, data centers are the central offices of the new network. As “switching” in the telco or mobile central offices might have been likened to the “brain” of voice operations, with the rest of the network the nervous system, so now data centers are the brains of the global network.
That will have any number of ramifications. The architecture of a voice network was build on the switching offices. Even the location of specific central offices was built on the amount of signal loss through a pair of copper wires connecting central offices with end user locations.
The architecture of new global networks is built on co-located servers inside data centers, and then connections between data centers over the wide area network, often with more traffic crossing the metro area than transiting the WAN, and then only traffic moving between a metro area data center and an end user location.
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.
The implications could not be clearer. By 2018, data center to end user traffic will constitute 17 percent of total. About nine percent of traffic will move from data center to data center. About 75 percent of global data center traffic will stay within the building, moving from server to server.
That explains the high interest by capacity providers in data centers. In the past, most of the revenue made by wide area network providers was supplying capacity across the wide area network.
In the future, it is likely much wide area network provider revenue will be made supporting data communications between servers and entities within data centers.
In other words, cloud data centers now are a major driver of WAN provider revenues. As potential owners of cloud data centers, WAN providers earn revenue by enabling data communications within the data centers, while also positioning to capture data center to data center revenues.