Today, we gave a keynote presentation at the Open Networking Summit, where we shared details about Espresso, Google’s peering edge architecture—the latest offering in our Software Defined Networking (SDN) strategy. Espresso has been in production for over two years and routes 20 percent of our total traffic to the internet—and growing. It’s changing the way traffic is directed at the peering edge, delivering unprecedented scale, flexibility and efficiency.

We view our network as more than just a way to connect computers to one another. Building the right network infrastructure enables new application capabilities that simply would not otherwise be possible. This is especially powerful when the capability is exposed to higher level applications running in our datacenters.

For example, consider real-time voice search. Answering the question “What’s the latest news?” with Google Assistant requires a fast, low-latency connection from a user’s device to the edge of Google’s network, and from the edge of our network to one of our data centers. Once inside a data center, hundreds—or even thousands—of individual servers must consult vast amounts of data to score the mapping of an audio recording to possible phrases in one of many languages and dialects. The resulting phrase is then passed to another cluster to perform a web search, consulting a real-time index of internet content. The results are then gathered, scored and returned to the edge of Google’s network back to the end user.

Answering queries in real-time involves coordinating dozens of internet routers and thousands of computers across the globe, often in the space of less than a second! Further, the system must scale to a worldwide audience that generates thousands of queries every second.

Early on, we realized that the network we needed to support our services did not exist and could not be bought. Hence, over the past 10+ years, we set out to the fill in the required pieces in-house. Our fundamental design philosophy is that the network should be treated as a large-scale distributed system and leverage the same control infrastructure we developed for Google’s compute and storage systems.