For five years, researchers have toiled over an obscure bit of fundamental internet infrastructure that promises to make the connections to our mobile devices faster and more reliable than ever, and if you’ve already downloaded Apple’s iOS 7 to your iPhone or iPad, you could be using it already.
It’s called multi-path TCP, and here’s why it matters and how it works: At present, if your phone or tablet is connected to Wi-Fi and a cellular network at the same time, it can only use one or the other connection to transmit data. But what if your Wi-Fi connection or your 3G connection drops? Whatever data was being transmitted—data for an app, a webpage, an iMessage—will fail to arrive, and you have to try again, usually after getting a frustrating error message or a blank page. Just as importantly, if one of your connections to the internet slows down, or speeds up, your phone has no ability to use its other connections to its advantage, leading to a poorer and slower experience overall.
Multi-path TCP allows your phone to send data by whatever way it’s connected to the internet, whether that’s Wi-Fi, 3G or ethernet (say, if it were running on a laptop connected to the internet via a cable). And if you want to activate it, says one of the researchers who built multi-path TCP, you have only to use Apple’s voice command software, Siri.
This is the first time that this new means of connecting to the internet has appeared in a commercial product. That it showed up in Apple’s software and not Google’s shows that Apple’s technical chops are substantial, even when the company isn’t highlighting what it’s up to.
The ability to connect and maintain a continuous connection to the internet over multiple wired and wireless connections might sound like a nice-to-have feature rather than one that’s all that important, but there’s a reason researchers worked on this problem for five years before coming up with a standard that could be widely implemented: Multi-path TCP is the future. It’s arguably the first and most important change to the low-level architecture of the internet to reflect the fact that our connections to it are more mobile and wireless than ever.
In a September 2013 presentation (pdf) to the Australian Network Operations Group, computer scientist Mark Smith suggested that Multi-path TCP was the beginning of a larger change in how the internet is built, in which individual devices decide how they will communicate with one another, rather than simply relying on the protocols that have already been built into the computers that pass along all our traffic to and from the internet. Such a “dumb” network connected to “smart” hosts—the smart hosts being our phones, tablets and PCs—would allow for rapid experimentation and evolution of the fundamental language of the data devices are passing back and forth.
This will be especially important as the internet—and our airwaves—become ever more congested. Already, the protocol that handles most requests for web pages and data for apps, plain old TCP, is being crowded out on some networks by another, less well-behaved protocol designed to stream video and audio. In some ways, multi-path TCP is an effort to address this competition: If your phone sees that your Wi-Fi network is begin strained by that episode of Breaking Bad you’re streaming or pirating, it can switch to your 3G connection to maintain a reliable connection.
So far, the only way that Apple’s devices appear to be using this protocol is to communicate with Siri, which makes sense: Understanding speech is a difficult enough problem that Apple, like Google, probably sends recordings of our voice into the cloud, where powerful servers can parse our speech, rather than processing it on our relatively wimpy mobile devices. For an application like this, speed is of the essence, and having as many paths to get data to and from Apple’s servers is critical.