The Android IM app that brought T-Mobile's network to its knees
According to the carrier's filings with the FCC, close to a year ago an Android-based instant messaging application "caused an overload of T-Mobile's facilities for an entire city." Grant Castle, director of T-Mobile's national planning and performance engineering, described the event in detail in statement filed with the FCC in January.
"T-Mobile network service was temporarily degraded recently when an independent application developer released an Android-based instant messaging application that was designed to refresh its network connection with substantial frequency," Castle wrote in the filing. "The frequent refresh feature did not create problems during the testing the developer did via the WiFi to wireline broadband environment, but in the wireless environment, it caused severe overload in certain densely populated network nodes, because it massively increased signaling--especially once it became more popular and more T-Mobile users began downloading it to their smartphones. One study showed that network utilization of one device increased by 1,200 percent from this one application alone. These signaling problems not only caused network overload problems that affected all T-Mobile broadband users in the area; it also ended up forcing T-Mobile's UMTS radio vendors to re-evaluate the architecture of their Radio Network Controllers to address this never-before-seen signaling issue. Ultimately, this was solved in the short term by reaching out to the developer directly to work out a means of better coding the application."
A T-Mobile spokesperson was not immediately able to provide details on the incident, including when and where it happened and what application, developer and vendors were involved. T-Mobile introduced the G1, the world's first Android phone, in September 2008, and has since significantly expanded its line of Android gadgets.
T-Mobile's IM incident clearly highlights the difficulties wireless network operators face in this new world of smartphones, third-party content offerings and high-bandwidth applications like streaming video. Indeed, the event speaks to the heart of the net neutrality debate, in which proponents argue wireless carriers should treat all data equally. In his filing, Castle argued wireless carriers must prioritize data and manage applications via techniques including scheduling algorithms, channel selection and, possibly, dividing applications up by frequency.
"These techniques either exist today or are in the development or deployment stages, and they will ultimately become a key component of network management as more and more bandwidth-intensive and performance-sensitive applications are brought onto the shared network," Castle wrote. "They will need to be employed on a near-constant basis to manage the network load and fairly serve the different needs of different users, devices and applications. Without the flexibility to employ such measures, all users and all applications would suffer."
T-Mobile, in its January filing, also highlighted the strains already-managed G1 traffic put on its network. "G1 handset users consume over 300 MB per month--more than 50 times the data of the average T-Mobile customer," the company wrote. "More than 40 percent of T-Mobile myTouch users access social-networking sites multiple times per day. Over 30 percent of T-Mobile data traffic already consists of video streaming--a majority of which is attributable to Android users."
Perhaps most interestingly, T-Mobile wrote that its network has come under significant strain from Apple's (NASDAQ:AAPL) iPhone. AT&T Mobility (NYSE:T) is the exclusive provider of the iPhone, although users can "jailbreak" their devices and run them on the networks of other carriers. USA Today in 2009 reported--citing unnamed sources--that T-Mobile had 300,000 unlocked iPhones running on its network. In April of this year, T-Mobile disclosed in an FCC filing that "when subscribers began connecting unlocked iPhones to T-Mobile's network, the devices repeatedly issued PDP Context Activation requests to establish a session and obtain an IP address. These repeated requests began to cause signal overload akin to a denial of service attack, requiring immediate action and network management to mitigate the massive signaling load on T-Mobile's Packet Core network." T-Mobile argued the iPhone situation also pointed to the need for wireless carriers to retain tight control over their networks. (It's worth noting that T-Mobile isn't the only carrier to suffer from signaling problems.)
While the FCC's push for an "open Internet" is admirable, the imposition of strict net neutrality guidelines on wireless is difficult to support based on T-Mobile's arguments. Further, T-Mobile's difficulties on the Android application front also shed new light on the rigid guidelines Apple maintains on the iPhone App Store--and its intent to continue doing so. After all, all it takes is one rogue app to bring down an entire wireless network. --Mike