WTF? Locating Performance Problems in Home Networks
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Most users of home networks have experienced the intense frustration that comes with diagnosing poor performance. Even determining something as simple as whether a performance problem lies with the ISP or somewhere in the home network is incredibly difficult; this lack of visibility results in unnecessary service calls to ISPs and a general inability to have the network perform as well as it should. In this paper, we design and develop WTF (Where’s The Fault?), a system that reliably determines whether a performance problem lies with the user’s ISP or inside the home network. The tool can also distinguish these problematic situations from the benign case when the network is simply under-utilized. WTF uses cross-layer techniques to discover signatures of various pathologies. We implemented WTF in an off-the-shelf home router; evaluated the techniques in controlled lab experiments under a variety of operating conditions; validated it in real homes where we can directly observe the home conditions and network setup; and deployed it in 30 home networks across North America. The real-world deployment sheds light on common pathologies that occur in home networks. We find, for instance, that many users purchase fast access links but experience significant (and frequent) performance bottlenecks in their home wireless network.