Late-binding: how to lose fewer packets during handoff

Current networking stacks were designed for a single wired network interface. Today, it is common for a mobile device connect to many networks that come and go, and whose rates are constantly changing. Current network stacks behave poorly in this environment because they commit an outgoing packet to a particular interface too early, making it hard to back out when network conditions change. By default, Linux will drop over 1,000 packets when a mobile client associates to a new WiFi network. In this paper, we introduce the concept of "late-binding" packets to their outgoing interfaces. Prior to the binding point different flows are kept separate, to prevent unnecessarily delaying latency-sensitive traffic. After the binding point buffers are minimized---in our design, down to just two packets---to minimize loss when network conditions change. We designed and implemented a late-binding Linux networking stack that empirically demonstrates the value of our proposition in minimizing delay of latency-sensitive packets and packet loss when networks come and go.