Measuring and extending multipath TCP

Tran, Viet Hoang [UCL]

TCP has been one of the most important Internet protocols since the early days of this network. The initial version of TCP assumed that (1) each device has a single interface, and (2) its network address is permanent. Today's Internet attached devices have multiple interfaces with dynamic addresses. These deployments do not match anymore the design principles of TCP. By decoupling the transport layer from the underneath IP layer, Multipath TCP brings several key benefits in a variety of use cases. However, this major TCP extension is also significantly more complex than the legacy TCP. Despite growing interests in Multipath TCP, there are still many unknowns about its behaviours and performance in the real world. Moreover, most Multipath TCP implementations are based on existing TCP stacks which are part of operating systems kernels. Therefore, it is challenging to build Multipath TCP stacks that adapt to different network scenarios and user requirements. The purpose of this thesis is to answer two main research questions: (1) how Multipath TCP and its current implementations behave and perform in the Internet, and (2) how to customize and extend Multipath TCP implementations to adapt them to current and future use cases. For the first question, we have conducted two measurement campaigns, one with traditional web services and the other with voice-activated services. For the second question, we have explored the capabilities of the eBPF infrastructure in the Linux kernel and leveraged it to extend both the TCP and the Multipath TCP stacks in the Linux kernel.