Turning the Internet into a multi-path environment could solve many difficulties network operators are facing today. There are already solutions to configure an IP network to offer multiple partially disjoint paths towards the destination. In this demo, we focus on the performance of how MPTCP can distribute the traffic along these paths. When the routes are not fully disjoint their throughput could be limited by some bottleneck links. Because of this dependency finding the maximal throughput in MPTCP may call for solving a complex maximization problem. Through constructing an example network as an illustrative model of real network conditions, we show, how complicated the underlying optimization problem MPTCP may face, and through measurements, demonstrate how the various congestion mechanisms deal with finding a solution.