PULSE, a Flexible P2P Live Streaming System With the widespread availability of inexpensive broadband Internet connections for home-users, a large number of bandwidth-intensive applications previously not feasible have now become practical. This is the case for multimedia live streaming, for which end-user’s dial-up/ISDN modem connections once were the bottleneck. The bottleneck is now mostly found on the server side: the bandwidth required for serving many clients at once is large and thus very costly to the broadcasting entity. Peer-to-peer systems for on-demand and live streaming have proved to be an encouraging solution, since they can shift the burden of content distribution from the server to the users of the network. In this work we introduce PULSE, a P2P system for live streaming whose main goals are flexibility, scalability, and robustness. We present the fundamental concepts that stand behind the design of PULSE along with its intended global behavior, and describe in detail the main algorithms running on its nodes.