This document describes a directed graph model using a peer-to-peer overlay structure and a gossip-based protocol to maintain the distributed membership. A protocol suite for peers to join the live streaming session, form the P2P streaming overlay, and exchange video packets with others has also been presented. The different capabilities of the heterogeneous peers are well depicted using an adaptive out-degree mechanism. The performance of the whole system is maintained by a contribution-aware mechanism, which ensures that the peers with large contribution will get more chance to be served than those with small or no contribution.