A Distributed Codec Placement Algorithm for Network-Embedded FEC

Network-embedded FEC (NEF) for overlay and peer-to-peer (p2p) multicast networks was introduced, and the impact of packet loss correlation on the performance of NEF was further analyzed and evaluated. In these previous works, a centralized codec placement algorithm and a greedy optimization algorithm to place a specified number of NEF codecs in a multicast distribution network were developed and analyzed. In the centralized codec placement algorithm, it has been assumed that the network topology and the loss rate on each branch of the network were known. In reality, it is very difficult to know the loss rate of each branch on the multicast tree beforehand. Further, the topology of a multicast session changes over time as users join and leave the session randomly. In this paper, we design and implement a distributed algorithm to place NEF codecs in the intermediate nodes of a multicast distribution network without knowledge of the network topology; the algorithm can also cope with the dynamics of the network very well. Our simulation results, based on the popular network simulator 2 (ns2), show that the proposed distributed NEF placement algorithm provides very competitive performance when compared to the centralized algorithm and it always outperforms traditional end-to-end FEC.