Placement of repair servers to support server-based reliable multicast

To support server-based reliable multicast, repair servers are used to store packets from sender(s) such that lost packets can be retransmitted to receivers from the repair servers. A repair server can be a specially designed host co-located with a router or a router with the functions of a repair server integrated in it. It may not be practical to place a repair server at each of the routers in the network if the size of the network is large. It is more economical to place repair servers at a subset of the nodes in the network such that the placement is cost-effective. Improper placement of repair servers may result in low utilization of the repair servers. It is desirable to place repair servers in the network such that they can be used effectively. Given a number of repair servers, we want to find a subset of the nodes in the network to place the repair servers such that the repair servers can be used effectively. To our knowledge, this problem has not been studied in previous researches. We propose three methods for the placement of repair servers. The performance of the three proposed methods are compared with that of a method which place the repair servers randomly in the network. Our simulation results show that the three proposed methods yield significant better performance than the random placement method. One of the three proposed methods, namely, k-maximum path count method, produces the best performance among the three proposed methods