Reliable Multicast Network Configuration

可靠组播作为信息传输系统的新一代技术受到了广泛的关注。它保证了大规模组播中信息的无差错传递。然而，可靠的组播方法存在两个主要问题。一个是，当只有发送方同时将丢失的数据包重传给所有接收方时，接收方数量增加，它们就不能很好地工作。这种重传方法称为全局恢复。另一个是ACK内爆。由于大量返回的ack集中，导致网络拥塞。针对这些问题，提出了局部恢复系统。它可以通过分组节点来定位重传的影响。已经提出了几种重传方式，例如使用单播、多播和子播。本文的研究重点是这些具有本地恢复系统的重传方法，因为它们必须是全球网络上大规模多播的较好解决方案。然而，适当的重传方法可能取决于网络拓扑结构。因此，本文比较了基于本地恢复的重传方法，找到了适合于典型网络拓扑类型的重传方法；星形，环状，三角星形，以及Waxman的模型，它代表了当前的互联网拓扑结构。从网络建设成本的角度讨论了适合可靠组播的网络拓扑结构。

Reliable multicast has got much attention as a next generation's technology on information delivery systems. It guarantees the information deliveries without errors on large-scale multicasting.However, reliable multicast methods have two major problems. One is that they cannot work well as the number of receivers increases when only the sender retransmits lost packets to all of receivers simultaneously. This retransmission method is called the global recovery. The other is ACK implosion. Network congestion occurs by concentration of many returned ACKs.Local recovery system has been presented to cope with these problems. It can localize the influence of retransmissions by grouping nodes. Several ways of retransmissions, for instance using unicast, multicast, and subcast, have already been proposed.This study focuses on these retransmission methods with local recovery systems since they must be the better solutions for large-scale multicasting on worldwide network. The appropriate retransmission method, however, may depend on network topologies. This paper therefore compares local-recovery-based retransmission methods and finds the suitable one for typical kinds of network topologies ; star, ring, delta-star, and Waxman's model which represents current Internet topology. The suitable network topology for the reliable multicasting is also discussed from the viewpoint of network construction cost.