A design and analysis of top-down based ACK-trees

For Reliable Multicast Service, to use tree hierarchy can be a promising solution to avoid well-known ACKimplosion. However, to build an efficient ACK-tree is very difficult for IP Multicast because it does not provide explicit membership and routing topology information to upper layer protocol. Due to the difficulties, not much study has been done on the control tree configuration yet, while it immensely affects the behavior and performance on a protocol using the mechanism. Previous approaches can be classified into top-down and bottom-up, and promising previous works have typically been focused on bottom-up construction mechanism, because top-down approach has some drawbacks like long tree creation time. However, ERS based mechanism, one of the representative Bottom-up mechanisms is known to cause heavy message overhead. Thus, we propose a novel method which takes benefits of top-down approach while relieves its most significant drawback, long tree creation time, as adopting concurrent tree creation concept from bottom-up approach. We show the proposed mechanism reduces message overhead as well as supports to build low level of tree. In addition, we achieve mediate performance on tree creation time.