Degree-Constrained ALM Tree Construction Algorithm for Heterogeneous Access Environment

Point-to-multipoint bulk data transfer using application-layer multicast (ALM) is discussed. In ALM, each host participating in an application session makes copies of received data by application-layer manipulation and forwards the copies to other hosts via unicast connections. Therefore, the performance, especially for access link speed, of hosts strongly affects overall delivery performance. In heterogeneous access environments, there is a strong possibility that some hosts with low-speed links decrease overall delivery performance. However, many previous solutions constructed ALM trees by introducing arbitrary degree allocations and by not well considering a diversity of access link speeds of hosts. This paper proposes an algorithm to construct an efficient ALM tree from hosts with heterogeneous access lines. This algorithm minimizes delivery completion time and lets many hosts complete reception of all data as fast as possible. The effectiveness of the algorithm is verified using simulations.