Building Low Delay Application Layer Multicast Trees

Application Layer Multicast (ALM) enables rapid deployment of multicast applications which have been hindered by sparse deployment of network layer multicast infrastructure. In ALM, application hosts organise themselves into an overlay topology on top of the underlying unicast network solutions. Application data is multicast over the overlay network. This paper investigates the problem of building a low delay overlay tree in a distributed manner. We study and propose an enhancement to an existing protocol called Tree Building Control Protocol (TBCP). We also propose a new strategy to maintain and improve the tree quality in a changing network environment. Our simulation results indicate that the enhancement and the new tree refinement technique outperform the previous proposals.