Virtual Direction Multicast for Overlay Networks

Abstract

Recently emerged Internet applications such as Internet TV, tele-conferencingand online education requires group communication, also known as "multicast". Manyresearchers have put their research focus on achieving a robust and efficient way ofsending traffic via multicast. Network layer multicast attracted the attention foryears; but, because of deployment issues of network layer multicast, it has not beendeployed widely. Overlay multicast (i.e., application layer multicast) is a promisingalternative solution in which multicast functionalities are implemented in the appli-cation layer.We propose Virtual Direction Multicast (VDM) which aims to minimize net-work usage and increase user-perceived quality for video multicast applications onpeer-to-peer overlay networks. VDM locates the end hosts relative to each otherbased on a virtualized orientation scheme and it builds its multicast tree by con-necting the nodes which are estimated to be in the same virtual direction that aredetermined by virtual distances among the nodes. By using the concept of direction-ality, we target to consume minimal resources of the underlying network and increaseuser satisfaction. Another aim of using virtual distance is to adapt overlay multicasttree to different performance targets desired by applications. Sensitivity of applica-tions differs against various network performance metrics, e.g., delay is crucial forvideo conferencing which includes interactivity while it is not so significant for videostreaming that is highly sensitive to loss. Calculating virtual distances based on givenapplication-specific preferences is a key capability of VDM and it enables the systemto accommodate specific performance targets while providing a generalized frameworkto establish the overlay trees. We perform extensive evaluation of VDM and compareit against the Host Multicast Tree Protocol (HMTP) that connects nearby nodes toconstruct the multicast tree. Our simulation results and Planetlab implementationshow that our proposed technique VDM consistently outperforms HMTP under dif-ferent churn rates for some key measures such as network usage and user-perceivedquality.