Modelling of Minimum Cost Overlay Multicast Tree in Two Layer Networks

Multicast realises the data delivering to a group of destinations simultaneously while using the minimum network resources. The first implementation of multicasting has been built using specialized multicast routers and is well known as IP Multicast. Such a network comprises some drawback including complex addressing and routing scheme, it requires the deployment of special routers that are rather expensive and finally, there has not been proposed a reasonable business model regarding cross-providers multicast realization. Thereby, for the past few years, a new interest in delivering multicast traffic has arisen and some multicast systems defined for end-hosts overlay network have been successfully proposed. Overlay multicast implements a multicast technique at the top of computer networks and creates a virtual topology of clients which duplicate packets and maintain a multicast structure. This overlay structure forms an independent layer with logical links between the nodes without the knowledge about the underlaying topology. In the work we take a look at flow cost minimization of multicast stream in a system which combines the advantages of overlays and underlaying network awareness. This papers presents three independent linear-based models aimed at optimization of multicast tree topology and its network level unicast realization. The proposed formulations can be applied for deriving either lower bound of flows costs in existing systems or for designing new cooperative multilayer protocols for effective multicast transmission.