Sharing the \Cost" of Multicast Trees: An Axiomatic Analysis1

Given the need to provide users with reasonable feedback about the \costs" their network usage incurs, and the increasingly commercial nature of the Internet, we believe that the allocation of cost among users will play an important role in future networks. This paper discusses cost allocation in the context of multicast ows. The question we discuss is this: when a single data ow is shared among many receivers, how does one split the cost of that ow among the receivers? Multicast routing reduces network usage by using a single shared delivery tree. We address the issue of how these savings are allocated among the various members of the multicast group. We rst consider an axiomatic approach to the problem, analyzing the implications of diierent distributive notions on the resulting allocations. We then consider a one-pass mechanism to implement such allocation schemes and investigate the family of allocation schemes such mechanisms can support.