Autonomous System alliances or federations are envisioned to emerge in the near future as a means of selling end-to-end quality assured services through interdomain networks. This collaborative paradigm mainly responds to the ever increasing Internet traffic volumes that requires assured quality, and constitutes a new business opportunity for Network Service Providers (NSPs). However, current Internet business rules are not likely to satisfy all involved partners in this emerging scenario. How the revenue is shared among NSPs must be agreed in advance, and should enforce economical incentives to join an alliance and remain in it, so that the alliance remains stable. In this paper, we work on the scenario of such federations, where service selling is formulated as a Network Utility Maximization (NUM) problem. In this context, we formally formulate the properties the revenue sharing (RS) method should fulfill and argue why the existing methods are not suitable. Finally, we propose a family of solutions to the RS problem such that the economical stability and efficiency of the alliance in the long term is guaranteed. The proposed method is based on solving a series of Optimization Problems and considering statistics on the incomes.