Epidemic-style diffusion schemes have been previously proposed for achieving
peer-to-peer live streaming. Their performance trade-offs have been deeply
analyzed for homogeneous systems, where all peers have the same upload
capacity. However, epidemic schemes designed for heterogeneous systems have not
been completely understood yet. In this report we focus on the peer selection
process and propose a generic model that encompasses a large class of
algorithms. The process is modeled as a combination of two functions, an aware
one and an agnostic one.