The Limitation of Random Network Coding
  It is already known that in multicast (single source, multiple sinks) network, random linear network coding can achieve the maximum flow upper bound. In this paper, we investigate how random linear network coding behaves in general multi-source multi-sink case, where each sink has different demands, and characterize all achievable rate of random linear network coding by a simple maximum flow condition. 
Yuan Li
cs.IT cs.NI math.IT