In a network, with network coding, intermediate nodes may send out packets that are linear combinations of previously received information. The famous max-flow min-cut theorem states that a source node s can send information through a network (V,E) to a sink node t at a date rate determined by the min-cut separating s and t. Recently it has been shown that this rate can also be achieved for multicasting to several sinks provided that network coding is allowed. The benefits for network coding are two-fold: 1) The optimal throughput possible without coding may be asymptotically smaller than the theoretical min-cut bound. With network coding, it is always possible to achieve this bound. 2) Without coding, finding optimal schedule is NP-hard, whereas combining the seemingly disparate fields of coding and network-flow, we can achieve the optimal solution in polynomial time.
In the end, we discuss an open problem which is a generalization of the single source multicasting.