could have acquired the same video from a single node, prior to the distribution process illustrated in Fig. 2. Three nodes (nodes C, D and E) receive video from these two source nodes. The three nodes in turn also act as sources to two further nodes (nodes F and G). Hence, nodes C, D and E download and upload at the same time, that is act as receivers and sources at the same time. All receiving nodes, C to G, are served by multiple sources. Moreover in Fig. 2, nodes F and G can receive data from an alternative source if a source ceases to be available.