Network multicast peer discovery methods

Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, can include establishing communications with one or more peers in a communication group via one or more unicast communication channels; sending a participation information request on a multicast communication channel of a local network to discover peers that participate in the communication group; receiving one or more responses to the participation information request on the multicast channel of the local network from one or more peers that participate in the communication group; selecting one or more of the peers from which the one or more responses were received based on a network topology condition to reduce communication latency in at least a portion of the communication group; and communicating with the one or more selected peers to distribute information within the communication group.