Methods, apparatus and systems are disclosed for managing streamed communication (such as video, audio, or audio-visual communication) between client devices and remote devices via a digital data communication network in situations where the data communication network comprises one or more routers operable to receive streamed data from one or more client devices and/or from one or more other routers, and to forward such streamed data to one or more remote devices and/or to one or more other routers such as to enable the client device and potentially-varying subsets of the one or more remote devices to participate in a communication session.