A method of managing streamed communication between a client device and one or more of a plurality of remote devices (21, 23, 24) via a digital data communication network, the data communication network comprising a plurality of routers (41, 42) each operable to receive streamed data having an indication of an intended recipient from one or more of said devices and/or from one or more other routers, and to forward said streamed data to one or more of said devices and/or to one or more other routers, the method comprising, at a proxy module functionally associated with the client device: intercepting streamed data intended to be received from one or more of said remote devices (21, 23, 24) by the client device along a path via at least one of the routers (41, 42) of the digital data communication network whereby to receive, at the proxy module, a first instance of said streamed data in one or more first router-side streams from at least one of said routers, and streaming said data in one or more client-side streams from the proxy module to the client device; receiving at the proxy module in one or more second router-side streams from at least one of said routers a second instance of streamed data corresponding to the first instance of streamed data while still receiving the first instance of streamed data in said one or more first router-side streams, the second instance of streamed data having traversed a different path to that traversed by the first instance of streamed data, via at least one different one of the routers; comparing the first and second instances of streamed data whereby to determine a discrepancy measure indicative of whether the first and second instances are synchronised with each other, and if not, introducing a delay (s24, s30) into one or other of said instances whereby to decrease or remove any discrepancy in synchronisation between the respective instances; then switching (s22, s26, s32) from streaming data received in said first instance in said one or more client-side streams from the proxy module to the client device, to streaming data received in said second instance in one or more client-side streams from the proxy module to the client device; characterised in that the step of comparing comprises determining whether one or more elements of the second instance have arrived at the proxy module associated with the client device before or after one or more corresponding elements of the first instance, and if before, introducing a delay into the second instance prior to said switching then gradually decreasing said delay after said switching; and if after, gradually introducing a delay into the first instance prior to said switching. intercepting streamed data intended to be received from one or more of said remote devices (21, 23, 24) by the client device along a path via at least one of the routers (41, 42) of the digital data communication network whereby to receive, at the proxy module, a first instance of said streamed data in one or more first router-side streams from at least one of said routers, and streaming said data in one or more client-side streams from the proxy module to the client device; receiving at the proxy module in one or more second router-side streams from at least one of said routers a second instance of streamed data corresponding to the first instance of streamed data while still receiving the first instance of streamed data in said one or more first router-side streams, the second instance of streamed data having traversed a different path to that traversed by the first instance of streamed data, via at least one different one of the routers; comparing the first and second instances of streamed data whereby to determine a discrepancy measure indicative of whether the first and second instances are synchronised with each other, and if not, introducing a delay (s24, s30) into one or other of said instances whereby to decrease or remove any discrepancy in synchronisation between the respective instances; then switching (s22, s26, s32) from streaming data received in said first instance in said one or more client-side streams from the proxy module to the client device, to streaming data received in said second instance in one or more client-side streams from the proxy module to the client device; characterised in that the step of comparing comprises determining whether one or more elements of the second instance have arrived at the proxy module associated with the client device before or after one or more corresponding elements of the first instance, and if before, introducing a delay into the second instance prior to said switching then gradually decreasing said delay after said switching; and if after, gradually introducing a delay into the first instance prior to said switching.