Multicasting is a unidirectional communication. Clients simply listen to data streams from a scheduled live event originating from Real or Mbone servers on the NIH network. Multicasting conserves bandwidth. VCR controls on the client software allow viewers to determine when the data stream starts, pause the stream without losing data, or move forward or backward in the data stream. Unicasting is a bidirectional communication.
Clients send requests to the server, and each connection from client to server uses bandwidth.