Multimedia teleconferencing over international packet switched networks

A description is presented of the current configuration and projected future work on the world's first multimedia teleconferencing system. The communications architecture (by which the authors refer to the protocols and supporting network management system) is based around the DARPA Internet Protocol suite, but with certain enhancements to support real time traffic. The CODEC runs a standard bitstream encoding of video, and this is packetized by the PC. However, this is not sufficiently flexible a protocol to traverse the Internet. The stream protocol (ST) gateway then runs two further protocols to carry the video and voice: (1) packet video protocol (PVP) and (2) voice traffic protocol (VT). Each of these is tuned to the special requirements of video and voice. To carry these in a reasonably consistent fashion, the gateways then run the ST. The performance of the system is limited mainly by the bandwidth of the first few hops of the path.<>