Multicast Video Conferencing works with UDP network type also called User Datagram Protocol. It is a data transfer protocol in which signal transmission is carried out directly from a user to a user, by-passing the video conferencing server, which significantly taking the load off the network and the video conferencing server. Wikipedia article on Multicast. By its nature, UDP is not reliable—messages may be lost or delivered out of order. However, it does a great job in speed since the to and fro of meta data is not involved. It’s like sending a courier for sure but not tracking its delivery second by second. This improves fast transmission with some compromise on quality but gaining all the more in transmission speed.
During a regular group video conference data transmission is carried out in sequence from one participant through the service server to all the other participants of a conference. This scheme is universal and most reliable in combination with the widely used methods of Internet security.
However passage of all the traffic through the video conferencing server:
› Significantly raises the load on it;
› Significantly narrows the existing bandwidth of the used channel, as it requires continuous availability of N*N streams in the channel, where N is the number of participants of a video conference (every participant uses one stream for transmission of a signal to the server, which sends it to N-1 – other participants of a video conference).
In cases when a direct transition of the UDP packages between the terminals is possible the use of Intercom technology allows the participants to exchange data directly with each other. This is possible due to the use of e.g. a retranslation hub (concentrator) or switching equipment (a switch, a router) with support of the UDP Multicast technology. In this case only the N number of information streams will be present in the channel – in accordance with the number of the video conference participants.