IP Multicasting And Video/Audio Conference Model Based On Multicast Technology

On the Internet,multimedia services such as Streaming Media,Video/Audio Conference,Voice Over IP and Video On Demand,become more and more important, end-to-end data transmission or unicast can't be competent for the task which have the characteristic of one-to-many transmission.if we use unicast,the server has to offer the packet with same context for each connection,which will consume too much bandwidth.then the broadcast is alternative selection for us to deliver data in the LAN,as we known,when broadcast technology used,all the PCs in the LAN will receive the broadcast packets regardless that you would like to or not. So we have to find the other solution for these conditions,the appearance of multicast give us a chance to solve the problem.multicast servers send the packets only to those terminals which are interested in the packets.Our document is made with four sections.Section one,we illuminate the conception of multicast.IP multicasting is the transmission of an IP datagram to a "host group",the datagram is not guaranteed to arrive intact at all members of the destination group or in the same order relative to other datagrams.Section two,This section describes RTP(real-time transport protocol) and RTCP(control protocol). RTF provides end-to-end network transport functions suitable for applications transmitting real-time data, such as audio, video or simulation data, over multicast or unicast network services.RTCP monitors the data delivery in a manner scalable to large multicast networks, and to provide minimal control and identification functionality.H.323 and SIP use the real-time transport protocol to transmit real-time data.at the end of this section, we provide the guidelines for writting of RTF Payload Format Specifications.Section three,ITU-T RECOMMENDATION H.323 and the Session Initiation Protocol(SIP) will been introduced. We give a outlook to the difference of the two protocols.Then we dwell on the H.323 protocol.at the end of the section we give the simplified video/audio conference model based on H.323.Section four,the implementation of the video/audio conference, we discuss the key technology around each functions of the model.In the remainder of this paper,the improvement about the implementation will been discussed.