[1]the Department of Electrical Engineering National Formosa University Yunlin 632;
[2]Dray Tec Corporation Hsinchu 30041;
[3]the Department of Electrical Engineering National Chung Cheng University Chiayi 621;
[4]Akademia Gorniczo-Hutnicza University of Science and Technology Krakow 30-059;
[5]the Department of Computer Science and Information Engineering and the Department of Bioinformatics and Medical Engineering Asia University Taichung 41354;
[6]the Department of Medical Research China Medical University Taichung 40402;
Application-layer conferences; hierarchical networks; multimedia conferences; path recovery; peer-to-topeer (P2P); session initiation protocol (SIP);