We are using OPNET for: 

We use OPNET for the research of " Realtime Data Transfer protocol R3TP and its Packet Loss Detection Scheme" 
We investigate realtime packet communication, now in emerging demand, focusing on relationships between error mainly due to packet losses and  timeliness of data reception. Traditionally,it has been assumed thaterror-dorreciong-code-based error recovery is more fasible for realtimeuse than retransmission-based error recovery,but recent advent of high speed and high throughput network makes the latter a material option. We have proposed high quality realtime data transfer protocol R3TP (Retransmission-based Reliable Realtime data Transfer Protocol)with block transfer technology and retransmission-based error recovery. Because retransmission-based error recovery in realtime data transfer requires a packet loss detection scheme with high responsibility,we have also proposed a novel scheme of packet loss detection employing RM (Resource Management)cell of ABT(ATM Block Transfer)thechnology as a packet loss identifier. We have been submit the paper which described  the packet loss detection scheme for R3TP and its evalation results  in comparison with conventional schemes os packet loss detection to the academy.