Abstract
The NS project is a famous simulator/emulator for network research. It has implemented many protocols that are widely used nowadays. However, when used for emulation, the real-time scheduler of the NS is very rough and cannot produce precise emulation. There are several reasons. First, the NS has to share the CPU resource with other processes. Thus, it might not be able to get the CPU when it needs to schedule or handle events at specified time. Second, burst of interrupts, say from the network, will tie up the system kernel. This also prevents the NS from scheduling its events at precise time instant. Third, the NS might not be able to dispatch events in time, which causes the scheduled event delay.In this thesis, we focus on the latter two issues. To solve the problem of interrupt burst, we incorporate RTLinux into the Linux pus the NS system to help. RTLinux allows us to control the signal of interrupts to Linux. It also helps to record more precisely the time when an interrupt occurs. Two techniques: interrupt control and traffic pattern maintaining, are developed on top of RTLinux to solve the burst interrupt problem. To solve the overrun problem, we develop an overrun control mechanism. Our experiments show that the developed techniques do improve overrun situation and the problem of interrupt burst.