A fundamental requirement for any network simulation environment is the realistic forwarding of packets from a source to a destination in the simulated topology.The routing decisions will be affected by topology changes.In almost all current simulators

all the nodes know the topology changes instantaneously

which is obviously unrealistic.The model of dynamic routing was presented and analyzed.Further an approach was proposed to compute the time needed for each node to know the topology changes

and dynamic MTree

N

ix routing mechanism was presented

which maintains static routing table and a message queue of topology changes

and looks up routing states according to the known time of different changes.Experimental results show that our approach can improve the realism of dynamic routing in network simulation

with high simulation efficiency.