Abstract: Considering the characteristic that network traffic change is dynamic and different traffics demand for congestion control and transmission cost are different,a link weights optimizing algorithm for multi-topology routing sub-layer based on niche particle swarm optimizer (NPSO) was proposed．The traffic matrix differentiated by periods and weight gene following different traffic demands were set to adapting the dynamic changing of network traffic．The congestion and transmission cost were considered in optimizing objective function,and NPSO was used to solve the optimization problem．The experimental result shows that the new algorithm can balance the load in network.

Key words: Traffic engineering,Link weight,Niche particle swarm optimizer,Multi-topology routing