Routing and wavelength assignment (RWA) is one of the key issues in the wavelength-routed optical networks.
Although some RWA algorithms have been well performed to meet the need of certain networks requirement, they
usually neglect the performance of the whole networks, especially the load balancing of the whole networks. This is
quite likely to lead to some links bearing excessive ligthpaths and traffic load, while other links being at an idle state. In
this paper, the load distribution vector ( LDV ) is introduced to describe the links load of the networks firstly. Then by
means of minimizing the LDV of the networks, the load balancing of the whole networks is tried to improve. Based on
this, a heuristic load balancing (HLB) strategy is presented. Moreover, a novel RWA algorithm adopting the heuristic
load balancing strategy is developed, as well as two other RWA algorithms adopting other load balancing strategies. At
last, the simulations of the three RWA algorithms with different load balancing strategies are done for comparison on the
basis of both the regular topology and the irregular topology networks. The simulation results show that the key
performance parameters such as the average variance of links, the maximum link load and the number of established
lightpath are improved by means of our novel RWA algorithm with the heuristic load balancing strategy.