Concerning the high complexity of multiple controller placement model in existing works, several metrics to improve network service quality were defined and an approach to partition network domain and implement controller placement for large scale Software Defined Network (SDN) was proposed. The network was partitioned into several domains based on Label Propagation Algorithm (LPA) and then the controllers in the small domains were deployed separately, which makes the model complexity be linear with the network size on consideration of control path average latency, reliability and the load balance. Simulation results show that our strategy improves the load balance dramatically compared with the original LPA, decreases the model complexity and enhances network service quality compared with CCP. In Internet2, the average control path latency decreases by 9% and the reliability increases by 10% at most.

In multi-controller Software Defined Network (SDN), since the existed switch migration strategies always have low efficiency and need to migrate many times which only consider single migration factor, a mechanism of switches migration based on progressive auction named PASMM (Progressive Auction based Switches Migration Mechanism) was proposed. To improve network benefit, the switch migration problem was optimized by auctioning controllers' remaining resources in the mechanism. By increasing the trading price of the over-demanded controllers' resources, PASMM completed the auction and redeployed the controllers and switches. The simulation results show that, compared with some typical switch migration policies, PASMM achieves good load balancing of controllers, reduces the response time of the PACKET_IN messages by an average of 13.5%, and spends the least migration time with the increasing of switches flow requests.

Network virtualization is recognized as a significant technology to solve the ossification of current Internet. Virtual Network Embedding (VNE) is a major challenge in network virtualization. The main object of VNE is to increase the acceptance ratio of Virtual Network (VN) and the revenue of infrastructure providers. Regarding VNE as an Integer Linear Programming (ILP) model with an assumption that substrate network needs to support path splitting, a new VNE algorithm based on hybrid swarm intelligence optimization was proposed. The proposed algorithm took advantage of the Genetic Algorithm (GA) and Particle Swarm Optimization (PSO) to optimize the mapping scheme in view of the balance of the mapping overhead and the mapping proportionality. Compared with the existing mainstream approaches, the simulation results demonstrate that the proposed algorithm can increase the long-term average revenue and acceptance ratio.

According to the research into how the users social characteristics and behavior properties influence the microblog fans network evolving, a new microblog fans network evolving model based on the attractive factor called SBPAF was proposed. The attractive factor for social characteristics and the attractive factor for behavior properties were defined. The nodes create new edges according to attractive factor preferential attachment principle and the two-step attachment principle. Besides, the dying out of the edges was also considered. The parameter in the model can be adjusted flexibly so that different microblog fans networks can be simulated. Finally, the mathematical analysis and computational experiments verify that SBPAF model is reasonable and available.