A Hierarchical SDN Controller Synergy Approach for Dynamic Load Balancing in SAGIN Networks: Enhanced Clustering and Optimization via DPC-K-Means and ISAO Algorithms

The surging demand for uninterrupted global connectivity and efficient information dissemination has significantly accelerated the evolution of space-air-ground integrated networks (SAGIN). Conventional network structures are becoming progressively insufficient in meeting the intricate demands of vast, fast-changing environments. To address this, SAGIN adopts a multicontroller collaborative framework supported by software-defined networking (SDN), which effectively mitigates the problem of load imbalance among SDN controllers caused by fluctuating satellite topologies and inconsistent service requests from users.To tackle these technical hurdles, a phased strategy for deploying and allocating SDN controllers is introduced. The strategy first enhances the traditional DPC-K-means algorithm by integrating the K-nearest neighbors (KNN) method. This integration aids in identifying clustering centers and defining boundaries more accurately by refining local density and relative distance measurements, thereby improving the algorithm’s clustering performance when applied to complex data environments.Additionally, a flexible buffer zone mechanism is incorporated to achieve more even load distribution among satellite controllers, enabling more precise and efficient regional segmentation. Following this, the snow ablation optimization algorithm (ISAO) is further developed through the incorporation of a composite chaotic system and a levy flight-based optimization method. These enhancements increase the diversity and adaptability of initial sample populations, leading to greater efficiency and accuracy in discovering optimal solutions for controller deployment in satellite networks.Simulation studies confirm that the proposed controller allocation scheme substantially improves performance. It balances the network load more effectively, enhances the reliability and adaptability of SDN-based SAGIN, and yields notable improvements: a 42% increase in the objective function value, a 28.5% improvement in time efficiency, and a 19% reduction in average transmission latency.In summary, the proposed strategy better supports the requirements of multidomain collaborative operations, including communication, data transfer, and network management across heterogeneous platforms. It offers a solid technical foundation for the robust implementation and advancement of SAGIN.