Multi-controller Traffic Engineering in Software Defined Networks

Distributed controller architectures in software defined networks raise the issue of switch-controller mapping. In a mapping approach where a switch distributes flow setup requests (traffic) to multiple controllers, a solution that finds the optimal switch-controller mapping and traffic distribution among the controllers for long term performance and responds effectively to network events such as short term traffic variation and controller failure is necessary. We develop a Multi-Controller Traffic Engineering (MCTE) scheme that: i) finds the long term switch-controller mapping and traffic distribution that minimizes flow setup time, ii) manages traffic distribution during short term variation, and iii) pre-computes backup controllers and traffic distribution upon controller failure. We formulate optimization problems for MCTE components and develop heuristic algorithms to obtain solutions in reasonable time. Numerical simulations show that the proposed algorithms achieve flow setup time within 2% of the lower bound and effectively manage traffic upon traffic variations and controller failures.