Flow Migrations in Software Defined Networks: Consistency, Feasibility, and Optimality

Abstract

Software defined networks always need to migrate flows to update the network configuration for a better system performance. However, the existing literature does not take flow path overlapping information into consideration when flows’ routes are re-allocated. Consequently, congestion happens, resulting in deadlocks among flows and link resources, which will block the update process and cause severe packet loss. This paper resolves deadlocks with the help of spare resources during the network update. An algorithm is proposed to determine the feasibility of the consistent flow migration. We demonstrate that even if there are multiple consistent migration plans, finding the optimal one that occupies the fewest leisure bandwidth resources is NP-hard. An approximation algorithm is proposed to sequentially migrate flows in a consistent way. Extensive simulations show that our solution achieves a much smaller traffic loss rate at the cost of an affordable spare link resource usage compared to prior methods.