Fast congestion-free consistent flow forwarding rules update in software defined networking

Abstract

In software defined networking (SDN), flow migration will be required when topology changes to improve network performance such as load balancing. However, black holes, loops and transient congestion may occur during flow migration due to the asynchronous update of switches on the data plane. Therefore, in this paper, we propose a novel segmented update method to shorten the time of rules update, and a novel transient congestion avoidance algorithm to minimize the number of delayed updating flows, which can both reduce update time of flows. Specifically, we construct three novel models to guarantee no black holes, no loops and no transient congestion, respectively. The first two models to avoid black holes and loops can update multiple nodes in each segment instead of updating the nodes one by one like Cupid. The third model to avoid transient congestion minimizes the number of delayed updating flows. Subsequently, three novel black holes avoidance algorithm, loops avoidance algorithm and congestion avoidance algorithm are respectively proposed. Furthermore, we propose a novel rules update (RU) algorithm which combines these three algorithms to update the rules to avoid black holes, loops and transient congestion simultaneously. Simulation results show that our scheme can increase the number of directly updated flows by 75% on a single congestion link and reduce the rules update time of the flows by 34% compared with the existing work.