Consistent Network Management for Software-Defined Networking Based Multicast

Updating a network is an essential and continual task in the management of today's softwarized networks. When applying updates on distributed network elements, desired network properties, such as drop- and loop-freeness, might be transiently violated. Although being crucial, update consistency has yet been less considered in network management. In this paper, we argue for incorporating the particularities of update consistency into the reconfiguration process of continuous network management. We present a generic management architecture allowing for an appropriate selection of an update mechanism and its parameters based on expected inconsistency effects. We investigate update consistency for the case of multicast routing and show in an extensive analysis why simultaneous drop- and duplicate-freeness is not possible. We present an update procedure for multicast routing updates that identifies critical update steps, which are fed back into the reconfiguration process, along with a lightweight approach that allows for the selection of an update strategy, preventing either drops or duplicates. Furthermore, we present an optimization of an existing powerful, but resource-intensive update approach as well as an approach for in-network filtering of duplicates.