SDN state inconsistency verification in openstack

In Software Defined Networks (SDN), users manage network services by abstracting high level service policies from lower level network functions. Edge-based SDN, which relies on end hosts to implement lower level network functions, has been rapidly developed and widely adopted in cloud system. A critical challenge in such an environment is to ensure that lower level network configurations, which are distributed in many end hosts, are in sync with the high level network service definitions, which are maintained in the central controller, as state inconsistency often arises in practice due to unreliable state dissemination, human errors, or software bugs. In this paper, we propose an approach to extract, analyze the network states of OpenStack from both controller and end hosts, and identify the inconsistencies between them across multiple network layers systematically. Through extensive experiments, we demonstrate that our system can correctly identify network state inconsistencies with little system and network overhead, therefore can be adopted in large-scale production cloud to ensure healthy operations of its network services.