Checking Intra-Switch Conflicts of Rules During Preprocessing of Network Verification in SDN

Software defined networking (SDN) has been proposed for improving network flexibility and programmability by decoupling control plane and data plane of the network. In SDN, the conflicts between rules need to be avoided, while the partitions of the packet headers need to be precomputed from the configuration rules for the network verification tools. Previous researches usually use the trie-based method and the exhaustive searching with BDD expression to partition the equivalent packet classes (ECs). In this letter, we describe PreChecker to dynamically identify the conflicting rules and divide the rules into ECs. The conflicts between rules are defined for the discrimination of intra-switch conflicts. The MTBDD-based algorithm is proposed for effectively partitioning ECs when updating rules. Both analysis and simulations demonstrate the validity and the better performance of the algorithm.