  Multi-tenant cloud networks have various security and monitoring service
functions (SFs) that constitute a service function chain (SFC) between two
endpoints. SF rule ordering overlaps and policy conflicts can cause increased
latency, service disruption and security breaches in cloud networks. Software
Defined Network (SDN) based Network Function Virtualization (NFV) has emerged
as a solution that allows dynamic SFC composition and traffic steering in a
cloud network. We propose an SDN enabled Universal Policy Checking (SUPC)
framework, to provide 1) Flow Composition and Ordering by translating various
SF rules into the OpenFlow format. This ensures elimination of redundant rules
and policy compliance in SFC. 2) Flow conflict analysis to identify conflicts
in header space and actions between various SF rules. Our results show a
significant reduction in SF rules on composition. Additionally, our conflict
checking mechanism was able to identify several rule conflicts that pose
security, efficiency, and service availability issues in the cloud network.
