SDN Policy-Driven Service Chain Placement in OpenStack

Network function virtualization has components au- tomatically deployed and scaled which prompts a new question of where to place instances of a function. Network services that op- erate transparently on the user data plane forward large amounts of traffic. A chain of services can benefit from co-location on the same host whereas a set of parallel services would compete for the host network bandwidth. Since bandwidth utilization is not known a priori to deployment, we have investigated the use of SDN policies to derive connectivity weights between components. In this paper, we present an extension of the OpenStack scheduler implementation that uses SDN forwarding policies to rank potential placement hosts. The solution finds the potential communication peers of a new virtual machine and weighs the forwarding rules to rank hosts with communication peers deployed. We discuss the policy weighing and describe our realization. Our testbed implementation shows that already in a simple service chain example, we can double service chain throughput.