Migration for VNF Instances Forming Service Chain

When migrating virtual network function (VNF) instances forming a service chain (SC), huge amount of memory pages dirtied due to packet processing extend the interval between the moments when each VNF instance is suspended due to live migration. The generated dirty pages extend termination of the flows through the SC until the instance moving to the target server completes preparation for packet processing. Moreover, after recovery of the flows, quality of the flows deteriorates since the flows are detoured via the instances split into the distant source-target servers. We propose a VNF instance-migration method for alleviating flow termination and flow-quality degradation. Our method migrates the ingress VNF instance in the source server to exploit the flow termination for facilitating completion of the migration before recovery of the flows. Our method avoids endless migration caused by termination and recovery of the flows as well. Numerical results indicate that our method mitigates the impact of flow termination and flow-quality degradation.