Proactive and Hitless vSDN Reconfiguration to Balance Substrate TCAM Utilization: From Algorithm Design to System Prototype

The combination of network virtualization and software-defined networking enables an infrastructure provider to create software-defined virtual networks (vSDNs) over a shared substrate network (SNT), for supporting new network services more timely and cost-effectively. Meanwhile, as both the services and traffic in the Internet are becoming more and more dynamic, how to properly maintain vSDNs in a dynamic network environment exhibits increasing importance but still has not been fully explored. In this paper, we conduct a study on how to realize proactive and hitless vSDN reconfiguration to balance the utilization of ternary content-addressable memory (TCAM) in a dynamic SNT. Specifically, we consider both algorithm design and system prototyping. From the algorithmic perspective, we try to solve the problems of “what to reconfigure” and “how to reconfigure”. A selection algorithm is designed to proactively choose the virtual switches (vSWs) that should be migrated to other substrate switches for balancing TCAM utilization, i.e., solving what to reconfigure. Then, for the problem of how to reconfigure, i.e., where to re-map the selected vSWs and the virtual links connecting to them, we formulate a mixed integer linear programming model to solve it exactly, and design two heuristics to improve time efficiency. Next, we move to the system part, implement the proposed algorithms in our protocol-oblivious forwarding enabled network virtualization hypervisor system, and conduct experiments to demonstrate proactive and hitless vSDN reconfiguration. The experimental results indicate that our proposal does make vSDN reconfiguration transparent to the vSDNs' virtual controllers and proactive, and when reconfiguring a vSDN with live traffic, it achieves hitless operations without traffic disruption.