Load Balancing - Towards Balanced Delay Guarantees in NFV/SDN

The goals of load balancing are diverse. We may distribute the load to servers in order to achieve the same utilizations or average latencies. However, these goods are not a perfect fit in virtualized or software-defined networks. First, it is more difficult to assume homogeneous server capacities. Even for two (virtualized) functions with the same capacities, the capacities seen by the customer might be heterogeneous simply because they belong to different providers, are shared by others, or locate themselves differently and the communication costs are different. Heterogeneous server capacity will blur the aim of keeping the same utilizations. Second, usually the metric of latency in those networks is the (stochastic) bound instead of average value. In this paper, we parameterize the server capacities, and use the stochastic latency bound as the metric to further support inferring load balancing. We also model the load balancing process as a Markov-modulated process and observe the influence of its parameters onto achieving balance. The proposed model will benefit the load balancing function implementation and infrastructure design in virtualized or software-defined networks.