Initial VM placement time minimization Future VM migration minimization VNFs may be implemented on any of the AIC flavors. The flavors differ in the resources pro- vided for consumption, for example, number of vCPUs, memory size, disk allocation, etc. Optimal resource consumption, overbooking, and overhead minimization can guide the deter- mination of choosing the optimal VNF flavor. The main tradeoffs for this determination are as follows: Smaller sizes will enable a more granular design, better resource utilization and hence bet- ter cost utilization and availability (especially for a larger number of small VFs). It might involve more scaling events that could result in higher overhead, violation of SLAs, and possible loss in revenue. Larger sizes could result in poorer resource utilization, but less scaling events and possible lower impact to SLAs. Larger VFs may imply they are less active instances and therefore have a lower reliability in case of an outage. Workload characteristics can also be used to determine the size of a VNF VM. The main trad- eoffs using this criterion are as follows: Dynamic workloads with peaked behavior could cause large scaling out (and resulting in events with high overhead) as compared to more predictable static workloads. The scaling overhead depends on the workload type. Generally, a network and storage-intensive work- load has a much higher overhead than a compute-intensive workload. Small workloads with a high growth rate would imply a larger VM sooner, compared to a VNF with slow growth rate. 16.13 AREAS FOR FURTHER STUDY In this section, we identify and describe some topics for further exploration: 1. Optimization algorithm improvements: There is a continued need for improvement in opti- mization algorithms that balance between speed of execution and increased efficiency. AT&T collaborates with universities in this regard and organized the AT&T SDN network design challenge in 2015. The task was to come up with a fast and efficient IP/optical network design and routing algori