We consider the availability of applications in a large provider network environment. Our primary goal is to design a service provider network for high-availability using multiple components that have different availability. Initially, we model a modern provider architecture that is spread across the access, metro and core regions. We want to answer the specific question as to what amount of over-the-top (OTT) services can be provisioned over a given network while achieving a predesired availability value. To this end, we formulate a constrained optimization model whose objective is revenue maximization subject to availability measures. Two heuristics are also proposed that fathom the breadth of the virtual network function (VNF) deployment parameters: VNF licensing cost and server utilization. A simulation model presents comparative data for efficiency and server utilization as well as validates our optimization model. The results stress the importance of our optimization model in planning the network, as well as planning VNF placement ahead in time.