  Network Functions Virtualization (NFV) allows implantation of network
functions to be independent of dedicated hardware devices. Any series of
services can be represented by a service function chain which contains a set of
virtualized network functions in a specified order. From the perspective of
network performance optimization, the challenges of deploying service chain in
network is twofold: 1) the location of placing virtualized network functions
and resources allocation scheme; and 2) routing policy for traffic flow among
different instances of network function. This article introduces service
function chain related optimization problems, summarizes the optimization
motivation and mainstream algorithm of virtualized network functions deployment
and traffic routing. We hope it can help readers to learn about the current
research progress and make further innovation in this field.
