Joint Virtual Network Function Placement and Routing of Traffic in Operator Networks

Network functions (e.g., firewalls, load balancers, etc.) are tra-ditionally provided by proprietary hardware appliances. These hardware-appliances can be hardwired back to back to form a service chain, which provide services to application layer pro-grams. So, hardware-based functions cannot be provisioned on demand since they are embedded in the network topology making creation, insertion, modification, upgrade and removal of service-chains complex while also slowing down service innovation. Hence, operators are interested in Virtual Network Functions (VNFs), which are virtualized over commodity hard-ware. These VNFs can be placed in Data Centers (DCs) or Network Function Virtualization (NFV)-capable network el-ements such as routers and switches. However, placement decisions of VNFs need to optimized according to the traffic in the network. In this document, we present a mathematical model for the placement of VNFs which ensures the service chaining required by traffic flows.