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

Network functions (e.g., firewalls, load balancers, etc.) are traditionally 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 programs. 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 hardware. These VNFs can be placed in Data Centers (DCs) or Network Function Virtualization (NFV)-capable network elements 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.