  Value-added services (e.g., overlaid video advertisements) have become an
integral part of today's Content Delivery Networks (CDNs). To offer
cost-efficient, scalable and more agile provisioning of new value-added
services in CDNs, Network Functions Virtualization (NFV) paradigm may be
leveraged to allow implementation of fine-grained services as a chain of
Virtual Network Functions (VNFs) to be placed in CDN. The manner in which these
chains are placed is critical as it both affects the quality of service (QoS)
and provider cost. The problem is however, very challenging due to the
specifics of the chains (e.g.,one of their end-points is not known prior to the
placement). We formulate it as an Integer Linear Program (ILP) and propose a
cost efficient Proactive VNF placement and chaining (CPVNF)algorithm. The
objective is to find the optimal number of VNFs along with their locations in
such a manner that the cost is minimized while QoS is met. Apart from cost
minimization, the support for large-scale CDNs with a large number of servers
and end-users is an important feature of the proposed algorithm. Through
simulations, the algorithm's behaviour for small-scale to large-scale CDN
networks is analyzed.
