Content placement in heterogeneous end-to-end virtual networks

One of the distinctive features of the new virtualized ecosystem, is the multi-stakeholder participation in the way cloud services are designed, deployed and offered. In this work, we address the emerging content replication problem a Content Delivery Network (CDN) provider needs to consider, when deploying its network over multi-domain, heterogeneous environments, where virtual network operators utilize both the CDN services and the virtualized infrastructures. In our model, the benefit that the CDN provider enjoys may be different per network operator for the same request, while our model takes into account the replication cost to every domain, as well as the user mobility, besides physical storage limitations. Since the optimal placement of the objects at the caches of the various domains resembles the multiple knapsack problem, which is NP-complete, we provide two approximate solutions to the emerging content placement problem. We evaluate the proposed policies through extensive simulations and we compare them against a myopic method, where a domain is unaware of the caching strategy of the other domains that is connected to.