## 2 Background
### Future Internet  
Many different research directions are being explored under the umbrella of Future Internet, either as evolutionary or as clean-slate proposals. We summarize here the significant research findings that focus on designing future Internet architecture through virtual networks, CCN or Cloud computing.  
Virtualization has been used as an enabler to deploy CDNs (e.g., [17]) and also to create experimental infrastructures such as **PlanetLab**[18] and **GENI**[19], which have built large-scale, distributed testbeds through many geographically distributed, global overlay networks. Virtualization provides a smooth path for migration towards more evolutionary approaches of the Internet and can be used to design and study new architectures. **Cabo**[2] presents a high-level architecture for a flexible and extensiblesystem that supports multiple simultaneous network architectures through network virtualization. Cabo identifies two different entities for the future Internet: infrastructure providers (e.g., the ISPs) who manage the substrate resources and service providers who operate their own customized network inside the allocated slices. A service provider's slice might be built on top of multiple infrastructure providers. The two-layer virtualization of Cabo has been further refined in **Cabernet** (Connectivity Architecture for Better Network Services) [20], which presents a three-layer network architecture by introducing a connectivity layer between the infrastructure provider and the service provider. A connectivity layer uses virtual links purchased from the infrastructure provider and runs virtual networks with the necessary geographic footprint, reliability, and performance for the service provider. **VNet** (Virtual Network) [21], an Internet architecture developed as part of the 4 WARD project, proposes to further split the role of the connectivity layer into Virtual Network Provider (VNP) and Virtual Network Operator (VNO). This provides a more granular splitting of responsibilities with respect to network provisioning, network operation, and service specific operations.  
A CCN is presented in [12], which introduces the notion of named content. It decouples a content's location from its identity, security and access, and retrieves a content by parsing its name. It uses a new approach of content-based routing and achieves scalability, security and performance. The European Future Internet Assembly has come up with a content-centric Internet architecture [22] that introduces _content object_, the smallest addressable unit in the Internet regardless of its location. A content object is composed of media, rules, behaviour, relations and characteristics. Similar to the CCN of [12], there exist other clean slate future Internet architectures (e.g., Data-Oriented Network Architecture (DONA) [23], information-centric Internet architecture [24]) where discovery and access is based on the name of data and services, not the address or hostname of their location.  
Although CDN is a widely deployed content delivery system (e.g., Akamai [10] has over 73,000 servers deployed in 70 countries [25]), the service is pricey and only affordable for large companies. Compared to CDN, Cloud computing providers offer budget rates for Internet accessible data storage and delivery through their Cloud storage service. **MetaCDN**[17], a low cost, high performance content delivery system exploits these storage resources by building an overlay to federate multiple storage providers. Thus, users' content is placed onto one or many storage locations and requests for content are redirected to the most appropriate replica to ensure good performance.