This session aims at setting the stage for cloud federation and for Software Defined Networking (SDN) and Network Function Virtualization (NFV) paradigms as its enablers. Cloud federations are coalitions of small- and medium-size cloud operators that collaborate in order to offer a wider range of services and resources, achieve load balancing, accommodate demand spikes, and improve coverage and Quality of Experience (QoE) by means of sophisticated coordination mechanisms. The effective implementation of a cloud federation requires the definition of appropriate business agreements among the participants and the broad use of online mechanisms that dynamically adapt to cloud environment changes and demand unpredictability to meet the SLAs.

The separation of the control plane from the data plane in SDN offers flexible and dynamic control over the underlying network infrastructure. Due to its rapid adaptation capabilities, SDN/NFV is expected to be a major candidate for enabling more efficient and greener cloud computing environments. Indeed, the solutions based on the SDN/NFV paradigm allow use of virtualization in networks to satisfy the needs of different tenants while can also manage and utilize available resources optimally. Moreover, SDN/NFV enables flexible and energy efficient network and cloud management, fair resource optimization and allocation, elasticity of service provisioning and automation capabilities. These are expected to lead to cost reduction for ISPs, data centers, users and other stakeholders, and to positive ecological effects.
In a cloud federation, regardless the cloud model adopted (IaaS, PaaS or SaaS), the resources of the individual clouds are combined according to business policy rules, to create a large virtual pool of resources at multiple network locations, to the mutual benefit of all participants. Depending on these rules, different types of federation may arise, ranging from an agreement on technical standardization only to an alliance for joint business. In the latter case, federations will lead to large “virtual” clouds that can efficiently provision their services over large geographical regions and across multiple networks, which is particularly important for expanding coverage and improving cloud service quality at the European level. However, the alignment of business requirements and processes of the technical capabilities necessary within a federation requires effort by the cloud operators, who (if successful) will increase their profits by enriching their service offerings and customer bases. Thus, to be sustainable, this new ecosystem also requires the right business models for the cloud operators, accompanied by appropriate pricing schemes for the services offered to other operators and to the end-user. Moreover, accountability will be a key factor to avoid strategic behavior by federation members, e.g. free-riding, and thus will support sustainability. 

Cloud federation is a very attractive paradigm, especially for small- and medium-sized cloud operators, since it offers the possibility to meet demand with spikes or requiring extended geographical presence, and thus address (among others) increasing end-user mobility and support global service mobility. Moreover, the end-users can be offered additional services due to the composition of the resources of different cloud operators, as well as services of third parties such as CDNs with enhanced QoE, e.g. higher resource availability, and lower latency since the service is brought closer to the user. SDN allows virtualization and, thus, delegation of some control via programmable APIs over cloud and network resources, which technologically enables the necessary mechanisms to support the extra flexibility required to meet the business policy rules.

The cloud federation is by definition a collaborative approach, where proper mechanisms are needed to enable inter-cloud communication to dynamically expose shareable resources. Moreover, proper service management should be provided by cloud operators to operate SLA mappings among services, and to ensure that services will be offered to the end-user in a flexible and transparent way, and with performance level as specified in the SLA. Ideally, automated SLA lifecycle management should also be supported, including SLA creation, publishing, negotiation, validation, provisioning, monitoring and termination. This gives rise to important inter-domain issues, such as apportioning of the SLA requirements among the various domains and validation of their conformance. This collaboration among the federated members will inevitably also include overheads and even possible short-term losses for some members. Thus, business rules should ensure that the federation is beneficial for all players involved. At the same time, the operation of a cloud federation and its dynamic nature will greatly influence the volumes and patterns of Internet traffic, which should be handled by ISPs in order to meet the QoE requirements of the users, of the cloud federations, and those of other applications. Indeed, the migration of load from one cloud to another generates significant amounts of inter-cloud traffic, most likely spanning the networks of multiple operators. This is an important issue, with possible negative effects to ISPs and users of other applications, which should be dealt with by the solutions for cloud federations.

During this session, experts from the industry, academia, and NRENs will address important questions, such as:  

• What are the benefits of cloud federation for cloud operators, OTTs and users? Do they outweigh the associated technical and other overheads?
• To what extent and how can SDN/NFV bring these benefits? 
• What is the impact of SDN/NFV-enabled cloud federations to ISPs? How will their traffic management be affected? What opportunities arise? 
• Can the value of information exchange between cloud operators (horizontally) and cloud operators and network operators (vertically) be assessed? What other issues apply (accounting, regulatory, privacy-related, etc.) and how can they be tackled? 
• Does SDN/NFV enable the provision of services seamlessly over a cloud federation incorporating heterogeneous services from different operators? What inter-domain issues arise? 
• What standardization activities are currently in progress, and what are their topics of highest interest? 
• Which solutions and standards are already in place that can be used to build and support cloud federations? What is missing in terms of protocols, mechanisms, business rules and SLAs etc. to deploy cloud federations? 
• What are the possible technological alternatives to develop and support cost- and energy-efficient and QoE-aware cloud federations except SDN and NFV?
• Which are some promising use cases for cloud federations? Which are key factors for success?