A Dynamic Virtual Networks Solution for Cloud Computing

The extensive use of virtualization technologies in Cloud environments has created the need for a new network access layer, due to requirements on networking for which traditional models are not well suited. For example, hundreds of users issuing Cloud requests for which full, privileged access to Virtual Machines (VMs) is requested, typically require the definition of network separation at layer 2 through the use of virtual LANs (VLANs). However, in large computing centers, due e.g. to the number of installed network switches, to their characteristics, to their heterogeneity, or to management policies, the dynamic or even static definition of many VLANs is often impractical or simply not possible. We present a solution called DVN (for Dynamic Virtual Networks) to the problem of dynamic virtual networking based on the use of the Generic Routing Encapsulation protocol (GRE). GRE is used to encapsulate VM traffic so that the configuration of the physical network layer does not need to change. In particular, we describe how DVN can be used to address problems such as scalable dynamic network isolation, mobility of VMs across hosts, and interconnection of geographically distributed resource centers. We also describe how DVN is being implemented in a production software framework providing and interconnecting Cloud and Grid resources.