Virtual machine technology and the ease with which VMs can be migrated within the LAN, has changed the scope of resource management from allocating resources on a single server to manipulating pools of resources within a data center. We expect WAN migration of virtual machines to likewise transform the scope of provisioning compute resources from a single data center to multiple data centers spread across the country or around the world. In this paper we present the CloudNet architecure as a cloud framework consisting of cloud computing platforms linked with a VPN based network infrastructure to provide seamless and secure connectivity between enterprise and cloud data center sites. To realize our vision of efficiently pooling geographically distributed data center resources, CloudNet provides optimized support for live WAN migration of virtual machines. Specifically, we present a set of optimizations that minimize the cost of transferring storage and virtual machine memory during migrations over low bandwidth and high latency Internet links. We evaluate our system on an operational cloud platform distributed across the continental US. During simultaneous migrations of four VMs between data centers in Texas and Illinois, CloudNet's optimizations reduce memory migration time by 65% and lower bandwidth consumption for the storage and memory transfer by 19GB, a 50% reduction.

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Edge clouds are emerging as a popular paradigm of computation. In edge clouds, computation and storage can be distributed across a large number of locations, allowing applications to be hosted at the edge of the network close to the end-users. Virtual machine live migration is a key mechanism which enables applications to be nimble and nomadic as they respond to changing user locations and workload. However, VM live migration in edge clouds poses a number of challenges. Migrating VMs between geographically separate locations over slow wide-area network links results in large migration times and high unavailability of the application. This is due to network reconfiguration delays as user traffic is redirected to the newly migrated location. In this paper, we propose the use of multi-path TCP to both improve VM migration time and network transparency of applications. We evaluate our approach in a commercial public cloud environment and an emulated lab based edge cloud testbed using a variety of network conditions and show that our approach can reduce migration times by up to 2X while virtually eliminating downtimes for most applications.

Today's cloud data centers host a wide range of applications including data analytics, batch processing, and interactive processing. These applications require high throughput, low latency, and high reliability from the network. Satisfying these requirements in the face of dynamically varying network conditions remains a challenging problem. Multi-Path TCP (MPTCP) is a recently proposed IETF extension to TCP that divides a conventional TCP flow into multiple subflows so as to utilize multiple paths over the network. Despite the theoretical and practical benefits of MPTCP, its effectiveness for cloud applications and environments remains unclear as there has been little work to quantify the benefits of MPTCP for real cloud applications. We present a broad empirical study of the effectiveness and feasibility of MPTCP for data center and cloud applications, under different network conditions. Our results show that while MPTCP provides useful bandwidth aggregation, congestion avoidance, and improved resiliency for some cloud applications, these benefits do not apply uniformly across applications, especially in cloud settings.