Virtualization is a key technology to enable cloud computing. It enhances resource availability and offers high flexibility and cost effectiveness. However, the driver domain-based model for network I/O virtualization exhibit poor networking performance. In this paper, we evaluate the networking performance of VMs based on Xen. The I/O channel transferring packets between the driver domain and the VMs is shown to be the bottleneck. To overcome this limitation, we proposed a packet aggregation-based mechanism to transfer packets from the driver domain to the VM. Experimental performance evaluation showed that our proposal allows the VMs throughput to scale up at line rates. Furthermore, we studied the impact of the aggregation on the packets delay. For this purpose, we proposed a system modeling based on queuing theory. The proposed model allowed us to dynamically tune the aggregation mechanism to achieve the best tradeoff between the packets delay and throughput. The proposed I/O virtualization model henceforth satisfies the infrastructure providers to offer cloud computing services.

Cloud computing is an emergent paradigm that allows to customers to rent infrastructure, platforms and software as a service. With resource sharing and reuse through virtualization technology, cloud environments become even more effective and flexible. Nevertheless, networking within virtualized cloud still presents some challenges in performance and resource allocation. In this paper, we propose to integrate an SLA-based Dynamic Bandwidth Allocator (DBA) in a virtualized cloud environment. DBA manages bandwidth allocation efficiently through allocating bandwidth according to the application requirements and the established agreement. It also adjusts the allocated bandwidth dynamically upon change and reduces physical resources usage by dropping packets in the virtual machines rather than the driver domain. Through experimental evaluation we showed the efficacy of the proposed algorithm and the agreements respect.

Cloud computing is an emergent paradigm that allows customers to rent infrastructure, platforms and software as a service. With resource sharing and reuse through virtualization technology, cloud environments become even more cost effective and flexible. Nevertheless, networking within virtualized cloud still presents some challenges in performance and resource allocation. In this paper, we propose DBA-VM, a Dynamic Bandwidth Allocator for Virtual Machines with regard to the established SLAs. The proposed scheme enforces the isolation between the virtual machines through the transmission bandwidth adjustment at the network I/O channel. The experimental performance evaluation shows that DBA-VM allows to the virtualized system to respect each virtual machine SLA while reducing the global physical resources (CPU and memory) consumption.

Network virtualization is a promising technology that offers high levels of flexibility, isolation, extensibility and cost-effectiveness. In this paper, we focus on router virtualization. We evaluate the forwarding performance of virtual routers when the data plane runs in the guests. This scenario offers a high level of isolation and flexibility, however, it suffers from performance limitations due to the virtualization overhead. We show that the he I/O communication between the driver domain and the guests is the bottleneck. To overcome this limitation, we propose a new packets aggregation mechanism that transfers groups of packets between the driver domain and the guests. This enhancement makes the forwarding performance of one guest scale up to 1600 Kp/s. Furthermore, we propose a dimensioning tool in order to determine the maximum achievable throughput with regard to the container size.

Router virtualization seems as the obvious next step to system virtualization and the key to easily deploy and manage next generation overlay virtual networks. In this paper, we investigate the viability of virtual routers on a Xen-based system. We first evaluate the system throughput when achieving forwarding in the virtual routers. Then, we consider the context where virtual routers are dedicated to flows of different types and propose a mechanism to guarantee the required throughput and latency to real time applications while maintaining an optimal aggregated system throughput. We achieved this through both configuring the Xen Credit scheduler and establishing priorities between packets in the driver domain before switching them to the target virtual router.

Virtual routers on commodity hardware are an attractive solution for service providers that look for extensibility, flexibility, reuse and low deployment cost. However, these routers still suffer from performance limitations due to the virtualization overhead and the commodity hardware architecture itself. In this paper, we first evaluate the baseline forwarding performance of virtual routers based on a Xen environment. Then, we show that the memory latency is the bottleneck. Hence, we propose a Fast Bridge that demultiplexes incoming packets and then transfers them to the destined guest machines. It constructs packets containers in the driver domain, based on their destination and their delay constraints. Then it transfers them as a unit to the guests. This allows transferring more packets and fastest memory access and results in a much better throughput with an acceptable guaranteed delay.