sNICh: Efficient last hop networking in the data center

Virtualization has fundamentally changed the data center network. The last hop of the network is no longer handled by a physical network switch, but rather is typically performed in software inside the server to switch among virtual machines hosted by that server. In this paper, we present the concept of a sNICh, which is a combination of a network interface card and switching accelerator for modern virtualized servers. The sNICh architecture exploits the proximity of the switching accelerator to the server by carefully dividing the network switching tasks between them. This division enables the sNICh to address the resource intensiveness of exclusively software-based approaches and the scalability limits of exclusively hardware-based approaches. Essentially, the sNICh hardware performs basic flow-based switching and the sNICh software handles flow setup based on packet filtering rules. The sNICh also minimizes I/O bus bandwidth utilization by transferring, whenever possible, inter-virtual machine traffic within the main memory. We also present a preliminary evaluation of this architecture using software emulation. We compare the performance of the sNICh with two existing software solutions in Xen, the Linux bridge and Open vSwitch. Our results show that the sNICh outperforms both of these existing solutions and also exhibits better scalability.