Using CPU as a traffic co-processing unit in commodity switches

Commodity switches are becoming increasingly important as they are the basic building blocks for the enterprise and data center networks. With the availability of all-in-one switching ASICs, these switches almost universally adopt single switching ASIC design. However, such design also brings two major limitations, i.e, limited forwarding table for flow-based forwarding scheme such as Openflow and shallow buffer for bursty traffic pattern. In this paper, we propose to use CPU in the switches to handle not only control plane but also data plane traffic. We show that this design can provide large forwarding table for flow-based forwarding scheme and deep packet buffer for bursty traffic. We build such a prototype switch on ServerSwitch platform. In our evaluation, we show that our prototype can achieve over 90% traffic offloading ratio, absorb large traffic bursts without a single packet drop, and can be easily programmed to detect and defend low-rate burst attacks.