Click vs. Linux: two efficient open-source IP network stacks for software routers

Software routers based on off-the-shelf hardware and open-source operating systems are gaining more and more momentum. The reasons are manifold: first, personal computer (PC) hardware is broadly available at low cost; second, large-scale production and the huge market spur the manufacturers to closely track the improvements made available by Moore´s Law; third, open-source software leaves the freedom to study the source code, learn from it, modify it to improve the performance, and tailor its operation to one´s own needs. In this paper we focus only on the data plane performance and compare the default Linux IP stack with the Click modular IP stack in terms of the forwarding throughput. The results are surprising and show that a high-end PC is easily able to fit into the multi-Gigabit-per-second routing segment, for a price much lower than commercial routers.