Efficient High-Speed Data Paths for IP Forwarding using Host Based Routers
Simon Walton, Anne K. Hutton · 2003
Host-based forwarding uses general purpose computers with two or more network interfaces to act as a router. These routers offer certain advantages over the use of dedicated hardware, allowing open, public source code access to the forwarding, queuing, and routing algorithms, and the use of more flexible, commodity host interfaces and host CPUs. The main drawback of host-based forwarding is its inefficiency in supporting high-bandwidth interfaces; although host I/O busses support gigabit throughputs, existing host routers achieve only 25% of this capacity. This paper examines a version of host-based forwarding that substantially increases the capacity of host-based routers, by transferring packets directly between host interfaces, rather than staging them through the host memory. On a 200 Mhz Pentium-Pro FreeBSD PC, the resulting system supports bandwidths in excess of 480 Mbps, a 45% increase compared to conventional techniques. KEYWORDS: host routers, IP forwarding, da...