1 Efficient High-Speed Data Paths for IP Forwarding using Host Based Routers

发布时间：2011-09-02 19:23:49

Efficient High-Speed Data Paths for IPForwarding using Host Based RoutersSimon Walton, Anne Hutton, JoeTouch†USC / Information Sciences InstituteAbstractHost-based forwarding uses general purpose computers with twoor more network interfaces to act as a router.These routers offercertain advantages over the use of dedicated hardware,allowingopen,public source code access to the forwarding,queuing,androuting algorithms,and the use of moreflexible,commodity hostinterfaces and host CPUs.The main drawback of host-basedforwarding is its inefficiency in supporting high-bandwidthinterfaces;although host I/O busses support gigabit throughputs,existing host routers achieve only25%of this capacity.This paperexamines a version of host-based forwarding that substantiallyincreases the capacity of host-based routers,by transferringpackets directly between host interfaces,rather than staging themthrough the host memory.On a200Mhz Pentium-Pro FreeBSD PC,the resulting system supports bandwidths in excess of480Mbps,a45% increase compared to conventional techniques.KEYWORDS:host routers,IP forwarding,data paths,peer DMA,router performance1.0 IntroductionHost workstations are increasingly being used as routers.Using commodity platforms and network interfaces,these host-based routers can be cheaper,and allow moreflexible configuration and programmability than production routers.This work optimizes the data path in a host-based router, to increase routing bandwidth, while reducing backplane bandwidth and CPU load.Production routers are special-purpose systems,which use custom backplanes and line interface cards,with closed,proprietary software.These systems are often limiting,because of †. This work is supported by the Defense Advanced Research Projects Agency through Ft. Huachuca contract#DABT63-93-C-0062entitled“Netstation Architecture and Advanced Atomic Network”.The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied,of the Department of the Army,the Defense Advanced Research Projects Agency,or the U.S. Government.1

1 Efficient High-Speed Data Paths for IP Forwarding using Host Based Routers

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