.\" .\" $FreeBSD: /repoman/r/ncvs/src/share/man/man4/dummynet.4,v 220.127.116.11 2002/11/18 21:51:16 luigi Exp $ .\" .Dd October 28, 2002 .Dt DUMMYNET 4 .Os Darwin .Sh NAME .Nm dummynet .Nd traffic shaper, bandwidth manager and delay emulator .Sh DESCRIPTION .Em dummynet is a system facility that permits the control of traffic going through the various network interfaces, by applying bandwidth and queue size limitations, implementing different scheduling and queue management policies, and emulating delays and losses. .Pp The user interface for .Em dummynet is implemented by the .Nm ipfw program, so the reader is referred to the .Xr ipfw 8 manpage for a complete description of the capabilities of .Nm and on how to use it. .Sh KERNEL OPTIONS The following options in the kernel configuration file are related to .Nm operation: .Bd -literal IPFIREWALL - enable ipfirewall (required for dummynet). IPFIREWALL_VERBOSE - enable firewall output. IPFIREWALL_VERBOSE_LIMIT - limit firewall output. DUMMYNET - enable dummynet operation. NMBCLUSTERS - set the amount of network packet buffers HZ - sets the timer granularity .Ed .Pp Generally, the following options are required: .Bd -literal options IPFIREWALL options DUMMYNET options HZ=1000 # strongly recommended .Ed .Pp additionally, one may want to increase the number of mbuf clusters (used to store network packets) according to the sum of the bandwidth-delay products and queue sizes of all configured pipes. .Sh SEE ALSO .Xr setsockopt 2 , .Xr bridge 4 , .Xr ip 4 , .Xr ipfw 8 , .Xr sysctl 8 .Sh HISTORY .Nm was initially implemented as a testing tool for TCP congestion control by .An Luigi Rizzo Aq firstname.lastname@example.org , as described on ACM Computer Communication Review, Jan.97 issue. Later it has been then modified to work at the ip and bridging level, integrated with the IPFW packet filter, and extended to support multiple queueing and scheduling policies.