1.\" 2.\" $FreeBSD: src/share/man/man4/dummynet.4,v 1.4.2.12 2002/11/18 21:51:16 luigi Exp $ 3.\" $DragonFly: src/share/man/man4/dummynet.4,v 1.2 2003/06/17 04:36:59 dillon Exp $ 4.\" 5.Dd October 28, 2002 6.Dt DUMMYNET 4 7.Os 8.Sh NAME 9.Nm dummynet 10.Nd traffic shaper, bandwidth manager and delay emulator 11.Sh DESCRIPTION 12.Em dummynet 13is a system facility that permits the control of traffic 14going through the various network interfaces, by applying bandwidth 15and queue size limitations, implementing different scheduling and queue 16management policies, and emulating delays and losses. 17.Pp 18The user interface for 19.Em dummynet 20is implemented by the 21.Nm ipfw 22program, so the reader is referred to the 23.Xr ipfw 8 24manpage for a complete description of the capabilities of 25.Nm 26and on how to use it. 27.Sh KERNEL OPTIONS 28The following options in the kernel configuration file are related to 29.Nm 30operation: 31.Bd -literal 32 IPFIREWALL - enable ipfirewall (required for dummynet). 33 IPFIREWALL_VERBOSE - enable firewall output. 34 IPFIREWALL_VERBOSE_LIMIT - limit firewall output. 35 DUMMYNET - enable dummynet operation. 36 NMBCLUSTERS - set the amount of network packet buffers 37 HZ - sets the timer granularity 38.Ed 39.Pp 40Generally, the following options are required: 41.Bd -literal 42 options IPFIREWALL 43 options DUMMYNET 44 options HZ=1000 # strongly recommended 45.Ed 46.Pp 47additionally, one may want to increase the number 48of mbuf clusters (used to store network packets) according to the 49sum of the bandwidth-delay products and queue sizes of all configured 50pipes. 51.Sh SEE ALSO 52.Xr setsockopt 2 , 53.Xr bridge 4 , 54.Xr ip 4 , 55.Xr ipfw 8 , 56.Xr sysctl 8 57.Sh HISTORY 58.Nm 59was initially implemented as a testing tool for TCP congestion control 60by 61.An Luigi Rizzo Aq luigi@iet.unipi.it , 62as described on ACM Computer Communication Review, Jan.97 issue. 63Later it has been then modified to work at the ip and bridging 64level, integrated with the IPFW packet filter, and extended to 65support multiple queueing and scheduling policies. 66