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