1.\" 2.\" $FreeBSD$ 3.\" 4.Dd September 10, 2021 5.Dt DUMMYNET 4 6.Os 7.Sh NAME 8.Nm dummynet 9.Nd traffic shaper, bandwidth manager and delay emulator 10.Sh DESCRIPTION 11The 12.Nm 13system facility 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.Nm 20is implemented by the 21.Xr dnctl 8 22utility, so please refer to the 23.Xr dnctl 8 24manpage for a complete description of the 25.Nm 26capabilities and how to use it. 27.Ss Kernel Options 28The following options in the kernel configuration file are related to 29.Nm 30operation: 31.Pp 32.Bl -tag -width ".Dv IPFIREWALL_VERBOSE_LIMIT" -offset indent -compact 33.It Dv IPFIREWALL 34enable ipfirewall (if 35.Nm 36is to be used with ipfw) 37.It Dv IPFIREWALL_VERBOSE 38enable firewall output 39.It Dv IPFIREWALL_VERBOSE_LIMIT 40limit firewall output 41.It Dv DUMMYNET 42enable 43.Nm 44operation 45.It Dv HZ 46set the timer granularity 47.El 48.Pp 49Generally, the following options are required: 50.Bd -literal -offset indent 51options IPFIREWALL 52options DUMMYNET 53options HZ=1000 # strongly recommended 54.Ed 55.Pp 56Additionally, one may want to increase the number 57of mbuf clusters (used to store network packets) according to the 58sum of the bandwidth-delay products and queue sizes of all configured 59pipes. 60.Sh SEE ALSO 61.Xr setsockopt 2 , 62.Xr if_bridge 4 , 63.Xr ip 4 , 64.Xr ipfw 8 , 65.Xr dnctl 8 , 66.Xr pf.conf 5 , 67.Xr sysctl 8 68.Sh HISTORY 69The 70.Nm 71facility 72was initially implemented as a testing tool for 73.Tn TCP 74congestion control by 75.An Luigi Rizzo Aq Mt luigi@iet.unipi.it , 76as described on ACM Computer Communication Review, Jan.97 issue. 77Later it has been modified to work at the 78.Tn IP 79and bridging levels, integrated with the 80.Xr ipfw 4 81packet filter, and extended to 82support multiple queueing and scheduling policies. 83