1.\" 2.Dd September 10, 2021 3.Dt DUMMYNET 4 4.Os 5.Sh NAME 6.Nm dummynet 7.Nd traffic shaper, bandwidth manager and delay emulator 8.Sh DESCRIPTION 9The 10.Nm 11system facility permits the control of traffic 12going through the various network interfaces, by applying bandwidth 13and queue size limitations, implementing different scheduling and queue 14management policies, and emulating delays and losses. 15.Pp 16The user interface for 17.Nm 18is implemented by the 19.Xr dnctl 8 20utility, so please refer to the 21.Xr dnctl 8 22manpage for a complete description of the 23.Nm 24capabilities and how to use it. 25.Ss Kernel Options 26The following options in the kernel configuration file are related to 27.Nm 28operation: 29.Pp 30.Bl -tag -width ".Dv IPFIREWALL_VERBOSE_LIMIT" -offset indent -compact 31.It Dv IPFIREWALL 32enable ipfirewall (if 33.Nm 34is to be used with ipfw) 35.It Dv IPFIREWALL_VERBOSE 36enable firewall output 37.It Dv IPFIREWALL_VERBOSE_LIMIT 38limit firewall output 39.It Dv DUMMYNET 40enable 41.Nm 42operation 43.It Dv HZ 44set the timer granularity 45.El 46.Pp 47Generally, the following options are required: 48.Bd -literal -offset indent 49options IPFIREWALL 50options DUMMYNET 51options HZ=1000 # strongly recommended 52.Ed 53.Pp 54Additionally, one may want to increase the number 55of mbuf clusters (used to store network packets) according to the 56sum of the bandwidth-delay products and queue sizes of all configured 57pipes. 58.Sh SEE ALSO 59.Xr setsockopt 2 , 60.Xr if_bridge 4 , 61.Xr ip 4 , 62.Xr ipfw 8 , 63.Xr dnctl 8 , 64.Xr pf.conf 5 , 65.Xr sysctl 8 66.Sh HISTORY 67The 68.Nm 69facility 70was initially implemented as a testing tool for 71.Tn TCP 72congestion control by 73.An Luigi Rizzo Aq Mt luigi@iet.unipi.it , 74as described on ACM Computer Communication Review, Jan.97 issue. 75Later it has been modified to work at the 76.Tn IP 77and bridging levels, integrated with the 78.Xr ipfw 4 79packet filter, and extended to 80support multiple queueing and scheduling policies. 81