1.\" 2.Dd October 28, 2002 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 ipfw 8 20utility, so please refer to the 21.Xr ipfw 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 (required for 33.Nm ) 34.It Dv IPFIREWALL_VERBOSE 35enable firewall output 36.It Dv IPFIREWALL_VERBOSE_LIMIT 37limit firewall output 38.It Dv DUMMYNET 39enable 40.Nm 41operation 42.It Dv HZ 43set the timer granularity 44.El 45.Pp 46Generally, the following options are required: 47.Bd -literal -offset indent 48options IPFIREWALL 49options DUMMYNET 50options HZ=1000 # strongly recommended 51.Ed 52.Pp 53Additionally, one may want to increase the number 54of mbuf clusters (used to store network packets) according to the 55sum of the bandwidth-delay products and queue sizes of all configured 56pipes. 57.Sh SEE ALSO 58.Xr setsockopt 2 , 59.Xr if_bridge 4 , 60.Xr ip 4 , 61.Xr ipfw 8 , 62.Xr sysctl 8 63.Sh HISTORY 64The 65.Nm 66facility 67was initially implemented as a testing tool for 68.Tn TCP 69congestion control by 70.An Luigi Rizzo Aq Mt luigi@iet.unipi.it , 71as described on ACM Computer Communication Review, Jan.97 issue. 72Later it has been modified to work at the 73.Tn IP 74and bridging levels, integrated with the 75.Xr ipfw 4 76packet filter, and extended to 77support multiple queueing and scheduling policies. 78