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DUMMYNET(4)            FreeBSD Kernel Interfaces Manual            DUMMYNET(4)

NAME
     dummynet - traffic shaper, bandwidth manager and delay emulator

DESCRIPTION
     The dummynet system facility permits the control of traffic going through
     the various network interfaces, by applying bandwidth and queue size
     limitations, implementing different scheduling and queue management
     policies, and emulating delays and losses.

     The user interface for dummynet is implemented by the ipfw(8) utility, so
     please refer to the ipfw(8) manpage for a complete description of the
     dummynet capabilities and how to use it.

   Kernel Options
     The following options in the kernel configuration file are related to
     dummynet operation:

           IPFIREWALL                    enable ipfirewall (required for
                                         dummynet)
           IPFIREWALL_VERBOSE            enable firewall output
           IPFIREWALL_VERBOSE_LIMIT      limit firewall output
           DUMMYNET                      enable dummynet operation
           NMBCLUSTERS                   set the amount of network packet
                                         buffers
           HZ                            set the timer granularity

     Generally, the following options are required:

           options IPFIREWALL
           options DUMMYNET
           options HZ=1000         # strongly recommended

     Additionally, one may want to increase the number of mbuf clusters (used
     to store network packets) according to the sum of the bandwidth-delay
     products and queue sizes of all configured pipes.

SEE ALSO
     setsockopt(2), bridge(4), ip(4), ipfw(8), sysctl(8)

HISTORY
     The dummynet facility was initially implemented as a testing tool for TCP
     congestion control by Luigi Rizzo <luigi@iet.unipi.it>, as described on
     ACM Computer Communication Review, Jan.97 issue.  Later it has been
     modified to work at the IP and bridging levels, integrated with the
     ipfw(4) packet filter, and extended to support multiple queueing and
     scheduling policies.

FreeBSD 11.0-PRERELEASE        October 28, 2002        FreeBSD 11.0-PRERELEASE

NAME | DESCRIPTION | SEE ALSO | HISTORY

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