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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 lim-
     itations, implementing different scheduling and queue management poli-
     cies, 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 modi-
     fied 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 5.4		       October 28, 2002 		   FreeBSD 5.4

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