dummynet(4) BSD Kernel Interfaces Manual dummynet(4)
NAME
dummynet -- traffic shaper, bandwidth manager and delay emulator
DESCRIPTION
dummynet is a system facility that 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 program, so
the reader is referred to the ipfw(8) manpage for a complete description
of the capabilities of dummynet and on 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 - sets 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
dummynet 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 then modified to
work at the ip and bridging level, integrated with the IPFW packet fil-
ter, and extended to support multiple queueing and scheduling policies.
Darwin October 28, 2002 Darwin
Mac OS X 10.9 - Generated Tue Oct 15 20:56:57 CDT 2013