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:
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),
if_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.