dummynet -- traffic shaper, bandwidth manager and delay emulator
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 [Toc] [Back]
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.
setsockopt(2), bridge(4), ip(4), ipfw(8), sysctl(8)
The dummynet facility was initially implemented as a testing tool for TCP
congestion control by Luigi Rizzo <[email protected]>, 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 5.2.1 October 28, 2002 FreeBSD 5.2.1 [ Back ] |
