DUMMYNET (4) | Special files and drivers | Unix Manual Pages | :man▋
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.
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 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), if_bridge(4), ip(4), ipfw(8), sysctl(8)