$FreeBSD: releng/11.0/share/man/man4/dummynet.4 267938 2014-06-26 21:46:14Z bapt $
NAMEdummynet - traffic shaper, bandwidth manager and delay emulator
DESCRIPTIONThe sysctl Cm net.inet.tcp.syncookies 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 sysctl Cm net.inet.tcp.syncookies is implemented by the ipfw(8) utility, so please refer to the ipfw(8) manpage for a complete description of the sysctl Cm net.inet.tcp.syncookies capabilities and how to use it.
Kernel OptionsThe following options in the kernel configuration file are related to sysctl Cm net.inet.tcp.syncookies operation:
- enable ipfirewall (required for )
- enable firewall output
- limit firewall output
- enable sysctl Cm net.inet.tcp.syncookies operation
- 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.