Dummynet is a live network emulation tool, originally designed for testing networking protocols, and since then used for a variety of applications including bandwidth management. It simulates/enforces queue and bandwidth limitations, delays, packet losses, and multipath effects. It also implements various scheduling algorithms. Dummynet can be used on the machine running the user's application, or on external boxes acting as routers or bridges. Dummynet runs within your operating system (FreeBSD, OSX, Linux, Windows) and works by intercepting selected traffic on its way through the network stack, as in the figure above, and passing packets to objects called pipes which implement a set of queues, a scheduler, and a link, all with configurable features (bandwidth, delay, loss rate, queue size, scheduling policy.). Trimble Geomatics Office Download Keygen. Traffic selection is done using the ipfw firewall, which is the main user interface for dummynet. Ipfw lets you select precisely the traffic and direction you want to work on, making configuration and use incredibly simple.

You can create multiple pipes, send traffic to different pipes, even build cascades of pipes. Just a few examples: • limit the total incoming TCP traffic to 2Mbit/s, and UDP to 300Kbit/s ipfw add pipe 2 in proto tcp ipfw add pipe 3 in proto udp ipfw pipe 2 config bw 2Mbit/s ipfw pipe 3 config bw 300Kbit/s • limit incoming traffic to 300Kbit/s for each host on network 10.1.2.0/24 ipfw add pipe 4 src-ip 10.1.2.0/24 in ipfw pipe 4 config bw 300Kbit/s queue 20 mask dst-ip 0x000000ff • simulate an ADSL link to the moon: ipfw add pipe 3 out ipfw add pipe 4 in ipfw pipe 3 config bw 128Kbit/s queue 10 delay 1000ms ipfw pipe 4 config bw 640Kbit/s queue 30 delay 1000ms dummynet is widely used. It is a standard component in FreeBSD and OSX, it is used as link emulator on Emulab, PlanetLab, Hen and many private testbeds.