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10 .Nd traffic shaper, bandwidth manager and delay emulator
13 is a system facility that permits the control of traffic
14 going through the various network interfaces, by applying bandwidth
15 and queue size limitations, implementing different scheduling and queue
16 management policies, and emulating delays and losses.
18 The user interface for
22 program, so the reader is referred to the
24 manpage for a complete description of the capabilities of
28 The following options in the kernel configuration file are related to
32 IPFIREWALL - enable ipfirewall (required for dummynet).
33 IPFIREWALL_VERBOSE - enable firewall output.
34 IPFIREWALL_VERBOSE_LIMIT - limit firewall output.
35 DUMMYNET - enable dummynet operation.
36 NMBCLUSTERS - set the amount of network packet buffers
39 Generally, the following options are required:
45 additionally, one may want to increase the number
46 of mbuf clusters (used to store network packets) according to the
47 sum of the bandwidth-delay products and queue sizes of all configured
49 Timer granularity is controlled by
52 .Va net.inet.ip.dummynet.hz ,
53 which is set to 1000 by default.
62 was initially implemented as a testing tool for TCP congestion control
64 .An Luigi Rizzo Aq luigi@iet.unipi.it ,
65 as described on ACM Computer Communication Review, Jan.97 issue.
66 Later it has been then modified to work at the ip and bridging
67 level, integrated with the IPFW packet filter, and extended to
68 support multiple queueing and scheduling policies.