2 .\" $FreeBSD: src/share/man/man4/dummynet.4,v 1.4.2.12 2002/11/18 21:51:16 luigi Exp $
9 .Nd traffic shaper, bandwidth manager and delay emulator
12 is a system facility that permits the control of traffic
13 going through the various network interfaces, by applying bandwidth
14 and queue size limitations, implementing different scheduling and queue
15 management policies, and emulating delays and losses.
17 The user interface for
21 program, so the reader is referred to the
23 manpage for a complete description of the capabilities of
27 The following options in the kernel configuration file are related to
31 IPFIREWALL - enable ipfirewall (required for dummynet).
32 IPFIREWALL_VERBOSE - enable firewall output.
33 IPFIREWALL_VERBOSE_LIMIT - limit firewall output.
34 DUMMYNET - enable dummynet operation.
35 NMBCLUSTERS - set the amount of network packet buffers
38 Generally, the following options are required:
44 additionally, one may want to increase the number
45 of mbuf clusters (used to store network packets) according to the
46 sum of the bandwidth-delay products and queue sizes of all configured
48 Timer granularity is controlled by
51 .Va net.inet.ip.dummynet.hz ,
52 which is set to 1000 by default.
61 was initially implemented as a testing tool for TCP congestion control
63 .An Luigi Rizzo Aq Mt luigi@iet.unipi.it ,
64 as described on ACM Computer Communication Review, Jan.97 issue.
65 Later it has been then modified to work at the ip and bridging
66 level, integrated with the IPFW packet filter, and extended to
67 support multiple queueing and scheduling policies.