.SH NAME
NetEm \- Network Emulator
.SH SYNOPSIS
-.B tc qdisc ... dev
-dev
-.B ] add netem [ limit
-packets
-.B ]
+.B "tc qdisc ... dev"
+.IR dev " ] "
+.BR "add netem"
+.I OPTIONS
-.B tc qdisc ... dev
-dev
-.B ] add netem [ logging
-LEVEL ]
-.B ]
+.IR OPTIONS " := [ " LIMIT " ] [ " DELAY " ] [ " LOSS \
+" ] [ " CORRUPT " ] [ " DUPLICATION " ] [ " REORDERING " ]"
-.B tc qdisc ... dev
-dev
-.B ] add netem [ delay
-TIME [ JITTER [CORRELATION]]]
-.B ]
-
-.B tc qdisc ... dev
-dev
-.B ] add netem [ distribution
-{uniform|normal|pareto|paretonormal} ]
-.B ]
-
-.B tc qdisc ... dev
-dev
-.B ] add netem [ drop
-PERCENT [CORRELATION]]
-.B ]
-
-.B tc qdisc ... dev
-dev
-.B ] add netem [ loss
-PERCENT [CORRELATION]]
-.B ]
-
-
-.B tc qdisc ... dev
-dev
-.B ] add netem [ query ] [ loss_GI
-ploss [burst_length [density [pisol [good_burst_length]]]]
-.B ]
-
-.B tc qdisc ... dev
-dev
-.B ] add netem [ query ] [ loss_4state
-[p13 [p31 [p32 [p23 [p14]]]]]
-.B ]
-
-.B tc qdisc ... dev
-dev
-.B ] add netem [ loss_gilb_ell
-p [r [1-h [1-k]]]
-.B ]
-
-.B tc qdisc ... dev
-dev
-.B ] add netem [ loss_gilb_ell_4s
-p [r [1-h [1-k]]]
-.B ]
-
-.B tc qdisc ... dev
-dev
-.B ] add netem [ loss_pattern
-FILENAME [REPETITIONS]]
-.B ]
-
-.B tc qdisc ... dev
-dev
-.B ] add netem [ corrupt
-PERCENT [CORRELATION]]
-.B ]
+.IR LIMIT " := "
+.B limit
+.I packets
+
+.IR DELAY " := "
+.BI delay
+.IR TIME " [ " JITTER " [ " CORRELATION " ]]]"
+.br
+ [
+.BR distribution " { "uniform " | " normal " | " pareto " | " paretonormal " } ]"
+
+.IR LOSS " := "
+.BR loss " { "
+.BI random
+.IR PERCENT " [ " CORRELATION " ] |"
+.br
+.RB " " state
+.IR p13 " [ " p31 " [ " p32 " [ " p23 " [ " p14 "]]]] |"
+.br
+.RB " " gemodel
+.IR p " [ " r " [ " 1-h " [ " 1-k " ]]]"
+
+.IR CORRUPT " := "
+.B corrupt
+.IR PERCENT " [ " CORRELATION " ]]"
-.B tc qdisc ... dev
-dev
-.B ] add netem [ duplicate
-PERCENT [CORRELATION]]
-.B ]
+.IR DUPLICATION " := "
+.B duplicate
+.IR PERCENT " [ " CORRELATION " ]]"
-.B tc qdisc ... dev
-dev
-.B ] add netem [ reorder
-PRECENT [CORRELATION] [ gap DISTANCE ]]
-.B ]
+.IR REODERING " := "
+.B reorder
+.IR PERCENT " [ " CORRELATION " ] [ "
+.B gap
+.IR DISTANCE " ]"
.SH DESCRIPTION
NetEm is an enhancement of the Linux traffic control facilities
.SH netem OPTIONS
netem has the following options:
-.B limit
-packets
+.SS limit packets
limits the effect of selected options to the indicated number of next packets.
-.B logging
-LEVEL
-
-sets a logging level. Actually it works with loss_GI, loss_4state, loss_bern,
-loss_gilb, loss_gilb_ell, loss_gilb_ell_4s, loss_pattern options. The default
-value is level 0, which means that no data will be logged. When logging level
-is set to 1 the kernel logs will include a line like "netem loss event
-algorithm [type] x RFPLE y" for each loss event. The acronym RFPLE means
-"Received From Previous Loss Event" and it counts the number y of good packets
-received between two loss events while x is the number of all lost packets and
-algorithm refers to the selected loss generation algorithm (4-state, gilb_ell
-or deterministic). The type label applies only to the GI algorithm and can be
-burst or isolated.
-
-.B delay
-TIME [ JITTER [CORRELATION]]]
-
+.SS delay
adds the chosen delay to the packets outgoing to chosen network interface. The
optional parameters allows to introduce a delay variation and a correlation.
Delay and jitter values are expressed in ms while correlation is percentage.
-.B distribution
-{uniform|normal|pareto|paretonormal}
-
+.SS distribution
allow the choose the delay distribution. If not specified, the default
distribution is normal. Additional parameters allow to consider situations in
which network has variable delays depending on traffic flows concurring on the
same path, that causes severeal delay peaks and a tail.
-.B drop
-PERCENT [CORRELATION]
-
-OR
-
-.B loss
-PERCENT [CORRELATION]
-
+.SS loss random
adds an independent loss probability to the packets outgoing from the chosen
network interface. It is also possibile to add a correlation, but this option
is now deprecated due to the noticed bad behaviour.
-.B query
-
-enables the query mode. It applies to loss_GI and loss_4state options. If it is
-used with the loss_GI option, the transition probabilities which correspond to
-the input intuitive parameters are calculated and printed to screen, without
-copying them in the netem qdisc. Similarly, if it is used with the loss_4state
-option, it calculates and prints the intuitive parameters that corresponds to
-the input transition probabilities.
-
-.B loss_GI
-ploss [burst_length [density [pisol [good_burst_length]]]]
-
-adds packet losses according to the GI (General and Intuitive) loss model,
-using the intuitive parameters. The parameter ploss is mandatory while the
-others are optional. The intuitive parameters are converted to the transition
-probabilities of the 4-state Markov model. If the only parameter specified is
-ploss, it corresponds to the Bernoulli model while the optional parameters
-allow to extend the model to 2-state (burst_length), 3-state (density), and
-4-state (pisol). If the good_burst_length is not specified the hyphotesis of
-statistical independence for the losses within the burst will be used.
-
-.B loss_4state
-p13 [p31 [p32 [p23 [p14]]]]
-
+.SS loss state
adds packet losses according to the 4-state Markov using the transition
probabilities as input parameters. The parameters p13 is mandatory and if used
alone corresponds to the Bernoulli model. The optional parameters allows to
State 1 corresponds to good reception, State 4 to independent losses, State 3
to burst losses and State 2 to good reception within a burst.
-.B loss_gilb_ell
-p [r [1-h [1-k]]]
-
+.SS loss gemodel
adds packet losses according to the Gilbert-Elliot loss model or its special
cases (Gilbert, Simple Gilbert and Bernoulli). To use the Bernoulli model, the
only needed parameter is p while the the others will be set to the default
the good states, 1-h is the loss probability in the bad state and 1-k is the
loss probability in the good state.
-.B loss_gilb_ell_4s
-p [r [1-h [1-k]]]
-
-adds packet losses according to the Gilbert-Elliot-4s loss model. It is a
-particular version of the GI model which behaviour is very similar to the
-Gilbert-Elliot's. The input parameters are the same of the real Gilbert-Elliot
-model or its special cases. The transition probabilities and GI parameters that
-corresponds to the Gilbert-Elliot input parameters are calculated and, if the
-query mode is enabled, printed to screen. This option is included to study the
-correspondence between GI model and the models available in the literature, it
-has no practical use at the moment.
-
-.B loss_pattern
-FILENAME [REPETITIONS]
-
-adds packet losses according to a deterministic loss pattern. It reads from the
-text file FILENAME a sequence of "1" and "0" where "1" are the loss events and
-"0" are the regular transmission of packets . The parameter repetitions is
-optional and is the number of "replicas" of the loss pattern file. It is
-optional and by default is 0 which means infinite repetition of the loss
-pattern.
-
-.B corrupt
-PERCENT [CORRELATION]]
-
+.SS corrupt
allows the emulate the random noise introducing an error in a random position
for a chosen percent of packets. It is also possible to add a correlation
through the proper parameter.
-.B duplicate
-PERCENT [CORRELATION]]
-
+.SS duplicate
using this option the chosen percent of packets is duplicated before queueing
them. It is also possible to add a correlation through the proper parameter.
-.B reorder
-PRECENT [CORRELATION] [ gap DISTANCE ]]
-
+.SS reorder
there are two ways to use this option:
-.B reorder
-gap 5 10 ms
-
+.B "reorder gap"
+.I 5 10
+.br
in this first example every 5th (10th, 15th) packet is sent immediately while
other packets are delayed by 10 ms
.B reorder
-25% 50%
-
+.I 25% 50%
+.br
in this second example 25% of packets are sent immediately (with correlation of
50%) while the other are delayed by 10 ms.
.SH LIMITATIONS
The main known limitation of Netem are related to timer granularity, since
-Linux is not a real-time operating system; to the choice of Pseudo-Random
-Number Generator (PRNG) and the original loss model.
+Linux is not a real-time operating system.
.SH SOURCES
-.TP
-o
+.IP " 1. " 4
Hemminger S. , "Network Emulation with NetEm", Open Source Development Lab,
April 2005
(http://devresources.linux-foundation.org/shemminger/netem/LCA2005_paper.pdf)
-.TP
-o
+.IP " 2. " 4
Netem page from Linux foundation, (http://www.linuxfoundation.org/en/Net:Netem)
-.TP
-o
+.IP " 3. " 4
Salsano S., Ludovici F., Ordine A., "Definition of a general and intuitive loss
model for packet networks and its implementation in the Netem module in the
Linux kernel", available at http://netgroup.uniroma2.it/NetemCLG
.BR tc-tbf (8)
.SH AUTHOR
-Netem was written by Stephen Hemminger at OSDL and is based on NISTnet. This
-manpage was created by Fabio Ludovici <fabio.ludovici at yahoo dot it> and
+Netem was written by Stephen Hemminger at Linux foundation and is based on NISTnet.
+This manpage was created by Fabio Ludovici <fabio.ludovici at yahoo dot it> and
Hagen Paul Pfeifer <hagen@jauu.net>
projects / lisovros / iproute2_canprio.git / commitdiff