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+.TH NETEM 8 "25 November 2011" "iproute2" "Linux"
+.SH NAME
+NetEm \- Network Emulator
+.SH SYNOPSIS
+.B "tc qdisc ... dev"
+.IR DEVICE " ] "
+.BR "add netem"
+.I OPTIONS
+
+.IR OPTIONS " := [ " LIMIT " ] [ " DELAY " ] [ " LOSS \
+" ] [ " CORRUPT " ] [ " DUPLICATION " ] [ " REORDERING " ] [ " RATE \
+" ] [ " SLOT " ]"
+
+.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 " ]]] } "
+.RB  " [ " ecn " ] "
+
+.IR CORRUPT " := "
+.B corrupt
+.IR PERCENT " [ " CORRELATION " ]]"
+
+.IR DUPLICATION " := "
+.B duplicate
+.IR PERCENT " [ " CORRELATION " ]]"
+
+.IR REORDERING " := "
+.B reorder
+.IR PERCENT " [ " CORRELATION " ] [ "
+.B gap
+.IR DISTANCE " ]"
+
+.IR RATE " := "
+.B rate
+.IR RATE " [ " PACKETOVERHEAD " [ " CELLSIZE " [ " CELLOVERHEAD " ]]]]"
+
+.IR SLOT " := "
+.BR slot " { "
+.IR MIN_DELAY " [ " MAX_DELAY " ] |"
+.br
+.RB "               " distribution " { "uniform " | " normal " | " pareto " | " paretonormal " | "
+.IR FILE " } " DELAY " " JITTER " } "
+.br
+.RB "             [ " packets
+.IR PACKETS " ] [ "
+.BR bytes
+.IR BYTES " ]"
+
+
+.SH DESCRIPTION
+NetEm is an enhancement of the Linux traffic control facilities
+that allow one to add delay, packet loss, duplication and more other
+characteristics to packets outgoing from a selected network
+interface. NetEm is built using the existing Quality Of Service (QOS)
+and Differentiated Services (diffserv) facilities in the Linux
+kernel.
+
+.SH netem OPTIONS
+netem has the following options:
+
+.SS limit packets
+
+maximum number of packets the qdisc may hold queued at a time.
+
+.SS delay
+adds the chosen delay to the packets outgoing to chosen network interface. The
+optional parameters allows one to introduce a delay variation and a correlation.
+Delay and jitter values are expressed in ms while correlation is percentage.
+
+.SS distribution
+allow the user to choose the delay distribution. If not specified, the default
+distribution is Normal. Additional parameters allow one to consider situations in
+which network has variable delays depending on traffic flows concurring on the
+same path, that causes several delay peaks and a tail.
+
+.SS loss random
+adds an independent loss probability to the packets outgoing from the chosen
+network interface. It is also possible to add a correlation, but this option
+is now deprecated due to the noticed bad behavior.
+
+.SS loss state
+adds packet losses according to the 4-state Markov using the transition
+probabilities as input parameters. The parameter p13 is mandatory and if used
+alone corresponds to the Bernoulli model. The optional parameters allows one to
+extend the model to 2-state (p31), 3-state (p23 and p32) and 4-state (p14).
+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.
+
+.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 others will be set to the default
+values r=1-p, 1-h=1 and 1-k=0. The parameters needed for the Simple Gilbert
+model are two (p and r), while three parameters (p, r, 1-h) are needed for the
+Gilbert model and four (p, r, 1-h and 1-k) are needed for the Gilbert-Elliot
+model. As known, p and r are the transition probabilities between the bad and
+the good states, 1-h is the loss probability in the bad state and 1-k is the
+loss probability in the good state.
+
+.SS ecn
+can be used optionally to mark packets instead of dropping them. A loss model
+has to be used for this to be enabled.
+
+.SS corrupt
+allows the emulation of 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.
+
+.SS duplicate
+using this option the chosen percent of packets is duplicated before queuing
+them. It is also possible to add a correlation through the proper parameter.
+
+.SS reorder
+to use reordering, a delay option must be specified. There are two ways to use
+this option (assuming 'delay 10ms' in the options list).
+
+.B "reorder "
+.I 25% 50%
+.B "gap"
+.I 5
+.br
+in this first example, the first 4 (gap - 1) packets are delayed by 10ms and
+subsequent packets are sent immediately with a probability of 0.25 (with
+correlation of 50% ) or delayed with a probability of 0.75. After a packet is
+reordered, the process restarts i.e. the next 4 packets are delayed and
+subsequent packets are sent immediately or delayed based on reordering
+probability. To cause a repeatable pattern where every 5th packet is reordered
+reliably, a reorder probability of 100% can be used.
+
+.B reorder
+.I 25% 50%
+.br
+in this second example 25% of packets are sent immediately (with correlation of
+50%) while the others are delayed by 10 ms.
+
+.SS rate
+delay packets based on packet size and is a replacement for
+.IR TBF .
+Rate can be
+specified in common units (e.g. 100kbit). Optional
+.I PACKETOVERHEAD
+(in bytes) specify an per packet overhead and can be negative. A positive value can be
+used to simulate additional link layer headers. A negative value can be used to
+artificial strip the Ethernet header (e.g. -14) and/or simulate a link layer
+header compression scheme. The third parameter - an unsigned value - specify
+the cellsize. Cellsize can be used to simulate link layer schemes. ATM for
+example has an payload cellsize of 48 bytes and 5 byte per cell header. If a
+packet is 50 byte then ATM must use two cells: 2 * 48 bytes payload including 2
+* 5 byte header, thus consume 106 byte on the wire. The last optional value
+.I CELLOVERHEAD
+can be used to specify per cell overhead - for our ATM example 5.
+.I CELLOVERHEAD
+can be negative, but use negative values with caution.
+
+Note that rate throttling is limited by several factors: the kernel clock
+granularity avoid a perfect shaping at a specific level. This will show up in
+an artificial packet compression (bursts). Another influence factor are network
+adapter buffers which can also add artificial delay.
+
+.SS slot
+defer delivering accumulated packets to within a slot. Each available slot can be
+configured with a minimum delay to acquire, and an optional maximum delay.
+Alternatively it can be configured with the distribution similar to
+.BR distribution
+for
+.BR delay
+option. Slot delays can be specified in nanoseconds, microseconds, milliseconds or seconds
+(e.g. 800us). Values for the optional parameters
+.I BYTES
+will limit the number of bytes delivered per slot, and/or
+.I PACKETS
+will limit the number of packets delivered per slot.
+
+These slot options can provide a crude approximation of bursty MACs such as
+DOCSIS, WiFi, and LTE.
+
+Note that slotting is limited by several factors: the kernel clock granularity,
+as with a rate, and attempts to deliver many packets within a slot will be
+smeared by the timer resolution, and by the underlying native bandwidth also.
+
+It is possible to combine slotting with a rate, in which case complex behaviors
+where either the rate, or the slot limits on bytes or packets per slot, govern
+the actual delivered rate.
+
+.SH LIMITATIONS
+The main known limitation of Netem are related to timer granularity, since
+Linux is not a real-time operating system.
+
+.SH EXAMPLES
+.PP
+tc qdisc add dev eth0 root netem rate 5kbit 20 100 5
+.RS 4
+delay all outgoing packets on device eth0 with a rate of 5kbit, a per packet
+overhead of 20 byte, a cellsize of 100 byte and a per celloverhead of 5 byte:
+.RE
+
+.SH SOURCES
+.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)
+
+.IP " 2. " 4
+Netem page from Linux foundation, (https://wiki.linuxfoundation.org/networking/netem)
+
+.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
+
+.SH SEE ALSO
+.BR tc (8),
+.BR tc-tbf (8)
+
+.SH AUTHOR
+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>