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tc(8): Negative indent and missing "-" after an escape
<groff: tc.8>:51: warning: total indent cannot be negative <groff: tc.8>:57: warning: escape character ignored before `i' ********************* Space at end of line removed General considerations a) Manuals should usually only be left justified. Use ".ad l" as the first regular command. b) Each sentence should begin on a new line. The conventions about the amount of space between sentences are different. This also makes a check on the number of space characters between words easier. c) Separate numbers from units with a (no-break) space. A no-break space can be code 0xA0, "\ " (\<space>), or "\~" (groff). d) Use macros "TS/TE" for tables with more than two columns. Then use '\" t as the first line in the source to tell "man" to use the "tbl" preprocessor. e) Protect last period (full stop) in abbreviations with "\&", if it is or might be (through new formatting of source) at the end of line, if it is also not an end of sentence. ********************* Originally filed at: http://bugs.debian.org/674704 Signed-off-by: Andreas Henriksson <andreas@fatal.se>
This commit is contained in:
Bjarni Ingi Gislason
Stephen Hemminger
parent
6fdd09d6a5
commit
7c34520bf5
178
man/man8/tc.8
178
man/man8/tc.8
@ -2,22 +2,22 @@
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.SH NAME
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tc \- show / manipulate traffic control settings
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.SH SYNOPSIS
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.B tc qdisc [ add | change | replace | link ] dev
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DEV
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.B
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[ parent
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qdisc-id
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.B | root ]
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.B [ handle
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.B tc qdisc [ add | change | replace | link ] dev
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DEV
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.B
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[ parent
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qdisc-id
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.B | root ]
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.B [ handle
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qdisc-id ] qdisc
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[ qdisc specific parameters ]
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.P
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.B tc class [ add | change | replace ] dev
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DEV
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.B parent
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qdisc-id
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.B [ classid
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.B parent
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qdisc-id
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.B [ classid
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class-id ] qdisc
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[ qdisc specific parameters ]
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.P
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@ -36,38 +36,38 @@ flow-id
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.B tc
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.RI "[ " FORMAT " ]"
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.B qdisc show [ dev
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DEV
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.B qdisc show [ dev
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DEV
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.B ]
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.P
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.B tc
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.B tc
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.RI "[ " FORMAT " ]"
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.B class show dev
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DEV
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.B class show dev
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DEV
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.P
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.B tc filter show dev
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DEV
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.B tc filter show dev
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DEV
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.ti -8
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.ti 8
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.IR FORMAT " := {"
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\fB\-s\fR[\fItatistics\fR] |
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\fB\-d\fR[\fIetails\fR] |
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\fB\-r\fR[\fIaw\fR] |
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\fB\-p\fR[\fIretty\fR] |
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\fB\i\fR[\fIec\fR] }
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\fB\-i\fR[\fIec\fR] }
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.SH DESCRIPTION
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.B Tc
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is used to configure Traffic Control in the Linux kernel. Traffic Control consists
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is used to configure Traffic Control in the Linux kernel. Traffic Control consists
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of the following:
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.TP
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.TP
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SHAPING
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When traffic is shaped, its rate of transmission is under control. Shaping may
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be more than lowering the available bandwidth - it is also used to smooth out
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When traffic is shaped, its rate of transmission is under control. Shaping may
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be more than lowering the available bandwidth - it is also used to smooth out
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bursts in traffic for better network behaviour. Shaping occurs on egress.
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.TP
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.TP
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SCHEDULING
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By scheduling the transmission of packets it is possible to improve interactivity
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for traffic that needs it while still guaranteeing bandwidth to bulk transfers. Reordering
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@ -80,34 +80,34 @@ arriving. Policing thus occurs on ingress.
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.TP
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DROPPING
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Traffic exceeding a set bandwidth may also be dropped forthwith, both on
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Traffic exceeding a set bandwidth may also be dropped forthwith, both on
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ingress and on egress.
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.P
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Processing of traffic is controlled by three kinds of objects: qdiscs,
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classes and filters.
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Processing of traffic is controlled by three kinds of objects: qdiscs,
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classes and filters.
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.SH QDISCS
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.B qdisc
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is short for 'queueing discipline' and it is elementary to
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understanding traffic control. Whenever the kernel needs to send a
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packet to an interface, it is
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.B qdisc
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is short for 'queueing discipline' and it is elementary to
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understanding traffic control. Whenever the kernel needs to send a
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packet to an interface, it is
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.B enqueued
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to the qdisc configured for that interface. Immediately afterwards, the kernel
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tries to get as many packets as possible from the qdisc, for giving them
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to the network adaptor driver.
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A simple QDISC is the 'pfifo' one, which does no processing at all and is a pure
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A simple QDISC is the 'pfifo' one, which does no processing at all and is a pure
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First In, First Out queue. It does however store traffic when the network interface
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can't handle it momentarily.
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.SH CLASSES
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Some qdiscs can contain classes, which contain further qdiscs - traffic may
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Some qdiscs can contain classes, which contain further qdiscs - traffic may
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then be enqueued in any of the inner qdiscs, which are within the
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.B classes.
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When the kernel tries to dequeue a packet from such a
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When the kernel tries to dequeue a packet from such a
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.B classful qdisc
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it can come from any of the classes. A qdisc may for example prioritize
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it can come from any of the classes. A qdisc may for example prioritize
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certain kinds of traffic by trying to dequeue from certain classes
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before others.
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@ -117,45 +117,45 @@ A
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is used by a classful qdisc to determine in which class a packet will
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be enqueued. Whenever traffic arrives at a class with subclasses, it needs
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to be classified. Various methods may be employed to do so, one of these
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are the filters. All filters attached to the class are called, until one of
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them returns with a verdict. If no verdict was made, other criteria may be
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are the filters. All filters attached to the class are called, until one of
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them returns with a verdict. If no verdict was made, other criteria may be
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available. This differs per qdisc.
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It is important to notice that filters reside
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It is important to notice that filters reside
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.B within
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qdiscs - they are not masters of what happens.
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.SH CLASSLESS QDISCS
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The classless qdiscs are:
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.TP
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.TP
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[p|b]fifo
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Simplest usable qdisc, pure First In, First Out behaviour. Limited in
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Simplest usable qdisc, pure First In, First Out behaviour. Limited in
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packets or in bytes.
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.TP
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pfifo_fast
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Standard qdisc for 'Advanced Router' enabled kernels. Consists of a three-band
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queue which honors Type of Service flags, as well as the priority that may be
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queue which honors Type of Service flags, as well as the priority that may be
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assigned to a packet.
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.TP
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red
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Random Early Detection simulates physical congestion by randomly dropping
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packets when nearing configured bandwidth allocation. Well suited to very
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large bandwidth applications.
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.TP
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.TP
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sfq
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Stochastic Fairness Queueing reorders queued traffic so each 'session'
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gets to send a packet in turn.
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.TP
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tbf
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The Token Bucket Filter is suited for slowing traffic down to a precisely
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configured rate. Scales well to large bandwidths.
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configured rate. Scales well to large bandwidths.
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.SH CONFIGURING CLASSLESS QDISCS
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In the absence of classful qdiscs, classless qdiscs can only be attached at
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In the absence of classful qdiscs, classless qdiscs can only be attached at
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the root of a device. Full syntax:
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.P
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.B tc qdisc add dev
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DEV
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.B root
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.B tc qdisc add dev
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DEV
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.B root
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QDISC QDISC-PARAMETERS
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To remove, issue
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@ -164,7 +164,7 @@ To remove, issue
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DEV
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.B root
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The
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The
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.B pfifo_fast
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qdisc is the automatic default in the absence of a configured qdisc.
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@ -172,85 +172,85 @@ qdisc is the automatic default in the absence of a configured qdisc.
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The classful qdiscs are:
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.TP
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CBQ
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Class Based Queueing implements a rich linksharing hierarchy of classes.
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Class Based Queueing implements a rich linksharing hierarchy of classes.
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It contains shaping elements as well as prioritizing capabilities. Shaping is
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performed using link idle time calculations based on average packet size and
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underlying link bandwidth. The latter may be ill-defined for some interfaces.
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.TP
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HTB
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The Hierarchy Token Bucket implements a rich linksharing hierarchy of
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The Hierarchy Token Bucket implements a rich linksharing hierarchy of
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classes with an emphasis on conforming to existing practices. HTB facilitates
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guaranteeing bandwidth to classes, while also allowing specification of upper
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limits to inter-class sharing. It contains shaping elements, based on TBF and
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can prioritize classes.
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.TP
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can prioritize classes.
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.TP
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PRIO
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The PRIO qdisc is a non-shaping container for a configurable number of
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classes which are dequeued in order. This allows for easy prioritization
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of traffic, where lower classes are only able to send if higher ones have
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no packets available. To facilitate configuration, Type Of Service bits are
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The PRIO qdisc is a non-shaping container for a configurable number of
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classes which are dequeued in order. This allows for easy prioritization
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of traffic, where lower classes are only able to send if higher ones have
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no packets available. To facilitate configuration, Type Of Service bits are
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honored by default.
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.SH THEORY OF OPERATION
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Classes form a tree, where each class has a single parent.
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Classes form a tree, where each class has a single parent.
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A class may have multiple children. Some qdiscs allow for runtime addition
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of classes (CBQ, HTB) while others (PRIO) are created with a static number of
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of classes (CBQ, HTB) while others (PRIO) are created with a static number of
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children.
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Qdiscs which allow dynamic addition of classes can have zero or more
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subclasses to which traffic may be enqueued.
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Qdiscs which allow dynamic addition of classes can have zero or more
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subclasses to which traffic may be enqueued.
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Furthermore, each class contains a
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.B leaf qdisc
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which by default has
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.B pfifo
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behaviour though another qdisc can be attached in place. This qdisc may again
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contain classes, but each class can have only one leaf qdisc.
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which by default has
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.B pfifo
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behaviour though another qdisc can be attached in place. This qdisc may again
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contain classes, but each class can have only one leaf qdisc.
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When a packet enters a classful qdisc it can be
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When a packet enters a classful qdisc it can be
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.B classified
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to one of the classes within. Three criteria are available, although not all
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to one of the classes within. Three criteria are available, although not all
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qdiscs will use all three:
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.TP
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.TP
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tc filters
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If tc filters are attached to a class, they are consulted first
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for relevant instructions. Filters can match on all fields of a packet header,
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as well as on the firewall mark applied by ipchains or iptables.
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If tc filters are attached to a class, they are consulted first
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for relevant instructions. Filters can match on all fields of a packet header,
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as well as on the firewall mark applied by ipchains or iptables.
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.TP
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Type of Service
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Some qdiscs have built in rules for classifying packets based on the TOS field.
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.TP
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skb->priority
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Userspace programs can encode a class-id in the 'skb->priority' field using
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Userspace programs can encode a class-id in the 'skb->priority' field using
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the SO_PRIORITY option.
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.P
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Each node within the tree can have its own filters but higher level filters
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may also point directly to lower classes.
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If classification did not succeed, packets are enqueued to the leaf qdisc
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If classification did not succeed, packets are enqueued to the leaf qdisc
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attached to that class. Check qdisc specific manpages for details, however.
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.SH NAMING
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All qdiscs, classes and filters have IDs, which can either be specified
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or be automatically assigned.
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or be automatically assigned.
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IDs consist of a major number and a minor number, separated by a colon.
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.TP
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.TP
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QDISCS
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A qdisc, which potentially can have children,
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gets assigned a major number, called a 'handle', leaving the minor
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number namespace available for classes. The handle is expressed as '10:'.
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It is customary to explicitly assign a handle to qdiscs expected to have
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A qdisc, which potentially can have children,
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gets assigned a major number, called a 'handle', leaving the minor
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number namespace available for classes. The handle is expressed as '10:'.
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It is customary to explicitly assign a handle to qdiscs expected to have
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children.
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.TP
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.TP
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CLASSES
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Classes residing under a qdisc share their qdisc major number, but each have
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a separate minor number called a 'classid' that has no relation to their
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parent classes, only to their parent qdisc. The same naming custom as for
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a separate minor number called a 'classid' that has no relation to their
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parent classes, only to their parent qdisc. The same naming custom as for
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qdiscs applies.
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.TP
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.TP
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FILTERS
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Filters have a three part ID, which is only needed when using a hashed
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filter hierarchy.
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@ -258,7 +258,7 @@ filter hierarchy.
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All parameters accept a floating point number, possibly followed by a unit.
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.P
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Bandwidths or rates can be specified in:
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.TP
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.TP
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kbps
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Kilobytes per second
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.TP
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@ -306,9 +306,9 @@ Microseconds.
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The following commands are available for qdiscs, classes and filter:
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.TP
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add
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Add a qdisc, class or filter to a node. For all entities, a
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Add a qdisc, class or filter to a node. For all entities, a
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.B parent
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must be passed, either by passing its ID or by attaching directly to the root of a device.
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must be passed, either by passing its ID or by attaching directly to the root of a device.
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When creating a qdisc or a filter, it can be named with the
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.B handle
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parameter. A class is named with the
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@ -317,15 +317,15 @@ parameter.
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.TP
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remove
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A qdisc can be removed by specifying its handle, which may also be 'root'. All subclasses and their leaf qdiscs
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A qdisc can be removed by specifying its handle, which may also be 'root'. All subclasses and their leaf qdiscs
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are automatically deleted, as well as any filters attached to them.
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.TP
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change
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Some entities can be modified 'in place'. Shares the syntax of 'add', with the exception
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that the handle cannot be changed and neither can the parent. In other words,
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that the handle cannot be changed and neither can the parent. In other words,
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.B
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change
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change
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cannot move a node.
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.TP
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@ -335,7 +335,7 @@ it is created.
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.TP
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link
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Only available for qdiscs and performs a replace where the node
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Only available for qdiscs and performs a replace where the node
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must exist already.
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.SH FORMAT
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