You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
149 lines
4.5 KiB
149 lines
4.5 KiB
.TH HTB 8 "10 January 2002" "iproute2" "Linux"
|
|
.SH NAME
|
|
HTB \- Hierarchy Token Bucket
|
|
.SH SYNOPSIS
|
|
.B tc qdisc ... dev
|
|
dev
|
|
.B ( parent
|
|
classid
|
|
.B | root) [ handle
|
|
major:
|
|
.B ] htb [ default
|
|
minor-id
|
|
.B ]
|
|
|
|
.B tc class ... dev
|
|
dev
|
|
.B parent
|
|
major:[minor]
|
|
.B [ classid
|
|
major:minor
|
|
.B ] htb rate
|
|
rate
|
|
.B [ ceil
|
|
rate
|
|
.B ] burst
|
|
bytes
|
|
.B [ cburst
|
|
bytes
|
|
.B ] [ prio
|
|
priority
|
|
.B ]
|
|
|
|
.SH DESCRIPTION
|
|
HTB is meant as a more understandable and intuitive replacement for
|
|
the CBQ qdisc in Linux. Both CBQ and HTB help you to control the use
|
|
of the outbound bandwidth on a given link. Both allow you to use one
|
|
physical link to simulate several slower links and to send different
|
|
kinds of traffic on different simulated links. In both cases, you have
|
|
to specify how to divide the physical link into simulated links and
|
|
how to decide which simulated link to use for a given packet to be sent.
|
|
|
|
Unlike CBQ, HTB shapes traffic based on the Token Bucket Filter algorithm
|
|
which does not depend on interface characteristics and so does not need to
|
|
know the underlying bandwidth of the outgoing interface.
|
|
|
|
.SH SHAPING ALGORITHM
|
|
Shaping works as documented in
|
|
.B tc-tbf (8).
|
|
|
|
.SH CLASSIFICATION
|
|
Within the one HTB instance many classes may exist. Each of these classes
|
|
contains another qdisc, by default
|
|
.BR tc-pfifo (8).
|
|
|
|
When enqueueing a packet, HTB starts at the root and uses various methods to
|
|
determine which class should receive the data.
|
|
|
|
In the absence of uncommon configuration options, the process is rather easy.
|
|
At each node we look for an instruction, and then go to the class the
|
|
instruction refers us to. If the class found is a barren leaf-node (without
|
|
children), we enqueue the packet there. If it is not yet a leaf node, we do
|
|
the whole thing over again starting from that node.
|
|
|
|
The following actions are performed, in order at each node we visit, until one
|
|
sends us to another node, or terminates the process.
|
|
.TP
|
|
(i)
|
|
Consult filters attached to the class. If sent to a leafnode, we are done.
|
|
Otherwise, restart.
|
|
.TP
|
|
(ii)
|
|
If none of the above returned with an instruction, enqueue at this node.
|
|
.P
|
|
This algorithm makes sure that a packet always ends up somewhere, even while
|
|
you are busy building your configuration.
|
|
|
|
.SH LINK SHARING ALGORITHM
|
|
FIXME
|
|
|
|
.SH QDISC
|
|
The root of a HTB qdisc class tree has the following parameters:
|
|
|
|
.TP
|
|
parent major:minor | root
|
|
This mandatory parameter determines the place of the HTB instance, either at the
|
|
.B root
|
|
of an interface or within an existing class.
|
|
.TP
|
|
handle major:
|
|
Like all other qdiscs, the HTB can be assigned a handle. Should consist only
|
|
of a major number, followed by a colon. Optional, but very useful if classes
|
|
will be generated within this qdisc.
|
|
.TP
|
|
default minor-id
|
|
Unclassified traffic gets sent to the class with this minor-id.
|
|
|
|
.SH CLASSES
|
|
Classes have a host of parameters to configure their operation.
|
|
|
|
.TP
|
|
parent major:minor
|
|
Place of this class within the hierarchy. If attached directly to a qdisc
|
|
and not to another class, minor can be omitted. Mandatory.
|
|
.TP
|
|
classid major:minor
|
|
Like qdiscs, classes can be named. The major number must be equal to the
|
|
major number of the qdisc to which it belongs. Optional, but needed if this
|
|
class is going to have children.
|
|
.TP
|
|
prio priority
|
|
In the round-robin process, classes with the lowest priority field are tried
|
|
for packets first. Mandatory.
|
|
|
|
.TP
|
|
rate rate
|
|
Maximum rate this class and all its children are guaranteed. Mandatory.
|
|
|
|
.TP
|
|
ceil rate
|
|
Maximum rate at which a class can send, if its parent has bandwidth to spare.
|
|
Defaults to the configured rate, which implies no borrowing
|
|
|
|
.TP
|
|
burst bytes
|
|
Amount of bytes that can be burst at
|
|
.B ceil
|
|
speed, in excess of the configured
|
|
.B rate.
|
|
Should be at least as high as the highest burst of all children.
|
|
|
|
.TP
|
|
cburst bytes
|
|
Amount of bytes that can be burst at 'infinite' speed, in other words, as fast
|
|
as the interface can transmit them. For perfect evening out, should be equal to at most one average
|
|
packet. Should be at least as high as the highest cburst of all children.
|
|
|
|
.SH NOTES
|
|
Due to Unix timing constraints, the maximum ceil rate is not infinite and may in fact be quite low. On Intel,
|
|
there are 100 timer events per second, the maximum rate is that rate at which 'burst' bytes are sent each timer tick.
|
|
From this, the minimum burst size for a specified rate can be calculated. For i386, a 10mbit rate requires a 12 kilobyte
|
|
burst as 100*12kb*8 equals 10mbit.
|
|
|
|
.SH SEE ALSO
|
|
.BR tc (8)
|
|
.P
|
|
HTB website: http://luxik.cdi.cz/~devik/qos/htb/
|
|
.SH AUTHOR
|
|
Martin Devera <devik@cdi.cz>. This manpage maintained by bert hubert <ahu@ds9a.nl>
|