ALTQ(4)

NAME
ALTQ - alternate queuing of network packets

SYNOPSIS
options ALTQ

options ALTQ_CBQ
options ALTQ_CODEL
options ALTQ_RED
options ALTQ_RIO
options ALTQ_HFSC
options ALTQ_CDNR
options ALTQ_PRIQ
options ALTQ_FAIRQ

DESCRIPTION
The ALTQ system is a framework which provides several disciplines for queuing outgoing network packets. This is done by modifications to the interface packet queues. See altq(9) for details.

The user interface for ALTQ is implemented by the pfctl(8) utility, so please refer to the pfctl(8) and the pf.conf(5) man pages for a complete description of the ALTQ capabilities and how to use it.

  Kernel Options
The following options in the kernel configuration file are related to ALTQ operation:

ALTQ
    Enable ALTQ.
ALTQ_CBQ
    Build the “Class Based Queuing” discipline.
ALTQ_CODEL
    Build the “Controlled Delay” discipline.
ALTQ_RED
    Build the “Random Early Detection” extension.
ALTQ_RIO
    Build “Random Early Drop” for input and output.
ALTQ_HFSC
    Build the “Hierarchical Packet Scheduler” discipline.
ALTQ_CDNR
    Build the traffic conditioner. This option is meaningless at the moment as the conditioner is not used by any of the available disciplines or consumers.
ALTQ_PRIQ
    Build the “Priority Queuing” discipline.
ALTQ_FAIRQ
    Build the “Fair Queuing” discipline.
ALTQ_NOPCC
    Required if the TSC is unusable.
ALTQ_DEBUG
    Enable additional debugging facilities.

Note that ALTQ-disciplines cannot be loaded as kernel modules. In order to use a certain discipline you have to build it into a custom kernel. The pf(4) interface, that is required for the configuration process of ALTQ can be loaded as a module.

SUPPORTED DEVICES
The driver modifications described in altq(9) are required to use a certain network card with ALTQ. They have been applied to the following hardware drivers: ae(4), age(4), alc(4), ale(4), aue(4), axe(4), bce(4), bfe(4), bge(4), bxe(4), cas(4), dc(4), em(4), epair(4), et(4), fxp(4), gem(4), igb(4), ix(4), jme(4), le(4), liquidio(4), msk(4), mxge(4), my(4), nfe(4), nge(4), qlxgb(4), re(4), rl(4), sge(4), sis(4), sk(4), ste(4), stge(4), ti(4), udav(4), vge(4), vr(4), vte(4), and xl(4).

The tun(4), if_bridge(4), if_vlan(4), and ng_iface(4) pseudo drivers also do support ALTQ.

An example:

    altq on igb0 cbq queue { def aq }
    queue def bandwidth 90% cbq (default borrow)
    queue aq bandwidth 10Mb cbq
    pass in on igb0.10 proto udp all queue aq keep state

SEE ALSO
pf(4), pf.conf(5), ipfw(8), pfctl(8), altq(9)

HISTORY
The ALTQ system first appeared in March 1997 and found home in the KAME project (https://www.kame.net). It was imported to FreeBSD in 5.3 .