Queuing discipline parameters

The following table shows which parameters are supported by which queuing discipline, and whether they are optional ($\circ$) or required ($\bullet$):

Parameter	cbq	dsmark	fifo	gred	htb	prio	red	sfq	tbf
avpkt	$\bullet$	.	.	.	.	.	$\bullet$	.	.
bands	.	.	.	.	.	$\circ$	.	.	.
bandwidth	$\bullet$	.	.	$\bullet$	.	.	$\bullet$	.	.
burst	.	.	.	.	.	.	$\bullet$	.	$\bullet$
default_index	.	$\circ$	.	.	.	.	.	.	.
ecn	.	.	.	.	.	.	$\circ$	.	.
ewma	$\circ$	.	.	.	.	.	.	.	.
grio	.	.	.	$\circ$	.	.	.	.	.
indices	.	$\circ$	.	.	.	.	.	.	.
limit	.	.	$\circ$	.	.	.	$\bullet$	.	$\bullet$
max	.	.	.	.	.	.	$\bullet$	.	.
min	.	.	.	.	.	.	$\bullet$	.	.
mpu	$\circ$	.	.	.	.	.	.	.	.
mtu	.	.	.	.	.	.	.	.	$\bullet$
peakrate	.	.	.	.	.	.	.	.	$\circ$
perturb	.	.	.	.	.	.	.	$\circ$	.
priomap	$\circ$	.	.	.	.	$\circ$	.	.	.
probability	.	.	.	.	.	.	$\circ$	.	.
quantum	.	.	.	.	.	.	.	$\circ$	.
r2q	.	.	.	.	$\circ$	.	.	.	.
rate	$\bullet$	.	.	.	.	.	.	.	$\bullet$
set_tc_index	.	$\circ$	.	.	.	.	.	.	.

The ingress queuing discipline has no parameters and has therefore been omitted from the above table.

Units and meaning of the parameters are described below:

Parameter	Unit	Description
avpkt	Bytes	Average packet size
bands	integer	Number of bands
bandwidth	bps	Interface bandwidth
burst	Bytes	Burst size, typically $>=$ MTU
default_index	integer	Index if no class matches
ecn	flag	Set CE instead of dropping [RFC3168]
ewma	integer	EWMA weight is $2^{-ewma}$
grio	flag	Enable RIO-like buffer sharing
indices	integer	Indices used for changing the DS field
limit	Bytes	Queue size limit in bytes
limit	pcks	Queue size limit in packets
max	Bytes	Minimum threshold ($min\_th$)
min	Bytes	Maximum threshold ($max\_th$)
mpu	Bytes	Minimum policed unit
mtu	Bytes	Maximum transmission unit
peakrate	bps	Peak data rate
perturb	secs	Perturbation interval
priomap	list of classes	Default class map
probability	floating-point	Maximum drop probability
quantum	Bytes	Maximum burst when scheduled
quantum	secs	Burst duration when scheduled (HTB only)
rate	bps	Nominal data rate
r2q	integer	Rate to quantum conversion ratio (deprecated)
set_tc_index	flag	Copy DS field to tc_index

In addition to the parameters described in this section, queuing disciplines with classes also allow default values for class parameters to be specified at the queuing discipline. They are listed in the next section.