Allied Telesis AlliedWare Plus

Page 25 | AlliedWare Plus™ OS: Overview of QoS

These fundamental curves are collected into RED curve groups. A group is a collection of

three curves, one for each of the three possible bandwidth classes, as shown in the following

figure.

Additionally, one other parameter is defined on each RED curve group. This parameter is the

averaging factor. The averaging factor influences how the queue length is calculated. If the

averaging factor is 0, then the queue length value that the shaper uses in its calculation of

whether a certain packet should be dropped is the exact current length of the queue. But, if

you increase the averaging factor, then the shaper starts calculating an average length of the

queue over a certain time period, and uses this averaged value in its “should-I-drop-the-

packet” calculation.

Applying

RED curves

to ports

To apply a set of RED curves to the egress queues on a given port, use the commands:

awplus(config)#interface <interface-name>

awplus(config-if)#mls qos queue-set <1-4> random-detect

If you enter this command without configuring the RED curve settings (see "Configuring RED

curve settings" on page 25), the switch uses the default queue set values. These are described

in "Default settings" on page 23.

Configuring

RED curve

settings

RED curve groups are defined in queue sets, so you can have up 4 different sets of RED

behaviour on the switch.

The commands for configuring the queue sets start with:

awplus(config)#mls qos queue-set <1-4> ...

After this, you can use the command to configure the averaging factor, the thresholds and the

drop probability. You can configure the queue-set parameters for all 8 egress queues, or for

any subset of the egress queues. Configuring a subset lets you configure different queue

shaping settings for different queues on a port.

Drop

Probability

100%

Start 3

Stop 3

Drop 3

Drop 2

Drop 1

Start 2

Stop 2

Start 1

Stop 1

Queue Length (bytes)

MAX queue length

Class 3

Class 2

Class 1

QoS3.eps