Allied Telesis AlliedWare Plus Overview page 26
Overview of quality of service features
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Also See for AlliedWare Plus:
- Overview (1 page) ,
- Configuration manual (29 pages) ,
- Installation manual (214 pages)
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Specifying which queues to act on
To specify which queues to configure, use the optional queues parameter:
Specify the desired queues as a space-separated list. For example:
To configure all queues, leave out the queues parameter.
If you do not configure RED curve settings on all the queues in a queue set, the unconfigured
queues use the default settings—see
Specifying the thresholds
To specify the maximum and minimum thresholds for each bandwidth class, use the
command:
Each threshold is a value from 1-16000000 bytes.
Specifying the drop probability
To specify the drop probability for each bandwidth class, use the command:
Each drop probability is a value from 0-15. The drop probability is 100% for a setting of 0 and
halves for each integer value increase. The following table shows probability values for drop
values of 0 to 7.
Drop value
% drop probability
Specifying the averaging factor
Dropping is based on the average queue length, which is calculated as:
New Average Queue Length =
(1 - 1/(2
where n is the averaging factor. If n is small, the average queue length follows the actual
queue length quickly and is more likely to cause global TCP synchronisation. A large value for
n means the average queue length follows the actual queue length slowly. This may prevent
global TCP synchronisation, but will drop more packets. The recommended averaging factor
is 9.
Page 26 | AlliedWare Plus™ OS: Overview of QoS
awplus(config)#mls qos queue-set <1-4> queues ...
awplus(config)#mls qos queue-set <1-4> queues 1 3 4 ...
awplus(config)#mls qos queue-set <1-4> [queues <list>] threshold
<minimum-green-threshold> <maximum-green-threshold>
<minimum-yellow-threshold> <maximum-yellow-threshold>
<minimum-red-threshold> <maximum-red-threshold>
awplus(config)#mls qos queue-set <1-4> [queues <list>]
drop-probability <green-drop-prob> <yellow-drop-prob> <red-drop-prob>
0
100%
n
)) * (Current Average Queue Length) + 1/(2
page
23.
1
2
3
12.5%
50%
25%
4
5
6
3.125% 1.562
6.25%
n
) * (Current Queue Length)
7
...
0.781
...
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