HP 6125XLG R2306-HP 6125XLG Blade Switch ACL and QoS Configuration Guide - Page 60

Displaying and maintaining WRED

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• Upper threshold and lower threshold-When the average queue size is smaller than the lower threshold, no packet is dropped. When the average queue size is between the lower threshold and the upper threshold, the packets are dropped based on the user-configured drop probability. When the average queue size exceeds the upper threshold, subsequent packets are dropped. • Drop priority-A parameter used for packet drop. The value 0 corresponds to green packets, the value 1 corresponds to yellow packets, and the value 2 corresponds to red packets. Red packets are preferentially dropped. • Exponent used for average queue size calculation-The bigger the exponent is, the less sensitive the average queue size is to real-time queue size changes. The average queue size is calculated using the formula: average queue size = previous average queue size × (1-2-n) + current queue size × 2-n, where n can be configured with the qos wred weighting-constant command. • Numerator for drop probability calculation in percentage-The larger the value is, the greater the drop probability is. To configure and apply a WRED table: Step 1. Enter system view. 2. Create a WRED table and enter its view. 3. (Optional.) Set the WRED exponent for average queue size calculation. Command system-view qos wred queue table table-name queue queue-value weighting-constant exponent Remarks N/A N/A The default setting is 9. 4. (Optional.) Configure the other WRED parameters. queue queue-value [ drop-level drop-level ] low-limit low-limit high-limit high-limit [ discard-probability discard-prob ] By default, low-limit is 100, high-limit is 1000, and discard-prob is 10. 5. (Optional.) Enable ECN for a queue. queue queue-value ecn By default, ECN is not enabled on any queue. 6. Enter interface view. interface interface-type interface-number N/A 7. Apply the WRED table to the interface. qos wred apply [ table-name ] By default, no WRED table is applied to an interface, and the tail drop is used on an interface. A WRED table can be applied to multiple interfaces. For a WRED table already applied to an interface, you can modify the values of the WRED table, but you cannot remove the WRED table. Displaying and maintaining WRED Execute display commands in any view. Task Command Display WRED configuration information on the display qos wred interface [ interface-type interface or all interfaces. interface-number ] 54

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54
•
Upper threshold and lower threshold
—When the average queue size is smaller than the lower
threshold, no packet is dropped. When the average queue size is between the lower threshold and
the upper threshold, the packets are dropped based on the user-configured drop probability. When
the average queue size exceeds the upper threshold, subsequent packets are dropped.
•
Drop priority
—A parameter used for packet drop. The value 0 corresponds to green packets, the
value 1 corresponds to yellow packets, and the value 2 corresponds to red packets. Red packets
are preferentially dropped.
•
Exponent used for average queue size calculation
—The bigger the exponent is, the less sensitive
the average queue size is to real-time queue size changes. The average queue size is calculated
using the formula: average queue size = previous average queue size × (1-2
-n
) + current queue size
× 2
-n
, where n can be configured with the
qos wred weighting-constant
command.
•
Numerator for drop probability calculation in percentage
—The larger the value is, the greater the
drop probability is.
To configure and apply a WRED table:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Create a WRED table
and enter its view.
qos wred queue table
table-name
N/A
3.
(Optional.) Set the
WRED exponent for
average queue size
calculation.
queue
queue-value
weighting-constant
exponent
The default setting is 9.
4.
(Optional.) Configure
the other WRED
parameters.
queue
queue-value
[
drop-level
drop-level
]
low-limit
low-limit
high-limit
high-limit
[
discard-probability
discard-prob
]
By default,
low-limit
is 100,
high-limit
is 1000, and
discard-prob
is 10.
5.
(Optional.) Enable ECN
for a queue.
queue
queue-value
ecn
By default, ECN is not enabled
on any queue.
6.
Enter interface view.
interface
interface-type interface-number
N/A
7.
Apply the WRED table
to the interface.
qos wred apply
[
table-name
]
By default, no WRED table is
applied to an interface, and the
tail drop is used on an interface.
A WRED table can be applied to
multiple interfaces. For a WRED
table already applied to an
interface, you can modify the
values of the WRED table, but
you cannot remove the WRED
table.
Displaying and maintaining WRED
Execute
display
commands in any view.
Task
Command
Display WRED configuration information on the
interface or all interfaces.
display qos wred interface
[
interface-type
interface-number
]