Advanced QoS Policies
Quality of Service Guide 683
high-rate-hold-time
Syntax [no] high-rate-hold-time seconds [active-min-only]
Context config>qos>adv-config-policy>child-control>offered-measurement
Description This command sets a time period that the current offered rate should be maintained for a child policer
or queue once it is seen that the offered rate is decreasing. The offered measurement that triggers the
hold time is used when the hold timer expires unless a higher offered rate is seen in the interim. When
a higher rate is observed, the hold timer is canceled and the higher offered rate is used immediately.
A possible reason to define a hold timer for an offered rate is to allow a child queue is to dampen the
effects of a child with a fluctuating rate on the virtual scheduler. This works similar to the max-
decrement in that the child holds on to bandwidth from the virtual scheduler in case it may be needed
in the near future.
This parameter has no effect on an increase to the child’s offered rate. If the rate increase is above the
change sensitivity, the new offered rate is immediately used.
When this command is not specified or removed, the virtual scheduler immediately reacts to measured
decreases in offered load.
The no form of this command is used to remove any currently configured hold time for all child
policers and queues associated with the policy. When the hold time is removed, any current hold timers
for child policers are automatically canceled.
Parameters seconds — The hold time configured must be specified in seconds. A value of 0 is equivalent to
no high-rate-hold-time.
Default 0
Values 0 to 60
active-min-only — When this optional parameter is specified, the high-rate-hold-time
command will accept the optional active-min-only parameter. Attempting to remove the
active-min-only parameter from the add command, or removing the add command itself, will
fail while active-min-only is enabled on the high-rate-hold-time command. When
specified, the respective rate or percentage is treated as the minimum offered rate for a queue
only when the queue has an actual non-zero offered rate. This is intended to limit the artificial
increase in offered rate to queues that are currently active. Once a queue’s measured offered
rate drops to zero, the system stops enforcing the minimum value.
time-average-factor
Syntax [no] time-average-factor taf-value [dec-only]
Context config>qos>adv-config-policy>child-control>offered-measurement
Description This command is used to weight the new offered rate with a portion of the previous offered rate. It
would be expected that this command would mainly be used with the dec-only option enabled.
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