Alcatel-Lucent 7950 Quality Of Service Manual page 560

Advanced Policy QoS Commands
distributed bandwidth between all children more often resulting in the possibility of lowering resources
available to other virtual scheduler instances on the slot.
A side effect of lower sensitivity (higher granularity) is that the parent virtual scheduler may distribute
insufficient bandwidth to the child resulting in dropped packets.
If the granularity command is used with a percent based value, the sensitivity is a function of the configured
PIR value on the policer or queue. In this case, care should be taken that the child is either configured with
an explicit PIR rate (other than max) or the child's administrative PIR is defined using the percent-rate
command with the local parameter enabled if an explicit value is not desired. When a maximum PIR is in
use on the child, the system attempts to interpret the maximum child forwarding rate. This rate could be very
large if the child is associated with multiple ingress or egress ports.
Except for the overall cap on the offered input into the virtual scheduler, the child's administrative PIR has
no effect on the calculated sensitivity if an explicit rate is specified.
If the child's administrative PIR is modified while a percent based granularity is in effect, the system
automatically uses the new relative sensitivity value the next time the child's offered rate is determined.
The no form of this command is used to restore the default offered rate sensitivity behavior to all child
policers and queues associated with the policy.
Parameters percent-of-admin-pir — When the percent qualifier is used, this parameter specifies the percentage of the
child's administrative PIR that should be used as the threshold sensitivity to offered rate change. If a
value of 0 or 0.00 is used, the system will interpret this equivalent to no granularity.
Default
Values
rate-in-kilobits-per-second — When the rate qualifier is used, this parameter specifies an explicit number of
kilobits-per-second (1000 bits-per-second) that should be as the child's offered rate change sensitivity
value. If a rate sensitivity of 0 is specified, the system interprets this equivalent to no granularity.
Default
Values
max-decrement
Syntax [no] max-decrement {percent percent-of-admin-pir | rate rate-in-kilobits-per-second}
Context config>qos>adv-config-policy>child-control>offered-measurement
Description
This command is used to limit how fast a child queue or policer can 'give up' bandwidth that it has been
allotted from the virtual scheduler in a single iteration. If the child's new offered rate has decreased by more
than the maximum decrement limit, the system ignores the new offered rate and instead uses the old offered
rate less the maximum decrement limit.
A possible reason to define a maximum decrement limit is to allow a child queue or policer to hold on to a
portion of bandwidth that has been distributed by the parent virtual scheduler in case the child's offered rate
fluctuates in an erratic manor. The max-decrement limit has a dampening effect to changes in the offered
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None, the sensitivity percentage value must be specified when the percent qualifier is
used.
1.00 — 100.00
None, the sensitivity rate value must be specified when the rate qualifier is used.
0 — 100,000,000
7950 XRS Quality of Service Guide