Alcatel-Lucent 7950 Quality Of Service Manual page 558

Advanced Policy QoS Commands
This command edits the parameters that control the child requested bandwidth and parental bandwidth
distribution for all policers and queues associated with the policy.
offered-measurement
Syntax offered-measurement
Context config>qos>adv-config-policy>child-control
Description
This command modifies the offered rate measurement used to determine the bandwidth the queue or policer
is requesting from its parent virtual scheduling context.
This command modifies the parameters that control the child requested bandwidth for all policers and
queues associated with the policy.
add
Syntax [no] add {percent percent-of-admin-pir | rate rate-in-kilobits-per-second} [min-only | active-min-
only]
Context config>qos>adv-config-policy>child-control>offered-measurement
Description This command is used to increase the measured rate of the policer or queue associated with the policy. The
offered rate (capped by the administrative PIR configured on the queue or policer) is usually used unaltered
by the parent virtual scheduler. The add command allows this measured rate to be increased by the specified
amount or by a percentage of the administrative PIR. The resulting rate will not exceed the administrative
PIR.
The parent scheduler uses the modified measured rate as the available work load for the queue or policer in
determining how much bandwidth the child should receive from the bandwidth distribution algorithm.
One example of when an increase in the measured offered rate may be desired is when a queue or policer is
handling VOIP traffic. A characteristic of VOIP is the step nature in how traffic is used. Each call typically
adds a certain maximum amount to the overall load. By using the add command, the bandwidth required for
the next added call may be included in the current measured rate. This allows the virtual scheduler to
allocate sufficient bandwidth to the queue or policer so that when the call is made the scheduling algorithm
does not need to run to increase the bandwidth.
A side effect of increasing the measured offered rate is that if the extra bandwidth is allocated by the virtual
scheduler, the available bandwidth to lower priority queues or policers is diminished even though the extra
allocated bandwidth may not be in use. If this is the case, the effect will be seen as an underrun in the
aggregate output of the virtual scheduler.
If the add command is used with a percent based value, the increase 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.
Page 558 7950 XRS Quality of Service Guide