Profile Preferred Mode Root Policers - Alcatel-Lucent 7950 Quality Of Service Manual

Egress Child Policer Stat-Mode

Profile Preferred Mode Root Policers

The profile-preferred option ensures that the root policer provides a preference to consume its PIR
bucket tokens at a given priority level to packets which have their profile state been set to in-
profile by the output of the child policer CIR bucket.
When this option is selected, all child policers parented to a root policer will have their FIR bucket
track the state of the CIR bucket. In other words, a green packet will always be blue and a yellow
packet will always be orange. When admitting packets from the child policers within a given
priority level, orange packets will be allowed up to the "discard-unfair" threshold while blue
packets will be allowed up to the "discard-all" threshold.
HPOL will no longer set the FIR bucket of the child policer based on fair share calculation.
Instead, the 'profile-preferred' option forces the FIR bucket to track the CIR bucket's decrement
rate and the threshold chosen for the CIR bucket would also be used in the FIR bucket (instead of
using the threshold associated with the PIR bucket).
The green/yellow output from the policer would be used for packet marking decisions. The blue/
orange child policer input to the parent policer would chose the discard-orange or discard-all
thresholds for the child policer's priority level within the parent policer.
The net result is that explicit in-profile packets stay blue up to the high CBS threshold, undefined
profile packets would stay blue up to the low CBS threshold (1x CBS) and explicit out-of-profile
packets would always be orange due to a 0 CBS threshold. Orange packets would be discarded by
the parent policer within the child policer's priority level before the blue packets, preferring blue
packets over orange once the discard-orange threshold is crossed.
The following is the CLI for the new option. The same option applies to overrides applied to the
instances of a policer control policy under a SAP or context.
config qos
policer-control-policy policy-name [create]
no policer-control-policy policy-name
Note that the profile-preferred option provides us a way to configure a specific FIR (since it uses
the CIR as FIR). In the direct-parented case (no intermediate arbiters present at all) the child
policers do not need to have their offered rate polled as each policer will always have PIR equal to
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description "description-string"
no description
root
max-rate {kilobits-per-second | max}
no max-rate
[no] profile-preferred
priority-mbs-thresholds
min-thresh-separation size [bytes | kilobytes]
no min-thresh-separation
priority level
mbs-contribution size [bytes | kilobytes] [fixed]
no mbs-contribution
7950 XRS Quality of Service Guide