Alcatel-Lucent 7950 Quality Of Service Manual page 593

is defined within the sap-ingress or sap-egress QoS policy in the policer context. When defining
the stat-mode, the counter resources needed to implement the mode must be available on all
forwarding planes where the policer has been created using the QoS policy unless the policer
instance has a stat-mode override defined. You can see the resources used and available by using
the tools dump system-resources command. If insufficient resources exist, the change in the
mode will fail without any change to the existing counters currently applied to the existing
policers. If the QoS policy is being applied to a SAP or context and insufficient counter resources
exist to implement the configured modes for the policers within the policy, the QoS policy will not
be applied. For SAPs, this means the previous QoS policy will stay in effect.
A stat-mode with at least minimal stats is required before the policer can be assigned to a parent
arbiter using the parent command.
Successfully changing the stat-mode for a policer causes the counters associated with the policer
to reset to zero. Any collected stats on the object the policer is created on will also reset to zero.
The system uses the forwarding plane counters to generate accounting statistics and for calculating
the operational PIR and FIR rates for a set of children when they are managed by a policer-control-
policy. Only the offered counters are used in hierarchical policing rate management. When
multiple offered stats are maintained for a child policer, they are summed to derive the total
offered rate for each child policer.
All ingress policers have a default CIR value of 0 meaning that by default, all packets except
packets classified as profile in will be output by the policer as out-of-profile. This may have a
negative impact on egress marking decisions (if in-profile and out-of-profile have different
marking values) and on queue congestion handling (WRED or queue tail drop decisions when out-
of-profile is less preferred). The following options exist to address this potential issue:
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Egress policers also have a default CIR set to 0, but in the egress case a value of 0 disables policer
profiling altogether. Egress packets on a CIR disabled egress policer retain their offered profile
state (soft-in-profile, soft-out-of-profile, hard-in-profile or hard-out-of-profile).
7950 XRS Quality of Service Guide
If all packets handled by the policer must be output as in-profile by the policer, either the
packet's forwarding class or sub-class can be defined as profile in or the CIR on the policer
can be defined as max
If some packets must be output as in-profile while others output as out-of-profile, three
options exist
−>The CIR may be left at '0' while mapping the packets that must be output as in-profile to
a forwarding class or sub-class provisioned as profile in
−>The CIR may be set to max while mapping the packets that must be output as out-of-
profile to a forwarding class or sub-class provisioned as profile out
−>Ignore the CIR on the policer and solely rely on the forwarding class or sub-class
profile provisioning to the proper policer CIR output
Ingress Child Policer Stat-Mode
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