Alcatel-Lucent 7450 Quality Of Service Manual page 866

Policer Interaction with Initial Profile, Discard Eligibility, and Ingress Priority
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
subscriber or multi-service site 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. For subscribers, it could
mean that the subscriber host event where the QoS policy is being applied will fail and the
subscriber host may be blocked or removed.
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:
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).
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• 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
Quality of Service Guide