Profile Capped Policers - Alcatel-Lucent 7450 Quality Of Service Manual

Profile Capped Policers

Profile capped mode has been introduced to enforce an overall in-profile burst limit to the
CIR bucket for ingress undefined, ingress explicit in-profile, egress soft-in-profile and egress
explicit in-profile packets. The default behavior when profile-capped mode is not enabled is
to ignore the CIR output state when an explicit in-profile packet is handled by an ingress or
egress policer. The explicit in-profile packets will consume CIR tokens up to 2xCBS at which
point the bucket stops incrementing and the CIR output for that type of packet enters the non-
conforming state.
However, the non-conforming state is ignored by the forwarding plane and the packet
continues to be handled as in-profile. Thus, the total amount of in-profile traffic can be greater
than the configured CIR.
The profile-capped mode makes two changes:
The idea is that a profile capped policer trusts the in-profile state determined at ingress
classification or egress re-classification, the initial in-profile traffic is preferentially handled
with the CIR bucket (2xCBS instead of 1xCBS used by undefined or soft-out-of-profile
traffic) and the total amount of in-profile traffic output by the policer cannot exceed the CIR
(including initial in-profile traffic).
One other aspect to consider with profile-capped mode is the effect on stat-mode behavior.
As will be seen below, each stat-mode has a fixed number of counters in the NP and Q. The
mapping of packets to a counter is also fixed by the offered packet state (profile in, profile
out, undefined, soft-in-profile and soft-out-of-profile) in conjunction with the output state of
the policer. The egress policer stat-modes and the behavior of soft-in-profile (from ingress)
and profile in (reclassified at egress) packets. In the non-capped mode, soft-in-profile is
considered undefined while in capped mode it is considered to be equivalent to profile in.
Another aspect that causes issues with ingress and egress stat-modes is the fact that initially
green (profile in at ingress and egress as well as soft-in-profile at egress), packets can actually
turn yellow in the policer output.
Table 74
of normal (non-profile-capped) and profile-capped mode policers.
Quality of Service Guide
• At egress, soft-in-profile packets (packets received from ingress as in-profile) are
treated the same as explicit in-profile (unless explicitly reclassified as out-of-profile)
and have an initial policer state of in-profile
• At both ingress and egress, any packet output from the policer with a non-conforming
CIR state are treated as out-of-profile (out-of-profile state is ignored for initial in-
profile packets when profile capped mode is not enabled)
demonstrates how the CIR rate and initial profile of each packet affects the output
Class Fair Hierarchical Policing (CFHP)
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