Hierarchical Policer Modes; Guarantee Mode - Juniper ACX1000 Configuration Manual

Hierarchical Policer Modes

Guarantee Mode

Copyright © 2017, Juniper Networks, Inc.
The method in which the micro-flow policer determines and manages the share of the
aggregate bandwidth for the micro-flow is defined by the hierarchical policer mode. ACX
routers support the following three hierarchical policer modes. You can configure the
mode or type of the policer for each hierarchical policer instance.
NOTE: Hierarchical policer is not applicable on ACX5048 and ACX5096
routers.
This topic contains the following sections that describe the three different modes of
operation of heirarchical policers:
This mode, also called bandwidth-guarantee mode, is used when the micro-flow policer
is used to specify that a portion of the aggregate parent policer bandwidth is guaranteed
for its micro-flow. When this micro-flow contains no traffic, then amount allocated for
this micro-flow out of the aggregate bandwidth is used by the other micro-flows that
are transmitting traffic with a size-limit or bandwidth that is higher than their respective
guaranteed bandwidth rates.
Consider a sample scenario in which the maximum allowed rate or peak information rate
(PIR) for a user is 140 Mbps. A total of four services or applications called expedited
forwarding (EF), Gold, Silver and Bronze are defined for the guaranteed bandwidth mode
of policer with a CIR of 50 Mbps, 40 Mbps, 30 Mbps, and 20 Mbps respectively. For
example, if 140 Mbps of trafic is received for each of the four services, then the permitted
traffic rates are 50, 40, 30 and 20 Mbps respectively. If 150 Mbps of Gold traffic is received,
only 140 Mbps is permitted for Gold traffic.
All the child policers must be of single-rate, single-bucket, and two-color modes for
bandwidth guarantee mode of hiearchical policer. This combination of attributes is also
called floor mode. The micro-flow policer value specifies the minimum guaranteed
bandwidth (CIR) for the micro-flow. The macro-flow policer value specifies the maximum
allowed bandwidth (PIR) for all the flows. The sum or the cumulative value of all CIR
values of the configured micro-flows must be less than or equal to the macro-flow PIR.
The burst size of macro-flow must be greater than the sum of the aggregate of the burst
size of all the child policers and the largest MTU of the physical interface among all the
physical interfaces of the logical interfaces or interface families to which the child policers
are attached.
Consider a sample configuration that has two child policers aggregated by a parent PIR
in bandwidth-guarantee mode. PIRs for the children policers and the parent policer are
configured. When two flows, flow 1 and flow 2, transmit traffic at a rate that exceeds the
configured PIR values, then the share of the parent PIR is adjusted to permit traffic for
the child policers based on their priorities defined for the flows, while the bandwidth is
maintained.
Chapter 27: Configuring Class of Service
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