Guidelines For Configuring Hierarchical Policers On Acx Routers - Juniper ACX1000 Configuration Manual

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Guidelines for Configuring Hierarchical Policers on ACX Routers

Copyright © 2017, Juniper Networks, Inc.
router ignores the preclassification of packets and can assign a higher or lower packet
loss priority.
A policer is then used to enforce the bandwidth profile and perform different actions,
depending on whether a certain packet confirms to the attributes in the bandwidth profile
or does not satisfy the values in the configured bandwidth profile. Hierarchical policers
can be considered to be an alternative technique for hierarchical queuing and shaping.
However, a few differences exist between the operations that a hierarchical policer
performs when matched against the processes that a hierarchical scheduler performs.
Hierarchical scheduler enables fine-grained bandwidth sharing in terms of percentages
of the available bandwidth, whereas hierarchical policing only enables a coarse-grained
bandwidth sharing based on the absolute micro-flow values of CIR and EIR. Hierarchical
policing enables the packet loss priority (PLP) and also the forwarding class to be modified
in certain cases, depending on whether the packet is confirming, exceeding, or violating
the particular bandwidth profile. Hierarchical scheduler does not cause any modifications
to the PLP or forwarding class values of a packet. Modifications are performed only for
violating packets.
ACX routers do not support hierarchical queuing and shaping. Ingress hierarchical policers
can work in conjunction with ingress, egress, or both ingress and egress hierarchical
queues. For example, a two-level ingress hierarchical policer combined with a two-level
egress queuing framework results in a four-level CoS capability.
Guidelines for Configuring Hierarchical Policers on ACX Routers on page 921
Hierarchical Policer Modes on page 923
Processing of Hierarchical Policers on page 928
Actions Performed for Hierarchical Policers on page 929
Configuring Aggregate Parent and Child Policers on ACX Series Routers on page 931
Keep the following points in mind when you configure hierarchical or aggregate policers:
You cannot specify the same policer as both a child policer and a parent policer.
The child policers of a hierarchical policer use the same resources as normal policers.
Therefore, the maximum number of child policers and normal policers in the system
for bridge domains and IPv4 services is as follows:
Family Bridge
A group of 124 entries of policers shared with other family-bridge filters.
A maximum of approximately 62 policers when no other family-bridge filters with
the count action for the firewall filter.
Along with 62 policers, you can configure up to 62 family-bridge filters without the
count action for the firewall filter.
Chapter 27: Configuring Class of Service
921