Traffic Policer Types; Single-Rate Two-Color Policers; Basic Single-Rate Two-Color Policer; Bandwidth Policer - Juniper EX9200 Features Manual

Traffic Policers Feature Guide for EX9200 Switches
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Traffic Policer Types

Single-Rate Two-Color Policers

8
Stateless Firewall Filter Overview.
Traffic Policer Types
Order of Policer and Firewall Filter Operations on page 11
Packet Flow Through the Junos OS CoS Process Overview
This topic covers the following information:
Single-Rate Two-Color Policers on page 8
Three-Color Policers on page 9
Two-Color and Three-Color Policer Options on page 9
You can use a single-rate two-color policer, or "policer" when used without qualification,
to rate-limit a traffic flow to an average bits-per-second arrival rate (specified by the
single specified bandwidth limit) while allowing bursts of traffic for short periods
(controlled by the single specified burst-size limit). This type of policer categorizes a
traffic flow as either green (conforming) or red (nonconforming). Packets in a green flow
are implicitly set to a loss priority and then transmitted. Packets in a red flow are
low
handled according to actions specified in the policer configuration. Packets in a red flow
can be marked—set to a specified forwarding class, set to a specified loss priority, or
both—or they can be discarded.
A single-rate two-color policer is most useful for metering traffic at the port (physical
interface) level.

Basic Single-Rate Two-Color Policer

You can apply a basic single-rate two-color policer to Layer 3 traffic in either of two ways:
as an interface policer or as a firewall filter policer. You can apply the policer as an
interface policer, meaning that you apply the policer directly to a logical interface at the
protocol family level. If you want to apply the policer to selected packets only, you can
apply the policer as a firewall filter policer, meaning that you reference the policer in a
stateless firewall filter term and then apply the filter to a logical interface at the protocol
family level.

Bandwidth Policer

A bandwidth policer is simply a single-rate two-color policer that is defined using a
bandwidth limit specified as a percentage value rather than as an absolute number of
bits per second. When you apply the policer (as an interface policer or as a firewall filter
policer) to a logical interface at the protocol family level, the effective bandwidth limit
is calculated based on either the physical interface media rate or the logical interface
configured shaping rate.
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