Juniper EX9200 Series, Features Manual

Page: 179 / 278

CHAPTER 15
Basic Two-Rate Three-Color Policers
• Two-Rate Three-Color Policer Overview on page 161
• Example: Configuring a Two-Rate Three-Color Policer on page 162
Two-Rate Three-Color Policer Overview
A two-rate three-color policer defines two bandwidth limits (one for guaranteed traffic
and one for peak traffic) and two burst sizes (one for each of the bandwidth limits). A
two-rate three-color policer is most useful when a service is structured according to
arrival rates and not necessarily packet length.
Two-rate three-color policing meters a traffic stream based on the following configured
traffic criteria:
•
Committed information rate (CIR)—Bandwidth limit for guaranteed traffic.
• Committed burst size (CBS)—Maximum packet size permitted for bursts of data that
exceed the CIR.
•
Peak information rate (PIR)—Bandwidth limit for peak traffic.
•
Peak burst size (PBS)—Maximum packet size permitted for bursts of data that exceed
the PIR.
Two-rate tricolor marking (two-rate TCM) classifies traffic as belonging to one of three
color categories and performs congestion-control actions on the packets based on the
color marking:
•
Green—Traffic that conforms to the bandwidth limit and burst size for guaranteed
traffic (CIR and CBS). For a green traffic flow, two-rate TCM marks the packets with
an implicit loss priority of
low and transmits the packets.
• Yellow—Traffic that exceeds the bandwidth limit or burst size for guaranteed traffic
(CIR or CBS) but not the bandwidth limit and burst size for peak traffic (PIR and PBS).
For a yellow traffic flow, two-rate TCM marks packets with an implicit loss priority of
medium-high
and transmits the packets.
•
Red—Traffic that exceeds the bandwidth limit and burst size for peak traffic (PIR and
PBS). For a red traffic flow, two-rate TCM marks packets with an implicit loss priority
of
high and, optionally, discards the packets.
161 Copyright © 2016, Juniper Networks, Inc.