Juniper EX9200 Features Manual page 4

Traffic Policers Feature Guide for EX9200 Switches
Chapter 4
Chapter 5
Part 2
Chapter 6
iv
Configuring Policer Rate Limits and Actions . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Policer Bandwidth and Burst-Size Limits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Policer Color-Marking and Actions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Single Token Bucket Algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Token Bucket Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Single Token Bucket Algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Conformance Measurement for Two-Color Marking . . . . . . . . . . . . . . . . . . . . 21
Dual Token Bucket Algorithms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Token Bucket Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Guaranteed Bandwidth for Three-Color Marking . . . . . . . . . . . . . . . . . . . . . . 22
Nonconformance Measurement for Single-Rate Three-Color Marking . . . . . 22
Nonconformance Measurement for Two-Rate Three-Color Marking . . . . . . . 23
Implementing Traffic Policers on EX 9200 Switches . . . . . . . . . . . . . . . . . . . 25
Policer Implementation Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Understanding the Benefits of Policers and Token Bucket Algorithms . . . . . . . . . 28
Scenario 1: Single TCP Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Scenario 2: Multiple TCP Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Determining Proper Burst Size for Traffic Policers . . . . . . . . . . . . . . . . . . . . . . . . . 30
Policer Burst Size Limit Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Effect of Burst-Size Limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Bursty Traffic Policed Without a Burst-Size Limit . . . . . . . . . . . . . . . . . . . 31
Burst-Size Limit Configured to Match Bandwidth Limit and Flow
Burstiness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Burst-Size Limit That Depletes All Accumulated Tokens . . . . . . . . . . . . . 31
Two Methods for Calculating Burst-Size Limit . . . . . . . . . . . . . . . . . . . . . . . . . 32
Calculation Based on Interface Bandwidth and Allowable Burst
Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Calculation Based on Interface Traffic MTU . . . . . . . . . . . . . . . . . . . . . . . 32
Comparison of the Two Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
10 x MTU Method for Selecting Initial Burst Size for Gigabit Ethernet
with 100 Kbps Bandwidth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
5 ms Method for Selecting Initial Burst Size for Gigabit Ethernet Interface
with 200 Mbps Bandwidth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
200 Mbps Bandwidth Limit, 5 ms Burst Duration . . . . . . . . . . . . . . . . . . 35
200 Mbps Bandwidth Limit, 600 ms Burst Duration . . . . . . . . . . . . . . . . 35
Configuring Layer 2 Policers
Two-Color and Three-Color Policers at Layer 2 . . . . . . . . . . . . . . . . . . . . . . . . 39
Two-Color Policing at Layer 2 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Guidelines for Configuring Two-Color Policing of Layer 2 Traffic . . . . . . . . . . 39
Statement Hierarchy for Configuring a Two-Color Policer for Layer 2
Traffic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Statement Hierarchy for Applying a Two-Color Policer to Layer 2 Traffic . . . 40
Three-Color Policing at Layer 2 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Guidelines for Configuring Three-Color Policing of Layer 2 Traffic . . . . . . . . . 41
Statement Hierarchy for Configuring a Three-Color Policer for Layer 2
Traffic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
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