Ethernet Switching Feature Guide

Modified: 2018-04-17

Copyright 2018, Juniper Networks, Inc.

Juniper Networks, Inc.1133 InnovationWaySunnyvale, California 94089USA408-745-2000www.juniper.net

Juniper Networks, the Juniper Networks logo, Juniper, and Junos are registered trademarks of Juniper Networks, Inc. and/or its affiliates inthe United States and other countries. All other trademarks may be property of their respective owners.

Juniper Networks assumes no responsibility for any inaccuracies in this document. Juniper Networks reserves the right to change, modify,transfer, or otherwise revise this publication without notice.

Ethernet Switching Feature GuideCopyright 2018 Juniper Networks, Inc. All rights reserved.

The information in this document is current as of the date on the title page.

YEAR 2000 NOTICE

Juniper Networks hardware and software products are Year 2000 compliant. Junos OS has no known time-related limitations through theyear 2038. However, the NTP application is known to have some difficulty in the year 2036.

ENDUSER LICENSE AGREEMENT

The Juniper Networks product that is the subject of this technical documentation consists of (or is intended for use with) Juniper Networkssoftware. Use of such software is subject to the terms and conditions of the End User License Agreement (EULA) posted athttps://www.juniper.net/support/eula/. By downloading, installing or using such software, you agree to the terms and conditions of thatEULA.

Copyright 2018, Juniper Networks, Inc.ii

https://www.juniper.net/support/eula/

Table of Contents

About the Documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxxi

Documentation and Release Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxxi

Supported Platforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxxi

Using the Examples in This Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxxii

Merging a Full Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxxii

Merging a Snippet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxxiii

Documentation Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxxiii

Documentation Feedback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxxv

Requesting Technical Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxxvi

Self-Help Online Tools and Resources . . . . . . . . . . . . . . . . . . . . . . . . . xxxvi

Opening a Case with JTAC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxxvi

Part 1 Configuring Ethernet Switching

Chapter 1 Layer 2 Networking Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Using the Enhanced Layer 2 Software CLI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Understanding Which Devices Support ELS . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Understanding How to Configure Layer 2 Features Using ELS . . . . . . . . . . . . . 3

Configuring a VLAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Configuring the Native VLAN Identifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Configuring Layer 2 Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Configuring Layer 3 Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Configuring an IRB Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Configuring an Aggregated Ethernet Interface and Configuring LACP

on That Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Understanding ELS Configuration Statement and Command Changes . . . . . . 7

Changes to the ethernet-switching-options Hierarchy Level . . . . . . . . . . 8

Changes to the Port Mirroring Hierarchy Level . . . . . . . . . . . . . . . . . . . . . 10

Changes to the Layer 2 Control Protocol Hierarchy Level . . . . . . . . . . . . . 10

Changes to the dot1q-tunneling Statement . . . . . . . . . . . . . . . . . . . . . . . 10

Changes to the L2 Learning Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Changes to Nonstop Bridging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Changes to Port Security and DHCP Snooping . . . . . . . . . . . . . . . . . . . . . 11

Changes to Configuring VLANs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Changes to Storm Control Profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Changes to the Interfaces Hierarchy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Changes to IGMP Snooping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Understanding the ELS Translator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Overview of Layer 2 Networking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Understanding Layer 2 Broadcasting on Switches . . . . . . . . . . . . . . . . . . . . . . . . . 22

Understanding Unicast . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

iiiCopyright 2018, Juniper Networks, Inc.

Ethernet Switching and Layer 2 Transparent Mode Overview . . . . . . . . . . . . . . . . 23

Chapter 2 Configuring Layer 2 Forwarding Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Layer 2 Learning and Forwarding for VLANs Overview . . . . . . . . . . . . . . . . . . . . . . 25

Understanding Layer 2 Forwarding Tables on Switches, Routers and NFX

Series Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Understanding Layer 2 Forwarding Tables on Security Devices . . . . . . . . . . . 26

Configuring Forwarding Mode on Switches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Understanding the Unified Forwarding Table on QFX Switches . . . . . . . . . . . . . . 28

Using the Unified Forwarding Table to Optimize Address Storage . . . . . . . . . 28

Understanding the Allocation of MAC Addresses and Host Addresses . . . . . 29

Understanding Ternary Content AddressableMemory (TCAM) and Longest

Prefix Match Entries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Host Table Example for Profile with Heavy Layer 2 Traffic . . . . . . . . . . . . . . . 34

Configuring the Unified Forwarding Table on Switches . . . . . . . . . . . . . . . . . . . . . 34

Configuring a Unified Forwarding Table Profile . . . . . . . . . . . . . . . . . . . . . . . . 35

Configuring the Memory Allocation for Longest Prefix Match Entries . . . . . . 36

Configuring the LPM TableWith Junos OS Releases 13.2X51-D10 and

13.2X52-D10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Configuring the LPM TableWith Junos OS Release 13.2x51-D15 and

Later . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Configuring Double-Tagged VLANs on Layer 3 Logical Interfaces . . . . . . . . . . . . . 42

Example: Configuring a Unified Forwarding Table Custom Profile on QFX Series

Switches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Chapter 3 Configuring MAC Addresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Introduction to the Media Access Control (MAC) Layer 2 Sublayer . . . . . . . . . . . . 47

Understanding MAC Address Assignment on an EX Series Switch . . . . . . . . . . . . 48

Configuring the Size of the MAC Address Table . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Configuring MAC Move Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Adding a Static MAC Address Entry to the Ethernet Switching Table (CLI

Procedure) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Adding a Static MACAddress Entry to the Ethernet Switching Table on a Switch

with ELS Support (CLI Procedure) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Example: Configuring the Default Learning for Unknown MAC Addresses . . . . . . 53

Configuring MAC Limiting (CLI Procedure) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Limiting the Number of MAC Addresses Learned by an Interface . . . . . . . . . 55

Limiting the Number of MAC Addresses Learned by a VLAN . . . . . . . . . . . . . 55

Chapter 4 Configuring MAC Learning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Understanding MAC Learning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Disabling MAC Learning on QFX Switches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Disabling MAC Learning on Devices with ELS Support . . . . . . . . . . . . . . . . . . . . . 58

Disabling MAC Learning in a VLAN on a QFX Switch . . . . . . . . . . . . . . . . . . . . . . . 59

Disabling MAC Learning for a VLAN or Logical Interface . . . . . . . . . . . . . . . . . . . . 60