Juniper Networks OS 10.4 User Manual

Junos®OS

MX Series 3D Universal Edge Routers Solutions Guide

Release

13.1R1

Published: 2013-02-13

Juniper Networks, Inc. 1194 North Mathilda Avenue Sunnyvale, California 94089 USA 408-745-2000 www.juniper.net

This productincludes the Envoy SNMP Engine, developed by Epilogue Technology, an Integrated Systems Company. Copyright© 1986-1997, Epilogue Technology Corporation. All rights reserved. This program and its documentation were developed at private expense, and no part of them is in the public domain.

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GateD software copyright © 1995, the Regents of the University. All rights reserved. Gate Daemon was originated and developed through release 3.0 by Cornell University and its collaborators. Gated is based on Kirton’s EGP, UC Berkeley’s routing daemon (routed), and DCN’s HELLO routing protocol. Development of Gated has been supported in part by the National Science Foundation. Portions of the GateD software copyright © 1988, Regents of the University of California. All rights reserved. Portions of the GateD software copyright © 1991, D. L. S. Associates.

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Junos®OS MX Series 3D Universal Edge Routers Solutions Guide

Revision History February 2013—Junos OS 13.1R1

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 the year 2038. However, the NTP application is known to have some difficulty in the year 2036.

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http://www.juniper.net/support/eula.html. By downloading, installing or using such software, you agree to the terms and conditions

of that EULA.

Abbreviated Table of Contents

About This Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii

Part 1 Overview

Chapter 1 Overview of Ethernet Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Part 2 Basic Solutions for MX Series Routers

Chapter 2 Basic Layer 2 Features on MX Series Routers . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Chapter 3 Virtual Switches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Chapter 4 VLANs Within Bridge Domain and VPLS Environments . . . . . . . . . . . . . . . . 43

Chapter 5 Bulk Administration of Layer 2 Features on MX Series Routers . . . . . . . . . . 63

Chapter 6 Dynamic Profiles for VLAN Interfaces and Protocols . . . . . . . . . . . . . . . . . . . 67

Chapter 7 MX Series Router as a DHCP Relay Agent . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

Chapter 8 MX Series Router in an ATM Ethernet Interworking Function . . . . . . . . . . . . 83

Part 3 Ethernet Filtering, Monitoring, and Fault Management Solutions

for MX Series Routers

Chapter 9 Layer 2 Firewall Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

Chapter 10 IEEE 802.1ag OAM Connectivity-Fault Management . . . . . . . . . . . . . . . . . . 109

Chapter 11 ITU-T Y.1731 Ethernet Frame Delay Measurements . . . . . . . . . . . . . . . . . . . . 125

Chapter 12 IEEE 802.3ah OAM Link-Fault Management . . . . . . . . . . . . . . . . . . . . . . . . . 143

Chapter 13 Ethernet Ring Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151

Part 4 Index

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185

Junos OS 13.1 MX Series 3D Universal Edge Routers Solutions Guide

About This Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii

Junos Documentation and Release Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii

Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiv

Audience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiv

Supported Routing Platforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv

Using the Indexes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv

Using the Examples in This Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv

Merging a Full Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv

Merging a Snippet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvi

Documentation Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvi

Documentation Feedback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xviii

Requesting Technical Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xviii

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

Opening a Case with JTAC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xix

Part 1 Overview

Chapter 1 Overview of Ethernet Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Ethernet Terms and Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Networking and Internetworking with Bridges and Routers . . . . . . . . . . . . . . . . . . . 6

Network Addressing at Layer 2 and Layer 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Networking at Layer 2: Benefits of Ethernet Frames . . . . . . . . . . . . . . . . . . . . . . . . 9

Networking at Layer 2: Challenges of Ethernet MAC Addresses . . . . . . . . . . . . . . . 10

Networking at Layer 2: Forwarding VLAN Tagged Frames . . . . . . . . . . . . . . . . . . . . 11

Networking at Layer 2: Forwarding Dual-Tagged Frames . . . . . . . . . . . . . . . . . . . . 13

Networking at Layer 2: Logical Interface Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

A Metro Ethernet Network with MX Series Routers . . . . . . . . . . . . . . . . . . . . . . . . . 15

Layer 2 Networking Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Part 2 Basic Solutions for MX Series Routers

Chapter 2 Basic Layer 2 Features on MX Series Routers . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Layer 2 Features for a Bridging Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Example Roadmap: Configuring a Basic Bridge Domain Environment . . . . . . . . . 22

Example Topology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Example Scenario . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Example Configuration Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Example Step: Configuring Interfaces and VLAN Tags . . . . . . . . . . . . . . . . . . . . . . 24

Example Step: Configuring Bridge Domains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Example Step: Configuring Spanning Tree Protocols . . . . . . . . . . . . . . . . . . . . . . . 32

Example Step: Configuring Integrated Bridging and Routing . . . . . . . . . . . . . . . . . 34

Junos OS 13.1 MX Series 3D Universal Edge Routers Solutions Guide

Chapter 3 Virtual Switches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Layer 2 Features for a Switching Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Configuring Virtual Switches as Separate Routing Instances . . . . . . . . . . . . . . . . 40

Chapter 4 VLANs Within Bridge Domain and VPLS Environments . . . . . . . . . . . . . . . . 43

VLANs Within a Bridge Domain or VPLS Instance . . . . . . . . . . . . . . . . . . . . . . . . . 43

Packet Flow Through a Bridged Network with Normalized VLANs . . . . . . . . . . . . 44

Configuring a Normalized VLAN for Translation or Tagging . . . . . . . . . . . . . . . . . . 45

Implicit VLAN Translation to a Normalized VLAN . . . . . . . . . . . . . . . . . . . . . . 45

Sending Tagged or Untagged Packets over VPLS Virtual Interfaces . . . . . . . 46

Configuring a Normalized VLAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Configuring Learning Domains for VLAN IDs Bound to Logical Interfaces . . . . . . . 47

Example: Configuring a Provider Bridge Network with Normalized VLAN Tags . . . 47

Example: Configuring a Provider VPLS Network with Normalized VLAN Tags . . . . 51

Example: Configuring One VPLS Instance for Several VLANs . . . . . . . . . . . . . . . . 55

Chapter 5 Bulk Administration of Layer 2 Features on MX Series Routers . . . . . . . . . . 63

Bulk Configuration of VLANs and Bridge Domains . . . . . . . . . . . . . . . . . . . . . . . . . 63

Example: Configuring VLAN Translation with a VLAN ID List . . . . . . . . . . . . . . . . . 63

Example: Configuring Multiple Bridge Domains with a VLAN ID List . . . . . . . . . . . 64

Chapter 6 Dynamic Profiles for VLAN Interfaces and Protocols . . . . . . . . . . . . . . . . . . . 67

Dynamic Profiles for VPLS Pseudowires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

Example: Configuring VPLS Pseudowires with Dynamic Profiles—Basic

Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

VPLS Pseudowire Interfaces Without Dynamic Profiles . . . . . . . . . . . . . . . . . 68

VPLS Pseudowire Interfaces and Dynamic Profiles . . . . . . . . . . . . . . . . . . . . 69

CE Routers Without Dynamic Profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

CE Routers and Dynamic Profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

Example: Configuring VPLS Pseudowires with Dynamic Profiles—Complex

Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

Configuration of Routing Instance and Interfaces Without Dynamic

Profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

Configuration of Routing Instance and Interfaces Using Dynamic

Profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

Configuration of Tag Translation Using Dynamic Profiles . . . . . . . . . . . . . . . . 76

Chapter 7 MX Series Router as a DHCP Relay Agent . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

MX Series Router as a Layer 2 DHCP Relay Agent . . . . . . . . . . . . . . . . . . . . . . . . . 79

Example: Configuring DHCP Relay in a Bridge Domain VLAN Environment . . . . . 80

Example: Configuring DHCP Relay in a VPLS Routing Instance Environment . . . . 81

Chapter 8 MX Series Router in an ATM Ethernet Interworking Function . . . . . . . . . . . . 83

MX Series Router ATM Ethernet Interworking Function . . . . . . . . . . . . . . . . . . . . . 83

Example: Configuring MX Series Router ATM Ethernet Interworking . . . . . . . . . . . 85

Configuring Router PE2 with a Layer 2 Circuit . . . . . . . . . . . . . . . . . . . . . . . . . 86

Configuring Router PE2 with a Layer 2 Circuit over Aggregated Ethernet . . . 88

Configuring Router PE2 with a Remote Interface Switch . . . . . . . . . . . . . . . . . 91

Configuring Router PE2 with a Remote Interface Switch over Aggregated

Ethernet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

Table of Contents

Part 3 Ethernet Filtering, Monitoring, and Fault Management Solutions

for MX Series Routers

Chapter 9 Layer 2 Firewall Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

Firewall Filters for Bridge Domains and VPLS Instances . . . . . . . . . . . . . . . . . . . . 101

Example: Configuring Policing and Marking of Traffic Entering a VPLS Core . . . . 102

Example: Configuring Filtering of Frames by MAC Address . . . . . . . . . . . . . . . . . 104

Example: Configuring Filtering of Frames by IEEE 802.1p Bits . . . . . . . . . . . . . . . 106

Example: Configuring Filtering of Frames by Packet Loss Priority . . . . . . . . . . . . 107

Chapter 10 IEEE 802.1ag OAM Connectivity-Fault Management . . . . . . . . . . . . . . . . . . 109

Ethernet Operations, Administration, and Maintenance . . . . . . . . . . . . . . . . . . . 109

Ethernet OAM Connectivity Fault Management . . . . . . . . . . . . . . . . . . . . . . . . . . 110

Example: Configuring Ethernet CFM over VPLS . . . . . . . . . . . . . . . . . . . . . . . . . . . 111

Example: Configuring Ethernet CFM on Bridge Connections . . . . . . . . . . . . . . . . . 118

Example: Configuring Ethernet CFM on Physical Interfaces . . . . . . . . . . . . . . . . . 122

Chapter 11 ITU-T Y.1731 Ethernet Frame Delay Measurements . . . . . . . . . . . . . . . . . . . . 125

Ethernet Frame Delay Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125

Configuring MEP Interfaces to Support Ethernet Frame Delay Measurements . . 128

Triggering an Ethernet Frame Delay Measurements Session . . . . . . . . . . . . . . . . 129

Viewing Ethernet Frame Delay Measurements Statistics . . . . . . . . . . . . . . . . . . . 130

Example: Configuring One-Way Ethernet Frame Delay Measurements with

Single-Tagged Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

Example: Configuring Two-Way Ethernet Frame Delay Measurements with

Single-Tagged Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136

Example: Configuring Ethernet Frame Delay Measurements with Untagged

Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140

Chapter 12 IEEE 802.3ah OAM Link-Fault Management . . . . . . . . . . . . . . . . . . . . . . . . . 143

Ethernet OAM Link Fault Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143

Example: Configuring Ethernet LFM Between Provider Edge and Customer

Edge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144

Example: Configuring Ethernet LFM for CCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145

Example: Configuring Ethernet LFM for Aggregated Ethernet . . . . . . . . . . . . . . . 146

Example: Configuring Ethernet LFM with Loopback Support . . . . . . . . . . . . . . . . 148

Chapter 13 Ethernet Ring Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151

Ethernet Ring Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151

Ethernet Ring Protection Using Ring Instances for Load Balancing . . . . . . . . . . . 153

Example: Configuring Ethernet Ring Protection for MX Series Routers . . . . . . . . 154

Example Topology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154

Router 1 (RPL Owner) Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155

Router 2 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157

Router 3 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158

Example: Configuring Load Balancing Within Ethernet Ring Protection for MX

Series Routers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160

Example: Viewing Ethernet Ring Protection Status—Normal Ring Operation . . . 177

Example: Viewing Ethernet Ring Protection Status—Ring Failure Condition . . . . 179

Junos OS 13.1 MX Series 3D Universal Edge Routers Solutions Guide

Part 4 Index

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185

List of Figures

Part 1 Overview

Chapter 1 Overview of Ethernet Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Figure 1: Native (Normal) and VLAN-Tagged Ethernet Frames . . . . . . . . . . . . . . . . 12

Figure 2: A Metro Ethernet Network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Figure 3: A Metro Ethernet Network with MX Series Routers . . . . . . . . . . . . . . . . . 16

Figure 4: VLAN Tags on a Metro Ethernet Network . . . . . . . . . . . . . . . . . . . . . . . . . 16

Part 2 Basic Solutions for MX Series Routers

Chapter 2 Basic Layer 2 Features on MX Series Routers . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Figure 5: Bridging Network with MX Series Routers . . . . . . . . . . . . . . . . . . . . . . . . 23

Figure 6: Designated, Root, and Alternate Ports . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Chapter 4 VLANs Within Bridge Domain and VPLS Environments . . . . . . . . . . . . . . . . 43

Figure 7: Provider Bridge Network Using Normalized VLAN Tags . . . . . . . . . . . . . 48

Figure 8: VLAN Tags and VPLS Labels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Figure 9: Many VLANs on One VPLS Instance . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

Chapter 8 MX Series Router in an ATM Ethernet Interworking Function . . . . . . . . . . . . 83

Figure 10: ATM Ethernet VLAN Interworking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

Figure 11: ATM Ethernet VLAN Interworking Packet Structure . . . . . . . . . . . . . . . . 84

Figure 12: CCC-to-Stacked VLAN Translation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

Figure 13: ATM Ethernet VLAN Interworking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

Part 3 Ethernet Filtering, Monitoring, and Fault Management Solutions

for MX Series Routers

Chapter 9 Layer 2 Firewall Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

Figure 14: Policing and Marking Traffic Entering a VPLS Core . . . . . . . . . . . . . . . . 102

Chapter 10 IEEE 802.1ag OAM Connectivity-Fault Management . . . . . . . . . . . . . . . . . . 109

Figure 15: Ethernet OAM with VPLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112

Figure 16: Ethernet CFM over a Bridge Network . . . . . . . . . . . . . . . . . . . . . . . . . . . 118

Figure 17: Ethernet CFM on Physical Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . 122

Chapter 11 ITU-T Y.1731 Ethernet Frame Delay Measurements . . . . . . . . . . . . . . . . . . . . 125

Figure 18: Ethernet OAM Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126

Chapter 12 IEEE 802.3ah OAM Link-Fault Management . . . . . . . . . . . . . . . . . . . . . . . . . 143

Figure 19: Ethernet LFM Between Provider Edge and Customer Edge . . . . . . . . . 144

Figure 20: Ethernet LFM for CCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145

Figure 21: Ethernet LFM for Aggregated Ethernet . . . . . . . . . . . . . . . . . . . . . . . . . . 147

Junos OS 13.1 MX Series 3D Universal Edge Routers Solutions Guide

Figure 22: Ethernet LFM with Loopback Support . . . . . . . . . . . . . . . . . . . . . . . . . 148

Chapter 13 Ethernet Ring Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151

Figure 23: Ethernet Ring Protection Example Nodes . . . . . . . . . . . . . . . . . . . . . . . 154

Figure 24: ERPwith Multiple Protection Instances Configured onThreeMX Series

Routers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162

List of Tables

About This Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii

Table 1: Notice Icons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvii

Table 2: Text and Syntax Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvii

Part 3 Ethernet Filtering, Monitoring, and Fault Management Solutions

for MX Series Routers

Chapter 11 ITU-T Y.1731 Ethernet Frame Delay Measurements . . . . . . . . . . . . . . . . . . . . 125

Table 3: Monitor Ethernet Delay Command Parameters . . . . . . . . . . . . . . . . . . . 129

Table 4: Show Ethernet Delay Command Parameters . . . . . . . . . . . . . . . . . . . . . . 131

Chapter 13 Ethernet Ring Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151

Table 5: Components of the Network Topology . . . . . . . . . . . . . . . . . . . . . . . . . . 162

Junos OS 13.1 MX Series 3D Universal Edge Routers Solutions Guide

About This Guide

This preface provides the following guidelines for using the Junos®OS MX Series 3D Universal Edge Routers Solutions Guide:

•

Junos Documentation and Release Notes on page xiii

•

Objectives on page xiv

•

Audience on page xiv

•

Supported Routing Platforms on page xv

•

Using the Indexes on page xv

•

Using the Examples in This Manual on page xv

•

Documentation Conventions on page xvi

•

Documentation Feedback on page xviii

•

Requesting Technical Support on page xviii

Junos Documentation and Release Notes

For a list of related Junos documentation, see

http://www.juniper.net/techpubs/software/junos/.

If the information in the latest release notes differs from the information in the documentation, follow the Junos Release Notes.

To obtain the most current version of all Juniper Networks®technical documentation, see the product documentation page on the Juniper Networks website at

http://www.juniper.net/techpubs/.

Juniper Networks supportsa technical bookprogram to publishbooks byJuniper Networks engineers and subject matter experts with book publishers around the world. These books go beyond the technical documentation to explore the nuances of network architecture, deployment, and administration using the Junos operating system (Junos OS) and Juniper Networks devices. In addition, the Juniper Networks Technical Library, published in conjunction with O'Reilly Media, explores improving network security, reliability, and availability using Junos OS configuration techniques. All the books are for sale at technical bookstores and book outlets around the world. The current list can be viewed at http://www.juniper.net/books.

Junos OS 13.1 MX Series 3D Universal Edge Routers Solutions Guide

Objectives

This guide provides an overview of the Layer 2 features of the Junos OS and describes how to configure the features to provide solutions to several network scenarios.

NOTE: For additional information about the Junos OS—either corrections to

or information thatmight havebeen omittedfrom this guide—see the software release notes at http://www.juniper.net/ .

Audience

This guide is designed for network administrators who are configuring and monitoring Layer 2 features of the Junos OS.

To use this guide, you need a broad understanding of networks in general, the Internet in particular, networking principles, and network configuration. You must also be familiar with one or more of the following Internet routing protocols:

•

Border Gateway Protocol (BGP)

•

Distance Vector Multicast Routing Protocol (DVMRP)

•

Intermediate System-to-Intermediate System (IS-IS)

•

Internet Control Message Protocol (ICMP) router discovery

•

Internet Group Management Protocol (IGMP)

•

Multiprotocol Label Switching (MPLS)

•

Open Shortest Path First (OSPF)

•

Protocol-Independent Multicast (PIM)

•

Resource Reservation Protocol (RSVP)

•

Routing Information Protocol (RIP)

•

Simple Network Management Protocol (SNMP)

Personnel operating the equipment must be trained and competent; must not conduct themselves in a careless, willfully negligent, or hostile manner; and must abide by the instructions provided by the documentation.

Supported Routing Platforms

For the Layer 2 features described in this manual, the Junos OS currently supports the following routing platforms:

•

Juniper Networks MX Series 3D Universal Edge Routers

Using the Indexes

This reference contains a standard index with topic entries.

Using the Examples in This Manual

If you want to use the examples in this manual, you can use the load merge or the load

merge relative command. These commands cause the software to merge the incoming

configuration into the current candidate configuration. The example does not become active until you commit the candidate configuration.

About This Guide

If the example configuration contains the top level of the hierarchy (or multiple hierarchies), the example is a full example. In this case, use the load merge command.

If the example configuration does not start at the top level of the hierarchy, the example is a snippet. In this case, use the load merge relative command. These procedures are described in the following sections.

Merging a Full Example

To merge a full example, follow these steps:

1. From the HTML or PDF version of the manual, copy a configuration example into a

text file, save the file with a name, and copy the file to a directory on your routing platform.

For example, copy the following configuration to a file andname the file ex-script.conf. Copy the ex-script.conf file to the /var/tmp directory on your routing platform.

system {

scripts {

commit {

file ex-script.xsl;

}

} interfaces {

fxp0 {

disable; unit 0 {

family inet {

address 10.0.0.1/24;

}

Junos OS 13.1 MX Series 3D Universal Edge Routers Solutions Guide

}

2. Merge the contents of the file into your routing platform configuration by issuing the

load merge configuration mode command:

[edit] user@host# load merge /var/tmp/ex-script.conf load complete

Merging a Snippet

To merge a snippet, follow these steps:

1. From the HTML or PDF version of the manual, copy a configuration snippet into a text

file, save the file with a name, and copy the file to a directory on your routing platform.

For example, copy the following snippet to a file and name the file

ex-script-snippet.conf. Copy the ex-script-snippet.conf file to the /var/tmp directory

on your routing platform.

commit {

file ex-script-snippet.xsl; }

2. Move to the hierarchy level that is relevant for this snippet by issuing the following

configuration mode command:

[edit] user@host# edit system scripts [edit system scripts]

3. Merge the contents of the file into your routing platform configuration by issuing the

load merge relative configuration mode command:

[edit system scripts] user@host# load merge relative /var/tmp/ex-script-snippet.conf load complete

For more information about the load command, see the CLI User Guide.

Documentation Conventions

Table 1 on page xvii defines notice icons used in this guide.

Table 1: Notice Icons

About This Guide

DescriptionMeaningIcon

Indicates important features or instructions.Informational note

Indicates a situation that might result in loss of data or hardware damage.Caution

Alerts you to the risk of personal injury or death.Warning

Alerts you to the risk of personal injury from a laser.Laser warning

Table 2 on page xvii defines the text and syntax conventions used in this guide.

Table 2: Text and Syntax Conventions

Represents text that you type.Bold text like this

Fixed-width text like this

Italic text like this

Text like this

Represents output that appears on the terminal screen.

•

Introduces or emphasizes important new terms.

•

Identifies book names.

•

Identifies RFC and Internet draft titles.

Represents variables (options for which you substitute a value) in commands or configuration statements.

Represents names of configuration statements, commands, files, and directories;configurationhierarchy levels; or labels on routing platform components.

ExamplesDescriptionConvention

To enter configuration mode, type theconfigure command:

user@host> configure

user@host> show chassis alarms

No alarms currently active

•

A policy term is a named structure that defines match conditions and actions.

•

Junos OS SystemBasics Configuration Guide

•

RFC 1997, BGP Communities Attribute

Configure the machine’s domain name:

[edit] root@# set system domain-name

domain-name

•

To configure a stub area, include the

stub statement at the[edit protocols ospf area area-id] hierarchy level.

•

The console portis labeled CONSOLE.

stub <default-metric metric>;Enclose optional keywords or variables.< > (angle brackets)

Junos OS 13.1 MX Series 3D Universal Edge Routers Solutions Guide

Table 2: Text and Syntax Conventions (continued)

ExamplesDescriptionConvention

| (pipe symbol)

# (pound sign)

[ ] (square brackets)

Indention and braces ( { } )

; (semicolon)

J-Web GUI Conventions

Bold text like this

Indicates a choice betweenthe mutually exclusivekeywords or variables on either side of the symbol. The set of choices is often enclosed in parentheses for clarity.

same lineas theconfiguration statement to which it applies.

Enclose a variable for which you can substitute one or more values.

Identify a level in the configuration hierarchy.

Identifies a leaf statement at a configuration hierarchy level.

Represents J-Web graphical user interface (GUI) items you click or select.

broadcast | multicast

(string1 | string2 | string3)

rsvp { # Required for dynamic MPLS onlyIndicates a comment specified on the

community name members [ community-ids ]

[edit] routing-options {

static {

route default {

nexthop address; retain;

}

•

In the Logical Interfaces box, select

All Interfaces.

•

To cancel the configuration, click

Cancel.

> (bold right angle bracket)

Documentation Feedback

We encourage you to provide feedback, comments, and suggestions so that we can improve the documentation. You can send your comments to

techpubs-comments@juniper.net, or fill out the documentation feedback form at

https://www.juniper.net/cgi-bin/docbugreport/ . If you are using e-mail, be sure to include

the following information with your comments:

•

Document or topic name

•

URL or page number

•

Software release version (if applicable)

Requesting Technical Support

Technical product support is available through the Juniper NetworksTechnical Assistance Center (JTAC). If you are a customer with an active J-Care or JNASC support contract,

Separates levels in a hierarchy of J-Web selections.

In the configuration editor hierarchy, select Protocols>Ospf.

or are covered under warranty, and need postsales technical support, you can access our tools and resources online or open a case with JTAC.

•

JTAC policies—For a complete understanding of our JTAC procedures and policies, review the JTAC User Guide located at

http://www.juniper.net/us/en/local/pdf/resource-guides/7100059-en.pdf.

•

Product warranties—For product warranty information, visit

http://www.juniper.net/support/warranty/.

•

JTAC Hours of Operation —The JTAC centers have resources available 24 hours a day, 7 days a week, 365 days a year.

Self-Help Online Tools and Resources

For quick and easy problem resolution, Juniper Networks has designed an online self-service portal called the Customer Support Center (CSC) that provides you with the following features:

•

Find CSC offerings: http://www.juniper.net/customers/support/

About This Guide

•

Find product documentation: http://www.juniper.net/techpubs/

•

Find solutions and answer questions using our Knowledge Base: http://kb.juniper.net/

•

Download the latest versions of software and review release notes:

http://www.juniper.net/customers/csc/software/

•

Search technical bulletins for relevant hardware and software notifications:

https://www.juniper.net/alerts/

•

Join and participate in the Juniper Networks Community Forum:

http://www.juniper.net/company/communities/

•

Open a case online in the CSC Case Management tool: http://www.juniper.net/cm/

To verify service entitlement byproduct serial number, useour SerialNumber Entitlement (SNE) Tool: https://tools.juniper.net/SerialNumberEntitlementSearch/

Opening a Case with JTAC

You can open a case with JTAC on the Web or by telephone.

•

Use the Case Management tool in the CSC at http://www.juniper.net/cm/.

•

Call 1-888-314-JTAC (1-888-314-5822 toll-free in the USA, Canada, and Mexico).

For international or direct-dial options in countries without toll-free numbers, visit us at

http://www.juniper.net/support/requesting-support.html

Junos OS 13.1 MX Series 3D Universal Edge Routers Solutions Guide

PART 1

Overview

•

Overview of Ethernet Solutions on page 3

Junos OS 13.1 MX Series 3D Universal Edge Routers Solutions Guide

CHAPTER 1

Overview of Ethernet Solutions

This chapter discusses the following topics:

•

Ethernet Terms and Acronyms on page 3

•

Networking and Internetworking with Bridges and Routers on page 6

•

Network Addressing at Layer 2 and Layer 3 on page 7

•

Networking at Layer 2: Benefits of Ethernet Frames on page 9

•

Networking at Layer 2: Challenges of Ethernet MAC Addresses on page 10

•

Networking at Layer 2: Forwarding VLAN Tagged Frames on page 11

•

Networking at Layer 2: Forwarding Dual-Tagged Frames on page 13

•

Networking at Layer 2: Logical Interface Types on page 14

•

A Metro Ethernet Network with MX Series Routers on page 15

•

Layer 2 Networking Standards on page 17

Ethernet Terms and Acronyms

Networking with a switch over Ethernet on a LAN is different than networking with a router with IP over a wider area. Even the words used to talk about Ethernet networking are different from those used in IP routing. This topic provides a list of all the terms and acronyms used in the Junos OS Layer 2 Configuration Guide, as well terms that apply to a complete network using Ethernet as a carrier technology.

•

802.1ad—The IEEE specification for “Q-in-Q” encapsulation and bridging of Ethernet frames.

•

802.1ah—The IEEE specification for media access control (MAC) tunneling encapsulation and bridging of Ethernet frames across a provided backbone-managed bridge.

•

802.3ag—The IEEEspecification for a wide rangeof EthernetOperations, Administration, and Maintenance (OAM) features. See also OAM, CFM, and ETH-DM.

•

802.3ah—The IEEE specification for link fault management (LFM), a method for OAM of Ethernet links.

•

802.1Q—The IEEE specification for adding virtual local area network (VLAN) tags to an Ethernet frame.

Junos OS 13.1 MX Series 3D Universal Edge Routers Solutions Guide

•

B–MAC—The backbone source and destination MAC address fields found in the IEEE

802.1ah provider MAC encapsulation header.

•

bridge—A network componentdefined by the IEEE that forwards frames from one LAN segment or VLAN to another. The bridging function can be contained in a router, LAN switch, or other specialized device. See also switch.

•

bridge domain—A set of logical ports that share the same flooding or broadcast characteristics.As ina virtualLAN, abridge domainspans oneor moreports ofmultiple devices. By default, each bridge domain maintains its own forwarding database of MAC addresses learned frompackets received on ports belonging tothat bridge domain. See also broadcast domain and VLAN.

•

B-TAG—A field defined in the IEEE 802.1ah provider MAC encapsulation header that carries the backbone VLAN identifier information. The format of the B-TAG field is the same as that of the IEEE 802.1ad S-TAG field. See also S-TAG.

•

B-VID—The specific VLAN identifier carried in a B-TAG.

•

CFM—Connectivity-fault management. Thepart ofEthernet OAM thatmonitors events at levels above the physical level, as does LFM. See also OAM, LFM, and ETH-DM.

•

CIST—Common and Internal Spanning Tree. The single spanning tree calculated by the spanning tree protocol (STP) and the rapid spanning tree protocol (RSTP) and the logical continuation of that connectivity through multiple spanning tree (MST) bridges and regions, calculated to ensure that all LANs in the bridged LAN are simply and fully connected. See also MSTI.

•

ETH-DM—Ethernet Frame Delay Measurements. See also OAM, CFM, and Y.1731.

•

Ethernet—A term loosely applied to a family of LAN standards based on the original proprietary Ethernet from DEC, Intel, and Xerox (DIX Ethernet), and the open specifications developed by the IEEE 802.3 committee (IEEE 802.3 LANs). In practice, few LANs comply completely with DIX Ethernet or IEEE 802.3.

•

IRB—Integrated bridging and routing. IRB provides simultaneous support for Layer 2 bridging and Layer 3 routing within the same bridge domain. Packets arriving on an interface of the bridge domain are Layer 2 switched or Layer 3 routed based on the destination MAC address. Packets addressed to the router's MAC address are routed to other Layer 3 interfaces.

•

I-SID—The 24–bit service instance identifier field carried inside an I-TAG. The I-SID defines the service instance to which the frame is mapped.

•

I-TAG—A field defined in the IEEE 802.1ah provider MAC encapsulation header that carries the service instance information (I-SID) associated with the frame.

•

learning domain—A MAC addressdatabasewhere theMAC addresses areadded based on the normalized VLAN tags.

•

LFM—Link fault management. A method used to detect problems on links and spans on an Ethernet network defined in IEEE 802.3ah. See also OAM.

•

MSTI—Multiple Spanning Tree Instance. One of a number of spanning trees calculated by MSTP within an MST region. The MSTI provides a simple and fully connected active topology for frames classified as belonging to a VLAN that is mapped to the MSTI by

Chapter 1: Overview of Ethernet Solutions

the MST configuration table used by the MST bridges of that MST region. See also CIST.

•

MSTP—Multiple Spanning Tree Protocol. A spanning-tree protocol used to prevent loops in bridge configurations. Unlike other types of STPs, MSTP can block ports selectively by VLAN. See also RSTP.

•

OAM—Operation, Administration, and Maintenance. A set of tools used to provide management for links, device, and networks. See also LFM.

•

PBB—Provider backbone bridge.

•

Q-in-Q—See 802.1ad.

•

PBBN—Provider backbone bridged network.

•

RSTP—Rapid Spanning Tree Protocol. A spanning-tree protocol used to prevent loops in bridge configurations. RSTP is not aware of VLANs and blocks ports at the physical level. See also MSTP.

•

S-TAG—A field defined in the IEEE 802.1ad Q-in-Q encapsulation header that carries the S-VLAN identifier information. See also B-TAG.

•

S-tagged service interface—The interface between a customer edge (CE) device and the I-BEBor IB-BEB network components. Framespassed through this interface contain an S-TAG field. See also B-tagged service interface.

•

S-VLAN—The specific service instance VLAN identifier carried inside the S-TAG field. See also B-VID.

•

switch—A network device that attempts to perform as much of the forwarding task in hardware as possible. The switch can function as a bridge (LAN switch), router, or some other specialized device, and forwards frames, packets, or other data units. See also bridge.

•

virtual switch—A routing instance that can contain one or more bridge domains.

•

VLAN—Virtual LAN. Defines a broadcast domain, a set of logical ports that share the same floodingor broadcast characteristics. VLANs span one or more ports on multiple devices. By default, each VLAN maintains its own Layer 2 forwarding database containing MAC addresses learned from packets received on ports belonging to the VLAN. See also bridge domain.

•

Y.1731—The international standard forEthernet Frame Delay Measurements (ETH-DM).

At this point, these acronyms and terms are just a bewildering array of letters and words. It is the goal of this manual to make the contents of this list familiar and allow you to place each of them in context and understand how they relate to each other. To do that, a basic understanding of modern Ethernet standards and technology is necessary.

Documentation

Ethernet Networking•

• Networking and Internetworking with Bridges and Routers on page 6

• Network Addressing at Layer 2 and Layer 3 on page 7

• Networking at Layer 2: Benefits of Ethernet Frames on page 9

Junos OS 13.1 MX Series 3D Universal Edge Routers Solutions Guide

• Networking at Layer 2: Challenges of Ethernet MAC Addresses on page 10

• Networking at Layer 2: Forwarding VLAN Tagged Frames on page 11

• Networking at Layer 2: Forwarding Dual-Tagged Frames on page 13

• Networking at Layer 2: Logical Interface Types on page 14

• A Metro Ethernet Network with MX Series Routers on page 15

• Layer 2 Networking Standards on page 17

Networking and Internetworking with Bridges and Routers

Traditionally, different hardware, software, and protocols have been used on LANs and on networks that cover wider areas (national or global). A LAN switch is different than a router, an Ethernet frame is different than an IP packet, and the methods used to find destination MAC addresses are different thanthose usedto find destination IPaddresses. This is because LANs basedon Ethernetwere intended fordifferent network environments than networks based on IP. The Internet protocol suite (TCP/IP) was intended as an internetworkingmethod toconnect local customer networks. Thelocal customer network that a service provider's IP routers connected was usuallybased on some form of Ethernet. This is why Ethernet and IP fit so well together: Ethernetdefines theLAN, and the Internet protocols define how these LANs are connected.

More specifically, Ethernet LANs and IP networks occupy different layers of the Internet’s TCP/IP protocol suite.Between sender and receiver, networks deal with thebottom three layers of the model: the physical layer (Layer 1), the data link or MAC layer (Layer 2), and the network layer (Layer 3).

NOTE: These layers are also found in the Open Systems Interconnect

Reference Model (OSI-RM); however, in this chapter they are applied to the TCP/IP protocol suite.

All digital networks ultimately deal with zeroes and ones, and the physical layer defines bit representation on the media. Physical layer standards alsodefine mechanical aspects of the network, such as electrical characteristics or connector shapes,functional aspects such as bit sequence and organization, and so on. The physical layer only “spits bits” and has very little of the intelligence required to implement a complete network. Devices that connect LAN segments at the physical layer are called hubs, and all bits that appear on one port of the hub are also sent out on the other ports. This also means that bad bits that appear on one LAN segment are propagated to all other LAN segments.

Above the physical layer, the data link layer defines the first-order bit structure, or frame, for the network type. Also loosely called the MAC layer (technically, the MAC layer is a sublayer required only on LANs), Layer 2 sends and receives frames. Frames are the last things that bits were before they left the sender and the first things that bits become when they arrive on an interface. Because frames have a defined structure, unlike bits, frames can be used for error detection, control plane activities (not all frames must carry user data: some frames are used by the network to control the link), and so forth. LAN

Chapter 1: Overview of Ethernet Solutions

segments can be linked at the frame level, and these devices are called bridges. Bridges examine arriving frames and decide whether to forward them on an interface. All bridges today are called learning bridges because they can find out more about the network than could older bridges that were less intelligent devices. Bridges learn much about the LAN segments they connect to from protocols like those in the Spanning Tree Protocol (STP) family.

The network layer (Layer 3) is the highest layer used by network nodes to forward traffic as part of the data plane. On the Internet, the network layer is the IP layer and can run either IPv4 or IPv6, which are independent implementations of the same functions. The IP layer defines the structure and purpose of the packet, which is in turn the content of the frame at Layer 2. As expected, LAN segments (which now form perfectly functional networks on their own at the frame level) can be linked at the network layer, and in fact that is one of the major functions of IP. Devices that link LANs at the network layer are called routers, and IP routers are the network nodes of the Internet.

Documentation

Ethernet Networking•

• Ethernet Terms and Acronyms on page 3

• Network Addressing at Layer 2 and Layer 3 on page 7

• Networking at Layer 2: Benefits of Ethernet Frames on page 9

• Networking at Layer 2: Challenges of Ethernet MAC Addresses on page 10

• Networking at Layer 2: Forwarding VLAN Tagged Frames on page 11

• Networking at Layer 2: Forwarding Dual-Tagged Frames on page 13

• Networking at Layer 2: Logical Interface Types on page 14

• A Metro Ethernet Network with MX Series Routers on page 15

• Layer 2 Networking Standards on page 17

Network Addressing at Layer 2 and Layer 3

The Internet is a global, public network with IP subnets connected by routers and exchanging packets. Can a global, public network consist of Ethernet LANs connected by bridges and exchanging frames? Yes, it can, but there are several differences that must be addressed before Ethernet can function as effectively as IP in the metropolitan area (Metro Ethernet), let alone globally. One of the key differences is the addresses used by Layer 2 frames and Layer 3 packets.

Both Ethernet and IP use globally unique network addresses that can be used as the basis for a truly global network. Ethernet MAC addresses come from the IEEE and IP subnet addresses come from various Internet authorities. (IP also employs a naming convention absent in Ethernet, but we'll ignore that in this discussion.) The keydifferences in how these addresses are assigned make all the difference when it comes to the basic functions of a bridge as opposed to a router.

Junos OS 13.1 MX Series 3D Universal Edge Routers Solutions Guide

NOTE: The opposite of a “globally unique network address” is the “locally

significant connection identifier” which connects two endpoints on a network. For example, MPLS labels such as 1000001 can repeat in a network, but a public IP address can appear on the Internet in only one place at a time (otherwise it is an error).

All devices on LANs that are attached to the Internet have both MAC layer and IP addresses. Frames and packets contain both source and destination addresses in their headers. In general:

•

MAC addresses are 48 bits long. The first 24 bits are assigned by the IEEE and form the organizationally unique identifier (OUI) of the manufacturer or vendor requesting the address. The last 24 bits form the serial number of the LAN interface cards and their uniqueness must be enforced by the company (some companies reuse numbers of bad or returned cards while others do not).

•

IPv4 addresses are 32 bits long. A variable number of the beginning bits are assigned by an Internet authority and represent a subnet located somewhere in the world. The remaining bits are assigned locally and, when joined to the network portion of the address, uniquely identify some host on a particular network.

•

IPv6 addresses are 128 bits long. Although there are significant differences, for the purposes of this discussion, it is enough to point out that there is also a network and host portion to an IPv6 address.

Note that MAC addresses are mainly organized by manufacturer and IP addresses are organized by network, which is located in a particular place. Therefore, the IP address can easily be used by routers for a packet's overall direction (for example, “192.168.27.48 is west of here”). However, the MAC addresses on a vendor's interface cards can end up anywhere in the world, and often do. Consider a Juniper Networks router as a simple example.Every Ethernet LAN interface on the router thatsends or receives packets places them inside Ethernet frames with MAC addresses. All of these interfaces share the initial 24 bitsassigned to Juniper Networks. Two might differ onlyin one digitfrom one interface to another. Yet the routers containing these MAC interfaces could be located on opposite sides of the world.

An Internet backbone router only needs a table entry for every network (not host) in the world. Most other routers only have a portion of this full table, and a default route for forwarding packets with no entries in their table. In contrast, to perform the same role, a bridge would need one table entry for every LAN interface, on host or bridge, in the world. This is hard enough to do for Ethernets that span a metropolitan area, let alone the entire world.

NOTE: There are other reasons that Ethernet would be hard-pressed to

become a truly global network, including the fact that MAC addresses do not often have names associated with them while IP addresses do (for example,

192.168.27.48 might be host48.accounting.juniper.net). This section addresses

only the address issues.

Chapter 1: Overview of Ethernet Solutions

Documentation

Ethernet Networking•

• Ethernet Terms and Acronyms on page 3

• Networking and Internetworking with Bridges and Routers on page 6

• Networking at Layer 2: Benefits of Ethernet Frames on page 9

• Networking at Layer 2: Challenges of Ethernet MAC Addresses on page 10

• Networking at Layer 2: Forwarding VLAN Tagged Frames on page 11

• Networking at Layer 2: Forwarding Dual-Tagged Frames on page 13

• Networking at Layer 2: Logical Interface Types on page 14

• A Metro Ethernet Network with MX Series Routers on page 15

• Layer 2 Networking Standards on page 17

Networking at Layer 2: Benefits of Ethernet Frames

In spite of the difficulties of using a bridge to perform the network role of a router, many vendors, customers, and service providers are attracted to the idea of using Ethernet in as many places of their networks as possible.

The perceived benefits of Ethernet are:

•

Most information starts and ends inside Ethernet frames. Today, this applies to data, as well as voice (for example, VoIP) and video (for example, Web cams).

•

Ethernet frames have all the essentials for networking, such as globally unique source and destination addresses, error control, and so on.

•

Ethernet frames can carry any kind of packet. Networking at Layer 2 is protocol independent (independent of the Layer 3 protocol). Layer 2 networks work for IP packets and all other Layer 3 protocols.

•

More layers added to the Ethernet frame only slow the networking process down (“nodal processing delay”).

•

Adjunct networking features such as class of service (CoS) or multicasting can be added to Ethernet as readily as IP networks.

If more of the end-to-end transfer of information from a source to a destination can be done in the form of Ethernet frames, more of the benefits of Ethernet can be realized on the network. Networking at Layer 2 can be a powerful adjunct to IP networking, but it is not usually a substitute for IP networking.

Junos OS 13.1 MX Series 3D Universal Edge Routers Solutions Guide

NOTE: Networking at the frame level says nothing about the presence or

absence of IP addressesat the packet level. Almost all ports, links, and devices on a network of LAN switches still have IP addresses, just as do all the source and destination hosts. There are many reasons for the continued need for IP, not the least of which is the need to manage the network. A device or link without an IP address is usually invisible to most management applications. Also, utilities such as remote access for diagnostics, file transfer of configurations and software, and so on cannot run without IP addresses as well as MAC addresses.

Documentation

Ethernet Networking•

• Ethernet Terms and Acronyms on page 3

• Networking and Internetworking with Bridges and Routers on page 6

• Network Addressing at Layer 2 and Layer 3 on page 7

• Networking at Layer 2: Challenges of Ethernet MAC Addresses on page 10

• Networking at Layer 2: Forwarding VLAN Tagged Frames on page 11

• Networking at Layer 2: Forwarding Dual-Tagged Frames on page 13

• Networking at Layer 2: Logical Interface Types on page 14

• A Metro Ethernet Network with MX Series Routers on page 15

• Layer 2 Networking Standards on page 17

Networking at Layer 2: Challenges of Ethernet MAC Addresses

If a networked Layer 2 device such as a bridge or LAN switch could contain a list of all known MAC addresses, then the network node could function in much the same way as a router, forwarding frames instead of packets hop-by-hop through the network from source LAN to destination LAN. However, the MAC address is much larger than the IPv4 address currently used on the Internet backbone (48 bits compared to the 32 bits of IPv4).

Documentation

This poses problems. Also, because the MAC address has no “network organization” like the IPv4or IPv6 address, anLayer 2network node must potentially store every conceivable MAC address in memory for next-hop table lookups. Instead of tables of about 125,000 entries, every Layer 2 network node would have to store millions of entries (for example, 24 bits, the potential NIC production from one Ethernet vendor, would require a table of more than 16 million entries).

Ethernet Networking•

• Ethernet Terms and Acronyms on page 3

• Networking and Internetworking with Bridges and Routers on page 6

• Network Addressing at Layer 2 and Layer 3 on page 7

+ 178 hidden pages