Table Of Contentjunos_ha_praise_page Page i Thursday, August 13, 2009 11:54 AM
Praise forJUNOS High Availability
“JUNOSHighAvailabilitycontainsallthetechnicalbuildingblocksnecessarytoplanand
maintain a medical grade network.”
—Jonathan Yantis, Network Engineer, Medical University of South
Carolina
“AtTownsendAnalytics,ourtradingclients,usingourRealTicktradingsuite,demandthat
our global network maintain an extremely high level of availability. Downtime translates
directly into lost money. JUNOS High Availability has great tips and guides to help
supportthisenvironment.Itincludeseverythingfromconceptualdetailsonsoftwareand
hardware,verydetailedroutingprotocolexamples,securityandauditing,andeverything
inbetween.Thisbookisamustforanyonewhoisinanywayinvolvedinmaintaininga
high level of service on their network!”
—Chris Rizzo, Senior Network Engineer, Townsend Analytics
“High availability is such a buzz phrase these days. It’s refreshing to see an approach that
breaks down all of the various conversations and shows what is required for an overall
continuoussystem.Gettingthebuildingblocksrightiscrucialtohavinganetworkthatis
truly highly available, and JUNOS High Availability will help you get it right and keep it
right.”
—Scott Stevens, Vice President, Technology, Juniper Networks
“Withdisasterrecoveryandbusinesscontinuitythecurrentbuzzwordsinourstategovern-
ment network as well as in most corporate networks around the world, this book has
come along at the perfect time to spur conversations on high availability, not only for
networksbuiltonJuniperNetworksequipment,butonothervendorequipmentaswell.
ThetopicscoveredinJUNOSHighAvailabilityarebroadenoughforengineerslookingto
designanoverarchinghighavailabilitypostureintheirnetwork,butalsodetailedenough
toallowengineerstoimplementtheirdesignsthroughprotocoltweaksandJUNOStools.
Thetransitionbetweenauthorskeepstopicsinterestingandprovidesamusingquipsalong
the way.”
—Aaron Robel, Systems Engineer, Washington State Department of
Information Services
junos_ha_praise_page Page ii Thursday, August 13, 2009 11:54 AM
“A fault-tolerant network is a must in our health care environment. JUNOS High Avail-
ability will serve as a great tool to help us maintain the high availability our clients have
come to expect.”
—James Hardy, Network Engineer, Carilion Clinic
“I like that JUNOS High Availability is reality-based. It boils buzzwords like redundancy
andhighavailabilityintomodelsthathavedesignandcost.Andthebookisnotmarketing
fodder—it does a good job of identifying the Juniper Networks hardware and JUNOS
software features that influence HA together with a lot of good information on Juniper
architecture in general. The configuration examples are useful, and the sections on the
JUNOS XML API and JUNOScript API stir up all sorts of creative ideas in the mind of
someone with even a little bit of scripting experience.”
—Dan Schmiedt, Chief Network Engineer, Clemson University
“JUNOS High Availability has exactly what my customers need to know in order to build
and maintain continuously available network systems. It is the book to read for those
responsible for any mission-critical network.”
—Robert F. Jaeger, Juniper Networks, Systems Engineer Manager
“JUNOSHighAvailabilityprovidesthereaderwiththeknowledgetodesignandconfigure
his network away from default settings toward a better design that provides rapid
convergence, increased scaling, and a resilient architecture. Both network architects and
operators will find value in the lessons taught within this book.”
—Tom Scholl, Principal IP Network Engineer, IP/MPLS Backbone
Design & Development, AT&T Labs
JUNOS High Availability
JUNOS High Availability
James Sonderegger, Orin Blomberg, Kieran Milne, and
Senad Palislamovic
Beijing • Cambridge • Farnham • Köln • Sebastopol • Taipei • Tokyo
JUNOS High Availability
by James Sonderegger, Orin Blomberg, Kieran Milne, and Senad Palislamovic
Copyright © 2009 James Sonderegger, Orin Blomberg, Kieran Milne, and Senad Palislamovic. All rights
reserved.
Printed in the United States of America.
Published by O’Reilly Media, Inc., 1005 Gravenstein Highway North, Sebastopol, CA 95472.
O’Reilly books may be purchased for educational, business, or sales promotional use. Online editions
are also available for most titles (http://my.safaribooksonline.com). For more information, contact our
corporate/institutional sales department: 800-998-9938 or corporate@oreilly.com.
Editor: Mike Loukides Indexer: Lucie Haskins
Production Editor: Sarah Schneider Cover Designer: Karen Montgomery
Copyeditor: Audrey Doyle Interior Designer: David Futato
Proofreader: Kiel Van Horn Illustrator: Robert Romano
Printing History:
August 2009: First Edition.
O’Reilly and the O’Reilly logo are registered trademarks of O’Reilly Media, Inc. JUNOS High Availa-
bility, the image of Bohemian waxwings, and related trade dress are trademarks of O’Reilly Media, Inc.
Many of the designations used by manufacturers and sellers to distinguish their products are claimed as
trademarks. Where those designations appear in this book, and O’Reilly Media, Inc. was aware of a
trademark claim, the designations have been printed in caps or initial caps.
While every precaution has been taken in the preparation of this book, the publisher and authors assume
no responsibility for errors or omissions, or for damages resulting from the use of the information con-
tained herein.
ISBN: 978-0-596-52304-6
[M]
1250189494
Table of Contents
Preface .................................................................... xvii
Part I. JUNOS HA Concepts
1. High Availability Network Design Considerations ............................. 3
Why Mention Cost in a Technical Book? 4
A Simple Enterprise Network 4
Redundancy and the Layered Model 6
Redundant Site Architectures 6
Redundant Component Architectures 8
Combined Component and Site-Redundant Architectures 10
Redundant System Architectures 12
Combined System- and Site-Redundant Architectures 15
Combined System- and Component-Redundant Architectures 17
Combined System-, Component-, and Site-Redundant Architectures 20
What Does It All Mean? 22
2. Hardware High Availability .............................................. 25
Divide and Conquer 25
The Brains: The Routing Engine 27
The Brawn: The Packet Forwarding Engine 32
Packet Flows 36
M Series 37
MX Series 39
T Series 40
EX Series 41
SRX Series 41
J Series 41
Redundancy and Resiliency 42
M Series 42
MX Series 43
vii
T Series 43
J Series 44
SRX Series 44
EX Series 45
3. Software High Availability ............................................... 47
Software Architecture 47
Stable Foundations 47
Modular Design 48
One OS to Rule Them 50
Single OS 51
One Release Architecture 52
Automation of Operations 52
Configuration Management 53
Application Programming Interfaces 53
Scripting 53
4. Control Plane High Availability ........................................... 57
Under the Hood of the Routing Engine 57
Routing Update Process 60
Graceful Routing Engine Switchover 66
Implementation and Configuration 67
Graceful Restart 75
Graceful Restart in OSPF 77
Graceful Restart in IS-IS 79
Graceful Restart in BGP 81
MPLS Support for Graceful Restart 84
Graceful Restart in RSVP 84
Graceful Restart in LDP 86
Graceful Restart in MPLS-Based VPNs 88
Graceful Restart in Multicast Protocols, PIM, and MSDP 91
Non-Stop Active Routing 93
Implementation Details and Configs 95
Non-Stop Bridging 98
Implementation Details and Configurations 98
Choosing Your High Availability Control Plane Solution 99
5. Virtualization for High Availability ....................................... 101
Virtual Chassis in the Switching Control Plane 102
VC Roles 104
IDs for VCs 105
Priorities and the Election Process 105
Basic VC Setup and Configuration 106
viii | Table of Contents
