Today, organizations are more dependent on their Cisco networks than ever before -- and their networks are growing ever more complex and interdependent. In this book, one of the world's leading network consultants shares practical, realistic techniques for maximizing reliability and availability in any network environment. This book discusses every leading approach to improving network availability, including key principles and tradeoffs -- guiding network professionals in choosing the most appropriate solutions for their own networks. Leading network consultant, Dr. Vincent Jones presents a series of common network scenarios, analyzes their weaknesses, and presents solutions -- demonstrating how to ensure that other services continue unaffected when parts of the network fail, and how to automate recovery. While the examples in the book are Cisco-focused, the principles and design tradeoffs apply to any contemporary router- or switch-based internetwork. For every network designer and administrator responsible for optimizing the reliability and availability of today's networks.
Book Description
Editorial Reviews
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This book explores and discusses a wide range of potential approaches to improving network availability, allowing you to choose those most appropriate for your organization and its unique needs and constraints. The goal is to show how to achieve higher network availability both in theory and in practice. In economic terms, this means pushing the design to the point where the cost of eliminating further unavailability exceeds the cost to the organization of the losses due to downtime.
While the theoretical aspects apply to networks of all sizes and technologies, the example solutions provided focus on the needs of moderate sized extended corporate networks using IP version 4 and stable, moderate performance technologies such as frame relay, ISDN, and Ethernet--not because these technologies are fundamentally more or less reliable than others, but because these tend to be the networks which have grown to the point of being critical to the day-to-day operations of the organization without a staff of dedicated network designers and architects to provide optimization and support. How to Use This Book
This book is written for those looking for design techniques to cost effectively improve network availability. The reader is assumed to be knowledgeable in the fundamentals of large network design and comfortable going to other references for more details on specific protocols and functions.
The basic approach of this book is divide and conquer. Each chapter attacks a general need of high availability network design, from defining what high availability really means and requires in the first chapter to the final chapter's discussion of the essential commitment to a full range of network management capabilities. Within each chapter, the general need is broken down into specific requirements. Within each specific requirement, the problem being addressed and possible solutions are first discussed on a general theoretical level. Wherever practical, one or more specific scenarios are defined and example solutions implemented, typically using Cisco routers.
Please read through the example implementations even if you never expect to touch a Cisco system. The examples and their accompanying discussions serve to flesh out the theoretical framework, showing typical adjustments required to get the theory presented to actually work in a real world environment. Many of these adjustments have nothing to do with Cisco, but rather reflect limitations in the current implementations of network protocols.
Technical managers and others will find this book's survey of all aspects of high availability network design invaluable. There are a vast array of considerations which should be part of any design and tunnel vision can be costly. It is very easy (and common) to implement point solutions which in the process of eliminating one weakness introduce other modes of failure. Choosing the best solution is rarely possible without a system-wide perspective.
Network implementors in a Cisco environment will find this book a cookbook of Cisco solutions that they can modify and install in their own network. These readers should still pay attention to the theoretical discussions preceding each example so they can identify modifications necessary to fit their unique environment.
It is essential for all to keep in mind that high availability is not just a design parameter, it is also an executive management commitment to funding adequate resources, staffing and training for the life of the network. At the same time, even though this book focuses on enhancing the availability of the network, we must always keep our sense of perspective. From the user's viewpoint, it is immaterial whether it is the network, the server, the software or the client platform which fails. Cost effective availability improvement needs to be balanced across all causes of failure to ensure that the resources required are applied where they will have the most impact on the bottom line.
This is much easier to say than it is to do, as few organizations even know what their current availability is or keep any statistics on the causes of failure. Even fewer organizations have proceeded to the stage of analyzing their bottom line costs for various failure modes. But higher network availability remains indisputably important. Fortunately, it is never too late to start on the road to higher availability. Chapter by Chapter
Chapter 1, "Reliability and Availability," introduces the theory and technology of high availability networks. First the stage is set with the potential cost of network downtime for mundane production as well as ''must run'' networks. The mathematical basis behind predicting availability, different approaches to providing higher availability, and the availability challenges unique to computer networks form the core of the chapter. The chapter ends with the need to provide physical diversity in multiply connected WANs and LANs, setting the stage for the rest of the book.
High availability is not an automatic result of adding redundant links and components to a network. Adding redundancy adds complexity to the network, which must be recognized and utilized. Chapter 2,"Bridging and Routing," starts out with a quick review of network terminology, then surveys the available layer two bridging approaches (simple learning, SR and TST) and popular layer three routing protocols for IP (static, RIP, OSPF, Integrated IS-IS, EIGRP and BGP), briefly discussing how each works and the strengths and weaknesses of each. Along the way, parameter tuning which may be appropriate to speed up response to failures is explored and examples provided.
Chapter 3, "Multihomed Hosts," extends the availability benefits of redundant connectivity all the way to the end system in an IP network. Starting with the simple step of adding a second NIC to an end system, the challenges presented in supporting applications when the server (or client) has two IP addresses are explored. Then two approaches to giving the two NICs the appearance of a single IP address (proprietary and via routing) are examined, with full configuration examples for the latter. The chapter concludes with a discussion of server cluster terminology, techniques and limitations.
Dial backup is a popular alternative to installing additional ''permanent'' links. In Chapter 4, "Dial Backup for Permanent Links," the first of two dedicated to dial backup, three different dial backup approaches are introduced, distinguished by how the router determines the need to place a call. After exploring the underlying assumptions behind each and how those assumptions affect their suitability for various applications, a basic ''how to'' for IP dial backup is provided. Using examples of ISDN dial backup applied to leased lines, frame relay, and DSL, the critical factors requisite to successful implementation are highlighted.
Chapter 5, "Advanced Dial Backup," extends the general concepts introduced in chapter 4 to meet the specific needs of a range of requirements. It starts with the challenge of using asynchronous modems rather than ISDN, then moves on to explore techniques for combining multiple dial links to provide higher bandwidth. After a brief look at providing IPX support, the chapter concludes with how to use BGP with generic dial-on-demand routing to provide dial backup driven by routing table changes without the limitations associated with Cisco's proprietary dialer watch facility.
Chapter 6, "Multiple Routers at a Single Site," focuses on eliminating the router as a single point of failure from the viewpoint of preventing end-systems at a location from being isolated from the rest of the WAN. Starting with solutions to the limitations inherent in the IP concept of a default gateway, the chapter then explores how to provide a second router without doubling the WAN communications costs by getting one router to provide dial backup for a link on another router. It then finishes with how to configure the routers on a physically extended LAN so that even if the LAN is split in two by a failure, IP systems on both halves of the LAN can still communicate with the outside world.
Chapter 7, "Hub and Spokes Topology," explores the unique requirements of hub and spokes networks. Hub and spokes is a popular topology for HQ data center and other applications because it allows major simplifications in the routing structure, but it can also introduce complications. The chapter starts with a discussion on how to get around limitations on the number of peers supportable on a single router and how to scale a hub and spokes design to handle an arbitrary number of spokes without requiring the spoke routers to maintain more than a handful of routes each. The focus then shifts to configuring dial-on-demand routing so that a spoke router can dial any of several routers at the hub without concern for which answers. Finally, critical considerations when the hub expands to actually be multiple sites, such as a primary and backup data center, are explored.
Chapter 8, "Connecting to Service Provide
About the Author
Vincent C. Jones, PhD, is founder and head of Network Unlimited, Inc., a consulting company specializing in applying the theory of networking to the solution of real-world problems. An acknowledged network authority, Dr. Jones has given many seminars on a variety of network topics, including "Network Design for High Availability." 0201704552AB04062001
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Most Helpful Customer Reviews
9 of 9 people found the following review helpful:
5.0 out of 5 stars
Tackles the Tough Topics,
This review is from: High Availability Networking with Cisco (Paperback)
This book is a fantastic, practical, detailed, readable reference for a huge range of very important networking topics relating to increasing the up-time of networks. It gives sample configurations for Cisco routers (with some reference to Bay/Nortel routers as well) in many environments (ISP connection, firewall, hub-and-spoke architecture, load-sharing, and so on), and provides supurb discussions of the decisions and trade-offs in the many ways of designing high-availablility networks. Difficult network problems, such as enabling backup data links for routers where the primary WAN interface fails "silently" (without a change in the interface status) are clearly addressed, with several detailed solutions presented, discussing the advantages, disadvantages and restrictions of each. There are none of those frustrating issues left for us to work out on our own, this is a tutorial book with all the answers, not a college textbook with questions. Redundant network components, including dual LAN adapters, LAN adapters with built-in dual ports, dual switches, routers with dual WAN interfaces, dual routers, dual DNS servers, dual firewalls, dual ISPs, and dual locations are all examined, showing what has to be done to actually get increased availability. Even though I likely won't be implementing these myself, I now know what I can ask of those who are configuring my routers, and I know how to look at network designs with a better knowledge about reliability and failure modes.
8 of 8 people found the following review helpful:
5.0 out of 5 stars
Essential for 24x7 infrastructure strategies,
By Mike Tarrani "www.tarrani.com" (Deltona, FL USA) - See all my reviews (COMMUNITY FORUM 04) (REAL NAME)
Amazon Verified Purchase(What's this?)
This review is from: High Availability Networking with Cisco (Paperback)
This book is an important addition to the body of knowledge of high availability in general and network availability in particular. Do not let the title mislead you, this book is not about high availability for Cisco - it uses that product family for examples. The information provided in this excellent book can be effectively applied to any vendor-specific or multi-vendor network architecture. I am not going to rehash the table of contents or the lengthly editorial review - I am going to jump into why I like this book and what I think makes it so valuable. First, no 24x7 system is a true highly available information resource unless you can access it. Try as I may, I cannot think of a single company that does not employ a network as the base infrastructure for their information systems. This book provides information necessary to create a foundation for high-availability and 24x7 operations. Second, the book is a catalog of high availability designs that will fit within any network architecture, regardless of complexity, products used or geographical scope. No matter what your network currently looks like you will find out what it takes to transform it into a reliable, resilient 24x7 network. The author has provided a design strategy for every conceivable situation and network configuration, and thoroughly discusses the underlying technical issues. This is where the "Cisco" part of the title comes in - he uses that particular product family as examples for achieving high availability designs for each scenario. Third, the disaster recovery section in the book is well thought out and shows that the author has a lot of knowledge and experience in business continuity planning and disaster recovery. This section alone is worth the price of the book. This book is, in my opinion, essential reading for network architects, consultants and integrators, and operations managers who are seeking a total solution to high-availability solutions. What I would love to see is a follow-on book that provides the design information reformatted as design patterns. This would be an invaluable resource for experienced network architects and consultants.
7 of 7 people found the following review helpful:
5.0 out of 5 stars
High Availability Networking,
By Alan Strassberg (Soquel, CA United States) - See all my reviews
Amazon Verified Purchase(What's this?)
This review is from: High Availability Networking with Cisco (Paperback)
Outstanding! This book details all the aspects of HA design. No handwaving here, discussions include tradeoffs, gotchas, and alternatives for resilent infrastructure, complete with working examples and explanations. A great cookbook that's a must-have.
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