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These materials are © 2015 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited. Software-Defined WAN For Dummies¨, CloudGenix Special EditionPublished byJohn Wiley & Sons, Inc.111 River St.Hoboken, NJ 07030!5774www.wiley.comCopyright © 2015 by John Wiley & Sons, Inc.No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning or”otherwise, except as permitted under Sections 107 or 108 of the 1976 United States Copyright Act, without the prior written permission of the Publisher. Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, (201) 748 !6011, fax (201) 748!6008, or online at http://www.wiley.com/go/permissions.Trademarks: Wiley, For Dummies, the Dummies Man logo, The Dummies Way, Dummies.com, Making Everything Easier, and related trade dress are trademarks or registered trade-marks of John Wiley & Sons, Inc. and/or its affiliates in the United States and other coun-tries, and may not be used without written permission. CloudGenix and the CloudGenix logo are registered trademarks of CloudGenix. All other trademarks are the property of their respective owners. John Wiley & Sons, Inc., is not associated with any product or vendor mentioned in this book.LIMIT OF LIABILITY/DISCLAIMER OF WARRANTY: THE PUBLISHER AND THE AUTHOR MAKE NO REPRESENTATIONS OR WARRANTIES WITH RESPECT TO THE ACCURACY OR COMPLETENESS OF THE CONTENTS OF THIS WORK AND SPECIFICALLY DISCLAIM ALL WARRANTIES, INCLUDING WITHOUT LIMITATION WARRANTIES OF FITNESS FOR A PARTICULAR PURPOSE. NO WARRANTY MAY BE CREATED OR EXTENDED BY SALES OR PROMOTIONAL MATERIALS. THE ADVICE AND STRATEGIES CONTAINED HEREIN MAY NOT BE SUITABLE FOR EVERY SITUATION. THIS WORK IS SOLD WITH THE UNDERSTANDING THAT THE PUBLISHER IS NOT ENGAGED IN RENDERING LEGAL, ACCOUNTING, OR OTHER PROFESSIONAL SERVICES. IF PROFESSIONAL ASSISTANCE IS REQUIRED, THE SERVICES OF A COMPETENT PROFESSIONAL PERSON SHOULD BE SOUGHT. NEITHER THE PUBLISHER NOR THE AUTHOR SHALL BE LIABLE FOR DAMAGES ARISING HEREFROM. THE FACT THAT AN ORGANIZATION OR WEBSITE IS REFERRED TO IN THIS WORK AS A CITATION AND/OR A POTENTIAL SOURCE OF FURTHER INFORMATION DOES NOT MEAN THAT THE AUTHOR OR THE PUBLISHER ENDORSES THE INFORMATION THE ORGANIZATION OR WEBSITE MAY PROVIDE OR RECOMMENDATIONS IT MAY MAKE. FURTHER, READERS SHOULD BE AWARE THAT INTERNET WEBSITES LISTED IN THIS WORK MAY HAVE CHANGED OR DISAPPEARED BETWEEN WHEN THIS WORK WAS WRITTEN AND WHEN IT IS READ.For general information on our other products and services, or how to create a custom For Dummies book for your business or organization, please contact our Business Development Department in the U.S. at 877!409!4177, contact firstname.lastname@example.org, or visit www.wiley.com/go/custompub. For information about licensing the For Dummies brand for”products or services, contact BrandedRights&Licenses@Wiley.com.ISBN: 978!1!119!09854!6 (pbk); ISBN: 978!1!119!09846!1 (ebk)Manufactured in the United States of America10 9 8 7 6 5 4 3 2 1PublisherÕs AcknowledgmentsSome of the people who helped bring this book to market include the following:Project Editor: Carrie A. JohnsonEditorial Manager: Rev MengleAcquisitions Editor: Steve HayesBusiness Development Representative: Karen HattanProduction Editor: Kinson RajaSpecial Help: Vijay Sagar, Aaron Edwards, Rebecca Salie
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These materials are © 2015 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited. IntroductionV irtualization and hypervisor technologies have allowed many data centers to transition from hardware!based to software!based data centers (SDDCs). Now, a similar transition is occurring with wide area networks (WANs).At the forefront is a need for hybrid connectivity for WANs. Traditional WANs use a single connectivity method such as Multiprotocol Label Switching (MPLS). A hybrid WAN dynamically supports MPLS, broadband Internet, cellular connections, and any other transport mechanism available to an enterprise.Dynamically choosing the correct paths for traffic is exceedingly complex with traditional hardware. In con-trast, this should be table stakes with a software!defined WAN (SD !WAN). As an example, the CloudGenix SD!WAN solution enable network managers to create policies using plain business language. These policies designate allowed paths for specific applications, users, and/or service level agreement (SLA) customers.About This BookSoftware-Defined WAN For Dummies, CloudGenix Special Edition, is designed to help you understand SD!WANs. This includes many of the benefits such as reduced cost, improved performance, an elastic secu-rity perimeter, and shorter deployment timelines. It
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2These materials are © 2015 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited. also outlines the requirements of a robust SD!WAN solution.Icons Used in This BookThis book uses the following icons to call your attention to information you may find helpful in particular ways. The information marked by this icon is important and therefore repeated for empha-sis. This way, you can easily spot noteworthy information when you refer to the book later. This icon points out extra!helpful information. This icon marks places where technical mat-ters, such as SD!WAN jargon, are discussed. Sorry, it canÕt be helped, but itÕs intended to be helpful. Paragraphs marked with the Warning icon call attention to common pitfalls that you may encounter.
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4These materials are © 2015 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited. protocols with APIs, and building policies based on application metrics rather than network metrics make this possible.A WAN connects two or more local area networks (LANs) located in separate geographical locations. For example, a WAN can connect a LAN in a main office location in San Jose with a LAN in a remote office in San Francisco. With this in mind, the simplest defini-tion of the SD!WAN is a WAN that utilizes software and virtualization technologies, instead of traditional hard-ware, such as routers, to connect remote locations.However, that simple definition doesnÕt tell the whole story. HereÕs a more technical and complete definition: The SD!WAN utilizes software and virtualization tech- nologies to create a WAN and includes the following three elements: “Separates the networkÕs data plane (or forwarding plane) from the networkÕs control plane Ñ you often see this process described as decoupling the data and control planes. “Provides centralized control “Is easily programmableTransitioning to SDXSoftware!defined everything (SDX) refers to the trend moving from systems that have tightly coupled soft-ware with proprietary hardware toward a model where software can be run as an application on commodity off the shelf x86 compute platforms.One of the primary drivers that has encouraged SDX is virtualization. Organizations have virtualized their com -puter infrastructure and moved to a software ! based
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5These materials are © 2015 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited. programmable and management model. The next logi-cal step was to use these technologies in SDNs and SDDCs. Over 50 percent of server workloads are virtual-ized through companies such as VMware, Microsoft, and Citrix, especially in large data centers.With virtualization you can often reduce the number of physical servers by a factor of ten. As an example, a data center hosting 500 physical servers can host the same number of virtual servers on 50 physical servers. This reduces operating costs and energy costs and can save an average of $3,000 annually for each virtualized server or, in this case, $1.35 million. With savings like that, itÕs no wonder so many organizations have fully embraced virtualization.The next logical step was a transition from hardware to software on networks leveraging some of these same virtualization techniques. It first started in the SDDC and is now expanding to the WAN with SD!WAN.SDN has grown exponentially in”recent years. According to SDxCentral, the 2013 SDN market was estimated at about $1″billion and is expected to exceed $35 billion by 2018. While fundamental differences do exist between SDNs and SD!WANs, it shouldnÕt surprise anyone to see a similar growth spurt with SD!WANs.Comparing SDNs for the Data Center and for the WANJust as SDNs use a controller to manage the network, SD!WANs also use controllers, but significant differ-ences exist in the functions of these controllers.
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6These materials are © 2015 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited. As an example, consider the SDN used within a data center. A data center is a highly controlled environment with significant physical security, high bandwidth, and low latency. Signals sent between the controller and other systems typically arrive in ten milliseconds or less. Moreover, unless the network has a problem, the bandwidth and latency are constant.In contrast, WAN connections have a high degree of variability. The controller is in a separate geographical location and may be thousands of miles, hundreds of milliseconds, away from branch locations with highly variable bandwidth and latency. Something as common as rain can disrupt signals sent between microwave links. The controller might enjoy 99.999 percent uptime, but itÕs highly unlikely that youÕll enjoy the same uptime with the transport connections.These issues arenÕt a concern for SDN controllers located in the data center, but SD!WAN controllers must tackle these issues. As an example, the CloudGenix SD!WAN controller doesnÕt assume good connectivity but instead constantly monitors the con-nections. If the controller gets disconnected from the rest of the WAN due to some extreme event, remote branch networks continue to operate. As long as the remote network still has connectivity to its transport connections (even if it doesnÕt have connectivity to the controller), users at the remote location wonÕt experi-ence any problems.Some key differences between the data plane in a data center and the data plane in a WAN include the following: “The centralized controller in the WAN is separated from the data plane, which is more distributed in a WAN than it is in a data center. This allows the
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7These materials are © 2015 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited. data plane at the remote locations of the WAN to enforce policies even if the WAN controller isnÕt accessible. “An organization owns and manages the data plane in the data center, and it has consistent, tightly controlled characteristics. In contrast, a WAN has a variety of different transports that the ” organization doesnÕt own or control, and these different transports have very different characteristics.The control plane is a collection of multiple protocols that administrators must deploy and configure. A WAN and a data center use different protocols. More, there are some key differences in these protocols: “Within a data center, an organization fully man- ages the protocols. However, service providers manage these protocols in a WAN. The inter !dependencies between different protocols add another level of complexity, making them more difficult to manage. “Protocols in a data center are relatively fast, con-stant, and predictable. In contrast, protocols in a WAN travel across great distances, resulting in huge latencies and various quality over the trans-port paths. The control plane within a data center uses metrics within link state and distance vector protocols, but these protocols are not ideal for determining the best path for application performance across a WAN.While the control plane architecture used within the SDDC meets the needs of data centers, it doesnÕt meet the needs of SD!WANs. Instead, the ideal SD!WAN
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