Day One: Junos Fusion Data Center Up and Running

Junos Fusion Data Center represents a significant leap forward in the evolving technology of Ethernet fabric architectures that can manage large numbers of switches and Ethernet ports. Day One: Junos Fusion Data Center Up and Running gets you started with the technical underpinnings and components of Junos Fusion, and then follows you into the lab to get it up and running. After a few chapters you will have achieved connectivity between hosts, servers, racks, and infrastructure, with all the scalability and ease of management that today’s modern data centers need to compete. It’s day one and you have a data center to build.

“Modern data center architectures change about as often as the seasons. With virtualization and SDN at the center of it all, you need a scalable, agile solution. Stefan Fouant takes you on a journey through implementing the Junos Fusion Data Center architecture that can solve these modern-day challenges. His technically sound writing style and years of experience make it all seem easy, and he lays out a straight-forward configuration path that would make the Wizard of OZ jealous.”

— Scott Ware, Security Engineer, Juniper Ambassador, GSEC, JNCIS-SEC, JNCDA


  • Understand the basic principles of modern day data centers and why fabric architectures are increasingly important.

  • Understand the concepts of underlay and overlay and how Junos Fusion Data Center fits into the equation.

  • Understand how Junos Fusion compares to Virtual Chassis and Virtual Chassis Fabric, and when to deploy Junos Fusion Data Center.

  • Understand the basic terminology and components of a Junos Fusion Data Center.

  • Configure a Junos Fusion Data Center using either a single aggregation device or multiple aggregation devices, and learn how to add satellites into the topology.

  • Manage the day-to-day operation of a Junos Fusion Data Center, including verification of satellite status, upgrading software on satellites, and removing satellites from the topology.

  • Connect to hosts in a Junos Fusion Data Center and take advantage of advanced concepts such as VLAN Autosensing and Uplink Failure Detection.

Sample Pages

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About the Author

Stefan Fouant is the Chief Architect at Copper River Information Technology with over 19 years of experience in the Service Provider and network security industries. He is a Juniper Ambassador and has worked with Juniper technologies since the inception of the M40 in 1998. He holds several patents in the area of DDoS detection and mitigation and is a co-author of drafts within the IETF DOTS working group relating to standardized signaling of coordinated DDoS attack filtering and mitigation mechanisms. He is a quadruple JNCIE (SP/ENT/SEC/DC), and a coauthor of Day One: Juniper Ambassadors Cookbook 2017. Find Stefan on Twitter: @sfouant and also check out his blog at

Author Q & A

What got you started on this book?

I have been working with a tremendous number of customers lately on data center migrations, specifically using the Juniper QFX Series switches. Virtual Chassis Fabric (VCF) has been one of the fabric technologies that I’ve successfully deployed quite a bit with my customers, but with an upper limit of around 20 VCF members and a total of roughly 768 server-facing ports, it’s only suitable for mid-sized data centers. Before Junos Fusion, if we wanted to scale beyond these limits, we needed to either create a PoD (Point of Delivery) design utilizing multiple VCF fabrics, or move to an all IP fabric. Both options allow for great scalability, but with these approaches we lose the single-pane-of-glass management features which are really attractive to data center architects.

Junos Fusion, on the other hand, gives us these highly desired single-pane-of-glass management capabilities while at the same time letting us scale to upwards of 128 satellites and a maximum of 6000 server-facing ports. At these densities, it truly becomes a viable alternative to an all IP fabric for very large data centers.

All of these things piqued my interest in Junos Fusion Data Center, but as I started in learning in earnest about this technology, I found that there was limited material available or it was scattered across multiple disparate sources of information. Furthermore, there wasn’t a single comprehensive resource available to quickly digest the architecture and deploy this technology. In an effort to fill that gap, I decided to write this Day One guide with the goal of allowing the reader to get a Junos Fusion Data Center up and running in the shortest amount of time possible.

Who is this book for?

This book is written for anyone with a heavy focus on data center technologies who wants to learn more about the latest evolution of Juniper’s overall solution portfolio with regards to building large scale Ethernet fabrics within a Data Center. Or more generally, anyone who has a basic knowledge of data center networking and would like to be more well versed in this emerging fabric solution.

After reading this book, what's the take away?

If I’ve accomplished my goal, I hope the reader will take away that a Junos Fusion Data Center is a viable alternative to the highly scalable but more complex architecture of an IP Fabric. Furthermore, my hope is that the reader will understand how easy a Junos Fusion Data Center is to deploy and how simple it is to manage once deployed. Lastly, I hope the reader sees the benefit of loosely coupled components, which are used in a Junos Fusion architecture, to be able to understand and articulate their benefits when compared to tightly coupled architectures.

What are you hoping that people will learn from this book?

My hope is that people will learn the basic architecture of a Junos Fusion Data Center, how it compares to other Ethernet fabric architectures, and how to configure and manage it within their data center. I’m also hopeful readers will be able to fully understand the benefits when compared to other Ethernet fabric architectures.

What do you recommend as the next item to read after this book?

This book is designed to “get your feet wet” with the Junos Fusion Data Center architecture, and help you get it up and running at a high level. But this book only scratches the surface of what’s truly capable. For a deeper understanding, I would certainly recommend the reader take a look at the excellent Junos Fusion Data Center documentation available at the Juniper TechLibrary to get a detailed understanding of the many other advanced features that are available. I would also highly recommend the O’Reilly book “Juniper QFX10000 Series: A Comprehensive Guide to Building Next-Generation Data Centers,” by Douglas Hanks, (O’Reilly Media, 2016), as this provides excellent additional coverage of the QFX10k platform.

What's your inspiration?

As a former JNCP trainer and proctor of the JNCIE exams, my inspiration is teaching and helping others. I’m blessed to work in a field that is constantly evolving and provides ample opportunity to learn. This, by far, is the single biggest factor that has attracted me to this industry. I love to share my passion and love of networking technologies with others. I pride myself on my ability to translate complex technologies and distill them in a way that everyone can understand, and it’s a great honor when I see those light bulbs going off and someone tells me they’ve learned something from me.

What's your favorite bit/part in the book?

My favorite part of the book is undoubtedly Chapter 5, where we actually connect to hosts in the Junos Fusion Data Center fabric. This is, of course, why we create a Junos Fusion fabric in the first place. This chapter really ties in all the concepts and shows how easy it is to create simplified Layer 2 connectivity between hosts that exist even across disparate satellite switches.