Day One: Exploring the Junos CLI, Second Edition

The Junos OS command-line interface (CLI) includes dozens of shortcuts to get things done in your network. You’ll spend much less time pounding away on your keyboard once you master these commands, and soon, with just a little effort, you’ll learn why so many people say that the Junos OS saves time (often lots of it), reduces repetitive tasks, and helps to avoid costly mistakes.

Day One: Exploring the Junos CLI, Second Edition is for beginning users of devices running the Junos OS, or as a refresher course when it’s time to scale Juniper technology. It not only lays the foundation for learning the Junos OS, but also facilitates understanding of the more advanced Junos OS books that populate the Day One library.

This Second Edition combines two previous best-selling Day One books – Day One: Exploring the Junos CLI and Day One: Configuring Junos Basics – into a single updated and revised Junos OS book that gets you started and then helps you get things done.

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About the Author(s)

Walter Goralski has been involved in networking and the Internet for many years. He has been an instructor, course developer, college professor, technical writer, and author of bestselling technical books and specializes in making new and complex technologies easy for everyone to understand. He has worked for Juniper Networks since 2000 and is now a member of Juniper’s iLX Solutions Group.

Author Q & A

What got you started on this book?

Patrick Ames asked me to look at two Day One books that had overlapping content and needed a fresh edition. I liked the first half of one and second half of the other, so I told him we should combine the two, eliminate the overlaps, and update the content. This second edition is the result of that effort, although my task was much easier given the great job Sean and Ian did in the first place.

Who is this book for?

Anyone new to Junos, really. The book assumes some familiarity with TCP/IP and other Internet protocols and topics, of course, but assumes absolutely nothing when it comes to Junos. If someone comes to you and says “We know you have no experience with Junos, but you have to configure this...” then you should start here. However, even those with Junos experience can benefit from the discussions of best practices and the recommendations for hands-on activities.

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

The tricky thing about device configuration is often what you overlook or has slipped your mind. This book emphasizes best practices and encourages a methodical approach to initial configuration and operation. It provides checklists for make sure to include many commonly used parameters, such as backup routers, and provides recommended steps, like making backup copies of configurations on a remote device (you’d be surprised how many people don’t do that and then manage to lose it all).

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

I hope they learn that everything is important enough to do correctly. Users often make a service call if they can’t find something quickly, or that is not explained clearly. The authors hope that by packing as much basic information into one place, we can cut down on the frustration (and hasty errors) that often result from not finding needed information efficiently--not so much complex or seldom-used protocols, but for the common and everyday things that other sources often assume are familiar.

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

This is the “FIRST” book in the Junos OS Fundamentals Series. Next would be Day One: Routing the Internet Protocol, then Day One: Finishing Junos Deployments, and then probably, This Week: Hardening Junos Devices, 2nd Edition. There are some “next steps” mentioned in the book text, mainly at the end of each chapter. There is certainly a lot to learn about routing protocols like OSPF, IS-IS and BGP, and layer 2 networking, such as VLANs. MPLS and VPNs are is also important. Depending on the role of the device, any one of these topics can be a good next step in learning.

What’s your inspiration?

Years ago, a science fiction author named Isaac Asimov wrote books and articles explaining modern physics and biology to general readers. When I got my graduate degree in computer science and started teaching, I wondered why no one was doing that with computers, networks, and the Internet. I wrote my first book on new technology in 1995 (it still has the only explanation of forward-error correction codes for non-mathematicians that I have ever seen) and I’ve made a long career out of that one simple idea. :-)

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

I like the explanation of what exactly happens when you create or change a Junos configuration: it’s quite complex and often understated or ignored in other sources. I also like the checklist to prevent overlooking essentials and the provision of a “sample” configuration that matches the configuration steps taken in the second half of the book. Sean and Ian were geniuses to have included these things in their editions.