Day One: Advanced Junos CoS Troubleshooting Cookbook

In large Enterprise and Service Provider networks, dropped packets can quickly escalate into large scale issues, and to fix these CoS issues you have to know how and where to troubleshoot them. Here are eight Junos CoS issues and the how-to steps to fix them. Written by an Advance JTAC engineer and a Resident Engineer for one of world’s largest Service Providers, these problem/solution/discussion recipes emphasize all the troubleshooting techniques available to the seasoned Junos engineer.

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About the Author(s)

Javed Syed has over 17 years of experience in the networking industry, with the last 8 years focusing on service provider networks. He is CCIE #2975, and JNCIP #727, and also holds various other industry certifications. Javed is currently employed by Juniper Networks, where he functions as a solution engineer in the Professional Services organization. Javed previously worked at Cisco Systems and IBM.

Nick Okerberg is a resident engineer for Juniper Networks in the Professional Services group, supporting a large service provider in the United States. He has been employed by Juniper for about 7 years and has 10 years of experience in the networking industry. Nick previously did contract work for Juniper Networks and MSN. He holds the JNCIE-M #362 and JNCIE-ENT #304 certifications, among others.

Author Q & A

What got you started on this book?

As an Advanced JTAC engineer and Resident Engineer who have worked with several enterprise customers and service providers, we have seen many issues in regards to class-of-service. Many of these issues were related to the way class-of-service was understood or software configuration. This book will help show some troubleshooting methods related to observed problems with class-of-service. Some of these troubleshooting methods can be taken further than just class-of-service and applied to other scenarios as well.

Who is this book for?

This book is for any network engineer, with some previous Junos knowledge, who deals with Juniper routers and wants to learn more about class-of-service behavior and different troubleshooting methods. The book will also be beneficial to experienced network engineers and expand their knowledge of troubleshooting techniques in the various problem scenarios.

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

After reading the book, you will be more aware of various class-of-service related behaviors and more troubleshooting methods.

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

The various class-of-service troubleshooting methods. Also, some of the troubleshooting steps can be applied to other scenarios as well instead of just to class-of-service related problems.

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

Packet Walkthrough

What’s your inspiration?

We wanted to help other network engineers who deal with Juniper routers better understand class-of-service behaviors and to understand more troubleshooting methods that can be applied to different problem scenarios. We didn’t see too much material covering a lot of the troubleshooting techniques that we used for this book, so we wanted to help other engineers understand the commands and techniques that we use in different problem scenarios.

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

The flexibility of firewall filters to help isolate a problem in multiple scenarios even outside of class-of-service issues.