At a recent meeting of network admins, the talk turned to uptime, and some bragged about the high availability of services in their network; they had 100% uptime. Wow, this normally is unthinkable. After more discussion, the truth came out. This figure is based on the fact that the service provider did not take into account outages in the network that made their service unavailable, because their service was still “up,” though totally unreachable. The same admins also admitted that they really didn’t keep records of actual outages. In their opinion, they had no reliability issues, but their customers would disagree with that.
This book is not about reliability theory. Theory addresses the full range of possibilities. This book is for those of us who have to keep the network working. It is a guide for students of the art of creating self-sustaining continuous systems.
As such, we fought to keep the book grounded not necessarily in what you can do, but more importantly, in what you should do as an administrator to protect availability and to keep the customers, internal or external, connected and happy. Most of the chapters include case studies that show you how things work and provide pointers on where you might investigate if your results differ. The topologies included are realistic and in many cases reflective of actual networks that we, the authoring team, have worked with at some point in our careers.
There are four authors on this book, and while we tried to homogenize the writing, you will see different styles and different approaches. Ultimately, we think that’s a good thing. It’s like working with your peers who are also maintaining the same network and who have different methods of working. The team shares a common goal and the variation in approaches brings strength through diversity.
Ultimately, this book is about Juniper Networks JUNOS Software and Juniper Networks boxes. You need to design a continuous system, and you need the right mix of equipment placed ideally on your topology, but eventually you come back to the network OS. And our chapters all come back to roost with JUNOS.
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