Our time together has come to an end. This book has given you both broad overview information into secure network design and specific guidance in building your own security system. As stated in the Introduction, this book doesn't focus too much on specific products from Cisco Systems or others because products and capabilities change and individual product documentation is more timely and accurate than this book could ever be.
Instead, this book provides best practices and design principles that don't fundamentally change with each new release of a vendor's product. These best practices and design principles can be brought together to solve real problems in your organization's network today. Whether you are a novice or an expert, I sincerely hope that this book serves you well in your information security endeavors. Secure network design is an inexact science, and, as I've stated throughout this book, the best thing you can do is understand the concepts written here and then apply them to the unique requirements of your own network. Whether that means implementing something similar to what is written here or deviating significantly from the guidelines set out in this text, the key task is to understand your network and security requirements and design your security system to best meet your needs.