I bought Open Source Network Administration by Kretchmar to answer this question. I was looking for open source tools to be used in a service provider environment and was unpleasantly surprised at what was revealed in this book. However, since it seems you're looking for enterprise-ish stuff, I highly recommend this.

You'll find many of the tools within to be quite useful during both day-to-day operations and troubleshooting as well as long term planning on your network. The author does a fairly decent job of walking you through a basic installation of each tool.

Slashdot reviewed it here.

Here are most of the tools discussed in this book.

...followed by an army of vendor-supplied consultants who barely know their name. 2 years later, the project is still on hold.