James Carlson
PPP Design and Debugging
Addison-Wesley, 1998. ISBN 0-201-18539-3. Pp.228.

Reviewed Chris Kottaridis
<chrisk@bsdi.com>

This book covers low-level PPP communications with detailed discussions of data encoding and how HDLC is used to encapsulate PPP transmissions. It addresses the Link Control Protocol and Authentication Protocol options and provides a complete state diagram for the negotiation of those options. The book also addresses the different Network Control Protocols available with PPP and provides a summary of the options for each Network Control Protocol. There is a chapter on data transforming layers that discusses data enryption and data compression over PPP links. The chapter on bandwidth management discusses topics such as demand dialing, multilink PPP, callback, and active bandwidth management techniques, some of which are not yet well defined. The author also includes a very practical chapter that aids in interpreting PPP traces that should be very helpful in solving real-life field problems.

I found the book to be very thorough. In fact, on a cursory reading of the book, I often got bogged down in too much detail. However, I am sure that I will appreciate the level of detail when I find myself struggling with a specific PPP problem.

It is great to have a single location that has references to all the pertinent RFCs and a discussion of the history of how various RFCs have superseded others. But more important than that is James Carlson's focus on interoperability with existing implementations. He makes a point to identify which options and features you can expect to run into which helps keep you focused on the pertinent aspects of the RFCs. This is most evident in his mentioning of Microsoft's extensions to PPP even though they were not approved by the IETF. Basically, he puts the RFCs into perspective for you.

The primary audience would be PPP code developers, although network administrators who are willing to get into the nitty-gritty details of packet sniffing would also find it useful. Most system administrators could find it useful for background knowledge, but their focus is usually more on management of peruser configuration files, which is implentation specific and not addressed in this book.

All in all, it is a book I will be keeping close at hand when I do any kind of PPP work. It will probably be the first place I look when I have a question about PPP.