I've been doing research in control planes for transport networks and needed to learn about GMPLS. This book does a very good job at explaining what GMPLS is, the set of protocols it involves and how each one works, including sequence diagrams for some of less known ones (to me) such as LMP. There are enough network diagrams associated with examples to give you a clear picture of what's going on. I would recommend this book to anyone interested in learning about GMPLS. If more in-depth information is required, you can always go look at the RFCs.