ledge in the field, and also enable learning in more areas through references, literature, and elsewhere. We wish you happy reading and a deeper love for acronyms. Jouni, Teemu, Jonne Acknowledgments First of all, we would like to acknowledge our families for their support for, and bearing with, us during the writing of this book. Without our families' support it would not have been possible to generate the effort that this book required. We would also like to thank our employers, Nokia, Nokia Siemens Networks, and Renesas Mobile, for not discouraging us to work from writing a book in our spare time, and also for providing us with years of work in the area of IPv6, standardization, and industry collaboration. Without being able to work on actual real-life issues, it would not have been possible to learn the things that form a major part of this book. Major acknowledgments also go to the Nokia devices unit, which has provided us with IPv6 capable devices. Latest of the devices was the 21M-02 USB-modem that was capable of opening IPv4v6 type of PDP Context, and hence made interesting new testing scenarios possible. Before that, a long line of handsets, since around 2004, made it possible to gather experience on cellular IPv6 usage. We would also like to acknowledge Illka Keisala from TeliaSonera Finland for arranging us, via Finnish TEKES WiBrA-project, IPv6-enabled SIM-cards that made it possible to try out IPv6 also in roaming scenarios - free of charge. Teemu sacrificed time from his three small children, Emil, Nea, and Elias, and spouse, Hanna, for creation of this book - mea culpa. Acknowledgments for helping Teemu to get to this point go to all managers, colleagues, and subordinates in Nokia who have provided the possibility to work with IPv6 implementations and standardization, made Teemu aware of interesting problems, and supported him in everyday work. Special acknowledgments go to Petri Vaipuro, who in 2001 hired Teemu to work on TCP/IPv6 implementation tasks and by SO doing provided the opportunity to ju