Tree-level planning in Agile, tracking an reaction

Agile is the main stream in a software development process today. There are so many articles and books describing SCRUM, Kanban and Lean but after reading you probably will think about how to adopt the described methodology in real life. In my article I am going to share a real experience in a multi-level planning in Agile what was adopted and tested in a real development center. I will observe quarter, release and sprint planning. Also I will touch a reaction mechanism on a customer when he changes plans and scope and what you need to be ready to that.