This document is representing not only the description of AAA protocol. It is representing real production problems which I encountered in many years of work with it. Each from this problem was taken separately. It was analyzed and the best solution was applied to it. Article is containing not only analyzing of the problem. In this document the solution described was developed and tested in time on different networks starting with few hundred devices and finishing with tens of thousands of them. On production, solution applied worked for years. Based on this point, I can conclude that problems which were on the production, where solved by applying of those solutions. In order to understand those problems, is needed to understand how this protocol is working and where are the bottleneck points of it.