Diameter
Read this article about the history of Diameter and why it was developed. What preceded Diameter as an authentication protocol? While you do not need to understand how Diameter authenticates, you should have a general idea of its authentication process.
7.Result
7.2.Startconnection API SUCCESS
StartConnection API is called resulting in SUCCESS, whose pre-requisite is
Initialization API which is SUCCESS; later UnInitialization is called which is
SUCCESS.
Figure 6: StartConnection API SUCCESS