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.
6.Diameter Client API
6.5.Terminatesession API
TerminateSession API is used to terminate the session which has been established
between the connected DIAMETER client and DIAMETER server which deals with the
deletion of sessions and its details.