Diameter

1Introduction

1.1 What is AAA?

AAA stands for Authentication, Authorization, and Accounting.

Authentication is the verification that a user who is requesting services is a valid user of the network services requested. The user must present an identity, like a user name or phone number, and credentials, like a password, a digital certificate, or one‐time passphrase, to the verifier in order to be authenticated.

Authorization is the determination of whether requested services can be granted to a user who has presented an identity and credentials based on their authentication, service request, and system state. Authorization state may change over the course of a user's session due to consumption limits or time of day.

Accounting is the tracking of the user's consumption of resources for billing, auditing, and/or system planning. Typical accounting data collected includes the identity of the user, the service delivered, and when the service started and stopped.

Consider a voice‐over IP (VoIP) service provider that offers telephony services to a large number of end users. End users can connect to the service with software for VoIP clients that runs on a smart phone, tablet or desktop PC, or they may use a purpose‐built hardware phone.

When the user's device contacts the VoIP network, the VoIP service provider will authenticate the user accessing their network. That is, the provider wants to determine that the user, or her device, is who they say they are. The authentication mechanisms and ...