The Diameter base protocol is intended to provide an Authentication,
Authorization and Accounting (AAA) framework for applications such as
network access or IP mobility. Diameter is also intended to work in
both local Authentication, Authorization & Accounting and roaming
situations. This document specifies the message format, transport,
error reporting, accounting and security services to be used by all
Diameter applications. The Diameter base application needs to be
supported by all Diameter implementations.
Authentication, Authorization and Accounting (AAA) protocols such as
TACACS [TACACS] and RADIUS [RADIUS] were initially deployed to
provide dial-up PPP [PPP] and terminal server access. Over time,
with the growth of the Internet and the introduction of new access
technologies, including wireless, DSL, Mobile IP and Ethernet,
routers and network access servers (NAS) have increased in complexity
and density, putting new demands on AAA protocols.