The Diameter protocol, using stream control transmission protocol (SCTP) for transport, is used widely in the all-IP, service-oriented IMS and LTE architectures. Within the IMS control and service planes, Diameter plays a central role in policy, charging, authentication and mobility management.
For years operators have employed signaling system 7 (SS7) as the international, standardized protocol to communicate globally between operator networks. ISDN user part (ISUP) is used for voice-oriented communication, CAMEL Application Part (CAP) is used for service control and mobile application part (MAP) for non-call-related signaling, including mobility management.
The digital era is on the horizon, yet the majority of operators around the globe still connect their networks through the exchange of well-defined SS7 messages. All of that is about to change.
This paper focuses on the signaling role that Diameter is going to play in end-to-end IP networks like LTE. Diameter’s part in service-related functions such as charging is not addressed in detail.