The Diameter protocol is a network communication protocol that provides authentication, authorization, and accounting (AAA) services for various applications in mobile telecommunications networks, such as 3G, 4G, IMS, and LTE. The Diameter protocol is based on the SS7 protocol family and uses the services of the TCAP layer. The Diameter protocol is an evolution and replacement of the RADIUS protocol, which was the previous standard for AAA services in mobile networks. In fact, the name DIAMETER was chosen because it is twice the size of RADIUS (it’s predecessor)
The Diameter protocol offers several advantages over RADIUS, such as:
- Higher scalability and reliability, as it supports TCP and SCTP as transport protocols, and allows multiple connections and sessions between nodes.
- Enhanced security and privacy, as it supports encryption and authentication of messages and data, and allows the use of certificates and keys.
- Greater flexibility and extensibility, as it supports various applications and services, and allows the definition of new messages and parameters.
Some of the common use cases of the Diameter protocol in mobile telecommunications networks are:
- Online charging: The Diameter protocol enables the online charging of mobile services, such as voice calls, SMS, and data, by exchanging messages and information between the network elements, such as the Online Charging System (OCS), the Policy and Charging Rules Function (PCRF), and the Serving Gateway (SGW). The Diameter protocol allows the network to authorize, rate, and bill the services in real-time, based on the usage and consumption of the subscribers.
- Roaming: The Diameter protocol enables the roaming of mobile subscribers across different networks and regions, by exchanging messages and information between the network elements, such as the Home Subscriber Server (HSS), the Visited Location Register (VLR), and the Mobile Switching Center (MSC). The Diameter protocol allows the network to authenticate, authorize, and account the services for the roaming subscribers, based on the agreements and policies of the network operators.
- Subscriber management: The Diameter protocol enables the subscriber management of mobile services, by exchanging messages and information between the network elements, such as the HSS, the PCRF, and the Application Server (AS). The Diameter protocol allows the network to manage the profiles, preferences, and policies of the subscribers, and to provide them with various value-added services and features, such as call forwarding, call waiting, and call barring.
These are some of the main use cases and functions of the Diameter protocol in mobile telecommunications networks. The Diameter protocol enables the implementation of various applications and services that enhance the quality and efficiency of the mobile communication.
