What is Diameter Protocol in 4G / 5G Networks?

Diameter protocol is a network communication protocol used primarily for Authentication, Authorization, and Accounting (AAA) purposes in various network systems, including mobile networks like 4G and 5G. Let’s break down its core functions.

  • Authentication
    Diameter verifies the identity of users before granting access to the network. For example, when you turn on your phone, Diameter checks your device’s credentials (e.g., username and password) to ensure you’re a legitimate subscriber.

  • Authorization
    Once the user is authenticated, Diameter determines the user’s access rights, such as the services they can use and the data limits they have. This is like a virtual bouncer, checking if you’re on the list before letting you into the club (network).

  • Accounting
    Diameter keeps track of user activities and resource usage, such as call duration, data consumption, and more. This information is used for billing, ensuring users are charged accurately for the services they’ve used.

  • Scalability
    Compared to its predecessor, the RADIUS protocol, Diameter is more scalable and can handle a larger number of simultaneous connections. This is essential as networks grow and more devices connect to the internet (e.g., IoT devices, smartphones).

  • Flexibility
    Diameter is designed to be flexible and extensible, meaning it can be easily adapted to support new network services and features. This allows for continuous improvement and innovation in the network systems it supports.

  • Reliability
    Diameter uses a reliable transport protocol (like TCP or SCTP) to ensure messages are delivered accurately and without loss. This is like a trusted courier ensuring your package arrives at its destination without any issues.

  • Some key Diameter protocol messages in 5G.

    • CER/CEA _ Establishing connections and sharing supported features between Diameter nodes.
    • DWR/DWA _ Maintaining connections and checking the availability of Diameter nodes.
    • AIR/AIA _ Authenticating users by verifying their credentials.
    • ULR/ULA _ Updating user location in the network for seamless communication.
    • MAR/MAA _ Managing network access and subscription profiles for users.
    • RAR/RAA _ Applying changes to user profiles and services during an active session.
    • STR/STA _ Terminating user sessions and releasing network resources.

In summary, Diameter protocol is a robust communication protocol that manages authentication, authorization, and accounting in network systems, ensuring secure and efficient access to network services. Its scalability, flexibility, and reliability make it a cornerstone of modern network communication.