What is the Diameter Protocol?

The Diameter Protocol provides authentication, authorization, and accounting (AAA) messaging services for network access and data mobility applications in 3G, IP Multimedia Systems (IMS), and LTE/4G networks.

What is the Diameter Protocol?

AAA services provided by the Diameter Protocol form the basis for service administration within the telecommunications industry, such as deciding which services a user can access, at what quality of service (QoS), and at what cost. 

The Diameter Protocol focuses on the application layer. AAA nodes receive positive or negative acknowledgment for each message exchanged between nodes and TCP and SCTP ensure reliability. 

A variety of LTE and IMS network functions make use of the Diameter Protocol, including the Policy and Charging Rules Function (PCRF), Home Subscriber Server (HSS), and Online Charging System (OCS) elements. 

Why is the Diameter Protocol Important?

Since the introduction of IP-based technology in a telecommunications network, Diameter Protocol has been chosen as the AAA protocol for all fixed and mobile networks. Diameter has the competitive edge over legacy AAA solutions (e. g. RADIUS) and is a foundation of the core Evolved Pack System (EPS) network that supports Long Term Evolution (LTE) technology.

The Diameter Protocol has been embraced by many standards bodies, such as 3GPP and ETSI NFV, as the foundation for all AAA functionalities in next-generation networks. Only Diameter Protocol supports upgrades in 4G such as real-time functionality for transactions. Other advantages include:

  • Unlimited scalability to enable growth
  • Fault tolerance to guarantee message delivery
  • Agent support to clearly define proxy, redirect, relay, or translation agents
  • Secure transmission of Diameter message packets
  • Reliable transmission over TCP or SCTP
How Does the Diameter Protocol Work?

Every host who implements the Diameter Protocol can act as a client or a server depending on the network architecture. The Diameter node that receives the user connection request will act as the Diameter client. After collecting user credentials (username and password), the client node will send an access request message to another Diameter node. This Diameter server node authenticates the user based on the information provided. If the information is accepted, the user will receive an access response by way of the corresponding Diameter client node. If rejected, the user will receive an access denied message.

Diameter Protocol also helps advance Domain Name System (DNS) security by tracking which services and resources are used. In cloud environments AAA services play a significant role in supporting globalized communities of subscribers seamlessly.

How F5 Supports Diameter Security and Traffic Management

As Diameter signaling messaging grows exponentially, service providers need a multi-functional Diameter platform. F5 has designed a dynamic architecture in signaling and security around Diameter, DNS, GTP, and SIP to help service providers offer quality customer experiences while rapidly rolling out new services successfully at scale.

F5 BIG-IP Diameter Traffic Management enables service providers to manage network complexity with context-aware routing, engage in secure roaming, and successfully integrate all Diameter and legacy elements.

During the transition from 4G LTE to 5G, balancing the migration to 5G, alongside subscribers’ expectations for quality-of-experience on 4G/LTE networks, requires insight and long-range planning. See our vision of the 5G evolution over the next few years.