2.11 Diameter Mediation

The Diameter Protocol has been designed with extensibility in mind. Standards bodies have defined quite a few applications on top of the base Diameter protocol for use in 3G, LTE and IMS networks. Over time, the standards bodies will continue to extend these applications by adding, altering or deleting AVPs or modifying the header to meet new market needs.

In an effort to differentiate themselves, Vendors often include additional functionality into the protocol by adding proprietary AVPs or overloading existing AVPs. Such additions do not pose an interoperability issue where all the equipment is provided by a single vendor, but that is rarely the case. As most operators rely on equipment from multiple vendors, interoperability issues are almost guaranteed. To make matters worse, vendors continue to extend their proprietary versions of the protocol making them incompatible with other elements that communicate using the previous version of the proprietary protocol.

Even in the absence of vendor-specific extensions, it is possible that two vendors interpret the standard in slightly different ways which could then lead to interoperability issues. The operator can mitigate this by forcing the two vendors to perform interoperability testing prior to deployment. However, in certain scenarios, such as the S9interface (HPCRF-VPCRF), where two operator networks have to exchange Diameter traffic between each other,performing interoperability exercises with all other operator networks is not practical.

Operators may choose to deploy components of a solution in a phased manner. For example, an operator can start with just the charging and billing systems and roll in the policy control parts of the solution at a later time. As new components are added to the solution, operators will have to ensure that these new components work seamlessly with the existing setup. In such situations, operators often see a need for performing activities such as Digit Manipulation or mapping of Result-Codes.

Therefore, as Diameter networks get more complex, inter-operability issues in a multi-vendor environment or interoperator Diameter traffic exchange could pose challenges. Also as new components are added to the solution,operators will have to ensure that these new components work seamlessly with the existing setup.

The Diameter Mediation feature offers an intuitive GUI that can be used by the operator to build mediation rules to resolve inter-operability issues. This logic can be seamlessly applied to all messages transiting the DSR. As an example, the mediation feature can be utilized by the customer for topology hiding. Operators often desire to hide the topology details of their network for protection purposes and for seamless interworking functionality. The customer is able to use the provided mediation framework to create the necessary rules that would implement topology hiding in their network. In addition mediation enables the DSR to route based on session-id. This is done by using the hashing mechanism to identify messages with matching session-ids that are then all configured to go to the same host.