Mediation Overview

References:

Diameter Mediation User 's Guide
Help > Diameter > Mediation
Help > Diameter > Reports

Diameter message mediation helps to solve interoperability issues by using rules to manipulate header parts and Attribute-Value Pairs (AVPs) in an incoming routable message and peer to peer messages, when data in the message matches some specified conditions at a specified point of message processing. Tasks of the “if condition matches, then do some action” type can be solved in the most efficient way.

The Diameter Mediation feature can make the routable decisions of send reply, drop the message or set the destination-realm.

This feature extends the CAPM (Computer-Aided Policy Making) framework to allow for easy creation of Mediation rules for use in 3G, LTE and IMS networks. Mediation Rule Templates are created to define the Conditions that must be matched in a message and the Actions that are applied to modify on the routing decisions.

A Condition defines a part of the message that is used in the comparison, an operator for the type of comparison, and a type of data that must match the data in the message part. Two or more Conditions in the same Rule Template are collectively referred to as a condition Set; the Condition Set are ANDed, ORed or Complex Expression in the comparison process.
An Action can modify the message header Version, Command-Code, or Application-ID Diameter components. Two or more Actions in a Rule Template are collectively referred to as an Action Set.

After a Rule Template definition is complete, a Rule Set can be generated from the Rule Template. The data needed for the Conditions and the Actions is provisioned in the generated Rule Set. A Mediation rule is an instance of the data needed for the execution of Mediation logic. The actual data needed for the Conditions and the Actions is provisioned in one or more rules in the generated Rule Set. All of the rules associated with one Mediation Rule Template are collectively referred to as the Rule Set for the Rule Template.

Rule Sets can be associated with pre-defined Request or Answer Trigger Points in the DSR message processing logic.

The available Diameter Mediation Triggers are the:

Diameter Routing Function, which supports RTP1, RTP10, ATP1, ATP10 and RTP11 triggers.
Diameter Connection Function, which supports CER, CEA, DWR, DWA, DPR and DPA triggers.
Application Function, which supports RTP4, RTP6, ATP4, and ATP6 triggers.

A user, who is designated as the Administrator can use the Rule Sets entries, Enumerations, Triggers, State & Properties and Internal Variables GUI screens, and other GUI screens to perform the following tasks, but cannot create, modify, copy, or export Rule Templates:

Add a rule to a Rule Set, and provision the actual data that is used by the rule in the message matching process.
Import/Export Rules that are provisioned in the rule templates in the "Test" or "Active" State.
Edit and delete rules in Rule Sets.
Delete Rule Sets.
Change the state of a Rule Template.
The Rule Template state can be changed to Test for testing its Rule Sets or to Active for enabling its Rule Sets for use with live traffic.

When Administrator privileges are deactivated, the state cannot be changed back to Development.
Set the Action Error Handling property of a Rule Set.
Enable the Status of Rule Counters to display the Rule Counters.
Test a Rule Set
A Diagnostics Tool is available to test Mediation rules before they are subjected to live traffic in the network. The DSR Diagnostics Tool logs the rules applied, Actions taken, and other diagnostics information when a test message is injected into the system. The tool generates traffic and sends Diameter Messages on a test connection. As a test message traverses the system, the DSR application logic generates diagnostics messages at Trigger points. The Diameter > Reports > Diagnostics Tool GUI is used to view the diagnostics log reports. See Reports in the DSR Diameter User’s Guide.
Associate Rule Sets with Triggers, and remove Rule Set associations with Triggers.
Import previously exported Rule Templates.
The state of an imported Rule Template is set to Test by default.
View, create, edit and delete the Internal Variables that can be used in the rules.
View, create, edit and delete the Enumeration types that can be used in the rules.
View, create, edit and delete the Vendors-specific AVPs that can be used in Rule Templates (see Vendors in the Diameter User's Guide)